15623	----	Proofreading Team. JUKES-EDWARDS A STUDY IN EDUCATION AND HEREDITY * * * * * BY A.E. WINSHIP, LITT.D. * * * * * HARRISBURG, PA.: R.L. Myers & Co. 1900. To HIM Who, more than any other, has taught us how to afford opportunity for neglected, unfortunate and wayward boys and girls to transform themselves into industrious, virtuous and upright citizens through the most remarkable institution in the land, WILLIAM R. GEORGE, FOUNDER OF THE GEORGE JUNIOR REPUBLIC, THIS STUDY IS DEDICATED. R.L. MYERS & CO., PUBLISHERS OF Standard Helps for Teachers, Standard School Books. SEND FOR CATALOGUE. HARRISBURG, PENNA. PREFACE. Of all the problems which America faces on the land and on the seas, no one is so important as that of making regenerates out of degenerates. The massing of people in large cities, the incoming of vast multitudes from the impoverished masses of several European and Asiatic countries, the tendency to interpret liberty as license, the contagious nature of moral, as well as of physical, diseases combine to make it of the utmost importance that American enterprise and moral force find ways and means for accomplishing this transformation. The grand results of the movement in New York city inspired by Jacob Riis; the fascinating benevolence of the Roycroft Shop in East Aurora, N.Y.; the marvelous transfiguration of character--I speak it reverently--at the George Junior Republic, Freeville, N.Y., added to the College Settlement and kindred efforts merely indicate what may be accomplished when philanthropy supplements saying by doing, and when Christianity stands for the beauty of wholeness and is satisfied with nothing less than the physical, mental and moral conversions of all classes among the masses at home as well as abroad, in the East as well as in the West. A problem is primarily something thrown at us as a challenge for us to see through it. To solve a problem is to loosen it so that it may be looked into or seen through. Whatever contributes to the loosening of a problem by throwing light upon the conditions is of value in aiding in its solution, hence the publication of this study of the family of Jonathan Edwards as a contrast to the Jukes. A.E.W. Somerville, Mass., _June 1, 1900_. TABLE OF CONTENTS. Page. THE JUKES, 7 A STUDY OF JONATHAN EDWARDS, 15 THE INHERITANCE AND TRAINING OF MR. EDWARDS, 20 THE CHILDREN'S START IN LIFE, 29 MRS. EDWARDS AND HOME TRAINING, 37 CAPACITY, CHARACTER AND TRAINING, 41 AARON BURR, 44 CONTRASTS, 53 TIMOTHY EDWARDS, 61 COLONEL WILLIAM EDWARDS, 67 THE MARY EDWARDS DWIGHT FAMILY, 74 CHAPTER I THE JUKES Education is something more than going to school for a few weeks each year, is more than knowing how to read and write. It has to do with character, with industry, and with patriotism. Education tends to do away with vulgarity, pauperism, and crime, tends to prevent disease and disgrace, and helps to manliness, success and loyalty. Ignorance leads to all those things that education tries to do away with, and it tends to do away with all the things that education tries to cultivate. It is easy to say these things, and every one knows they are true, but few realize how much such statements mean. It is not easy to take a view of such matters over a long range of time and experience. A boy that leaves school and shifts for himself by blacking boots, selling papers, and "swiping" fruit often appears much smarter than a boy of the same age who is going to school all the time and does not see so much of the world. A boy of twelve who has lived by his wits is often keener than a boy of the same age who has been well brought up at home and at school, but such a boy knows about as much and is about as much of a man at twelve as he will ever be, while the boy that gets an education becomes more and more of a man as long as he lives. But this might be said a thousand times to every truant, and it would have very little effect, because he thinks that he will be an exception. He never sees beyond his own boyish smartness. Few men and women realize how true it is that these smart rascally fellows, who persist in remaining in ignorance, are to be the vicious, pauper, criminal class who are to fill the dens of vice, the poorhouses, and the prisons; who are to be burglars, highwaymen, and murderers. In place of opinions, it is well sometimes to present facts so clear and definite that they cannot be forgotten. R.A. Dugdale, of New York State, began the study of "The Jukes" family in 1874, and in 1877 in the twentieth annual report of the New York Prison Commission he made a statement of the results.[Footnote: G.P. Putnam's Sons, New York, reprinted this study in "The Jukes."] This brief summary of "the Jukes" is based upon the facts which Mr. Dugdale has published. "The Jukes" is a name given to a large family of degenerates. It is not the real name of any family, but a general term applied to forty-two different names borne by those in whose veins flows the blood of one man. The word "jukes" means "to roost." It refers to the habit of fowls to have no home, no nest, no coop, preferring to fly into the trees and roost away from the places where they belong. The word has also come to mean people who are too indolent and lazy to stand up or sit up, but sprawl out anywhere. "The Jukes" are a family that did not make good homes, did not provide themselves with comforts, did not work steadily. They are like hens that fly into the trees to roost. The father of "The Jukes" Mr. Dugdale styled "Max." He was born about 1720 of Dutch stock. Had he remained with his home folk in the town and been educated, and thrifty like the rest of the boys, he might have given the world a very different kind of family from "The Jukes." Max was a jolly good fellow and not very bad. He was popular and he could tell a good story that made everybody laugh. Of course he was vulgar, such jolly good fellows are usually vulgar. He would not go to school, because he did not like it. He would not stay in evenings, for he did not like that. He did not enjoy being talked to, but always wanted to talk himself, and to talk to boys who would laugh at his yarns. He would not work for he did not like it. He wanted to go fishing, hunting, and trapping; so he left home early and took to the woods. Max liked nature. He thought he was lots better than town people because he knew more about nature. He found a lovely spot on the border of a beautiful lake in New York State, where the rocks are grand, the waters lovely, the forest glorious. There was never a more charming place in which to be good and to love God than this place where Max built his shanty about 1750. But he did not go there to worship or to be good. He went simply to get away from good people, to get where he would not have to work, and where he would not be preached to, and this beautiful spot became a notorious cradle of crime. Nature is lovely, but it makes all the difference in the world how we know nature and why we love it. In 1874 Richard L. Dugdale was employed by the New York Prison Commission to visit the prisons of the state. In this visit he was surprised to find criminals in six different prisons whose relatives were mostly criminals or paupers, and the more surprised to discover that these six criminals, under four different names, were all descended from the same family. This led Mr. Dugdale to study their relatives, living and dead. He gave himself up to this work with great zeal, studying the court and prison records, reports of town poorhouses, and the testimony of old neighbors and employers. He learned the details of 540 descendants of Max in five generations. He learned the exact facts about 169 who married into the family. It is customary to count as of a family the men who marry into it. He traced in part others, which carried the number up to 1,200 persons of the family of the Jukes. The Jukes rarely married foreign-born men or women, so that it may be styled a distinctively American family. The almost universal traits of the family were idleness, ignorance, and vulgarity. They would not work, they could not be made to study, and they loved vulgarity. These characteristics led to disease and disgrace, to pauperism and crime. They were a disgustingly diseased family as a whole. There were many imbeciles and many insane. Those of "the Jukes" who tended to pauperism were rarely criminal, and those who were criminal were rarely paupers. The sick, the weak, and goody-goody ones were almost all paupers; the healthy, strong ones were criminals. It is a well-known fact in sociology that criminals are of three classes: First, those who direct crime, the capitalists in crime, who are rarely arrested, who seldom commit any crime, but inspire men to crime in various ways. These are intelligent and have to be educated to some extent. They profit by crime and take slight risks. Second, those who commit heroic crimes and find some satisfaction in the skill and daring required. Safe-breaking, train robbery, and some types of burglary require men of ability and pluck, and those who do these things have a species of pride in it. Third, those who commit weak and imbecile crimes, which mark the doer as a sneak and a coward. These men rob hen roosts, waylay helpless women and old men, steal clothing in hallways, and burn buildings. They are always cowardly about everything they do, and never have the pluck to steal chickens even until they are half drunk. They often commit murder, but only when they are detected in some sneaking crime and shoot because they are too cowardly to face their discoverer. Now the Jukes were almost never of the first or second class. They could not be criminals that required capital, brains, education or nerve. Even the kind of pauperism and crime in which they indulged was particularly disgraceful. This is inevitably true of all classes of people who combine idleness, ignorance, and vulgarity. They are not even respectable among criminals and paupers. There is an honorable pauperism. It is no disgrace to be poor or to be in a poorhouse if there is a good reason for it. One may be manly in poverty. But the Jukes were never manly or honorable paupers, they were weaklings among paupers. They were a great expense to the state, costing in crime and pauperism more than $1,250,000. Taken as a whole, they not only did not contribute to the world's prosperity, but they cost more than $1,000 a piece, including all men, women, and children, for pauperism and crime. Those who worked did the lowest kind of service and received the smallest wages. Only twenty of the 1,200 learned a trade, and ten of those learned it in the state prison. Even they were not regularly employed. Men who work regularly even at unskilled labor are generally honest men and provide for the family. A habit of irregular work is a species of mental or moral weakness, or both. A man or woman who will not stick to a job is morally certain to be a pauper or a criminal. One great benefit of going to school, especially of attending regularly for eight or ten months each year for nine years or more, is that it establishes a habit of regularity and persistency in effort. The boy who leaves school to go to work does not necessarily learn to work steadily, but often quite the reverse. Few who graduate from a grammar school, or who take the equivalent course in a rural school, fail to be regular in their habits of effort. This accounts in part for the fact that few unskilled workmen ever graduated from a grammar school. Scarcely any of the Jukes were ever at school any considerable time. Probably no one of them ever had so much as a completed rural school education. It is very difficult to find anyone who is honest and industrious, pure and prosperous, who has not had a fair education, if he ever had the opportunity, as all children in the United States now have. It is an interesting fact developed from a study of the Jukes that it is much easier to reform a criminal than a pauper. Here are a few facts by way of conclusion. On the basis of the facts gathered by Mr. Dugdale, 310 of the 1,200 were professional paupers, or more than one in four. These were in poorhouses or its equivalent for 2,300 years. Three hundred of the 1,200, or one in four, died in infancy from lack of good care and good conditions. There were fifty women who lived lives of notorious debauchery. Four hundred men and women were physically wrecked early by their own wickedness. There were seven murderers. Sixty were habitual thieves who spent on the average twelve years each in lawless depredations. There were 130 criminals who were convicted more or less often of crime. What a picture this presents! Some slight improvement was apparent when Mr. Dugdale closed his studies. This resulted from evening schools, from manual training schools, from improved conditions of labor, from the later methods of treating prisoners. CHAPTER II A STUDY OF JONATHAN EDWARDS The story of the Jukes as published by Mr. Dugdale has been the text of a multitude of sermons, the theme of numberless addresses, the inspiration of no end of editorials and essays. For twenty years there was a call for a companion picture. Every preacher, orator, and editor who presented the story of the Jukes, with its abhorrent features, wanted the facts for a cheery, comforting, convincing contrast. This was not to be had for the asking. Several attempts had been made to find the key to such a study without discovering a person of the required prominence, born sufficiently long ago, with the necessary vigor of intellect and strength of character who established the habit of having large families. In 1897 a professional scholarly organization--to which the author has the honor to belong--assigned to him, without his knowledge or consent, the duty of preparing an essay upon Jonathan Edwards for the May meeting of 1898. The study then begun led to a search for the facts regarding his family, and when it came to light that one of Jonathan Edwards' descendants presided over the New York Prison Commission when it employed Mr. Dugdale to make a study of the Jukes, the appropriateness of the contrast was more than ever apparent. In this study the sources of information are the various genealogies of families in which the descendants of Mr. Edwards play a part, various town histories and church and college publications, but chiefly the biographical dictionaries and encyclopaedias in which the records of the men of the family are chronicled. It would be impossible to follow out the positions occupied by the various members but for the pride they all feel in recording the fact that they are descendants of Jonathan Edwards. A good illustration of this may be had in the current announcements of the marvelously popular novel, "Richard Carvel," in which it is always emphasized that Mr. Winston Churchill, the author, is a descendant of Jonathan Edwards. Only two Americans established a considerable and permanent reputation in the world of European thought prior to the present century,--Benjamin Franklin and Jonathan Edwards. In 1736, Dr. Isaac Watts published in England Mr. Edwards' account of the beginning of the great awakening in the Connecticut valley. Here more than a century and a half ago, when the colonies were small, their future unsuspected and the ability of their leaders unrecognized, Jonathan Edwards "erected the standard of Orthodoxy for enlightened Protestant Europe." Who can estimate the eloquence of that simple fact? Almost everything of his which was published in the colonies was speedily republished in England. Of what other American philosopher and theologian has this been true? Here are a few of the tributes to Mr. Edwards: _Daniel Webster_: "The Freedom of the Will" by Mr. Edwards is the greatest achievement of the human intellect. _Dr. Chalmers_: The greatest of theologians. _Robert Hall_: He was the greatest of the sons of men. _Dugald Stewart_: Edwards on the Will never was answered and never will be answered. _Encyclopaedia_: One of the greatest metaphysicians of his age. _Edinburgh Review_: One of the acutest and most powerful of reasoners. _London Quarterly Review_: His gigantic specimen of theological argument is as near to perfection as we may expect any human composition to approach. He unites the sharpness of the scimetar and the strength of the battle-axe. _Westminster Review_: From the days of Plato there has been no life of more simple and imposing grandeur than that of Jonathan Edwards. _President McCosh, of Princeton_: The greatest thinker that America has produced. _Lyman Beecher_: A prince among preachers. In our day there is no man who comes within a thousand miles of him. _Griswold's Prose Writers_: The first man of the world during the second quarter of the eighteenth century. _Hollister's History of Connecticut_: The most gifted man of the eighteenth century, perhaps the most profound thinker in the world. _Moses Coit Tyler_: The most original and acute thinker yet produced in America. This is the man whose intellectual life has thrilled in the mental activity of more than 1,400 men and women of the past century and a half, and which has not lost its virtue or its power in all these years. England and Scotland are not wont to sit at our feet even in this day, and yet they sat at the feet of Jonathan Edwards as in the presence of a master when he was a mere home missionary, living among the Indians, to whom he preached every Lord's day. The birth of fame is always an interesting study. It is easy to play the part of a rocket if one can sizzle, and flash, and rise suddenly in darkness, but to take one's place among luminaries and shine with permanent brilliancy is so rare an experience as to present a fascinating study. Jonathan Edwards was twenty-eight years of age, had been the pastor of a church on the frontier, as Northampton was, for four years without any notable experience, when he was invited to preach the annual sermon before the association of ministers at Boston. Never since that day have Boston and Harvard been more thoroughly the seat of culture and of intellectual power than then. It was a remarkable event for a young man of twenty-eight to be invited to come from the Western limit of civilization and preach the annual sermon before the philosophical, theological, and scholastic masters of the East. This sermon was so powerful that the association published it. This was his first appearance in print. So profoundly moved by this effort were the churches of New England that the clergymen generally gave public thanks to the Head of the Church for raising up so great a teacher and preacher. Thus was born the fame of Jonathan Edwards. It is nearly 170 years since then. Science and invention, enterprise and ambition have done great things for America and for Americans. We have mighty universities, libraries, and laboratories, but we have no man who thinks more clearly, writes more logically, speaks more vigorously than did Jonathan Edwards, and we have never had such a combination of spirit and power in any other American. This mastery is revealing itself in various ways in hundreds of his descendants to-day, and it has never ceased to do it since his blood gave tonic to the thought and character of his children and his children's children. CHAPTER III THE INHERITANCE AND TRAINING OF MR. EDWARDS No man can have the intellectual power, nobility of character, and personal grandeur of Jonathan Edwards and transmit it to his children's children for a century and a half who has not himself had a great inheritance. The whole teaching of the culture of animals and plants leaves no room to question the persistency of character, and this is so grandly exemplified in the descendants of Mr. Edwards that it is interesting to see what inheritances were focused in him. It is not surprising to find that the ancestors of Mr. Edwards were cradled in the intellectual literary activities of the days of Queen Elizabeth. The family is of Welsh origin and can be traced as far as 1282, when Edward, the conquerer, appeared. His great-great-grandfather, Richard Edwards, who went from Wales to London about 1580, was a clergyman in the Elizabethan period. Those were days which provided tonic for the keenest spirits and brightest minds and professional men profited most from the influence of Spencer, Bacon, and Shakespeare. Among the first men to come to the new colonies in New England was William, a son of this clergyman, born about 1620, who came to Hartford, where his son Richard, born 1647, the grandfather of Jonathan, was an eminently prosperous merchant. Richard was an only son. The father of Jonathan, Timothy Edwards, was an only son in a family of seven. Aristocracy was at its height in the household of the merchants of Hartford in the middle of the seventeenth century. Harvard was America's only college, and it was a great event for a young man to go from Hartford to Harvard, but this Timothy Edwards did, and he took all attainable honors, graduating in 1661, taking the degrees of A.B. and A.M. the same day, "an uncommon mark of respect paid extraordinary proficiency in learning." This brilliant graduate of Harvard was soon settled over the church at East Windsor, Conn., where he remained sixty-five years as pastor. Who can estimate the inheritance which comes to a child of such a pastor who had been born in a merchant's home. In the four generations which stood behind Jonathan Edwards were two merchants and two preachers, a grand combination for manly and intellectual power. In this pastor's home Jonathan Edwards was born October 5, 1703. Those were days in which great men came into the world. There were born within fifteen years of Jonathan Edwards a wonderful array of thinkers along religious and philosophic lines, men who have molded the thought and lives of a multitude of persons. Among these intellectual giants born within fifteen years of Mr. Edwards were John Wesley, George Whitefield, Swedenborg, Voltaire, Rousseau, and Hume. In order to appreciate the full significance of Mr. Edwards' legacy to the world, it is well to study some conditions of his life. It would not be easy to find a man whose surroundings and training in childhood were better than those of Jonathan Edwards. The parsonage on the banks of the Connecticut was a delightful home. His parents and his grandparents were ideal American Christian educated persons. He was prepared for college by his father and mother. He was a devout little Christian before he was twelve years of age. When he was but ten years old he, with two other lads about his own age, made a booth of branches in a retired spot in a neighboring wood, where the three went daily for a season of prayer. He began the study of Latin at six and at twelve had a good preparation for college in Latin, Greek, and Hebrew, all of which had come from home study. He not only knew books, but he knew nature and loved her. From early childhood to advanced years this remained true. He entered Yale college at twelve years of age. In a letter which he wrote while a college freshman he speaks of himself as a child. Not many freshmen take that view of themselves, but a lad of twelve, away from home at college could have been little more than a child. He was the fifth in a family of eleven children, so that he had no lack of companionship from both older and younger sisters. The older sisters had contributed much to his preparation for college. They were a never-failing source of inspiration. At fourteen he read in a masterly way "Locke on the Human Understanding." It took a powerful hold on his mind and greatly affected his life. In a letter to his father he asked a special favor that he might have a copy of "The Art of Thinking," not because it was necessary to his college work, but because he thought it would be profitable. While still in his teens he wrote a series of "Resolutions," the like of which it would be difficult to duplicate in the case of any other youth. These things are dwelt upon as indicating the way in which every fibre of his being was prepared for the great moral and intellectual legacy he left his children and his children's children. Here are ten of his seventy resolutions: _Resolved_, to do whatever I think to be my duty, and most for the good and advantage of mankind in general. _Resolved_, so to do, whatever difficulties I meet with, how many soever, and how great soever. _Resolved_, to be continually endeavoring to find out some new contrivance and invention to promote the forementioned things. _Resolved_, never to lose one moment of time, but to improve it in the most profitable way I possibly can. _Resolved_, to live with all my might while I do live. _Resolved_, to be endeavoring to find out fit objects of charity and liberality. _Resolved_, never to do anything out of revenge. _Resolved_, never to suffer the least motions of anger towards irrational beings. _Resolved_, never to speak evil of any one, so that it shall tend to his dishonor, more or less, upon no account except for some real good. _Resolved_, to maintain the strictest temperance in eating and drinking. Yale in the days of Mr. Edwards was not the Yale of the closing year of the nineteenth century. It has now 2,500 students and has had 19,000 graduates. It had a very humble beginning in March, 1702, the year before Mr. Edwards was born. It began with one lone student. The father of Jonathan Edwards had been greatly interested in the starting of the college. In 1701, Rev. Mr. Russell, of Branford, a graduate of Harvard, as was the senior Edwards, invited to his home ten other Connecticut pastors of whom nine were graduates of Harvard. Each brought from his library some of his most valuable books, and laying them upon Mr. Russell's table, said: "I give these books for the founding of a college in this colony." This produced a profound impression upon the clergymen of Connecticut, notably upon the graduates of Harvard. The first year the college was nominally located at Saybrook, but as there was only one student he lived with the president at Killingworth, now Clinton, nine miles away. When Jonathan Edwards, a lad of twelve, entered college, there had been, all told, only about fifty graduates. It was during the time that he was a student that the college took the name of Yale. The first year he was there the college was in three places at the same time because of dissensions among the students, and the very small class graduated in two places because neither faction would go to the other place. In all these agitations Mr. Edwards took no part. He simply devoted himself to his studies and followed the line of least resistance so far as taking sides in a senseless controversy was concerned. After graduation he remained at Yale two years for post-graduate work, mostly in theology, and then accepted an invitation to preach for the leading Presbyterian church in New York City; but after eight months he returned to Yale as a tutor and remained two years. At this time he was very severe in discipline, bending every energy to securing the right conditions for the most and best work. This is what he wrote in his diary when he was twenty-one: "By a sparingness in diet, and eating, as much as may be, what is light and easy of digestion, I shall doubtless be able to think more clearly, and shall gain time: 1. By lengthening out my life. 2. Shall need less time for digestion after meals. 3. Shall be able to study more closely, without injury to my health. 4. Shall need less time for sleep. 5. Shall more seldom be troubled with the headache." Mr. Edwards was twenty-three years of age when he was ordained at Northampton as associate pastor with his grandfather Stoddard, then in his 84th year, and the 54th year of his pastorate. Soon after this Mr. Stoddard died and Mr. Edwards became pastor in full charge and remained for twenty-five years. He was a great student and thinker. He rose at four o'clock and spent thirteen hours a day in his study. It is worth while to follow the personal intellectual habits of the man whose descendants we are to study. When he was ready for the consideration of a great subject he would set apart a week for it and mounting his horse early Monday morning would start off for the hills and forests. When he had thought himself up to a satisfactory intensity he would alight, fasten his horse, go off into the woods and think himself through that particular stage of the argument, then he would pin a bit of paper on some particular place on his coat as a reminder of the conclusion he had reached. He would then ride on some miles further and repeat the experience. Not infrequently he would be gone the entire week on a thinking expedition, returning with the front of his coat covered with the scalps of intellectual victories. Without stopping for any domestic salutations he would go at once to his study and taking off these bits of paper in the same order in which he had put them on would carefully write out his argument. In nothing did Jonathan Edwards stand out so clearly as boy, youth and man as in his sacrifice of every other feature of his life for the attainment of power as a thinker. Mr. Edwards has gone into history as a theologian of the most stalwart character. It is undeniable that he preached the most terrific doctrine ever uttered by an American leader, but this was only the logical result of the intellectual projection of his effort to make sacrifices in order to benefit humanity. As a child he sacrificed everything for health and virtue that he might have influence, and as a man he knew no other plan or purpose in life. His masterpiece is upon the "will" which he developed to the full in himself. The greatest religious awakening that the Western world has ever known was started in his church at Northampton, not over ecclesiastical differences, or theological discussion but over a question of morality among the young people of the town. It had to do with the impropriety of the young ladies entertaining their gentlemen friends on Sunday evenings and especially of their allowing them to remain to such unreasonable hours. And the issue which ultimately drove him from his pastorate, after twenty-five years of service, by an almost unanimous vote was not one of ecclesiasticism or theology, but of morals among the young people. He insisted upon vigorous action in relation to the loose and as he thought immoral reading of the youth of the town. As this involved some prominent families he had to retire from the pastorate. The views of Mr. Edwards on pastoral work reveal the singleness of purpose of the man as a student and thinker. He never made pastoral calls. He had no criticism to make of those pastors who had talent for entertaining people by occasional calls, but as he had no gifts in that direction he regarded it advisable to use his time in cultivating such talents as he had. Whoever wished to talk with him about personal, moral or religious conditions found in him a profitable counsellor. In his preaching, which was equal to anything America has ever known, he made no attempt to win his hearers by tricks of oratory or by emotional appeals, though he had a most fascinating personality. He was six feet in height, slender in form, with a high, broad forehead, eyes piercing and luminous and a serene countenance. In the pulpit he was graceful, easy, natural and earnest, though he had little action. He rested his left elbow on the pulpit and held his manuscript in his left hand while with his right he turned the leaves. In him were combined the intellectual and moral vigor which are calculated to make the progenitor of a great family. CHAPTER IV THE CHILDREN'S START IN LIFE The eleven children of Jonathan Edwards had an unenviable start in life so far as their environment was concerned. The oldest was still in her teens when serious trouble arose in the parish at Northampton. Mr. Edwards was pastor at Northampton for twenty-five years, and a more fruitful pastorate or a more glorious ministerial career for a quarter of a century no man could ask. He made that church on the frontier the largest Protestant church in the world, and it was the most influential as well as the best known. There began the greatest religious awakening of modern times. In his church, resulting from his preaching, began a revival which stirred into activity every church in Massachusetts, every church in the colonies, and most of the Protestant churches of Great Britain and Europe. After this long and eminently successful pastorate, Mr. Edwards preached a sermon about the reading and conversation of young people upon subjects of questionable propriety, which led to such local excitement that upon the recommendation of an ecclesiastical council he was dismissed by a vote of 200 to 20, and the town voted that he be not permitted on any occasion to preach or lecture in the church. Mr. Edwards was wholly unprepared financially for this unusual ecclesiastical and civic action. He had no other means of earning a living, so that, until donations began to come in from far and near, Mrs. Edwards, at the age of forty, the mother of eleven children with the youngest less than a year old, was obliged to take in work for the support of the family. After a little time Mr. Edwards secured a small mission charge in an Indian village where there were twelve white and 150 Indian families. Here he remained eight years in quiet until, a few weeks before his death, he was called to the presidency and pastorate of Princeton, then a young and small college. The last four years of their life at Northampton were indescribably trying to the children. Human nature was the same then as now, and everyone knows how heavily the public dislike of a prominent man bears upon his children. The conventionalities which keep adults within bound in speech and action are unknown to children, and what the parents say behind a clergyman's back, children say to his children's face. This period of childhood social horror ended only by removal to a missionary parsonage among the Stockbridge Indians, where they lived for eight years. Their playmates were Indian children and youth. Half the children of the family talked the Indian language as well and almost as much as they did the English language. In the years of aspiration these children were away from all society life and educational institutions, in the home of a poor missionary family among Indians when Indian wars were a reality. When Mr. Edwards accepted gratefully this mission church his oldest child, a daughter, was twenty-two, his youngest son was less than a year old. All of the boys and three of the girls were under twelve years of age when they went to the Indian village, and all but one were under twenty. When their missionary home was broken up five of them were still under twenty, so that the children's inheritance was not of wealth, of literary or scholastic environment, or of cultured or advantageous society. Everything tends to show how completely Mr. Edwards' sons and daughters were left to develop and improve their inheritance of intellectual, moral, and religious aspiration. In these years Mr. Edwards was writing the works which will make him famous for centuries. One of the daughters married Rev. Aaron Burr, the president of Princeton, then a very small institution. Upon the death of this son-in-law, Mr. Edwards was chosen to succeed him, but while at Princeton, before he had fairly entered upon his duties at the college, he died of smallpox. His widowed daughter, who cared for him, died a few days later leaving two children, and his widow, who came for the grandchildren, soon followed the husband and daughter to the better land. Mr. Edwards died at fifty-six, and his widow a few weeks later. Both died away from home, for the family was still among the Stockbridge Indians. The oldest son was but twenty, and there were five children younger than he. The youngest son was eight and the other only thirteen. To make the picture more clear it must be understood that to these six orphans, under twenty-one, there came at the time of their father's and mother's deaths two little orphans aged four and two respectively, Sarah Burr and her brother Aaron. Here was a large family from which father and mother, older sister and brother-in-law had been taken almost at a single blow, with two extra orphans to care for. And with all this there was no adequate financial inheritance. The inventory of Jonathan Edwards' property is interesting. Among the live stock, which included horses and cows, was a slave upon whom a moderate value was placed. The slave was named Titus, and he was rated under "quick stock" and not "live stock," at a value of $150. The silver was inventoried as a tankard valued at $60, a can and porringer at $47, and various other articles valued at $85. The chief material legacy was his library, which was inventoried as consisting of 301 volumes, 536 pamphlets, forty-eight maps, thirty unpublished manuscripts and 1,074 manuscript sermons prepared for the printer. It was valued at $415. If Jonathan Edwards did not leave a large financial legacy, he did impart to his children an intellectual capacity and vigor, moral character, and devotion to training which have projected themselves through eight generations without losing the strength and force of their great ancestor. Of the three sons and eight daughters of Jonathan Edwards there was not one, nor a husband or wife of one, whose character and ability, whose purpose and achievement were not a credit to this godly man. Of the seventy-five grandchildren, with their husbands and wives, there was but one for whom an apology may be offered, and nearly every one was exceptionally strong in scholarship and moral force. We have paused long enough on the threshold of the descendants of Jonathan Edwards. We have seen the estimate in which he was held by his contemporaries at home and abroad, and by close students of the history of his times. We have seen what he inherited and by what training and in what environment he was developed. We have also seen the terrible strain to which his children were subjected in childhood from lack of school privileges and pleasing social conditions. It remains to be seen what kind of men and women these children became with childhood disadvantages, but with a grand inheritance and the best of home training. Remember the size, ages, and financial condition of the family when the father died--the sons being aged eight, thirteen and twenty--and then consider the fact that the three sons graduated from Princeton, and five of the daughters married college graduates, three of them of Yale and one each of Harvard and Princeton. A man might well be content to die without lands or gold when eight sons and sons-in-laws were to be men of such capacity, character, and training as are found in this family. They were not merely college graduates, but they were eminent men. One held the position of president of Princeton and one of Union College, four were judges, two were members of the Continental Congress, one was a member of the governor's council in Massachusetts, one was a member of the Massachusetts war commission in the Revolutionary war, one was a state senator, one was president of the Connecticut house of representatives, three were officers in the Revolutionary war, one was a member of the famous constitutional convention out of which the United States was born, one was an eminent divine and pastor of the historic North church of New Haven, and one was the first grand master of the Grand Lodge of Masons in Connecticut. This by no means exhausts the useful and honorable official positions occupied by the eight sons and sons-in-law of Jonathan Edwards, and it makes no account of their writings, of noted trials that they conducted, but it gives some hint of the pace which Mr. Edwards' children set for the succeeding generations. It should be said that the daughters were every way worthy of distinguished husbands, and it ought also to be said that the wives of the sons were worthy of these men in intellectual force and moral qualities. Contrast this group of sixteen men and women with the five sons of Max and the women with whom they lived. In this group there was not a strain of industry, virtue, or scholarship. They were licentious, ignorant, profane, lacking ambition to keep them out of poverty and crime. They drifted into whatever it was easiest to do or to be. Midday and midnight, heaven and its opposite, present no sharper contrasts than the children and the children-in-law of Jonathan Edwards and of Max. The two men were born in rural communities, they both lived on the frontier; but the one was born in a Christian home, was the son of a clergyman, of a highly educated man who took the highest honors Harvard could give, was himself highly educated in home, school, and at Yale College, always associated with pure-minded, earnest persons, and devoted his thought and activity to benefiting mankind. Max was the opposite of all this. There is no knowledge of his childhood or of his parentage. He was not bad, as bad men go; he was jolly, could tell a good story, though they were always off color, could trap unwary animals skillfully, was a fairly good shot; but no one was the better for anything that he ever said, thought, or did. Jollity, shiftlessness, and lack of purpose in one man have given to the world a family of 1,200, mostly paupers and criminals; while Mr. Edwards, who never amused any one, who was always chaste, earnest, and noble, has given to the world a family of more than 1,400 of the world's noblemen, who have magnified strength and beauty all over the land, illustrating grandly these beautiful lines of Lowell: "Be noble! and the nobleness that lies In other men, sleeping, but never dead, Will rise in majesty to meet thine own." CHAPTER V MRS. EDWARDS AND HOME TRAINING Much of the capacity and talent, intensity and character of the more than 1,400 of the Edwards family is due to Mrs. Edwards. None of the brothers or sisters of Jonathan Edwards had families with any such marvelous record as his, and to his wife belongs not a little of the credit. At the age of twenty-four Mr. Edwards was married to Sarah Pierrpont, aged seventeen. She had an inheritance even more refined and vigorous than that of Mr. Edwards. She was descended on her father's side from the choicest of the Pierrpont family of England and New England. Her father was one of the most famous of New Haven clergymen, one of the principal founders, and a trustee and lecturer of Yale College. On her mother's side she was a granddaughter of Rev. Thomas Hooker, of Hartford, "the father of the Connecticut churches," and one of the grand men in early American history. Personally, she was so beautiful and so noble-minded that at the age of thirteen she was known far and near for her Christian character and exceptional ability. While she was still but thirteen and Mr. Edwards twenty, he wrote in a purely disinterested way of the remarkable girl: "She is of a wonderful sweetness, calmness, and universal benevolence of mind. She will sometimes go about from place to place singing sweetly; and seems to be always full of joy and pleasure; and no one knows for what." Mr. Edwards was desirious of being married when he went to Northampton as associate pastor with his grandfather, Dr. Stoddard. Miss Pierrpont was only sixteen years of age, and she declined to be married until she was seventeen. He insisted, but she persisted in her refusal. Mrs. Edwards lived in her children. To her husband came honor and glory in his lifetime, but to her came denial, toil and care. At eighteen, this young, beautiful, brilliant wife became a mother, and until she was forty, there was never a period of two years in which a child was not born to them, and no one of the eleven children died until after the last child was born. It was a home of little children. Her husband had no care for the household and she wished him to have none. It was her insistence that he should have thirteen hours of every twenty-four for his study. Whatever may have been the contribution of Mr. Edwards to the inheritance of the family, they owed the charming environment of the home to their mother. This was a delightful home, as many persons have testified who knew it. I saw recently the diary of the famous George Whitefield, where he wrote that he sometimes wondered if it was not the Lord's will that he should marry, that he might thereby be more useful, and that if it was the Lord's will that he should marry, he wished to be reconciled thereto, but he did hope that the Lord would send him as a wife such a woman as Mrs. Edwards, whom he considered the most beautiful and noble wife for a Christian minister that he had ever known. If there be a more charming tribute to woman than this, I have not seen it. In view of the character of her children and their great success in life, it may be interesting to know how she brought up the children, of whom there were so many, and for which the schools did so little. This is the testimony of one who knew of her home life well: "She had an excellent way of governing her children; she knew how to make them regard and obey her cheerfully. She seldom punished them, and in speaking to them used gentle and pleasant words. When she had occasion to reprove or rebuke, she would do it in a few words, without warmth and noise, and with all calmness and gentleness of mind. In her directions and reproofs of matters of importance, she would address herself to the reason of her children, that they might not only know her inclination and will, but at the same time be convinced of the reasonableness of it. She had need to speak but once and she was obeyed; murmuring and answering again were not known among them. In their manners they were uncommonly respectful to their parents. When their parents came into the room, they all rose instinctively from their seats and never resumed them until their parents were seated; and when either parent was speaking, no matter with whom they had been conversing, they were all immediately silent. "Quarreling and contention were in her family wholly unknown. She carefully observed the first appearance of resentment and ill-will in her young children towards any person whatever, and did not connive at it, but was careful to show her displeasure, and suppress it to the utmost; yet not by angry, wrathful words. "Her system of discipline began at a very early age, and it was her rule to resist the first, as well as every subsequent exhibition of temper or disobedience in the child, however young, until its will was brought into submission to the will of the parents." It is needless to say that all this added materially to the good inheritance of the children. CHAPTER VI CAPACITY, CHARACTER AND TRAINING In view of what has been learned regarding Jonathan Edwards, his ancestors and his children, his grandchildren might have found some excuse for presuming upon the capacity and character which they inherited. In their veins was the blood of famous lines of noble men and women; the blood of Edwards, Stoddard, Pierrpont, and Hooker was thrilling in their thought and intensifying their character. They had inherited capacity and character at their best, but they did not presume upon it. If ever inheritance would justify indifference to training, it was in the case of the grandchildren of Jonathan Edwards, but they were far from indifferent to their responsibility. It must be understood that the "family of Jonathan Edwards" includes not only his descendants, but the men who married into the family and whose children became descendants of Mr. Edwards. At first this may not seem the proper interpretation, but there is no other that is legitimate. In the case of the "Jukes" Mr. Dugdale includes in the family both the men and the women who married into the family, but in the case of Mr. Edwards there is no call to include the women who thus came into the family, and it would have magnified the study needlessly. Until quite recently there has been no way to discover the standing of married women in American life except as we know the social, scholastic, and professional position of their husbands. In most families a son-in-law becomes a representative factor of a family. Therefore, whenever the "Edwards family" is spoken of it includes the sons-in-law, but it does not include the daughters-in-law, nor does it go beyond Jonathan Edwards to include his brothers and sisters or their descendants. The "Jukes" had no inherited capacity or training upon which they could safely presume. Their only chance lay in nursing every germ of hope by means of industry and education, through the discipline of the shop, the training of the schools, and the inspiration of the church. Did they appreciate this? Far from it. Instead of developing capacity by training, not one of the 1,200 secured even a moderate education, and only twenty of them ever had a trade, and ten of these learned it in the state prison. On the other hand, although the Edwards family inherited abundant capacity and character, every child has been educated from early childhood. Not all of the college members of the family have been discovered, and yet among the men alone I have found 285 graduates and a surprisingly large number of these have supplemented the college course with post-graduate or professional study. Just as the "Jukes" have intensified their degeneracy by neglect, the Edwards family has magnified capacity and character by industry and education. Among the 285 college graduates of the Edwards family there are thirteen presidents of colleges and other higher institutions of learning, sixty-five professors of colleges, and many principals of important academies and seminaries. Forty-five American and foreign colleges and universities have this family among the alumni. From this family have come presidents for Yale, Princeton, Union, Hamilton, Amherst, the University of California, the University of Tennessee, the famous Litchfield (Conn.) law school, the Columbia law school, and Andover Theological Seminary. Among these are such men as President Timothy Dwight, Yale, 1794-1817; Theodore Dwight Woolsey, Yale, 1846-71; Timothy Dwight, Yale, 1886-97; Jonathan Edwards (Jr.), Union, 1799-1801; Daniel C. Gilman, Johns Hopkins; Merrill E. Gates, Amherst; and Edwards A. Park, Andover. CHAPTER VII AARON BURR Undoubtedly some readers are already impatient at the delay in dealing with Aaron Burr. There was a time when it was the fashion to refer to Colonel Burr as sufficiently infamous to prove that heredity was of no appreciable value. As a matter of fact it is rather refreshing to have one upon whom the imagination can play. It simply intensifies the white light of the rest of the record. Colonel Burr was not a saint after the model presented by his father, the Rev. Dr. Aaron Burr, the godly president of Princeton; by his grandfather, Jonathan Edwards; or by at least 1,394 of the other members of the family of Mr. Edwards. There is no purpose to give him saintly enthronement, but it may not be amiss to suggest that the abuse of him has been overdone. Colonel Aaron Burr died at eighty after thirty years of the worst treatment ever meted out to a man against whom the bitterest enemies and the most brilliant legal talent could bring no charge that would stand in the eyes of the law. I have no purpose to lessen the verdict of prejudice, for the study of the Edwards family is all the more fascinating because of one such meteor of error. It must be confessed, however, that a study of the last thirty years of Colonel Burr's life makes one more exasperated with human nature under a political whip than with Colonel Burr's mistake. At forty-nine Aaron Burr was one of the most brilliant, most admired, and beloved men in the United States. For thirty years his had been a career with few American parallels. He had but one real and intense enemy, and that man had hated him all those years. Alexander Hamilton had never missed an opportunity to vilify Mr. Burr, and his attack had never been resented. Calmly had Aaron Burr pursued his upward and onward course, simply smiling at the vituperation of Hamilton. Could those two men have agreed, they would have been the greatest leaders any nation ever had. Their hatred was as expensive as was that of Blaine and Conklin in after years. Every age must have a political scapegoat, one upon whose head is placed symbolically the sins of the period, and after he is sent into the wilderness of obscurity it becomes a social and political crime to befriend him. There have been several such in our country's history, and there will be others. Aaron Burr suffered more than any other simply because the glory from which he departed was greater. On March 2, 1805, Aaron Burr, vice-president of the United States, and president of the senate, retired from the chair two days before his term expired. He made a farewell address, which produced a greater impression upon that body than any other words ever spoken there. Every senator was weeping, and for a long time no one could leave his seat or propose any business. It was a sight for the nation to look upon and wonder. For fourteen years he had been one of the most conspicuous members of that body. Aaron Burr's ultimate ruin was wrought by his colonization experiment in Louisiana. In popular opinion, there was something traitorous in that unsuccessful venture of his. In 1805 Mr. Burr paid $50,000 for 400,000 acres of land which had been purchased of Spain in 1800, before it passed to France and then to the United States in 1803. Of the motive of Colonel Burr we must always be ignorant; that he was not guilty of any crime in connection therewith we are certain, for the highest tribunal of the land acquitted him. President Jefferson and the entire political force of the administration were bent upon his conviction, but Chief Justice Marshall, as capable, honorable, and incorruptible a jurist as the country has known, would not have it so. Unfortunately, the brilliant arraignment by William Wirt was printed and read for half a century, while the calm rulings of Chief Justice Marshall never went beyond the court room. Why did a man of his capabilities, upon retirement from the vice-presidency, attempt, at fifty years of age to start life anew under such unpromising conditions? Because he was suddenly politically and professionally ruined. Ruined because he had killed Alexander Hamilton in a duel. Why did he do it? It is a long story. To make it intelligent, his life must be reviewed. After a brilliant military career, which began when he was nineteen and left him an heroic colonel, he studied law and practiced in Albany. At the age of twenty-eight he was a leader in the New York legislature, and was chairman of the most important committees, always with the people, against the aristocracy--an unpardonable mistake in those times. At thirty-four he was attorney-general of the state, and his great decisions were accepted by all other states. At thirty-four he established the Manhattan bank of New York city. He was the only man with the ability or courage to find a way to establish a bank for the people, and the solidity of that institution for a hundred years is an all-sufficient vindication of his plan. At thirty-five he was appointed and confirmed as a supreme court judge of New York state, but he declined the honor, and was the same year elected to the United States senate. He was re-elected, serving in all fourteen years. At the second presidential election Senator Burr received one vote in the electoral college, at the third he received thirty, and in the fourth received seventy-three. Jefferson also received seventy-three and the election was thrown into the house. This was in 1800 and Mr. Burr was forty-years of age. The choice lay with New York, which could be carried by no man but Aaron Burr. Alexander Hamilton was the leader of the Federalists. He also was of New York. It was a battle of the giants. These two men measured swords. The presidency of the United States was the prize both parties--the Federalists and the Democrats--were seeking. New York had always been with the Federalists. In this great struggle it went against Hamilton and for Burr. This ended the political career of Hamilton, and would have done so had he lived longer. He was one of America's greatest statesmen, but one of the poorest politicians. No one could get along with him but Washington, and when he died the political end of Hamilton came. Jefferson and Burr each received seventy-three votes for president, and Adams received sixty-five. New York had twelve votes, so that if she had remained with the Federalist candidate Adams, he would have won, seventy-seven to sixty-one. This defeat angered Hamilton beyond endurance. He and Burr had been deadly rivals for thirty years, first for the love of woman, then for military preferment, and later in the political arena. When Burr established the Manhattan bank, Hamilton's brother-in-law, inspired by Hamilton, attacked Burr's motive, with the result of a duel in which neither was harmed. Notwithstanding Hamilton's greatness, he was always in trouble with men and women. He never ceased his abuse of Burr, whose election as senator angered him. Later, when Burr was the choice of congress as minister to Paris, backed especially by Madison and Monroe, Hamilton succeeded in compassing his defeat. Again, when Adams had decided upon some important appointment for Burr, Hamilton succeeded in defeating him. This made Burr's promotion to the vice-presidency and his own downfall the more exasperating to Hamilton. Four years passed. Burr won high honor as president of the senate, and the party nominated him for governor of New York with practical unanimity. This was too much for Hamilton, who had nothing to lose by indulging his enmity to the full. The campaign against Burr was one of the basest on record. It was one of vilification. Being vice-president, he was at a disadvantage when it came to conducting the campaign, and he was defeated. There were many features of this campaign that were peculiarly annoying to Burr, and for the second time in his life he resorted to the duel, and Hamilton was killed. Had Burr died in that hour, history would have a different place for him as well as for Hamilton, but in his death Hamilton was glorified. The most preposterous stories, such as his firing into the air, were invented and believed. The time and the conditions were as bad as they could be for Burr. The North never condoned a duel that ended fatally, and then less than ever. I have no word of apology to offer for the duel. It was weakness, as it always is, and from it came all the ills that befell Aaron Burr. Censure him all you choose, and then look at the conditions of his childhood and wonder that he lived to fifty years of age before the lack of early care brought forth its fruit. Aaron Burr received as good an intellectual and moral legacy as any one of the 1,400 of the Edwards family. His father and mother, grandfather and grandmother would have given him as good an environment and training as any one of them enjoyed, but--his father died before he was two years old, and his mother, grandfather, and grandmother died when he was two years old, and he and his sister, four years old, went to live with his oldest uncle, Timothy Edwards, who was only twenty. This uncle was also bringing up two younger brothers aged eight and thirteen, and three young sisters. While Timothy Edwards made an eminently worthy citizen and reared a family of noble sons and daughters, he was not prepared at nineteen to support so many younger children and give a two-year-old boy the attention that he needed. At twelve years of age Aaron Burr went to college, and after this time he never had even the apology of a home, indeed he never had a home such as his nature demanded. There are three pictures of the child which satisfy me that the right training would have enabled Aaron Burr to go into history as the noblest Roman of them all. At four years of age he was at school, where the treatment was so severe that he ran away from school and home and could not be found for three days. At seven years of age he was up in a cherry tree when a very prim and disagreeable spinster came to call, and he indulged in the childish luxury of throwing cherries at her. She sought "Uncle Timothy," who took the seven-year-old child into the house, gave him a long and severe lecture, offered a long prayer of warning, and then "licked me like a sack." At ten years of age he ran away from the severity of his uncle, and went to New York and shipped as cabin boy. His uncle followed him, and when the little fellow saw him he went to the top of the masthead and refused to come down until his uncle agreed not to punish him. It is easy to see that his uncle aroused in him all the characteristics that should have been calmed, and gave him none of that care which father or mother would have provided him. At twelve he entered Princeton, and graduated with honors at sixteen. College life had its temptations, but he conducted himself with unusual decorum, and upon graduation went to study with an eminent clergyman. Apparently he expected to enter the ministry, but the theology of Dr. Bellamy did not commend itself to him, and even less did the spirit with which the theologian met his queries, so that for the remaining sixty odd years of life he would not talk about theology. Here was a brilliant lad, fresh from college, with the inheritance of Burr and Edwards, who might have been led into a glorious career, but was instead repelled, and went back to his uncle's home, with no profession and no plan for life, with no one to advise him. The battle of Bunker hill aroused Burr to patriotic purpose, and, though but nineteen, he started for Cambridge to enlist. He was stricken with fever, however, and before he was recovered he heard of Arnold's proposed expedition to Quebec, and, though he had better be in bed, he took his musket and walked to Newburyport, 30 miles, in season to ship with the troops. Two men were there ahead of him awaiting his arrival with instructions from his uncle to bring him back to New Jersey. This was too much for young Burr, who did not recognize the right of his uncle to interfere, and he expressed his mind so vigorously as to command the admiration of the soldiers and arouse the fears of the two messengers, who returned without him. This was the last of his uncle's interference. Who that reads of the childhood life of this orphan can wonder that he lacked patience under the severe reverse of political fortune at fifty years of age? That he is the one illustrious exception among the 1,400 need cause no surprise. CHAPTER VIII CONTRASTS It has already been emphasized that the Jukes always mingled blood of their own quality in their descendants, and that the Edwards family has invariably chosen blood of the same general tone and force. Who can think for a moment that the Jukes would have remained on so low a level if the Edwards blood had been mixed with theirs, or that the Edwards would have retained their intellectual supremacy if they had married into the Jukes. The fact is that in 150 years the Jukes never did mingle first-class blood with their own, and the Edwards family has not in 150 years degenerated through marriage. It is pre-eminently true that a mighty intellectual and moral force does plough the channel of its thought and character through many generations. It would be well for any doubter to study the records of thoroughbreds in the animal world. The highest record ever made for milk and butter was by an animal of no family, and she was valuable only for what she could earn. None of her power went to her offspring. She was simply a high-toned freak, but an animal with a clean pedigree back to some great progenitor is valuable independently of individual earning qualities. No more would any one claim that the Jukes would not have been immensely improved by education and environment, or that the Edwards family could have maintained its record without education, training, and environment. The facts show that the Jukes first, last, and all the time neglected these advantages, and that the Edwards family, with all its intermarrying, has never neglected them. The Jukes were notorious law breakers, while the Edwards family has furnished practically no lawbreakers, and a great array of more than 100 lawyers, thirty judges, and the most eminent law professor probably in the country. James Bryce in his comments upon America places one of this family at the head of legal learning on this continent. This was Theodore William Dwight, LL.D., born in New Haven, July 18, 1822; graduated from Hamilton College, 1840; professor there 1842-58. In 1858 he went to Columbia College, organized the law school and was its president for thirty-three years. Some of the most eminent official city attorneys of Philadelphia, New York and Chicago have been found in this family. Ex-Governor Hoadley, of Ohio, a descendant of Jonathan Edwards, is now the head of perhaps the leading law firm of New York City or of the country. When one studies the legal side of the family it seems as though they were instinctively and chiefly lawyers and judges. It simply means that whatever the Edwards family has done it has done ably and nobly. There is no greater test of intellectual majesty than that which the practice of law puts upon a man. When James Bryce pays his grand tribute to Dr. Theodore W. Dwight, president of Columbia College law school, it signifies more intellectually than to have said that he was president of the United States. None of the Jukes had the equivalent of a common school education, while there are few of the Edwards family that have not had more than that. Few were satisfied with less than academy or seminary if they did not go to college. There is not a leading college in the country in which their names are not to be found recorded. They have not only furnished thirteen college presidents and a hundred and more professors, but they have founded many important academies and seminaries in New Haven and Brooklyn, all through the New England states, and in the Middle, Western, and Southern states. They have contributed liberally to college endowments. One gave a quarter of a million as an endowment for Yale. In Yale alone have been more than 120 graduates. Among these are nearly twenty Dwights, nearly as many Edwards, seven Woolseys, eight Porters, five Johnsons, four Ingersolls, and several of most of the following names: Chapin, Winthrop, Shoemaker, Hoadley, Lewis, Mathers, Reeve, Rowland, Carmalt, Devereaux, Weston, Heermance, Whitney, Blake, Collier, Scarborough, Yardley, Gilman, Raymond, Wood, Morgan, Bacon, Ward, Foote, Cornelius, Shepards, Bristed, Wickerham, Doubleday, Van Volkenberg, Robbins, Tyler, Miller, Lyman, Pierpont, and Churchill, the author of "Richard Carvel," is a recent graduate. In Amherst at one time there were of this family President Gates and Professors Mather, Tyler, and Todd. Wherever found they are leaders even in college faculties. Those who know what Gates, Mather, Tyler, and Todd have stood for as president and professors of Amherst will appreciate what Jonathan Edwards' blood has done for this college. Of the Jukes, 440 were more or less viciously diseased. The Edwards family was healthy and long lived. Of the eleven children of Mr. and Mrs. Edwards, four lived to be more than seventy years of age,--seventy-three, seventy-five, seventy-seven and seventy-nine,--and three others were fifty, fifty-six, and sixty-three. Only one died unmarried, none died in childhood. The record for health and longevity continues through every generation. They have also done much to alleviate the sufferings of mankind. There have been sixty physicians, all marked men. Dr. Richard Smith Dewey was an eminent surgeon in the Franco-Prussian war, having charge of the Prussian hospital at Hesse Cassel. Dr. Sereno Edwards Dwight was a physician and surgeon in the British regular army. The physicians of the family have had important connection with insane asylums and hospitals. The legislative action of New York, by which the first insane asylum of the state was built, was largely the result of a physician of this family. The medical superintendent of the Illinois state insane asylum was another of the family. Eminent names in the medical annals of San Francisco, Chicago, Detroit, New York, Boston, and other cities can be traced to Jonathan Edwards. The Jukes neglected all religious privileges, defied and antagonized the church and all that it stands for, while the Edwards family has more than a 100 clergymen, missionaries, and theological professors, many of the most eminent in the country's history. America has had no more brilliant preachers and theologians than some of those that bear the names of Edwards, Dwight, Woolsey, Park, Ingersoll. There have been no more noted missionaries than this family has sent for faithful and successful work in Asia Minor, India, Africa, China, Hawaii, and the South Sea islands. Dwight's famous five volumes on theology are a product of a worthy descendant of Jonathan Edwards. Edwards A. Park, the longtime head of Andover theological seminary, whose vigor of thought, keenness of logic, and pulpit power are unsurpassed, was a descendant of Mr. Edwards. The family has furnished several army chaplains and one eminent chaplain of the United States senate. They have made many churches prominent for the vigor of their pulpit utterances. The famous Second church, Portland, Park street church of Boston, and many in New Haven and other Connecticut cities and towns as well as many churches in the Middle and Western States owe much to the descendants of Mr. Edwards. Not one of the Jukes was ever elected to a public office, while more than eighty of the family of Jonathan Edwards have been especially honored. Legislatures in all sections of the country, governor's councils, state treasuries, and other elective offices have been filled by these men. They have been mayors of New Haven, Cleveland, and Troy; governors of Connecticut, Ohio, and South Carolina; they have been prominent in the Continental congress, in the constitutional conventions of Massachusetts, Connecticut, New York, Ohio, Illinois, and Wisconsin. They have represented the United States at several foreign courts; several have been members of congress; three have been United States senators, and one vice-president of the United States. The Jukes lacked the physical and moral courage, as well as the patriotic purpose, to enlist, but there were seventy-five officers in the army and navy from the family of Mr. Edwards. This family has been prominent as officers, chaplains, or surgeons, in the army and navy in the three great wars. In the Civil war they were at Shiloh, New Orleans, and with the Red river expedition, at Fort Fisher and Newbern, at Big Bethel, Antietam, and Gettysburg, on Lookout mountain with Hooker, with Sheridan in the Shenandoah, and were on the march to the sea with Sherman. One spinster of the family residing in Detroit expressed much regret that she had no husband. The reason she gave, however, was highly complimentary to the sterner sex,--because she had no husband to send to the Civil war. Having none, she paid the regulation bounty and had a man in the service of her country for three years in lieu of the husband she would have sent if she had had one. The Jukes were as far removed as possible from literature. They not only never created any, but they never read anything that could by any stretch of the imagination be styled good reading. In the Edwards family some sixty have attained prominence in authorship or editorial life. "Richard Carvel," is by Mr. Winston Churchill, a descendant of Mr. Edwards, and I have found 135 books of merit written by the family. Eighteen considerable journals and periodicals have been edited and several important ones founded by the Edwards family. The Jukes did not wander far from the haunts of Max. They stagnated like the motionless pool, while the Edwards family is a prominent factor in the mercantile, industrial, and professional life of thirty-three states of the union and in several foreign countries, in ninety-two American and many foreign cities. They have been pre-eminently directors of men. The Pacific steamship line and fifteen American railway systems have had as president, superintendent, or otherwise active in the management one of this family. Many large banks, banking houses, and insurance companies have been directed by them. They have been owners or superintendents of large coal mines in Pennsylvania and West Virginia, of large iron plants and vast oil interests in Pennsylvania, and of silver mines in Nevada. There is scarcely any great American industry that has not had one of this family among its chief promoters. Eli Whitney of cotton-gin fame married a granddaughter of Jonathan Edwards. Prison reform has found its leading advocates in this family. Wilberforce's best American friend was of this fold, and Garibaldi valued one of the family above all other American supporters. Whatever the Jukes stand for, the Edwards family does not. Whatever weakness the Jukes represent finds its antidote in the Edwards family, which has cost the country nothing in pauperism, in crime, in hospital or asylum service. On the contrary, it represents the highest usefulness in invention, manufacture, commerce, founding of asylums and hospitals, establishing and developing missions, projecting and energizing the best philanthropies. CHAPTER IX TIMOTHY EDWARDS To make more clear, if possible, the persistence of intellectual activity and moral virtue, let us study samples of the family. Take for instance the eldest son, Timothy. He was a member of and leader in the famous Massachusetts council of war in the Revolution, a colonel in the militia, and a judge. His descendants have been leaders in Binghamton, Pittsburg, Indianapolis, Bangor, St. Louis, Northampton, New Bedford, San Francisco, New York, New Haven, and many other cities and towns in New England, New York, Pennsylvania, West Virginia, and Ohio. From his descendants a Connecticut town, Chaplin, is named; Newark, Ohio, had a long-time principal, Jonathan E. Chaplin; Andover Theological Seminary had one of its most famous treasurers, Samuel Farrar; the American board of missions had one of its grandest leaders and secretaries, Dr. Elias Cornelius; the American Baptist Missionary Union had one of its eminent secretaries, Dr. Solomon Peck; the American Missionary Association had as its great treasurer, W.E. Whiting; the famous young ladies' seminary of Lenox, Mass., had for thirty years its great principal, Elizabeth Sedgwick; Boston had a prominent lawyer, a graduate of Harvard, William Minot; St. Louis had a leading lawyer, William D. Sedgwick; Antietam had in the list of killed the gallant Major Sedgwick; San Francisco recorded among her distinguished sons the long-time superintendent of the Pacific mail steamship company; the United States navy counted as one of her able officers a surgeon, Dr. George Hopkins; Amherst had as her most famous instructor Professor W.S. Tyler, D.D., LL.D., at the head of the Greek department for half a century; she also has the present brilliant professor of biology, John M. Tyler; Sheridan had as a brilliant colonel in the grand ride of the Shenandoah Colonel M.W. Tyler; invention claims the discoverer of the Turbine wheel, W.W. Tyler; Knox College has claimed as a leader at one time, as has Smith at another, Professor Henry H. Tyler. A detailed study of the family of the eldest son is suggestive. He was the sixth child, born in Northampton, 1738, when the father was thirty-five and the mother twenty-eight. He was but twenty years old when the father and mother died and the care of the family devolved upon him. He had graduated from Princeton the previous year but the responsibility of a large family prevented his entering upon professional life. Two years after the death of his father he married and removed to Elizabethtown, N.J., where he resided for ten years. In 1770 he returned to Stockbridge, Mass. Berkshire county was still on the frontier and was sparsely settled. The store which Mr. Edwards opened in 1770 was the first in the county. The settlers raised wheat on the newly cleared land. This Mr. Edwards bought and sent to New York, bringing back goods in return. In five years he became the most prosperous man in the county, buying and clearing a very large farm on which he employed as many as fifty men in the busy season. The outbreak of the Revolutionary struggle was a most inopportune time for Timothy Edwards; but for that he would have become one of the wealthiest men of his day. All business was suspended and he gave himself to his country's cause with intense devotion. He was at once appointed on a commission with General Schuyler to treat with the Indians; was appointed commissary to look after the supply of the army with provisions. From 1777 to 1780 he was a leader in the Legislature of Massachusetts; was elected to the Continental Congress with John Hancock and John Adams; was a colonel in the Massachusetts militia and a judge of probate. When the war broke out Timothy Edwards was worth $20,000, which he had accumulated in addition to all his other burdens. When the war closed he had nothing, and was $3,000 in debt to New York merchants. To understand what sacrifices he made it must be understood that when the government was in great straits he took $5,000 of money that was as good as gold and let the government have it, taking in return money that was of slight value. He also took fifty tons of flour to Springfield and let the government have it for paper money at par. There were no greater heroes in the Revolutionary war than such men as Timothy Edwards. He was nearly fifty years old when the war closed and he found himself the father of thirteen children and without property or business. Full of courage and enterprise he succeeded in supporting his family in comfort and in regaining a substantial property before his death, which occurred in the midst of the next war, October 27, 1813. It was not an easy thing to educate children in those times. When the Revolutionary war broke out his oldest child was but thirteen, and when it ended he had ten children under twenty-one. There were only three books in the schools at Stockbridge during the war, Dilworth's Spelling Book and Arithmetic and the Book of Psalms. From these the children of Timothy Edwards received their education and that it was a good training subsequent events show. The first born, a daughter, married Benjamin Chaplin, Jr., a graduate of Yale (1778), and for her second husband Capt. Dan Tyler, of Brookline, Ct., a graduate of Harvard. Her second child, Edward, became Register of Probate. Jonathan, the second born, had several children who became prominent in professional and business life. Phoebe married Rev. Asahel Hooker, an eminent graduate of Yale, and for her second husband Rev. Samuel Farrer, a graduate of Harvard, and for many years treasurer and financial agent of Andover Theological Seminary. Her children were noted men and women, graduates of Yale and Dartmouth, clergymen, theological professors, secretary of the American Board of Foreign Missions, and secretary American Baptist Missionary Union, prominent teachers and authors. Rhoda Edwards, another of Timothy's daughters, married Col. Josiah Dwight, of Springfield. Among their fifteen children and their descendants are the founder of a famous young ladies' school at Lenox; an author of "Spanish Conquest of America," and five other considerable works; clerk of supreme court of Massachusetts; a Boston lawyer, graduate of Harvard; an eminent linguist and graduate of Harvard; music teacher in New York City, educated in Germany; St. Louis lawyer, graduate of Harvard college and law school, who studied in Germany; major in Civil war, wounded at Antietam; hospital nurse in Civil war; graduate of Yale; graduate of Cambridge, Eng., and author of "Five Years in an English University;" a graduate of Amherst and Andover, and missionary in Southern India; lawyer in Springfield; eminent teacher at Northampton; leading physician at Northampton; leading physician at New Bedford; supt. Pacific Mail Steamship Company; merchant in New York; insurance manager, New York; author of "Greece and Roman Mythology," and five other important works; supt. Cincinnati, Hamilton & Dayton R.R.; a New York lawyer and graduate of Yale; author of "History of Virginia," and two other works; graduate Dartmouth and Andover; assistant surgeon U.S. Navy; and an officer in Civil war, who fought in thirty battles. Mary Edwards, another daughter of Timothy, married Mason Whiting, District Attorney of New York, and member of New York Legislature. In this family of eight children and their descendants are an authoress; a colonel in Civil war; treasurer American Missionary Association; Rev. W.S. Tyler, D.D., LL.D., a graduate of Amherst and Andover, professor of Greek for fifty years at Amherst; Col. Mason Whiting Tyler, graduate of Amherst, gallant soldier in Civil war; Wm. W. Tyler, graduate of Amherst, manufacturer of famous Turbine Water Wheels; Henry Mather Tyler, graduate of Amherst, professor of Greek at Knox College, pastor at Galesburg, Fitchburg and Worcester, and professor of Greek at Smith College; John Mason Tyler, graduate of Amherst and Union Theological Seminary, studied at Gothenburg and Leipsic, professor of Biology at Amherst and eminent lecturer. To William Edwards, another son of Timothy, oldest son of Jonathan Edwards, an entire chapter will be given. CHAPTER X COLONEL WILLIAM EDWARDS Fascinating is the story of Colonel William Edwards, grandson of Jonathan Edwards, the inventor of the process of tanning by which the leather industry of the world was revolutionized. In no respect did the intellectual and moral inheritance show itself more clearly than in the recuperative force of the family of Colonel Edwards. Attention has already been called to the remarkable way in which the father, Timothy Edwards, re-established himself and educated his large family after his great financial reverses in the period of the Revolutionary war, but the story of Colonel William Edwards is even a more striking illustration of this same power. He was born at Elizabeth, New Jersey, November 11, 1770. He was a mere child during the Revolutionary struggle. Before he was two years old the father removed to Stockbridge, Mass., and the boy grew up in as thoroughly a rural community as could be found. The school privileges were very meagre. No books were printed in the American colonies because of British prohibition. From early childhood he had to work, first as his mother's assistant, tending the children and doing all kinds of household work such as a handy boy can do. As soon as he could sit on a horse he rode for light ploughing and by the time he was ten was driving oxen for heavy ploughing and teaming. William Edwards was only thirteen when he was put out as an apprentice to a tanner in Elizabethtown, N.J. To reach this place the lad had to ride horseback to the Hudson river, about thirty miles, make arrangements to have the horse taken back, and take passage on a West Indies cattle brig to New York. It took him a week to get to New York. He then took the ferry for Elizabethtown. When young Edwards began life as a tanner it took twelve months for the tanning of hides. This was by far the most extensive tannery in America. It had a capacity of 1,500 sides. The only "improvement" then known--1784--was the use of a wooden plug in the lime vats and water pools to let off the contents into the brook. The bark was ground by horse power. There was a curb fifteen feet in diameter, made of three-inch plank, with a rim fifteen inches high. Within this was a stone wheel with many hollows and the wooden wheel with long pegs. Two horses turned these wheels which would grind half a cord of bark in a day of twelve hours. The first year William was at work grinding bark. All the pay received for the year's work was the knowledge gained of the art of grinding bark, very poor board (no clothing, no money), and the privilege of tanning for himself three sheep skins. The fourth half year he received his first money, $2.50 a month, which was paid out of friendliness for the Edwards family. Before he was twenty he set up in business for himself. He had saved $100; his father, still poor, gave him $300; he bought land for his plant for $700 on long credit. After years of great struggle he succeeded in business and developed the process by which instead of employing one hand for every one hundred sides he could tan 40,000 with twenty lads and the cost was reduced from twelve cents a pound to four cents. The quality was improved even more than the cost was reduced. When the war of 1812 broke out he had practically the only important tannery in the United States, but the war scare and attendant evils led to his failure in 1815. He was now 45 years old with a wife and nine children. He went to work in a factory for day wages to keep his family supplied with the necessities of life. By some misunderstanding and a combination of law suits his patents were lost to him. When Colonel Edwards failed in 1815 he owed considerable sums of money and nine years later the courts released him from all obligations, yet between the age of 69 and 75 he paid every cent of this indebtedness amounting to $25,924. The chief interest in Colonel Edwards centers in his children. When his failure came there were nine children, five boys and four girls. The youngest was a few months old and the eldest 19. Seven of them were under 12 years of age. In the first four years of their reverses two others were born, so that his large family had their preparation and start in life in the years of struggle. Nevertheless they took their places among the prosperous members of the Edwards family. The eldest son, William W. Edwards, was one of the eminently successful men of New York. He lived to be 80 years old and his life was fully occupied with good work. He was engaged in the straw goods business in New York; helped to develop the insurance business to large proportions; organized the Dime Savings Bank of Brooklyn, of which he was treasurer and cashier. He was one of the founders of the American Tract Society and of the New York Mercantile Library. He was a member of the State legislature for several terms. Henry Edwards was one of Boston's most eminent merchants and a most useful man. He had the only strictly wholesale silk house in Boston for nearly half a century. He was born in Northampton, 1798. At the age of fifteen he entered the employ of a prominent Boston importing house and began by opening the store, building the fires, and carrying out goods. By the time he was twenty he was the most trusted employee. He was a born trader. His brother in New York knowing that twist buttons were scarce in that city suggested that Henry buy up all there were in Boston before the dealers discovered the fact that they were scarce in New York and send them on to him. They cleared $500 in a few weeks. He was an earnest student. Not having had the advantages of an education he made up for it by studying evenings. They imported their silks from France which led him to study French until he was accomplished in the art of reading and speaking the French language. It is rather remarkable that learning the language in this way, he was able to go to France and out-rank most foreigners in Parisian society. An Edwards did not absolutely need the college and the university in order to be eminently scholarly in any special line. At the age of twenty-five he went into business as the senior partner of the house of Edwards & Stoddard on State street, Boston. It was the only house that made its whole business the importing of silks. At the age of twenty-eight he went to Paris to purchase silks and remained there many years. They did a highly profitable business for nearly fifty years. He received much social attention while in Paris. General Lafayette was specially friendly, and the families visited frequently. He was also highly honored in Boston, where he was a member of the city government--it was an honor in those days--for nine years, one of the trustees of Amherst College for forty years, a member of the Massachusetts legislature and received several important appointments of trust and honor from Governor John A. Andrew and President Lincoln. Boston had few men in his day who were more prosperous or more highly honored. Ogden E. Edwards was for several years at the head of one of the largest leather houses of New York City, eminently prosperous and of great service to the public. Alfred Edwards was founder and senior partner in one of the largest wholesale dry goods houses of New York for fifty years, known as Alfred Edwards & Co. Amory was for many years a member of the firm of Alfred Edwards & Co. He was also United States Consul at Buenos Ayres, and traveled extensively in South America. His nephew, Wm. H. Edwards, wrote of these travels. This nephew, resident at Coalbough, West Virginia, is the author of a famous work on "The Butterflies of North America," and also of an important work on "Shaksper nor Shakespeare." Richard C. Edwards was also a member of the firm of Alfred Edwards & Co. and shared the prosperity of the house with his brother. Rebecca T. Edwards, the eldest daughter, married Benjamin Curtis, a wealthy merchant in business in New York and Paris. She was married in Paris and General Lafayette gave her away in place of her father. Sarah H. Edwards married Rev. John N. Lewis, a successful clergyman. Elizabeth T. Edwards married Henry Rowland, an eminently successful and useful citizen of New York, whose children, like himself, have been honored in many ways. Ann Maria Edwards married Professor Edwards A. Park, D.D., the president of Andover Theological Seminary and the most eminent theologian of the day. Their son, Rev. William Edwards Park, of Gloversville, New York, is a preacher of rare ability. Rev. W.E. Park has two sons, graduates of Yale, young men of great promise. The ten children of Colonel Edwards lived to great age, and each of the sons was eminently successful in business, and all were highly esteemed. Each of the daughters married men eminent in commercial or professional life. None of them were privileged to receive a liberal education because of the great financial reverses that came to the father in their youth, but every one of them was closely identified with educational institutions and all were rated as scholarly men and women. CHAPTER XI THE MARY EDWARDS DWIGHT FAMILY After studying at some length the family of the eldest son of Jonathan Edwards, it is worth while to study the family of one of the daughters. Mary, the fourth child born at Northampton (1734), was married at the age of 16 to Timothy Dwight, born in Vermont (1726) and graduated from Yale in 1744. It is interesting to find a daughter of Jonathan Edwards marrying a Yale graduate, who "had such extreme sensibility to the beauty and sweetness of always doing right, and such a love of peace, and regarded the legal profession as so full of temptations to do wrong, in great degree and small" that he persistently refused to study law, though it had been his father's great desire. The conscientiousness of Major Dwight is well illustrated by this incident. There was a lottery in the interest of Princeton college, authorized by the legislature of New Jersey, and Dwight was sent twenty tickets for sale. He returned them, but the time required for the mail in those days was so long that they did not reach the destination until after the drawing. Major Dwight was notified that one of his twenty tickets had drawn $20,000 and all but one ticket had drawn some prize. Major Dwight paid for the one blank ticket and would not take a cent of the large prize money. This was worthy a son-in-law of Mr. Edwards, the progenitor of a family of mighty men. Major Dwight was a merchant in Northampton, a selectman, judge of probate for sixteen years and was for several years a member of the legislature. At the time of his death, 1778, he was possessed of 3,000 acres of valuable land in Northampton, and he willed his wife $7,050, and each of his thirteen children $1,165. At that time there were but five painted houses in Northampton and but two were carpeted. Of the fourteen children, thirteen grew up, and twelve were married; and their entire family adds greatly to the glory of the family of Jonathan Edwards. The oldest son, Dr. Timothy Dwight, president of Yale, said with much tenderness and force, "All that I am and all that I shall be, I owe to my mother." She was a woman of remarkable will power and intellectual vigor. She was but seventeen when her first child was born and was the mother of fourteen children at forty-two. The first-born, President Timothy Dwight, S.T.D., LL.D., born 1752, was one of the most eminent of Americans. He learned his alphabet at a single sitting while a mere child, and at four knew the catechism by heart. He graduated from Yale at seventeen; taught the Hopkins school in New Haven at seventeen and eighteen; was tutor in Yale from nineteen to twenty-five years of age; wrote the "Conquest of Canada," which was reprinted in London, at nineteen. This work was dedicated to George Washington by permission. At twenty-three, he was in the fore front of the advocates of independence. At twenty-two, General Washington appointed him a chaplain in the army, and personally requested that he accept. His widow received $350 a year pension because of this service. He was a member of the Massachusetts legislature and secured an important grant to Harvard university. He was offered a professorship at Harvard and could have gone to Congress without opposition, but he declined both, and at thirty-two accepted a country pastorate at Greenfield Hill, Connecticut. He remained there twenty-two years. His salary was $750. He also had a gift of $1,500 for accepting the call, a parish lot of six acres, and twenty cords of wood annually. This was said to be the largest ministerial salary in New England. At forty-three he was called from the country parish to the presidency of Yale. His salary as president was $334. Later he had $500, from which he paid $150 for two amanuenses which he required because his sight had failed him. He published fourteen important works. He was largely instrumental in organizing the American Board of Commissioners of Foreign Missions; the American Missionary Society and the American Bible Society. To him is largely due the establishment of theological seminaries in the country. For forty-six years he taught every year either in a public or private school or college, and all but one year of that time he preached every week and almost invariably he prepared a new sermon. When he died, from a cancer at sixty-five, the children insisted that the estate should be for the mother during her lifetime, and when she died there was found to be $26,000 although his salary had always been ridiculously small. The eight children were all boys, and all but one grew to manhood. Timothy was a hardware merchant in New Haven and New York for more than forty years. He endowed the "Dwight Professorship of Didactic Theology in Yale," which was named for him. There were nine children, grandchildren of President Dwight by his eldest son. Of these the eldest, also Timothy, was the leading paper manufacturer in the trust mill headquarters at Chicago, and his six children were enterprising and successful business men in Illinois and Wisconsin. John William Dwight was one of the leading manufacturers of chemicals in Connecticut. Edward Strong Dwight, of Yale, 1838, and of Theological Seminary, Yale, was for many years a trustee of Amherst and a prominent clergyman. J.H. Lyman, M.D., and Edward Huntington Lyman, M.D., were names that added luster to the family of President Dwight. Benjamin Woolsey Dwight, M.D., another son of the President of Yale, was a graduate of Yale and treasurer of Hamilton college for nineteen years. Among his descendants are Richard Smith Dewey, M.D., of Ann Arbor, in charge of Brooklyn City Hospital; charge of military hospital at Hesse Cassel in Franco-Prussian war; assistant superintendent Illinois State Insane hospital at Elgin. Also Elliott Anthony, of Hamilton, 1850; Chicago lawyer; city attorney; a member of the Illinois Constitutional Convention in 1862 and again in 1870; founder of the Law Institute, Chicago, and for several years the president. Also Edward Woolsey Dwight, who was a leading citizen and legislator of Wisconsin. It is impracticable to give the record of many of the distinguished members of such a family, but a brief notice of a few will give some idea of the standard of the family. Benj. Woodbridge Dwight, Ph.D., b. 1816, g. Hamilton 1835, Yale Theological Seminary, professor in Hamilton; founded Central Presbyterian church, Joliet, Ill.; established "Dwight's High School," Brooklyn; editor-in-chief of "The Interior" of Chicago, which he owned and edited; contributor to many magazines; author of several scholarly works; had the first preparatory school which placed German on a level with Greek in importance, and founded a large preparatory boarding school at Clinton, N.Y. He was a man of rare ability, character and success. Prof. Theodore William Dwight, LL.D., b. 1822, g. Hamilton 1840, g. Yale Law S.; professor Hamilton College sixteen years; dean of Columbia College Law S. from 1858 to 1892. James Brice of England placed him at the head of legal learning in the United States and said: "It would be worth an English student's while to cross the Atlantic to attend his course." Another eminent English lawyer, A.V. Dicey, in "Legal Education" wrote of him as "the greatest living American teacher of law." He gave a course of lectures each year at Cornell; was a member of the N.Y. Constitutional Convention in 1867; was a member of the famous committee of seventy in N.Y. City that exposed the Tweed ring; was president of the New York Prison Association and presided when Mr. Dugdale was employed to study the Jukes; associate editor "American Law Register;" was legal editor of "Johnson's Encyclopædia," and made many important contributions to the legal literature of the country. There have been few men of equal eminence in our country's history. President Theodore Dwight Woolsey, D.D., LL.D., b. New York City, October 31, 1801, was the grandson of Mary Edwards Dwight and great grandson of Jonathan Edwards; g. Yale 1820; studied at Princeton Theological Seminary and g. at Yale L.S.; studied in German universities; professor in Yale twenty-two years; president of Yale 1846-1871. Wesleyan conferred degree of LL.D. and Harvard that of LL.D. and S.T.D. all before he was fifty years of age. President of the Evangelical Alliance held in N.Y. City 1873, the leading American on the Committee for the Revision of the Bible. After resigning the presidency he continued to lecture at Yale until his death, 1889. There was no more eminent American in unofficial life from 1840 to 1890 than he. President Hayes once said that he was greatly perplexed at one time as to the line of public policy which he should pursue until it occurred to him that President Woolsey was the one American on whose judgment he could rely, and after consulting him his course was entirely clear and his action wise. He was the author of several valuable and standard works. Yale's first great advance was in the time of President Timothy Dwight, its second was in the administration of President Theodore Dwight Woolsey. When he became president the classes about doubled in size. He introduced new departments at once and endowments came in, such as had never been considered possible. The tuition was raised from $33 to $90; the salaries were greatly increased, graduate courses were introduced; many new buildings were erected and everything went forward at a radically different pace. Yale and American thought owe much to President Woolsey. He wrote many scholarly works. There were thirteen children born to President Woolsey. Of these, one daughter married Rev. Edgar Laing Heermance, a graduate of Yale and a useful and talented man; one of the sons, Theodore Salisbury, was a graduate of Yale, and professor of International Law at Yale. President Timothy Dwight, D.D., LL.D., b. 1828, g. Yale 1849, g. Yale Theological School, studied at Bonn and Berlin in Germany; was professor at Yale and president from 1886 to 1897. He has been an eminent American scholar for half a century. If there were but two or three such men in a family it would make it memorable. Yale gave him the degree of D.D., and both Harvard and Princeton that of LL.D. He was editor of "The New Englander." It is a singular fact that the three great advances which Yale has made have been in the times of the two Dwights and of Woolsey, all descendants of Jonathan Edwards. By the end of his third year the number of students had risen to 1365 and the sixth year to 1784. The gifts to Yale in each of the fifteen years of his administration were fabulous as compared with any past experiences, often above $350,000. President Sereno Edwards Dwight, D.D., g. Yale 1803, practiced law in New Haven; author of important books which were republished in England; became a clergyman at the age of twenty-nine; pastor of Park St. Church, Boston; was chaplain of the U.S. Senate; established successful boarding school in New Haven. Among his students were the two boys who afterwards made the famous Andrews & Stoddard's Latin Grammar. His literary work was extensive and valuable. Standing by himself he would shed lustre upon the names he bore, Edwards and Dwight. He was a tutor in Yale and was third president of Hamilton College. William Theodore Dwight, D.D., b. 1795, g. Yale 1813, tutor at Yale, practiced law in Philadelphia; became a clergyman; pastor in Portland; overseer of Bowdoin College. He was offered three professorships, which he declined. He was one of the religious leaders of America for many years. Hon. Theodore Dwight, b. 1764, lawyer. Editor "The Connecticut Mirror" and "The Hartford Courant;" member of Congress, where he won honors by successfully combating the famous John Randolph; secretary of the famous Hartford Convention; established and edited 1815-17 the "Albany Daily Advertiser;" established and edited the "New York Daily Advertiser" 1817-36; wrote "Life of Thomas Jefferson," and many other works of importance. There were few men in his day who occupied a position of such influence. Theodore Dwight, 2d, b. 1796, g. Yale 1814, eminent scholar, imprisoned in Paris for distributing the New Testament gratis in the streets; spoke seven languages; was the warmest American friend of Garibaldi and was authorized by him to edit his works in this country; was director N.Y. Asylum for the Blind, and of the N.Y. Public School Assn.; was instrumental in having music introduced into the schools of N.Y. City; was prominent in religious and philanthropic as well as educational work. In the Kansas crisis he induced 3,000 settlers to go to Kansas, and indirectly caused nearly 10,000 to go at that critical time. He edited at various times "The N.Y. Daily Advertiser," "The Youths Penny Paper," "The American Magazine," "The Family Visitor," "The N.Y. Presbyterian," "The Christian Alliance," and wrote several successful text-books and many literary and historical works. He was a leader in the noblest sense of the term. Nathaniel Dwight, M.D., b. 1770, surgeon in United States Army, practiced medicine in Providence; prepared the first school geography ever published in the United States; wrote many historical works; original advocate of special institutional care for the insane. After eleven years of ardent championship he saw the first insane retreat established. Henry E. Dwight, M.D., b. 1832, g. Yale 1852, g. Andover Theological Seminary 1857, studied in Germany and France and was an eminent physician in Philadelphia. Rev. S.G. Dwight, g. Union Theological Seminary, and was a missionary in the Sandwich Islands. Here are a few who can only be named: John W. Dwight, b. 1820, g. Yale, eminent divine and trustee of Amherst College for many years. Mrs. Rensselaer Nicol, of New Haven, a leader in prison reform and other philanthropic movements. Thomas B. Dwight, b. 1857, g. Yale, district attorney of Philadelphia and eminent lawyer. Sereno E. Dwight, surgeon in British army. James A. Dwight, b. 1855, in United States navy. Samuel H. Stunner was with Sherman in his march to the sea. Mrs. R.H. Perkins, b. 1819, eminent teacher, principal Duffield school, Detroit. William H. Sumner, officer in U.S. regular army. Thomas Berry, banker in Cleveland. General Robert Montgomery, of Pennsylvania. O.H. Kennedy, officer in U.S. navy. Fenton Rockwell, judge advocate and provost judge in New Orleans; officer in Civil war, and in many important battles. William R. Dwight, New York banker. George S. Dwight, large railroad contractor. William Allerton, leather merchant in Boston. Mrs. Egbert C. Smyth, wife of the dean of Andover Theological Seminary. Rossiter W. Raymond, eminent specialist, author, and lecturer. W.M. Bell, manufacturer, Allegheny. Colonel A.S.M. Morgan, U.S.A. J.E. Jacobs, insurance manager, Chicago. E.S. Churchill, Portland, Me., merchant. W.D. Bell, manufacturer, Philadelphia. George Collier, rich St. Louis banker. E.A. Hitchcock, tea merchant, Hong Kong. M.D. Collier, graduated from Yale; St. Louis lawyer. H.R. Bell, Chicago physician. D.W. Bell, Pittsburg lawyer. A.S. Bell, Pittsburg lawyer. George Hoadley, born in 1781; graduated from Yale; mayor New Haven; eight times mayor of Cleveland. W.W. Hoadley, born in 1814; Cincinnati banker. Dr. T.F. Pomeroy, Detroit. General J.H. Bates, U.S.A.; Ohio state senate. Governor George Hoadley, born in 1826; graduated from Western Reserve College; supreme court judge; president Democratic convention that nominated General Hancock for the presidency. Major W.W. Winthrop of the Civil war; graduated from Tale. Major W.T. Johnson, graduated from Yale; killed at battle of Big Bethel. Theodore Weston, graduated from Yale; civil engineer of Croton water works. J.M. Woolsey, born in 1796; graduated from Yale; capitalist, Cleveland. Sarah C. Woolsey is "Susan Coolidge." Mrs. Daniel C. Grilman, wife of the president of Johns Hopkins University, and formerly president of University of California. Samuel Carmalt, wealthy land owner in Pennsylvania. Dr. W.W. Woolsey, born in 1831; graduated from Yale; physician, Dubuque, Ia. T.B. Woolsey, flour merchant, New York. Samuel W. Johnson, graduated from Princeton and Harvard law school; New York lawyer. Woolsey Johnson, M.D., graduated from Princeton and New York Medical College; physician, New York. Theodore S. Woolsey, graduated from Yale; professor in Yale. Charles F. Johnson, graduated from Yale; professor United States Naval Academy, Annapolis. W.W. Johnson, graduated from Yale; professor Kenyon College. J.H. Rathburn, lawyer, Utica. J.O. Pease, merchant, Philadelphia. A.S. Dwight, lieutenant U.S.A.; killed at Petersburg. George P.B. Dwight, New York custom house. Henry E. Dwight, born in 1813; Southern planter. Theodore Woolsey Porter, b. 1799, g. Yale 1819, eminent teacher; principal of Washington Institute, New York City. Timothy Dwight Porter, M.D., b. 1797, g. Yale 1816, was in the New York senate and a successful practitioner. Imperfectly as these names represent the achievements of the descendants of Mary Edwards Dwight they do hint strongly at the vigor, character and scholarship for which the family of Jonathan Edwards stands in American life. There is another large family of Dwights, direct descendants of Jonathan Edwards, through his granddaughter, Rhoda Edwards, but these are not, of course, included in this list of Mary's descendants. Many of these are eminent men, and reference is here made to their omission, lest some one should think the facts regarding them were not gathered. A MODERN INSTANCE It was known that John Eliot Woodbridge removed to Youngstown, O., about one hundred years ago, but no trace of him was found until these chapters were in type when it appeared that this undiscovered remainder was a most important branch of the family. Congressman R.W. Taylor, of Ohio, chairman of the committee to pass upon the case of Mr. Roberts of Utah, is a descendant of Jonathan Edwards through John Eliot Woodbridge. His masterly treatment of the case is recognized throughout the country. Here is what the "Detroit Free Press" said of him at the time of the investigation: "In appearance he is not of the robust order of statesmen. With fair face, shoulders that he has always permitted to droop, indispensable eyeglasses, and hands that nine women out of ten would envy, modest demeanor, and kindly instincts, he is among the last of men that a casual observer would pick as fitting leaders where nerve, aggressiveness, and fearless determination must be joined with an ability to give and take in legal controversy. "But this passing judgment would be at widest variance with the truth. College mates of Taylor will recall the deceptiveness of this outward appearance. It concealed muscles of steel and a will that had only to be right in order to be invincible. He was the peer of any amateur baseball catcher in his day, and held the same enviable place as a student of the classics. He was the strong man for the D.K.E. initiations, and took the same rank in all scholastic competitions." Dr. Timothy Woodbridge, of Youngstown, was a graduate of the medical college of Philadelphia, and was one of the eminent physicians of Eastern Ohio. His grandson, Benjamin Warner Wells, of Chicago, was a graduate of Annapolis naval academy. He was Admiral Schley's flag secretary in the engagement at Santiago. Dr. John Eliot Woodbridge, Cleveland, is an eminent specialist in typhoid fever cases. Robert Walker Taylor was comptroller of the United States treasury for fifteen years. 
52312	----	THE METHODS AND SCOPE OF GENETICS CAMBRIDGE UNIVERSITY PRESS London: FETTER LANE, E.C. C. F. CLAY, MANAGER [Illustration: Logo] Edinburgh: 100, PRINCES STREET Berlin: A. ASHER AND CO. Leipzig: F. A. BROCKHAUS New York: G. P. PUTNAM'S SONS Bombay and Calcutta: MACMILLAN AND CO., LTD. _All rights reserved_ THE METHODS AND SCOPE OF GENETICS _AN INAUGURAL LECTURE DELIVERED 23 OCTOBER 1908_ by W. BATESON, M.A., F.R.S. PROFESSOR OF BIOLOGY IN THE UNIVERSITY OF CAMBRIDGE Cambridge: at the University Press 1912 _First Edition 1908_ _Reprinted 1912_ PREFATORY NOTE The Professorship of Biology was founded in 1908 for a period of five years partly by the generosity of an anonymous benefactor, and partly by the University of Cambridge. The object of the endowment was the promotion of inquiries into the physiology of Heredity and Variation, a study now spoken of as Genetics. It is now recognized that the progress of such inquiries will chiefly be accomplished by the application of experimental methods, especially those which Mendel's discovery has suggested. The purpose of this inaugural lecture is to describe the outlook over this field of research in a manner intelligible to students of other parts of knowledge. W. B. _28 October, 1908_ THE METHODS AND SCOPE OF GENETICS The opportunity of addressing fellow-students pursuing lines of inquiry other than his own falls seldom to a scientific man. One of these rare opportunities is offered by the constitution of the Professorship to which I have had the honour to be called. That Professorship, though bearing the comprehensive title "of Biology," is founded with the understanding that the holder shall apply himself to a particular class of physiological problems, the study of which is denoted by the term Genetics. The term is new; and though the problems are among the oldest which have vexed the human mind, the modes by which they may be successfully attacked are also of modern invention. There is therefore a certain fitness in the employment of this occasion for the deliverance of a discourse explaining something of the aims of Genetics and of the methods by which we trust they may be reached. You will be aware that the claims put forward in the name of Genetics are high, but I trust to be able to show you that they are not high without reason. It is the ambition of every one who in youth devotes himself to the search for natural truth, that his work may be found somewhere in the main stream of progress. So long only as he keeps something of the limitless hope with which his voyage of discovery began, will his courage and his spirit last. The moment we most dread is one in which it may appear that, after all, our effort has been spent in exploring some petty tributary, or worse, a backwater of the great current. It is because Genetic research is still pushing forward in the central undifferentiated trunk of biological science that we confess no guilt of presumption in declaring boldly that whatever difficulty may be in store for those who cast in their lot with us, they need fear no disillusionment or misgiving that their labour has been wasted on a paltry quest. In research, as in all business of exploration, the stirring times come when a fresh region is suddenly unlocked by the discovery of a new key. Then conquest is easy and there are prizes for all. We are happy in that during our own time not a few such territories have been revealed to the vision of mankind. I do not dare to suggest that in magnitude or splendour the field of Genetics may be compared with that now being disclosed to the physicist or the astronomer; for the glory of the celestial is one and the glory of the terrestrial is another. But I will say that for once to the man of ordinary power who cannot venture into those heights beyond, Mendel's clue has shown the way into a realm of nature which for surprising novelty and adventure is hardly to be excelled. It is no hyperbolical figure that I use when I speak of Mendelian discovery leading us into a new world, the very existence of which was unsuspected before. The road thither is simple and easy to follow. We start from a common fact, familiar to everyone, that all the ordinary animals and plants began their individual life by the union of two cells, the one male, the other female. Those cells are known as germ-cells or _gametes_, that is to say, "marrying" cells. Now obviously the diversity of form which is characteristic of the animal and plant world must be somehow represented in the gametes, since it is they which bring into each organism all that it contains. I am aware that there is interplay between the organism and the circumstances in which it grows up, and that opportunity given may bring out a potentiality which without that opportunity must have lain dormant. But while noting parenthetically that this question of opportunity has an importance, which some day it may be convenient to estimate, the one certain fact is that all the powers, physical and mental that a living creature possesses were contributed by one or by both of the two germ-cells which united in fertilisation to give it existence. The fact that _two_ cells are concerned in the production of all the ordinary forms of life was discovered a long while ago, and has been part of the common stock of elementary knowledge of all educated persons for about half a century. The full consequences of this double nature seem nevertheless to have struck nobody before Mendel. Simple though the fact is, I have noticed that to many it is difficult to assimilate as a working idea. We are accustomed to think of a man, a butterfly, or an apple tree as each _one_ thing. In order to understand the significance of Mendelism we must get thoroughly familiar with the fact that they are each _two_ things, double throughout every part of their composition. There is perhaps no better exercise as a preparation for genetic research than to examine the people one meets in daily life and to try in a rough way to analyse them into the two assemblages of characters which are united in them. That we are assemblages or medleys of our parental characteristics is obvious. We all know that a man may have his father's hair, his mother's colour, his father's voice, his mother's insensibility to music, and so on, but that is not enough. Such an analysis is true, inasmuch as the various characters _are_ transmitted independently, but it misses the essential point. For in each of these respects the individual is double; and so to get a true picture of the composition of the individual we have to think how _each_ of the two original gametes was provided in the matter of height, hair, colour, mathematical ability, nail-shape, and the other features that go to make the man we know. The contribution of each gamete in each respect has thus to be separately brought to account. If we could make a list of all the ingredients that go to form a man and could set out how he is constituted in respect of each of them, it would not suffice to give one column of values for these ingredients, but we must rule two columns, one for the ovum and one for the spermatozoon, which united in fertilisation to form that man, and in each column we must represent how that gamete was supplied in respect of each of the ingredients in our list. When the problem of heredity is thus represented we can hardly avoid discovering, by mere inspection, one of the chief conclusions to which genetic research has led. For it is obvious that the contributions of the male and female gametes may in respect of any of the ingredients be either the same, or different. In any case in which the contribution made by the two cells is the same, the resulting organism--in our example the man--is, as we call it, _pure-bred_ for that ingredient, and in all respects in which the contribution from the two sides of the parentage is dissimilar the resulting organism is _cross-bred_. To give an intelligible account of the next step in the analysis without having recourse to precise and technical language is not very easy. We have got to the point of view from which we see the individual made up of a large number of distinct ingredients, contributed from two sources, and in respect of any of them he may have received two similar portions or two dissimilar portions. We shall not go far wrong if we extend and elaborate our illustration thus. Let us imagine the contents of a gamete as a fluid made by taking a drop from each of a definite number of bottles in a chest, containing tinctures of the several ingredients. There is one such chest from which the male gamete is to be made up, and a similar chest containing a corresponding set of bottles out of which the components of the female gamete are to be taken. But in either chest one or more of the bottles may be empty; then nothing goes in to represent that ingredient from that chest, and if corresponding bottles are empty in both chests, then the individual made on fertilisation by mixing the two collections of drops together does not contain the missing ingredient at all. It follows therefore that an individual may thus be "pure-bred," namely alike on both sides of his composition as regards each ingredient in one of two ways, either by having received the ingredient from the male chest and from the female, or in having received it from neither. Conversely in respect of any ingredient he may be "cross-bred," receiving the presence of it from one gamete and the absence of it from the other. The second conception with which we have now to become thoroughly familiar is that of the individual as composed of what we call presences and absences of all the possible ingredients. It is the basis of all progress in genetic analysis. Let me give you two illustrations. A blue eye is due to the absence of a factor which forms pigment on the front of the iris. Two blue-eyed parents therefore, as Hurst has proved, do not have dark-eyed children. The dark eye is due to either a single or double dose of the factor missing from the blue eye. So dark-eyed persons may have families all dark-eyed, or families composed of a mixture of dark and light-eyed children in certain proportions which on the average are definite. Two plants of _Oenothera_ which I exhibit illustrate the same thing. One of them is the ordinary _Lamarckiana_. I bend its stem. It will not break, or only breaks with difficulty on account of the tough fibres it contains. The stem of the other, one of de Vries' famous mutations, snaps at once like short pastry, because it does not contain the factor for the formation of the fibres. Such plants may be sister-plants produced by the self-fertilisation of one parent, but they are distinct in their composition and properties--and this distinction turns on the presence or absence of elements which are treated as definite entities when the germ-cells are formed. When we speak of such qualities as the formation of pigment in an eye, or the development of fibres in a stem, as due to transmitted elements or factors, you will perhaps ask if we have formed any notion as to the actual nature of those factors. For my own part as regards that ulterior question I confess to a disposition to hold my fancy on a tight rein. It cannot be very long before we shall _know_ what some of the factors are, and we may leave guessing till then. Meanwhile however there is no harm in admitting that several of them behave much as if they were ferments, and others as if they constructed the substances on which the ferments act. But we must not suppose for a moment that it is the ferment, or the objective substance, which is transmitted. The thing transmitted can only be the power or faculty to produce the ferment or the objective substance. So far we have been considering the synthesis of the individual from ingredients brought into him by the two gametes. In the next step of our consideration we reverse the process, and examine how the ingredients of which he was originally compounded are distributed among the gametes that are eventually budded off from him. Take first the case of the components in respect of which he is pure-bred. Expectation would naturally suggest that all the germ-cells formed from him would be alike in respect of those ingredients, and observation shows, except in the rare cases of originating variations, the causation of which is still obscure, that this expectation is correct. Hitherto though without experimental evidence no one could have been certain that the facts were as I have described them, yet there is nothing altogether contrary to common expectation. But when we proceed to ask how the germ-cells will be constituted in the case of an individual who is cross-bred in some respect, containing that is to say, an ingredient from the one side of his parentage and not from the other, the answer is entirely contrary to all the preconceptions which either science or common sense had formed about heredity. For we find definite experimental proof in nearly all the cases which have been examined, that the germ-cells formed by such individuals do either contain or not contain a representation of the ingredient, just as the original gametes did or did not contain it. If _both_ parent-gametes brought a certain quality in, then all the daughter gametes have it; if neither brought it in, then none of the daughter gametes have it. If it came in from one side and not from the other, then on an average in half the resulting gametes it will be present and from half it will be absent. This last phenomenon, which is called segregation, constitutes the essence of Mendel's discovery. So recurring to the simile of the man as made by the mixing of tinctures, the process of redistribution of his characters among the germ-cells may be represented as a sorting back of the tinctures again into a double row of bottles, a pair corresponding to each ingredient; and each of the germ-cells as then made of a drop from one or other bottle of each pair: and in our model we may represent the phenomenon of segregation in a crude way by supposing that the bottles having no tincture in them, instead of being empty contained an inoperative fluid, say water, with which the tincture would not mix. When the new germ-cells are formed, the two fluids instead of diluting each other simply separate again. It is this fact which entitles us to speak of the purity of germ-cells. They are pure in the possession of an ingredient, or in not possessing it; and the ingredients, or factors, as we generally call them, are units because they are so treated in the process of formation of the new gametes and because they come out of the process of segregation in the same condition as they went in at fertilisation. As a consequence of these facts it follows that however complex may be the origin of two given parents the composition of the offspring they can produce is limited. There is only a limited number of types to be made by the possible recombinations of the parental ingredients, and the relative numbers in which each type will be represented are often predicable by very simple arithmetical rules. For example, if neither parent possesses a certain factor at all, then none of the offspring will have it. If either parent has two doses of the factor then all the children will have it; and if either parent has one dose of the factor and the other has none, then on an average half the family will have it, and half be without it. To know whether the parent possesses the factor or not may be difficult for reasons which will presently appear, but often it is quite easy and can be told at once, for there are many factors which cannot be present in the individual without manifesting their presence. I may illustrate the descent of such a factor by the case of a family possessing a peculiar form of night-blindness. The affected individuals marrying with those unaffected have a mixture of affected and unaffected children, but their unaffected children not having the responsible ingredient cannot pass it on[1]. In such an observation two things are strikingly exemplified, (1) the fact of the permanence of the unit, and (2) the fact that a _mixture_ of types in the family means that one or other parent is cross-bred in some respect, and is giving off gametes of more than one type. The problem of heredity is thus a problem primarily analytical. We have to detect and enumerate the factors out of which the bodies of animals and plants are built up, and the laws of their distribution among the germ-cells. All the processes of which I have spoken are accomplished by means of cell-divisions, and in the one cell-union which occurs in fertilisation. If we could watch the factors segregating from each other in cell-division, or even if by microscopic examination we could recognize this multitudinous diversity of composition that must certainly exist among the germ-cells of all ordinary individuals, the work of genetics would be much simpler than it is. But so far no such direct method of observation has been discovered. In default we are obliged to examine the constitution of the germ-cells by experimental breeding, so contrived that each mating shall test the composition of an individual in one or more chosen respects, and, so to speak, sample its germ-cells by counting the number of each kind of offspring which it can produce. But cumbersome as this method must necessarily be, it enables us to put questions to Nature which never have been put before. She, it has been said, is an unwilling witness. Our questions must be shaped in such a way that the only possible answer is a direct "Yes" or a direct "No." By putting such questions we have received some astonishing answers which go far below the surface. Amazing though they be, they are nevertheless true; for though our witness may prevaricate, she cannot lie. Piecing these answers together, getting one hint from this experiment, and another from that, we begin little by little to reconstruct what is going on in that hidden world of gametes. As we proceed, like our brethren in other sciences, we sometimes receive answers which seem inconsistent or even contradictory. But by degrees a sufficient body of evidence can be attained to show what is the rule and what the exception. My purpose today must be to speak rather of the regular than of the irregular. One clear exception I may mention. Castle finds that in a cross between the long-eared lop-rabbit and a short-eared breed, ears of intermediate length are produced: and that these intermediates breed approximately true. Exceptions in general must be discussed elsewhere. Nevertheless if I may throw out a word of counsel to beginners, it is: Treasure your exceptions! When there are none, the work gets so dull that no one cares to carry it further. Keep them always uncovered and in sight. Exceptions are like the rough brickwork of a growing building which tells that there is more to come and shows where the next construction is to be. You will readily understand that the presentation here given of the phenomena is only the barest possible outline. Some of the details we may now fill in. For example, I have spoken of the characters of the organism, its colour, shape, and the like, as if they were due each to one ingredient or factor. Some of them are no doubt correctly so represented; but already we know numerous bodily features which need the concurrence of several factors to produce them. Nevertheless though the character only appears when all the complementary ingredients are together present, each of these severally and independently follows, as regards its transmission, the simple rules I have described. This complementary action may be illustrated by some curious results that Mr Punnett and I have encountered when experimenting with the height of Sweet Peas. There are two dwarf varieties, one the prostrate "Cupid," the other the half-dwarf or "Bush" Sweet Peas. Crossed together they give a cross-bred of full height. There is thus some element in the Cupid which when it meets the complementary element from the Bush, produces the characteristic length of the ordinary Sweet Pea. We may note in passing that such a fact demonstrates at once the nature of Variation and Reversion. The Reversion occurs because the two factors that made the _height_ of the old Sweet Pea again come together after being parted: and the Variations by which each of the dwarfs came into existence must have taken place by the dropping out of one of these elements or of the other. Conversely there are factors which by their presence can prevent or inhibit the development and appearance of others present and unperceived. For example, all the factors for pigmentation may be present in a plant or an animal; but in addition there may be another factor present which keeps the individual white, or nearly so. There are cases in which the action of the factors is superposed one on top of the other, and not until each factor is removed in turn can the effects of the underlying factors be perceived. So in the mouse if no other colour-factor is present, the fur is chocolate. If the next factor in the series be there, it is black. If still another factor be added, it has the brownish grey of the common wild mouse. Conversely, by the variation which dropped out the top factor, a black mouse came into existence. By the loss of the black factor, the chocolate mouse was created, and for aught we can tell there may be still more possibilities hidden beneath. In the disentanglement of the properties and interactions of these elementary factors, the science we must call to our aid is Physiological Chemistry. The relations of Genetics with the other branches of biology are close. Such work can only be conducted by those who have the good fortune to be able to count upon continual help and advice from specialists in the various branches of Zoology, Physiology, and Botany. Often we have questions with which only a cytologist can deal, and often it is the experience of a systematist we must invoke. The school of Genetics in Cambridge starts under happy auspices in that we are surrounded by colleagues qualified, and as we have often found, willing to give us such aid unstinted. But with chemical physiology, we stand in an even closer relation; and from the little I have dared to say respecting the action and interaction of factors, it is evident that for their disentanglement there must one day be an intimate and enduring partnership arranged with the physiological chemists. Now, as the whole of the elaborate process by which the various elements are apportioned among the gametes must be got through in a few cell-divisions at most, and perhaps in one division only, it is not surprising that there is sometimes an interaction between factors that have quite distinct rôles to perform. These interactions are probably of several kinds. One, which I shall illustrate presently, is probably to be represented as a repulsion between two factors. As a consequence of its operations when the various factors are sorted out into the gametes, if the individual be cross-bred in respect of the _two_ repelling factors, having received so to speak only a single dose of each, then the gametes are made up in such a way that each takes one or other of the two repelling factors, not both. Mutual repulsions of this kind probably play a significant part in the phenomena of heredity. A single concrete case which Mr Punnett and I have been investigating for some years will illustrate several of these principles. We crossed together a pure white Sweet Pea having an erect standard, with another pure white Sweet Pea having a hooded standard. The result is, as you see, a purple flower with an erect standard. The colour comes from the concurrence of complementary elements. A dose of a certain ingredient from one parent meets a dose of another ingredient from the other parent and the two make pigment in the flower. From other experiments we know that the _purple_ colour of the pigment is due to a dose of a third ingredient brought in from the hooded parent; and that in the absence of that blue factor, as we may call it, the flower would be red. The standard is erect because it contains a dose of the erectness-factor from the erect parent, and the hooded parent can readily be proved to owe its peculiar shape to the absence of that element. Our purple plant is thus cross-bred for four factors, containing only one dose of each. We let it fertilise itself, and its offspring show all the possible combinations of the four different factors and their absences which the genetic constitution of the plant can make. Note that one of the combinations we expect to find is missing. There are white erect and white hooded--white because they are lacking one or other of the complementary ingredients necessary to the production of pigment. There are purple erect and purple hooded, of which the purple erect must perforce contain all the four factors, and the purple hooded must similarly contain all of them except that for erectness. But when we turn to the red class we are surprised to find that they are all erect, none hooded. One of the possible combinations is missing. If you examine this series of facts you will find there is only one possible interpretation: namely that the ingredient which turns the flower purple--alkalinity, perhaps we may call it--never goes into the same germ-cell as the ingredient which makes the standard erect. There are plenty of ways of testing the truth of this interpretation. For example, it follows that the purple erects from such a family will in perpetuity have offspring 1 purple hooded: 2 purple erect: 1 red erect; also that all the white hooded crossed with pure reds will give purples, and so on. These experiments have been made and the result has in each case been conformable to expectation. Between these two factors, the purpleness and the erectness of standard, some antagonism or repulsion must exist. In some way therefore the chemical and the geometrical phenomena of heredity must be inter-related. Some one will say perhaps this is all very well as a scientific curiosity, but it has nothing to do with real life. The right answer to such criticism is of course the lofty one that science and its applications are distinct: that the investigator fixes his gaze solely on the search for truth and that his attention must not be distracted by trivialities of application. But while we make this answer and at least try to work in the spirit it proclaims, we know in our hearts that it is a counsel of perfection. I suspect that even the astronomer who at his spectroscope is analysing the composition of Vega or Capella has still an eye sometimes free for the affairs of this planet, and at least the fact that his discoveries may throw light on our destinies does not diminish his zeal in their pursuit. And surely to the study of Heredity, preeminently among all the sciences, we are looking for light on human destiny. To pretend otherwise would be mere hypocrisy. So while reserving the higher line of defence I will reply that again and again in our experimental work we come very near indeed to human affairs. Sometimes this is obvious enough. No practical dog-breeder or seeds-man can see the results of Mendelian recombination without perceiving that here is a bit of knowledge he can immediately apply. No sociologist can examine the pedigrees illustrating the simple descent of a deformity or a congenital disease, and not see that the new knowledge gives a solid basis for practical action by which the composition of a race could be modified if society so chose. More than this: we know for certain in one case, from the work of Professor Biffen, that the power to resist a disease caused by the invasion of a pathogenic organism, wheat-rust, is due to the absence of one of the simple factors or ingredients of which I have spoken, and what we know to be true in that one case we are beginning to suspect to be true of resistance to certain other diseases. No pathologist can see such an experiment as this of Professor Biffen's without realizing that here is a contribution of the first importance to the physiology of disease. There is no lack of utility and direct application in the study of Genetics. I have alluded to some strictly practical results. If we want to raise mangels that will not run to seed, or to breed a cow that will give more milk in less time, or milk with more butter and less water, we can turn to Genetics with every hope that something can be done in these laudable directions. But here I would plead what I cannot but regard as a higher usefulness in our work. Genetic inquiry aims at providing knowledge that may bring, and I think will bring, certainty into a region of human affairs and concepts which might have been supposed reserved for ages to be the domain of the visionary. We have long known that it was believed by some that our powers and conduct were dependent on our physical composition, and that other schools have maintained that nurture not nature, to use Galton's antithesis, has a preponderating influence on our careers; but so soon as it becomes common knowledge--not a philosophical speculation, but a certainty--that liability to a disease, or the power of resisting its attack, addiction to a particular vice, or to superstition, is due to the presence or absence of a specific ingredient; and finally that these characteristics are transmitted to the offspring according to definite, predicable rules, then man's views of his own nature, his conceptions of justice, in short his whole outlook on the world, must be profoundly changed. Yet as regards the more tangible of these physical and mental characteristics there can be little doubt that before many years have passed the laws of their transmission will be expressible in simple formulae. The blundering cruelty we call criminal justice will stand forth divested of natural sanction, a relic of the ferocious inventions of the savage. Well may such justice be portrayed as blind. Who shall say whether it is crime or punishment which has wrought the greater suffering in the world? We may live to know that to the keen satirical vision of Sam Butler on the pleasant mountains of Erewhon there was revealed a dispensation, not kinder only, but wiser than the terrific code which Moses delivered from the flames of Sinai. If there are societies which refuse to apply the new knowledge, the fault will not lie with Genetics. I think it needs but little observation of the newer civilisations to foresee that _they_ will apply every scrap of scientific knowledge which can help them, or seems to help them in the struggle, and I am good enough Selectionist to know that in that day the fate of the recalcitrant communities is sealed. The thrill of discovery is not dulled by a suspicion that the discovery can be applied. No harm is done to the investigator if he can resist the temptation to deviate from his aim. With rarest exceptions the discoveries which have formed the basis of physical progress have been made without any thought but for the gratification of curiosity. Of this there can be few examples more conspicuous than that which Mendel's work presents. Untroubled by any itch to make potatoes larger or bread cheaper, he set himself in the quiet of a cloister garden to find out the laws of hybridity, and so struck a mine of truth, inexhaustible in brilliancy and profit. I will now suggest to you that it is by no means unlikely that even in an inquiry so remote as that which I just described in the case of the Sweet Pea, we may have the clue to a mystery which concerns us all in the closest possible way. I mean the problem of the physiological nature of Sex. In speaking of the interpretation of sexual difference suggested by our experimental work as of some practical moment, I do not imply that as in the other instances I have given, the knowledge is likely to be of immediate use to our species; but only that if true it makes a contribution to the stock of human ideas which no one can regard as insignificant. In the light of Mendelian knowledge, when a family consists of more than one type the fact means that the germ-cells of one or other parent must certainly be of more than one kind. In the case of sex the members of the family are thus of two kinds, and the presumption is overwhelming that this distinction is due to a difference among the germ-cells. Next, since for all practical purposes the numbers of the two sexes produced are approximately equal, sex exhibits the special case in which a family consists of two types represented in equal numbers, half being male, half female. But I called your attention to the fact that equality of types results when _one_ parent was cross-bred in the character concerned, having received one dose only of the factor on which it depends. So we may feel fairly sure that the distinction between the sexes depends on the presence in one or other of them of an unpaired factor. This conclusion appears to me to follow so immediately on all that we have learnt of genetic physiology that with every confidence we may accept it as representing the actual fact. The question which of the two sexes contains the unpaired factor is less easy to answer, but there are several converging lines of evidence which point to the deduction that in Vertebrates at least, and in some other types, it is the female, and I feel little doubt that we shall succeed in proving that in them femaleness is a definite Mendelian factor absent from the male and following the ordinary Mendelian rules. Before showing you how the Sweet Pea phenomenon aids in this inquiry I must tell you of some other experimental results. The first concerns the common currant moth, _Abraxas grossulariata_. It has a definite pale variety called _lacticolor_. With these two forms Doncaster has made a remarkable series of experiments. When he began, _lacticolor_ was only known as a female form. This was crossed with the _grossulariata_ male and gave _grossulariata_ only, showing that the male was pure to type. The hybrids bred together gave _grossulariata_ males and females and _lacticolor_ females only. But the hybrid males bred to _lacticolor_ females produced all four combinations, _grossulariata_ males and females, and _lacticolor_ males and females. When the _lacticolor_ males were bred to _grossulariata_ females, whether hybrid, or wild from a district where _lacticolor_ does not exist, the result was that all the males were _grossulariata_ and all the females _lacticolor_! It is difficult to follow the course of such an experiment on once hearing and all I ask you to remember is first that there is a series of matings giving very curious distributions of the characters of type and variety among the two sexes. And then, what is perhaps the most singular fact of all, that the wild typical _grossulariata_ female can when crossed with the _lacticolor_ male produce all females _lacticolor_. This last fact can, we know, mean only one thing, namely that these wild females are in reality hybrids of _lacticolor_; though since the males are pure _grossulariata_, that fact would in the natural course of things never be revealed. When we encounter such a series of phenomena as this, our business is to find a means of symbolical expression which will represent all the factors involved, and show how each behaves in descent. Such a system or scheme we have at length discovered, and I incline to think that it must be the true one. If you study this case you will find that there are nine distinct kinds of matings that can be made between the variety, the type and the hybrid, and the scheme fits the whole group of results. It is based on two suppositions: 1. That the female is cross-bred, or as we call it heterozygous for femaleness-factor, the male being without that factor. The eggs are thus each destined from the first to become either males or females, but as regards sex the spermatozoa are alike in being non-female. 2. That there is a repulsion between the femaleness-factor and the _grossulariata_ factor. Such a repulsion between two factors we are justified in regarding as possible because we have had proof of the occurrence of a similar repulsion in the case of the two factors in the Sweet Pea. If the case of this moth stood alone it would be interesting, but its importance is greatly increased by the fact that we know two cases in birds which are closely comparable. The simpler case to which alone I shall refer has been observed in the Canary. Like the Currant moth it has a kind of albino, called Cinnamon, and males of this variety when mated with ordinary dark green hen canaries produce dark males and Cinnamons which are always hens; while the green male and the Cinnamon hen produce nothing but greens of both sexes. This case, which has been experimentally studied by Miss Durham, offers a certain complication, but in its main outlines it is exactly like that of the moth, and the same interpretation is applicable to both. The particular interpretation may be imperfect and even partially wrong; but that we are at last able to form a working idea of the course of such phenomena at all is a most encouraging fact. If we are right, as I am strongly inclined to believe, we get a glimpse of the significance of the popular idea that in certain respects daughters are apt to resemble their fathers and sons their mothers; a phenomenon which is certainly sometimes to be observed. There are several collateral indications that we are on the right track in our theory of the nature of sex. One of these, derived from the peculiar inheritance of colour-blindness, is especially interesting. That affection is common in men, rare in women. Men who are colour-blind can transmit the affection but men who have normal vision cannot. Women however who are ostensibly normal may have colour-blind sons; and women who are colour-blind have, so far as we know, no sons who are not colour-blind[2]. Mendelian analysis of these facts shows that colour-blindness is due, not, as might have been supposed, to the absence of something from the composition of the body, but to the presence of something which affects the sight. Just as nicotine-poisoning can paralyse the colour sense, so may we conceive the development of a secretion in the body which has a similar action. The comparative exemption of the woman must therefore mean that there is in her a positive factor which counteracts the colour-blindness factor, and it is not improbable that the counteracting element is no other than the femaleness-factor itself[3]. I think I have said enough to prove that after all, those curiosities collected from observation of Sweet Peas and Canaries have no remote bearing on some very fascinating problems of human life. Lastly I suppose it is self-evident that they have a bearing on the problem of Evolution. The facts of heredity and variation are the materials out of which all theories of Evolution are constructed. At last by genetic methods we are beginning to obtain such facts of unimpeachable quality, and free from the flaws that were inevitable in older collections. From a survey of these materials we see something of the changes which will have to be made in the orthodox edifice to admit of their incorporation, but he must be rash indeed who would now attempt a comprehensive reconstruction. The results of genetic research are so bewilderingly novel that we need time and an exhaustive study of their inter-relations before we can hope to see them in proper value and perspective. In all the discussions of the stability and fitness of species who ever contemplated the possibility of a wild species having one of its sexes permanently hybrid? When I spoke of adventures to be encountered in genetic research I was thinking of such astonishing discoveries as that. There are others no less disconcerting. Who would have supposed it possible that the pollen-cells of a plant could be all of one type, and its egg-cells of two types? Yet Miss Saunders' experiments have provided definite proof that this is the condition of certain Stocks, of which the pollen grains all bear doubleness, while the egg-cells are some singles and some doubles. We cannot think yet of interpreting these complex phenomena in terms of a common plan. All that we know is that there is now open for our scrutiny a world of varied, orderly and specific physiological wonders into which we have as yet only peeped. To lay down positive propositions as to the origin and inter-relation of species in general, now, would be a task as fruitless as that of a chemist must have been who had tried to state the relationship of the elements before their properties had been investigated. For the first time _Variation_ and _Reversion_ have a concrete, palpable meaning. Hitherto they have stood by in all evolutionary debates, convenient genii, ready to perform as little or as much as might be desired by the conjuror. That vaporous stage of their existence is over; and we see Variation shaping itself as a definite, physiological event, the addition or omission of one or more definite elements; and Reversion as that particular addition or subtraction which brings the total of the elements back to something it had been before in the history of the race. The time for discussion of Evolution as a problem at large is closed. We face that problem now as one soluble by minute, critical analysis. Lord Acton in his inaugural lecture said that in the study of history we are at the beginning of the documentary age. No one will charge me with disrespect to the great name we commemorate this year, if I apply those words to the history of Evolution: Darwin, it was, who first showed us that the species have a history that can be read at all. If in the new reading of that history, there be found departures from the text laid down in his first recension, it is not to his fearless spirit that they will bring dismay. FOOTNOTES: [1] The investigation of this remarkable family was made originally by Cunier. The facts have been reexamined and the pedigree much extended by Nettleship. The numerical results are somewhat irregular, but it is especially interesting as being the largest pedigree of human disease or defect yet made. It contains 2121 persons, extending over ten generations. Of these persons, 135 are known to have been night-blind. In no single case was the peculiarity transmitted through an unaffected member. It should be mentioned that for night-blindness such a system of descent is peculiar. More usually it follows the scheme described for colour-blindness. It is not known wherein the peculiarity of this family consists. [2] We have knowledge now of seven colour-blind women, having, in all, 17 sons who are all colour-blind. Most of these cases have been collected by Mr Nettleship. [3] An alternative and perhaps more satisfactory interpretation of the same facts has been proposed by Doncaster (_Jour. Genetics_ I, Pt 4, p. 377). Until more progress has been made with the analysis of sexual differentiation it is not possible to decide which of the two interpretations is correct. The numerical results predicted on both systems are the same; but by introducing a more complicated though quite reasonable formula for the representation of the sex-differences Doncaster's method shows that colour-blindness may be a _recessive_ due to the absence of a factor which produces normal colour-vision. Cambridge: PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS. 
36993	----	generously made available by The Internet Archive.) BODY, PARENTAGE AND CHARACTER IN HISTORY. _BY THE SAME AUTHOR._ Ready--New and Cheaper Edition, in great part Rewritten, 2/- CHARACTER AS SEEN IN BODY AND PARENTAGE, with a Chapter on EDUCATION, CAREER, MORALS, AND PROGRESS. A remarkable and extremely interesting book.--_Scotsman._ A delightful book, witty and wise, clever in exposition, charming in style, readable and original.--_Medical Press._ Men and women are both treated under these heads (types of character) in an amusing and observant manner.--_Lancet._ We cordially commend this volume.... A fearless writer.... Merits close perusal.--_Health._ Mr. Jordan handles his subject in a simple, clear, and popular manner.--_Literary World._ Full of varied interest.--_Mind._ KEGAN PAUL, TRENCH, TRÜBNER, AND CO. LIMITED. BODY, PARENTAGE AND CHARACTER IN HISTORY: NOTES ON THE TUDOR PERIOD. BY FURNEAUX JORDAN, F.R.C.S. LONDON: KEGAN PAUL, TRENCH, TRÜBNER & CO. LIMITED, 1890. Birmingham: Printed by Hall and English. PREFACE. In my little work on "Character as Seen in Body and Parentage" I have put forward not a system, but a number of conclusions touching the relationship which I believe to exist between certain features of character on the one hand and certain peculiarities of bodily configuration, structure, and inheritance on the other. These conclusions, if they are true, should find confirmation in historic narrative, and their value, if they have any, should be seen in the light they throw on historic problems. The incidents and characters and questions of the Tudor period are not only of unfailing interest, but they offer singularly rich and varied material to the student of body and character. If the proposal to connect the human body with human nature is distasteful to certain finely-strung souls, let me suggest to them a careful study of the work and aims and views of Goethe, the scientific observer and impassioned poet, whom Madame de Staël described as the most accomplished character the world has produced; and who was, in Matthew Arnold's opinion, the greatest poet of this age and the greatest critic of any age. The reader of 'Wilhelm Meister' need not be reminded of the close attention which is everywhere given to the principle of inheritance--inheritance even of 'the minutest faculty.' The student of men and women has, let me say in conclusion, one great advantage over other students--he need not journey to a museum, he has no doors to unlock, and no catalogue to consult; the museum is constantly around him and on his shelves; the catalogue is within himself. TABLE OF CONTENTS. PAGE NOTE I.--THE VARIOUS VIEWS OF HENRY VIII.'S CHARACTER. Momentous changes in sixteenth century 1 Many characters given to noted persons 3 A great number given to Henry 3 The character given in our time 6 Attempt to give an impartial view 8 Need of additional light 14 NOTE II.--THE RELATION OF BODY AND PARENTAGE TO CHARACTER. Bodily organisation and temperaments 15 Leading types in both 16 Elements of character run in groups 17 Intervening gradations 20 NOTE III.--HENRY'S FAMILY PROCLIVITIES. Henry of unimpassioned temperament 21 Took after unimpassioned mother 22 Derived nothing from his father 23 Character of Henry VII. 24 Henry VIII., figure and appearance 26 NOTE IV.--THE WIVES' QUESTION. Henry's marriages, various causes 27 Passion not a marked cause 28 Henry had no strong passions 30 Self-will and self-importance 31 Conduct of impassioned men 31 NOTE V.--THE LESS CHARACTERISTIC FEATURES OF HENRY'S CHARACTER. Characteristics common to all temperaments 32 Henry's cruelty 33 Henry's piety 35 NOTE VI.--THE MORE CHARACTERISTIC FEATURES OF HENRY'S CHARACTER. Always doing or undoing something 37 Habitual fitfulness 38 Self-importance 40 Henry and Wolsey: Which led? 41 Love of admiration 43 NOTE VII.--HENRY AND HIS COMPEERS. Henry's political helpers superior to theological 45 Cranmer 46 Sir Thomas More 47 Wolsey 49 NOTE VIII.--HENRY AND HIS PEOPLE AND PARLIAMENT. No act of constructive genius 51 Parliament not abject, but in agreement 53 Proclamations 54 Liberty a matter of race 55 NOTE IX.--HENRY AND THE REFORMATION. Teutonic race fearless, therefore truthful 56 Outgrew Romish fetters 57 French Revolution racial 58 The essential and the accidental in great movements 60 Wyclif 61 Erasmus, Luther, Calvin, Knox 62 Henry's part in the Reformation 64 No thought of permanent division 65 The dissolution of the monasteries 66 NOTE X.--QUEEN ELIZABETH AND QUEEN MARY. Henry VIII. and Elizabeth much alike 69 Elizabeth less pious but more fitful 71 Elizabeth and marriage 72 Elizabeth's part in the Reformation 73 Elizabeth and Mary Stuart very unlike 74 Lofty characters with flaws 76 Mary's environment and fate 79 Bodily peculiarities of the two Queens 81 THE VARIOUS VIEWS OF HENRY VIII.'S CHARACTER. NOTE I. The progress of an individual, of a people, or even of a movement is never up, and their decadence is never down, an inclined plane. Neither do we see sudden and lofty flights in progress nor headlong falls in decadence. Both move rather by steps--steps up or steps down. The steps are not all alike; one is short another long; one sudden another gradual. They are all moreover the inevitable sequences of those which went before, and they as inevitably lead to those which follow. Our Fathers took a long step in the Tudor epoch, but older ones led up to it and newer ones started from it. The long step could not possibly be evaded by a Teutonic people. Rome lay in the path, and progress must needs step over the body of Rome--not a dead body then, though wounded from within, not a dead body yet, though now deeply and irreparably wounded from without. Civilization must everywhere step over the body of Rome or stand still, or turn backwards. Two factors are especially needed for progress: brain (racial brain), which by organisation and inheritance tends to be large, free, capable; and secondly, circumstance, which continually calls forth capability, and freedom, and largeness. All the schools of supernaturalism, but above all the Romish school, compress and paralyse at least a portion of the brain: if a portion is disabled all is enfeebled. If a bodily limb even, a mere hand or foot, be fettered and palsied, the body itself either dies or droops into a smaller way of life. It is so with a mental limb--a mental hand or foot in relation to the mental life. To the group of ever-present and subtle forces which make for progress, there were added in the sixteenth century seemingly new and conspicuous forces. The art of printing or writing by machinery sowed living seed broadcast over a fertile soil; the "new learning" restored to us the inspiring but long hidden thought of old Aryan friends and relatives, and this again in some degree relaxed the grip of alien and enslaving Semitic ideas which the exigencies of Roman circumstance had imposed on Europe with the edge of the sword. New action trod on the heels of new thought. New lands were traversed; new seas were sailed; new heavens were explored. The good steed civilisation--long burdened and blindfolded and curbed,--had lagged somewhat; but now the reins were loose, the spurs were sharp, the path was clear and the leap which followed was long. While our fathers were taking, or were on the eve of taking, this long step, a notable young man, the son of a capable and wise father and of a not incapable but certainly unwise mother, stepped into the chief place in this country. A student who was in training for an Archbishop was suddenly called upon to be a King. What this King was, what he was not; what organisation and parentage and circumstance did for him; how he bore himself to his time--to its drift, its movements, its incidents, its men, and, alas, to its women--is now our object to inquire. The study of this theological monarch and of his several attitudes is deeply instructive and of unfailing interest. The Autocrat of the breakfast table wittily comments on the number of John's characters. John had three. Notable men have more characters than "John." Henry VIII. had more characters than even the most notable of men. A man of national repute or of high position has the characters given to him by his friends, his enemies, and characters given also by parties, sects, and schools. Henry had all these and two more--strictly, two groups more--one given to him by his own time, another given to him by ours. If we could call up from their long sleep half a dozen representative and capable men of Henry's reign to meet half a dozen of Victoria's, the jury would probably not agree. If the older six could obtain all the evidence which is before us, and the newer six could recall all which was familiar to Henry's subjects at home and his compeers abroad; if the two bodies could weigh matters together, discuss all things together--could together raise the dead and summon the living--nevertheless in the end two voices would speak--a sixteenth century voice and a nineteenth. The older would say in effect: "We took our King to be not only a striking personality; not only an expert in all bodily exercises and mental accomplishments; we knew him to be much more--to be industrious, pious, sincere, courageous, and accessible. We believed him to be keen in vision, wise in judgment, prompt and sagacious in action. We looked round on our neighbours and their rulers, and we saw reason to esteem ourselves the most prosperous of peoples and our King the first, by a long way the first, of his fellow Kings. Your own records prove that long years after Henry's death, in all time of trouble the people longed for Henry's good sense and cried out for Henry's good laws. He was a sacrilegious miscreant you say; if it were so the nation was a nation of sacrilegious miscreants, for he merely obeyed the will of the people and carried out a policy which had been called for and discussed and contrived and, in part, carried out long before our Henry's time. Upwards of a century before, the assembled knights of the shire had more than once proposed to take the property of the Church (much of it gained by sinister methods) and hand it over for military purposes. The spirit of the religious houses had for some time jarred on the awakening spirit of a thinking people. Their very existence cast a slur on a high and growing ideal of domestic life. Those ancient houses detested and strove to keep down the knowledge which an aroused people then, as never before, passionately desired to gain." "You say he was a 'monster of lust.' Lust is not a new sin: our generation knew it as well as yours; detected it as keenly as yours; hated it almost as heartily. But consider: No king anywhere has been, in his own time, so esteemed, so trusted, nay even so loved and reverenced as our king. Should we have loved, trusted, and reverenced a 'monster of lust'? If you examine carefully the times before ours and the times since, you will find that monsters of lust, crowned or uncrowned, do not act as Henry acted. The Court, it is true, was not pure, but it was the least voluptuous Court then existing, and Henry was the least voluptuous man in it. While still in his teens the widow of an elder brother, a woman much older than he, and who was also old for her years, was married to him on grounds of state policy. Not Henry only, but wise and learned men, Luther and Melancthon among others, came to believe that the marriage was not legal. Henry himself, indeed, came to believe that God's curse was on it--in our time we fervently believed in God's curse. A boy with promise of life and health was the one eager prayer of the people. But boy after boy died and of four boys not one survived. If one of Catharine's boys had lived: nay more, if Ann Boleyn had been other than a scheming and faithless woman; or if, later, Jane Seymour had safely brought forth her son (and perhaps other sons), Henry would assuredly never have married six wives. You say he should have seen beforehand the disparity of years, the illegality, the incest--should have seen even the yet unfallen curse: in our time boys of eighteen did not see so clearly all these things." "Alas," the juror might have added, "marriage and death are the two supreme incidents in man's life: but marriage comes before experience and judgment--these are absent when they are most needed; experience and judgment attend on death when they are needless." "Bear in mind, moreover," resumes the older voice, "that in our time the marriage laws were obscure, perplexing, and unsettled. High ideals of marriage did not exist. The first nobleman in our Court was the Earl of Suffolk who twice committed bigamy and was divorced three times; his first wife was his aunt, and his last his daughter-in-law. Papal relaxations and papal permissions were cheap and common--they permitted every sort of sexual union and every sort of separation. Canon law and the curious sexual relationships of ecclesiastics, high and low, shed no light but rather darkness on the matter. The Pope, it is true, hesitated to grant Henry's divorce, but not, as the whole world knew, on moral or religious grounds: at heart he approved the divorce and rebuked Wolsey for not settling the matter offhand in England. All the papal envoys urged the unhappy Catharine to retire into a religious house; but Catharine insisted that God had called her to her position"--forgetting, we may interpose, that if He called her to it He also in effect deposed her from it. God called her daughter Mary, so Mary believed, to burn Protestants; God called Elizabeth, so Elizabeth exclaimed ('it was marvellous in her eyes'), to harass Romanists. "But the one paramount circumstance which weighed with us, and we remember a thousand circumstances while you remember the 'six wives' only, was the question of succession. If succession was the one question which more than all others agitated your fathers in Anne's time, try to imagine what it was to us. You, after generations of order, peace and security--you utterly fail to understand our position. We had barely come out of a lawless cruel time--a time born of the ferocity and hate of conflicting dynasties. Fathers still lived to tell us how they ate blood, and drank blood, and breathed blood. They and we were weary of blood, and our two Henrys (priceless Henrys to us,) had just taken its taste out of our mouths. No queen, be it well noted, had ruled over us either in peaceful or in stormy times; we believed with our whole souls, rightly or wrongly, that no queen could possibly preserve us from destruction and ruin. It was our importunity mainly--make no mistake on this point,--which drove our king, whenever he was wifeless, to take another wife. His three years of widowhood after Jane Seymour's death was our gravest anxiety." The newer voice replies: "You were a foolish and purblind generation. The simplicity of your Henry's subjects, and the servility of his parliament have become a bye-word. It is true your king, although less capable than you suppose, was not without certain gifts--their misuse only adds to his infamy. It is true also that he had been carefully educated,--his father was to be thanked for that. It would seem, moreover, that quite early in life he was not without some attractiveness in person and manners, but you forget that bodily grossness and mental irritability soon made him a repulsive object. An eminent Englishman of our century says he was a big, burly, noisy, small-eyed, large-faced, double-chinned and swinish-looking fellow, and that indeed so bad a character could never have been veiled under a prepossessing appearance. Your King was vain, ostentatious, and extravagant. With measured words we declare that his hypocrisy, cruelty, sacrilege, selfishness and lust, were all unbounded. He was above all an unrivalled master of mean excuses: did he wish to humble and oppress the clergy--they had violated the statute of premunire. Did his voluptuous eye fall on a dashing young maid of honour--he suddenly discovered that he was living in incest, and that his marriage was under God's curse. Did the Pope hesitate to grant him a divorce--he began to see that the proper head of the English Church was the English king. Was his exchequer empty--he was convinced that the inmates of the wealthy religious houses led the lives and deserved the fate of certain cities once destroyed by fire and brimstone. Did a defiant Pole carry his head out of Harry's reach--it was found that Pole's mother, Lady Salisbury, was the centre of Yorkist intrigue, and that the mother's head could be lopped off in place of the son's." The two voices it is clear have much to say for themselves. It is equally clear that the two groups of jurymen will not agree on their verdict. It is commonly held and as a rule on good grounds, that the judgment of immediate friends and neighbours is less just than the opinion of foreigners and of posterity. This is so when foreigners and posterity are agreed, and are free from the tumult, and passion, and personal bias of time and place. It is not so in Henry's case. Curiously enough, foreign observers, scholars, envoys, travellers, agree with--nay, outrun Henry's subjects in their praise of Henry. Curiously too the tumult and passion touching Henry's matrimonial affairs--touching all his affairs indeed,--have grown rather than diminished with the progress of time. Epochs, like men, have not the gift of seeing themselves as others see them. Unnumbered Frenchmen ate and drank, and made merry, and bought and sold; married their children and buried their parents, not knowing that France was giving a shock to all mankind for all time to come. The assassins of St. Bartholomew believed that in future a united Christendom would bless them for performing a pious and uniting deed. We see all at once the bare and startling fact of six wives. Henry's subjects saw and became familiar with a slow succession of marriages, each of which had its special cloud of vital yet confusing circumstance. So too the Reformation has its different phases. In the sixteenth century it was looked on as a serious quarrel, no doubt, but no one dreamed it was anything more. Then each side thought the other side would shortly come to its senses and all would be well; no one dreamt of two permanently hostile camps and lasting combat. If personal hate and actual bloodshed have passed away, and at the present moment the combat shews signs of still diminishing bitterness, it is because a new and mysterious atmosphere is slowly creeping over both--slowly benumbing both the armies. An attempt must be made here to sketch Henry's character with as much impartiality as is possible. But no impartial sketch will please either his older friends or his newer enemies. Although Henry came to the throne a mere boy, he was a precocious boy. In the precocious the several stages of life succeed each other more quickly than in others, and probably they themselves do not wear so well. When Henry was twenty-five he was little less wise and capable than he was at thirty-five or forty-five. At forty he was probably wiser than he was at fifty. The young king's presence was striking; he had a fresh rosy complexion, and an auburn though scanty beard. His very limbs, exclaims one foreign admirer, "glowed with warm pink" through his delicately woven tennis costume. He was handsome in feature; large and imposing in figure; open and frank in manners; strong, active, and skilled in all bodily exercises. He was an admirer of all the arts, and himself an expert in many of them. Henry had indeed all the qualities, whatever their worth may be, which make a favourite with the multitude. Those qualities, no matter what change time brought to them, preserved his popularity to the last. Henry was neither a genius nor a hero; but they who deny that he was a singularly able man will probably misread his character; misread his ideals, his conduct, and his various attitudes. Henry's education was thorough and his learning extensive. His habit of mind tended perhaps rather to activity and versatility and obedience to old authority than to intensity or depth or independence. His father, who looked more favourably on churchmen and lawyers than on noblemen, destined his second son for the Church. At that time theology, scholastic theology--for Colet and Erasmus and More had not then done their work--was the acutest mental discipline known as well as the highest accomplishment. For when the "new learning" reached this country it found theology the leading study, and therefore it roused theology; in Italy on the other hand it found the arts the predominant study, and there it roused the arts. Henry would doubtless have made a successful bishop and escaped thereby much domestic turmoil; but, on the whole, he was probably better fitted to be a King; while his quiet, contemplative, and kindly father would at any rate have found life pleasanter in lawn sleeves than he found it on a throne. It would be well if men and women were to write down in two columns with all possible honesty the good and the evil items in the characters (not forgetting their own) which interest them. The exercise itself would probably call forth serviceable qualities, and would frequently bring to light unexpected results. Probably in this process good characters would lose something and the bad would gain. From such an ordeal Henry VIII. would come out a sad figure, though not quite so sad as is popularly considered. It is not proposed in this sketch of character to separate, if indeed separation is possible, the good qualities which are held to be more or less inborn from those which seem to be attainable by efforts of the will. Freedom of the will must of course be left in its native darkness. Neither can the attempt be made to estimate, even if such estimate were possible, how much the individual makes of his own character and how much is made for him. Some features of character, again, are neither good nor evil, or are good or evil only when they are excessive or deficient or unsuitable to time and place. Love of pageantry is one of these; love of pleasure another; so, too, are the leanings to conservation or to innovation. In thought and feeling and action Henry was undoubtedly conservative. His conservatism was modified by his self-will and self-confidence, but it assuredly ranked with the leading features of his character--with his piety his egotism and his love of popularity. To shine in well-worn paths was his chief enjoyment: not to shine in these paths, or to get out of them, or to get in advance of them, or to lag behind, was his greatest dread. The innovator may or may not be pious, but conservatism naturally leans to piety, and Henry's piety, if not deep or passionate, was at any rate copious and sincere. Henry, it has been said, was not a hero, not a genius, neither was he a saint. But if his ideals were not high, and if his conduct was not unstained, his religious beliefs were unquestioning and his religious observances numerous and stringent. The fiercer the light which beat upon his throne, the better pleased was Henry. He had many phases of character and many gifts, and he delighted in displaying his phases and in exercising his gifts. The use and place of ceremony and spectacle are still matters of debate; but modern feeling tends more and more to hand them over to children, May-day sweeps, and Lord-mayors. In Henry's reign the newer learning and newer thought had it is true done but little to undermine the love of gewgaws and glitter, but Henry's devotion to them, even for his time, was so childish that it must be written down in his darker column. We may turn now to the less debatable items in Henry's character, and say which shall go into the black list and which into the white. We are all too prone perhaps to give but one column to the men we approve, and one only to the men we condemn. It is imperative in the estimation of character that there be "intellect enough," as a great writer expresses it, to judge and material enough on which to pronounce judgment. If we bring the "sufficient intellect," especially one that is fair by habit and effort, to the selection of large facts--for facts have many sizes and ranks, large and small, pompous and retiring--and strip from these the smaller confusing facts, strip off too, personal witcheries and deft subtleties--then we shall see that all men (and all movements) have two columns. The 'monster' Henry had two. In his good column we cannot refuse to put down unflagging industry--no Englishman worked harder--a genuine love of knowledge, a deep sense of the value of education, and devotion to all the arts both useful and elevating--the art of ship-building practically began with him. His courage, his sincerity, his sense of duty, his frequent generosity, his placability (with certain striking exceptions) were all beyond question. His desire for the welfare of his people, although tempered by an unduly eager desire for their good opinion, was surely an item on the good side. The good column is but fairly good; the black list is, alas, very black. Henry was fitful, capricious, petulant, censorious. His fitfulness and petulance go far to explain his acts of occasional implacability. Failing health and premature age explain in some degree the extreme irritability and absence of control which characterised his later years. In his best years his love of pleasure, or rather his love of change and excitement, his ostentation, and his extravagance exceeded all reasonable limits. Ostentation and love of show are rarely found apart from vanity, and Henry's vanity was colossal. Vain men are not proud, and Henry had certainly not the pride which checks the growth of many follies. A proud man is too proud to be vain or undignified or mean or deceitful, and Henry was all these. Pride and dignity usually run together; while, on the other hand, vanity and self-importance keep each other company as a rule. Henry lacked dignity when he competed with his courtiers for the smiles of Ann Boleyn in her early Court days; he lacked it when he searched Campeggio's unsavoury carpet-bag. He seemed pleased rather than otherwise that his petty gossip should be talked of under every roof in Europe. It is true that in this direction Catharine descended to a still lower level of bed-room scandal; but her nature, never a high one, was deteriorated by a grievous unhappiness and by that incessant brooding which sooner or later tumbles the loftiest nature into the dust. Henry's two striking failings--his two insanities--were a huge self-importance and an unquenchable thirst for notoriety and applause. I have said 'insanities' designedly, for they were not passions--they were diseases. The popular "modern voice" would probably not regard these as at all grave defects when compared with others so much worse. This voice indeed, we well know, declares him to have been the embodiment of the worst human qualities--of gross selfishness, of gross cruelty, and of gross lust. These charges are not groundless, but if we could believe them with all the fulness and the vehemence with which they are made, we must then marvel that his subjects trusted him, revered him, called (they and their children) for his good sense and his good laws; we can but marvel indeed that with one voice of execration they did not fell him lifeless to the ground. He was unguarded and within reach. If the charges against Henry come near to the truth, Nero was the better character of the two. Nero knew not what he did; he was beyond question a lunatic and one of a family of lunatics. Henry's enormities were the enormities of a fairly sane and responsible man. In order to read Henry's character more correctly, if that be possible, than it is read by the "two voices," more light is needed. Let us see what an examination of Henry's bodily organisation, and especially of his parentage, will do for us. In this light--if it be light, and attainable light--it will be well to examine afresh (at the risk of some repetition) the grave charges which are so constantly and so confidently laid at his door and see what of vindication or modification or damning confirmation may follow. Before looking specially at Henry's organisation and inheritance, I purpose devoting a short chapter to a general view of the principles which can give such an examination any value. It will be for the most part a brief statement of views which I have already put forward in my little work on character as seen in body and parentage. THE RELATION OF BODY AND PARENTAGE TO CHARACTER. NOTE II. It is unwise to turn aside from the investigation of any body of truths because it can only be partial in its methods or incomplete in its results. We do this however in the study of the science of character. It is true that past efforts have given but little result--little result because they ignored and avowedly ignored the connection which is coming to be more and more clearly seen to exist between character on the one hand and bodily organisation and proclivity, and especially the organisation and proclivity of the nervous system, on the other hand. Those who ignore the bearings of organisation and inheritance on character are, for the most part, those who prefer that "truth should be on their side rather than that they should be on the side of truth." It is contended here that much serviceable knowledge may be obtained by the careful investigation, in given individuals, of _bodily_ characteristics, and the union of these with _mental_ and _moral_ characteristics. The relationship of these combined features of body and mind to parentage, near and remote, and on both sides, should be traced as far back as possible. The greater the number of individuals brought under examination, the more exact and extensive will be the resulting knowledge. Very partial methods of classifying character are of daily utility. We say, for example, speaking of the muscular system only, that men are strong or weak. But this simple truth or classification has various notable bearings. Both the strong and the weak may be dextrous, or both may be clumsy; both may be slow, or both may be quick; but they will be dextrous or clumsy, slow or quick, in different ways and degrees. So, going higher than mere bodily organisation, we may say that some men are bold and resolute while others are timid and irresolute; some again are parsimonious and others prodigal. Now these may possibly be all intelligent or all stupid, all good or all bad; but, nevertheless, boldness and timidity, parsimony and generosity, modify other phases of character in various ways. The irresolute man, for example, cannot be very wise, or the penurious man truly good. It must always be remembered in every sort of classification of bodily or of mental characteristics, that the lines of division are not sharply defined. All classes merge into each other by imperceptible degrees. One of the most, perhaps the most, fundamental and important classification of men and women is that which puts them into two divisions or two temperaments, the active, or tending to be active, on the one hand, and the reflective, or tending to be reflective, on the other. To many students of character this is not anew suggestion, but much more is contended for here. It is contended that the more active temperament is alert, practical, quick, conspicuous, and--a very notable circumstance--less impassioned; the more reflective temperament is less active, less practical, or perhaps even dreamy, secluded, and--also a very notable circumstance--more impassioned. It is not so much that men of action always desire to be seen, or that men of thought desire to be hidden; action naturally brings men to the front; contemplation as naturally hides them; when active men differ, the difference carries itself to the housetops; when thinking men differ, they fight in the closet and by quieter methods. Busy men, moreover, are given to detail, and detail fills the eye and ear; men of reflection deal more with principles, and these lie beyond the range of ordinary vision. The proposition which I here put forward, based on many years of observation and study, is fundamental, and affects, more or less, a wide range of character in every individual. The proposition is that in the active temperament the intellectual faculties are disproportionately strong--the passions are feebler and lag behind; in the reflective temperament the passions are the stronger in proportion to the mental powers. Character is dominated more by the intellect in one case, more by the emotions in the other. In all sane and healthful characters (and only these are considered here) the intellectual and emotional elements are both distinctly present. The most active men think; the most reflective men act. But in many men and women the intellect takes an unduly large share in the fashioning of life; these are called here the "less impassioned," the "unimpassioned," or for the sake of brevity, "the passionless." In many others the feelings or emotions play a stronger part; these are the "more impassioned" or the "passionate." Character is not made of of miscellaneous fragments, of thought and feeling, of volition and action. Its elements are more or less homogeneous and run in uniform groups. The less impassioned, or passionless, for example, are apt to be changeable and uncertain; they are active, ready, alert; they are quick to comprehend, to decide, to act; they are usually self-confident and sometimes singularly self-important. They often seek for applause but they are sparing in their approval and in their praise of others. When the mental endowment is high, and the training and environment favourable, the unimpassioned temperament furnishes some of our finest characters. In this class are found great statesmen and great leaders. A man's _public_ position is probably determined more by intellectual power than by depth of feeling. Now and then, especially when the mental gifts are slight, the less pleasing elements predominate: love of change may become mere fitfulness; activity may become bustle; sparing approval may turn to habitual detraction and actual censoriousness. Love of approbation may degenerate into a mania for notoriety at any cost; self-importance may bring about a reckless disregard of the well-being of others. Fortunately the outward seeming of the passionless temperament is often worse than the reality, and querulous speech is often combined with generous action. Frequently, too, where there is ineradicable caprice there is no neglect of duty. The elements of character which, in various ways and degrees, cluster together in the more impassioned or passionate temperament are very different in their nature. In this temperament we find repose or even gentleness, quiet reflection, tenacity of purpose. The feelings--love, or hate, or joy, or grief, or anger, or jealousy--are more or less deep and enduring. In this class also there are fine characters, especially (as in the unimpassioned) when the mental gifts are high and the training refined. In this class too are found perhaps the worst characters which degrade the human race. In all save the rarest characters, the customary tranquillity may be broken by sullen cloud or actual storm. In the less capable and less elevated, devotion may become fanaticism, and tenacity may become blind prejudice, or sheer obstinacy. In this temperament too, in its lower grades, we meet too often--not all together perhaps, certainly not all in equal degree--with indolence, sensuality, inconstancy; or morbid brooding, implacability, and even cruelty. I contend then that certain features of character, it may be in very varying degrees of intensity, belong to the more active and passionless temperament, and certain other features attend on the more reflective and impassioned temperament. If it can be shown that there are two marked groups of elements in character--the more impassioned group and the less impassioned group--and that each group may be inferred to exist if but one or two of its characteristic elements are clearly seen, why even then much would be gained in the interpretation of history and of daily life. But I contend for much more than this; the two temperaments have each their characteristic bodily signs; the more marked the temperament, the more striking and the more easily read are the bodily signs. In the intermediate temperament--a frequent and perhaps the happiest temperament--the bodily signs are also intermediate. The bodily characteristics run in groups also, as well as the mental. The nervous system of each temperament is enclosed in its own special organisation and framework. In my work on "character as seen in body and parentage," I treat this topic with some fulness, and what is stated there need not be repeated now. It may be noted, however, that in the two temperaments there are peculiarities of the skin--clearness or pigmentation; of the hair--feebleness or sparseness, or closeness and vigour of growth; of the configuration of the skeleton and consequent pose of the figure. If the conclusions here put forward are true, they give a key which opens up much character to us. They touch, as I have already said, a great range of character in every individual, but they make no pretension to be a system. They have only an indirect bearing on many phases of character; for in both the active and reflective temperaments there may be found, for example, either wisdom or folly, courage or cowardice, refinement or coarseness. It must always be remembered, too, that besides the more marked types of character, whether bodily or mental, there are numberless intervening gradations. When the temperaments, moreover, are distinctly marked, the ordinary concurrent elements may exist in very unequal degrees and be combined in very various ways. One or two qualities may perhaps absorb the sum-total of nerve force. In the passionless man or woman extreme activity may repress the tendency to disapprove; immense self-importance may impede action. In the impassioned individual, inordinate love or hate may enfeeble thought; deep and persistent thought may dwarf the affections. As I have said elsewhere: 'For the ordinary purposes of life, especially of domestic and social life, the intervening types of character (combining thought and action more equally, though probably each in somewhat less degree) produce perhaps the most useful and the happiest results. But the progress of the world at large is mainly due to the combined efforts of the more extreme types--the supremely reflective and impassioned and the supremely active and unimpassioned. Both are needed. If we had men of action only, we should march straight into chaos; if we had men of thought only, we should drift into night and sleep!' HENRY'S FAMILY PROCLIVITIES. NOTE III. If there is any truth in the views put forward in the foregoing chapter, and if history has at all faithfully portrayed a character concerning which it has had, at any rate, much to say, it is clear that Henry must be placed in the less impassioned class of human beings. When I first called attention to the three sorts of character--and the three groups of characteristics--the active, practical, and more or less passionless on the one hand; the less active, reflective, and impassioned on the other; and, thirdly, the intermediate class, neither Henry nor his period was in my mind. But when, at a later time (and for purposes other than the special study of character), I came to review the Reformation with its ideas, its men, its incidents, I saw at once, to my surprise, that Henry's life was a busy, active, conspicuous, passionless life. He might have sat for the portrait I had previously drawn. Markedly unimpassioned men tend to be fitful, petulant, censorious, self-important, self-willed, and eager for popularity--so tended Henry. The unimpassioned are frequently sincere, conscientious, pious, and conservative--Henry was all these. They often have, especially when capable and favourably encompassed, a high sense of duty and a strong desire to promote the well-being of those around them--these qualities were conspicuous in Henry's character. How much of inherited organisation, how much of circumstance, how much of self-effort go to the making of character is a problem the solution of which is yet seemingly far off. Mirabeau, with fine perception, declared that a boy's education should begin, twenty years before he is born, with his mother. Unquestionably before a man is born the plan of his character is drawn, its foundations are laid, and its building is foreshadowed. Can he, later, close a door here or open a window there? Can he enlarge this chamber or contract that? He believes he can, and is the happier in the belief; but in actual life we do not find that it is given to one man to say, I will be active, I will be on the spot, I will direct here and rebuke there; nor to another man to say, I will give myself up to thought, to dreams, to seclusion. Henry never said, with unconscious impulse or with conscious words, "I will be this, or I will not be that." Henry VIII. took altogether after his mother's side, and she, again, took after her father. Henry was, in fact, his grandfather Edward IV. over again. He had, however, a larger capacity than his mother's father, and he lived in a better epoch. Edward, it was said in his time, was the handsomest and most accomplished man in Europe. Henry was spoken of in similar words by his compeers both at home and abroad. Both were large in frame, striking in contour, rose-pink in complexion--then, as now, the popular ideal of manly perfection--and both became exceedingly corpulent in their later years. Both were active, courteous, affable, accessible; both busy, conspicuous, vain, fond of pleasure, and given to display. Both were unquestionably brave; but they were also (both of them) fickle, capricious, suspicious, and more or less cruel. Both put self in the foremost place; but Edward's selfishness drifted rather to self-indulgence, while Henry's took the form of self-importance. Extreme self-importance is usually based on high capacity, and Edward's capacity did not lift him out of the region of pomposity and frequent indiscretion. Edward IV. was nevertheless an able man although less able than Henry. Like Henry he belonged to the unimpassioned class; he was without either deeply good or deeply evil passion, but probably he had somewhat stronger emotions than his grandson. In other words Henry had more of intellect and less of passion than his grandfather. Edward's early and secret marriage was no proof of passion. Early marriages are not the monopoly of any temperament; sometimes they are the product of the mere caprice, or the self-will and the feeble restraint of the passionless, and sometimes the product of the raw and immature judgment of the passionate. Edward deserves our pity, for he had everything against him; he had no models, no ideals, no education, no training. The occupation of princes at that time brought good neither to themselves nor anyone else. They went up and down the country to slay and be slain; to take down from high places the severed heads of one worthless dynasty and put up the heads of another dynasty equally worthless. The eighth Henry derived nothing from his father--the seventh,--nothing of good, nothing of evil. One of the most curious errors of a purely literary judgment on men and families is seen in the use of the epithet "Tudor." We hear for example of the "Tudor" blood shewing itself in one, of the "Tudor" spirit flashing out in another. Whether Henry VII. was a Tudor or not we may not now stop to inquire. Henry VIII. we have seen took wholly after his Yorkist mother. Of Henry's children, Mary was a repetition of her dark dwarfish Spanish mother; the poor lad Edward, whether a Seymour or a Yorkist, was certainly not a Tudor. The big comely pink Elizabeth was her father in petticoats--her father in body, her father in mind. Henry VIII. in fact while Tudor in name was Lancastrian in dynasty, and Yorkist in blood. No two kings, no two men indeed could well have been more unlike, bodily, mentally, and morally, than the two Henrys--father and son. The eighth was communicative, confiding, open, frank; the seventh was silent, reserved, mysterious. The son was active, busy, practical, conspicuous; the father, although not indolent, and not unpractical, was nevertheless quiet, dreamy, reflective, self-restrained, and unobtrusive. One was prodigal, martial, popular; the other was prudent, peaceful, steadfast, and unpopular. He is said indeed to have been parsimonious, but the least sympathetic of his historians confess that he was generous in his rewards for service, that his charities were numerous, and that his state ceremonies were marked by fitting splendour. Henry VIII. changed (or destroyed) his ministers, his bishops, his wives, and his measures also, many times. Henry VII. kept his wife--perverse and mischievous as she was,--till she died; kept his ministers and bishops till they died; kept his policy and his peace till he died himself. Henry VII. is noteworthy mainly for being but little noticed. The scribe of whatever time sees around him only that which is conspicuous and exceptional and often for the most part foolish, and therefore the documents of this Henry's reign are but few in number. The occupants of high places who are careful and prudent are rarely popular. His unpopularity was moreover helped on in various ways. Dynastic policy thrust upon him a wife of the busy unimpassioned temperament--a woman in whom deficient emotion and sympathy and affection were not compensated by any high qualities; a woman who was restless, mischievous, vain, intriguing, and fond of influence. Elizabeth of York had all the bad qualities of her father and her son and had very few of their good ones. A King Henry in feminine disguise without his virtues was not likely to love or be loved. Domestic sourness is probably a not infrequent cause of taciturnity and mystery and seclusion in the characters of both men and women. It was well that Henry was neither angry nor morose. It says much for him moreover that while he was the object of ceaseless intrigue and hostility and rancour he yet never gave way to cynicism or revenge or cruelty. With a tolerably happy marriage, an assenting and a helpful nobility, and an unassailed throne, it is difficult to put a limit to the good which Henry VII. might have done and which it lay in him to do. As it was he smoothed the way for enterprise and discovery, for the printing press and the new learning. He was the first of English monarchs who befriended education--using the word in its modern sense. It is curious that the acutest changes in our history--the death of a decrepit mediævalism, the birth of the young giant modernism--happened in our so-called sleepiest reign. Surely the "quiet" father had a smaller share of popular applause than he deserved, and as surely the "dashing" son a much larger share. But in all periods, old and new, popularity should give us pause: yesterday, for example, inquisitors were knelt to, hailed with acclamation and pelted with flowers, and heretics were spat upon, hissed at, and burnt, but to-day's flowers are for the heretics and the execrations are for the inquisitors. Thus then in all characteristics--intellectual, moral and bodily--Henry VIII. must be placed in the unimpassioned class. It may be noted too in passing that all the portraits of Henry show us a feeble growth of hair on the face and signs of a convex back--convex vertically and convex transversely. We do not see the back it is true, but we see both the head and the shoulders carried forwards and the chin held down towards the chest--held indeed so far downward that the neck seems greatly shortened. It is interesting to observe the pose of the head and neck and shoulders in the portraits of noted personages. The forward head and shoulders, the downward chin (the products of a certain spinal configuration) are seen in undoubtedly different characters but characters which nevertheless have much in common: they are seen in all the portraits of Napoleon I. and, although not quite so markedly, in those of our own General Gordon. Napoleon and Gordon were unlike in many ways, and the gigantic self-importance and self-seeking of Napoleon were absent in the simpler and finer character. In other ways they were much alike. Both were brave active busy men; but both were fitful, petulant, censorius, difficult to please, and--which is very characteristic--both although changeable were nevertheless self-willed and self-confident. Both were devoid of the deeper passions. THE WIVES QUESTION. NOTE IV. It is affirmed that no one save a monster of lust would marry six wives--a monster of lust being of course a man of over-mastering passion. It might be asked, in passing, seeing that six wives is the sign of a perfect "monster" if three wives make a semi-monster? Pompey had five wives, was he five-sixths of a monster. To be serious however in this wife question, it will probably never be possible to say with exactness how much in Henry's conduct was due to religious scruples; how much to the urgent importunity (state-born importunity) of advisers and subjects; how much to the then existing confusion of the marriage laws; how much to misfortune and coincidence; how much to folly and caprice; how much to colossal self-importance, and how much to "unbounded license." History broadly hints that great delusions, like great revolutions, may overcome--especially if the overcoming be not too sudden--both peoples and persons without their special wonder. In such delusions and such revolutions the actors and the victims are alike often unconscious actors and unconscious victims. Neither Henry nor his people dreamt that the great marriage question of the sixteenth century would excite the ridicule of all succeeding centuries. Luther did not imagine that his efforts would help to divide religious Europe into two permanently hostile camps. Robespierre did not suspect that his name would live as an enduring synonym for blood. But to marry six wives, solely on licentious grounds, is a proceeding so striking and so uncomplicated that no delusion could possibly come over the performer and certainly not over a watchful people. Yet something akin to delusion there certainly was; its causes however were several and complex, and lust was the least potent of them. The statement may seem strange, but there was little of desire in Henry's composition. A monster he possibly was of some sort of folly; but strange as it may seem he was a monster of folly precisely because he was the opposite of a monster of passion. Unhappily unbounded lust is now and then a feature of the impassioned temperament. It is never seen however in the less impassioned, and Henry was one of the less impassioned. The want of dignity is itself a striking feature in the character of passionless and active men, and want of dignity was the one conspicuous defect in Henry's conduct in his marriage affairs. Perhaps too, dignity--personal or national--is, like quietness and like kindliness, among the later growths of civilisation. No incident or series of incidents illustrative of character in any of its phases, no matter how striking the incidents, or how strong the character or phase of character, have ever happened once only. If libertinism, for example, had ever shown itself in the selection and destruction of numerous wives, history would assuredly give information pertinent thereto: it gives none. Nothing happens once only. Even the French Revolution, so frequently regarded as a unique event, was only one of several examples of the inherent and peculiar cruelty of the French celt.[1] The massacre of Bartholomew was more revolting in its numbers and in its character. The massacre of the commune, French military massacres and various massacres in French history deprive the "great" Revolution of its exceptional character. But to return. There were licentious kings and princes before Henry, granting he was licentious, and there have been notably licentious kings and princes since: their methods are well known and they were wholly unlike his. [1] From historic comparison we may feel sure that no such cruelty was found in the Gothic and Frankish and Norman blood of France. Certain incidents concerning Henry's marriages are of great physiological interest: a fat, bustling, restless, fitful, wilful man approaching mid-life--a man brim full of activity but deficient in feeling, waited twenty years before the idea of divorce was seriously entertained; and several more years of Papal shiftiness were endured, not without petulance enough, but seemingly without storm or whirlwind. When Jane Seymour died, three years of single life followed. It is true the three years were not without marriage projects, but they were entirely state projects, and were in no way voluptuous overtures. The marriage with Anne of Cleves was a purely state marriage, and remained, so historians tell us, a merely nominal and ceremonial marriage during the time the King and the German princess occupied the same bed--a circumstance not at all indicative of "monstrous" passion. The very unfaithfulness of Anne Boleyn and Catherine Howard is not without its significance, for the proceedings of our Divorce Court show that as a rule (a rule it is true not without exceptions) we do not find the wives of lustful men to be unfaithful. In the case of a Burns or a Byron or a King David it is not the wife who is led astray; it is the wives of the Henrys and the Arthurs, strikingly dissimilar as they were in so many respects, who are led into temptation. No _sane_ man is the embodiment of a single passion. Save in the wards of a lunatic asylum a simple monster of voluptuousness, or monster of anger, or monster of hate has no existence; and within those wards such monsters are undoubted examples of nerve ailment. It is true one (very rarely one only) passion may unduly predominate--one or more may be fostered and others may be dwarfed; but as a very general rule the deeper passions run together. One passion, if unequivocally present, denotes the existence of other passions, palpable or latent--denotes the existence, in fact, of the impassioned temperament. Henry VIII., startling as the statement may seem, had no single, deep, unequivocal passion--no deep love, no profound pity, no overwhelming grief, no implacable hate, no furious anger. The noisy petulance of a busy, censorious, irritable man and the fretfulness of an invalid are frequently misunderstood. On no single occasion did Henry exhibit overmastering anger. Historians note with evident surprise that he received the conclusion of the most insulting farce in history--the Campeggio farce--with composure. When the Bishop of Rochester thrust himself, unbidden, into the Campeggio Court in order to denounce the king and the divorce, Henry's only answer was a long and learned essay on the degrees of incestuous marriage which the Pope might or might not permit. When his own chaplains scolded him, in coarse terms, in his own chapel, he listened, not always without peevishness, but always without anger. Turning to other emotions, no hint is given of Henry's grief at the loss of son after son in his earlier married years. If a husband of even ordinary affection _could_ ever have felt grief, it would surely show itself when a young wife and a young mother died in giving birth to a long-wished-for son and heir. Not a syllable is said of Henry's grief at Jane Seymour's death; and three weeks after he was intriguing for a Continental, state, and purely diplomatic marriage. It is true that he paraded a sort of fussy affection for the young prince Edward--carried him indeed through the state apartments in his own royal arms; but the less impassioned temperament is often more openly demonstrative than the impassioned, especially when the public ear listens and the public eye watches. Those who caress in public attach as a rule but little meaning to caresses. If Henry's affections were small we have seen that his self-importance was colossal; and the very defections--terrible to some natures--of Anne Boleyn and of Catherine Howard wounded his importance much more deeply than they wounded his affections. If we limit our attention for a moment to the question of deep feeling, we cannot but see how unlike Henry was to the impassioned men of history. Passionate king David, for example, would not have waited seven years while a commission decided upon his proposed relationship to Bathsheba; and the cold Henry could not have flung his soul into a fiery psalm. The impassioned Burns could not have said a last farewell to the mother of his helpless babe without moistening the dust with his tears, while Henry could never have understood why many strong men cannot read the second verse of "John Anderson my Jo" with an unbroken voice. THE LESS CHARACTERISTIC FEATURES OF HENRY'S CHARACTER. NOTE V. It is well now, after considering the question of Henry's parentage and organisation, to look again and a little more closely, at certain significant features in his character--his caprice, his captiousness, his love of applause, his self-will, self-confidence, and self-importance. These elements of character frequently run together in equal or unequal degrees, and they are extremely characteristic of the more markedly passionless temperament. But before doing this it is well to look, in a brief note, at some features of Henry's character which are found in the less impassioned and the more impassioned temperaments alike. Both temperaments, for example, may be cruel or kindly; both may tend to conservatism or to innovation; pious persons or worldly may be found in both. But the cruelty or kindliness, the conservatism or innovation, the piety or worldliness differ in the different temperaments--they differ in their motives, in their methods, in their aims. The cruelty of the unimpassioned man is, for the most part, a reckless disregard for the happiness or well-being or (in mediæval times especially) for the lives of those who stand in his way or thwart his plans or lessen his self-importance. Such cruelty is more wayward resentful and transitory than deliberative or implacable or persistent. The cruelty of the impassioned man is perhaps the darkest of human passions. It is the cruelty born of hate--cruelty contrived with deliberation and watched with glee. Happily it is a kind which lessens with the growth of civilisation. Often it attends on the strong convictions of strong natures obeying strong commands--commands which are always strongest when they are believed to have a supernatural origin; for belief in supernaturalism is the natural enemy of mercy; it demands obedience and forbids compassion. Cruelty was at its worst when supernatural beliefs were strongest; for happily natural reason has grown, and supernatural belief has dwindled. The unimpassioned and the impassioned temperaments may alike scale the highest or descend to the lowest levels of character, although probably the most hateful level of human degredation is reached by the more impassioned nature. It cannot be denied that, even for his time, Henry had a certain unmistakable dash of cruelty in his composition. A grandson of Edward IV., who closely resembled his grandfather, could not well be free from it. But the cruelty of Henry, like that of Edward, was cruelty of the passionless type. He swept aside--swept too often out of existence--those who defied his will or lessened his importance. How much of Henry's cruelty was due to the resolve to put down opposition, how much was due to passing resentment and caprice, and how much, if any, to the delight of inflicting pain, not even Henry's compeers could easily have said. His cruelty in keeping the solitary Mary apart from her solitary mother was singularly persistent in so fickle a man; but even here weak fear and a weak policy were stronger than cruel feeling. It was Henry's way of meeting persistent obstinacy. It is needless to discuss the cruelty of the executions on religious grounds during Henry's reign; they were the order of the day and were sanctioned by the merciful and the unmerciful alike. But Henry's treatment of high personages was a much deeper stain--deeper than the stain of his matrimonial affairs. People and parliament earnestly prayed for a royal son and heir, but no serious or popular prayer was ever offered up for the heads of Fisher or More or Lady Salisbury. Henry's cruelty had always practical ends in view. Great officials who had failed, or who were done with, were officials in the way, and _their_ heads might be left to the care of those who were at once their rivals and their enemies. The execution of Lady Salisbury will never fail to rouse indignation as long as history is history and men are men. Henry might have learned a noble lesson from his father. Henry VII. put his own intriguing mother-in-law into a religious house, and the proper destination of a female Yorkist intriguer--no matter how high or powerful--was a convent, not a scaffold. In the execution of Elizabeth Barton meanness was added to cruelty, for the wretched woman confessed her impostures and exposed the priests who contrived them for her. The cruelty which shocked Europe most, and has shocked it ever since, was the execution of Sir Thomas More. More's approval would have greatly consoled the King, but More's approval fell far short of the King's demands. The silence of great men does _not_ give consent, and More was silent. More was, next to Erasmus, the loftiest intellect then living on this planet. Throughout Europe men were asking what More thought of "the King's matter." More's head was the only answer. But however indignant we may be, let us not be unjust; Henry, cruel as he was, was less cruel than any of his compeers--royal, imperial, or papal, or other. The cruelty of our Tudor ruler has always been put under a fierce light; the greater cruelty of distant rulers we are too prone to disregard. We are too prone also to forget that the one thing new under the sun in _our_ time is greater kindliness--kindliness to life, to opinion, to pocket. If fate had put a crown on Luther's head, or Calvin's, or later, on Knox's, their methods would have been more stringent than Henry's. Henry and his Parliament, it is true, proposed an Act of Parliament "to abolish diversity of opinion in matters of religion." But Luther and Calvin and Knox, nay even More (Erasmus alone stood on a higher level), were each and all confident of their possession of the _one_ truth and of their infallibility as interpreters thereof; each and all were ready, had the power been theirs, to abolish "diversity of religious opinion." There are two kinds of religion, or at any rate two varieties of religious character--both are sincere--the religion of the active and passionless and that of the reflective and impassioned. One is a religion of inheritance, of training, of habit, of early and vivid perception; with certain surroundings it is inevitable; if shaken off it returns. George Eliot acutely remarks of one of her notably passionless characters, "His first opinions remained unchanged, as they always do with those in whom perception is stronger than thought and emotion." The other is a religion (two extremes are spoken of here, but every intermediate gradation exists) a religion of thought and emotion, of investigation and introspection. It is marked by deep love of an ideal or real good, and deep hate of what may also often be called an ideal or real evil. Henry's religion was of the first sort. It would be deeply interesting to know the sort of religion of the great names of Henry's time. We lack however the needful light on their organisation, parentage, and circumstance. But in all the provinces of life the men who have imprinted their names on history have been for the most part active, practical, and unimpassioned men. They, in their turn, have owed much to the impassioned, thinking, and often unpractical men whose names history has not troubled itself to preserve. And now, in the light shed by organisation and inheritance, we may gain further information on the more characteristic features of Henry's character--his caprice, his captiousness, his uncertainty, and his peevishness, his resolve never to be hidden or unfelt or forgotten. THE MORE CHARACTERISTIC FEATURES OF HENRY'S CHARACTER. NOTE VI. Henry was always doing something or undoing something. Whether he was addressing Parliament, admonishing and instructing subordinates, or exhorting heretics; whether he was restoring order in Northern England, or (with much wisdom) introducing order into Wales, or (with much folly) disorder into Scotland; whether he was writing letters to Irish chieftains or Scottish councillors, or Northern pilgrims; whether he was defending the Faith or destroying religious houses; whether he was putting together six articles to the delight of Catholics, or dropping them in a few weeks to the exultation of Protestants; whether burning those who denied the miracle of the Real Presence, or hanging those who denied his headship of the Church; whether he was changing a Minister, a Bishop, or a wife, his hands were always full. And in Henry's case at least--probably in most cases--Satan found much mischief for busy hands to do. The man who is never at rest is usually a fitful man. Constant change, whether of ministers or of views or of plans, is in itself fitfulness. But fitfulness is something more than activity: it implies an uncertainty of thought or conduct which forbids calculation or prediction, and therefore forbids confidence; it is an inborn proclivity. Happily vigorous reasoning power often accompanies it and keeps it in check. In poorly endowed intellects, whether in men or women, fitfulness and its almost constant associate petulance harass many circles and many hearths. It is recorded that when the disgraced Wolsey took his departure from Court, the King sent after him a hurried messenger with a valuable ring and comforting words. The incident has excited much perplexity and comment among historians. What was its meaning? what its object? Probably the incident had no precise meaning; probably it was merely the involuntary deed of an irresistible constitutional tendency; possibly, too, there lurked in the motive which led to it some idea of future change and exigency. The active, practical, serviceable man sows many seeds and keeps on sowing them. Time and circumstance mainly decide which seeds shall grow and which shall not. Caprice is not unfrequently associated with high faculties. Sometimes it would seem to be due to the gift--not a common one--of seeing many sides of a question, and of seeing these so vividly that action is thereby enfeebled or frequently changed. Sometimes it is a conservative instinct which sees that a given step is too bold and must be retraced. It certainly is not selfishness: a long-pondered policy is often dashed to the ground in an instant, or a long-sought friendship is ended by a moment's insult. At root caprice is an inborn constitutional bias. Henry was the first powerful personage who declared that the Papal authority was Divine--declaring this, indeed, with so much fervour that the good Catholic More expostulated with him. But Henry was also the first high personage who threw Papal authority to the winds. It is on record that Henry would have taken Wolsey into favour again had Wolsey lived. Not Wolsey only but all Henry's Ministers would have been employed and dismissed time after time could they but have contrived to keep their heads on their shoulders. Henry might even have re-married his wives had they lived long enough. One circumstance only would have lessened their chances--attractive women were more numerous than experts in statecraft: for one Wolsey there were a thousand fair women. Habitual fitfulness, it has already been noted, is not often found apart from habitual petulance, and both these qualities were conspicuous in Henry's character. There was something almost impish in the spirit which led him to don gorgeous attire--men had not then got out of barbaric finery, and women are still in its bondage--on the day of Anne Boleyn's bloodshed. Nay more, there was undoubtedly a dash of cruelty in it, as there was in the acerbity which led him to exclaim that the Pope might send a Cardinal's hat to Fisher, but he would take care that Fisher had no head to put it on. Now and then his whims were simply puerile; it was so when he signalised some triumph over a Continental potentate by a dolls' battle on the Thames. Two galleys, one carrying the Romish and the other the English decorations, met each other. After due conflict, the royalists boarded the papal galley and threw figures of the pope and sundry cardinals into the water--king and court loudly applauding. But again, let us not forget that those days were more deeply stained than ours with puerility and cruelty and spite. More, it is true, rose above the puerility of his time; Erasmus rose above both its cruelty and its puerility; Henry rose above neither. No charge is brought against Henry with more unanimity and vehemence than that of selfishness. And the charge is not altogether a baseless one; but the selfishness which stained Henry's character is not the selfishness he is accused of. When Henry is said to have been a monster of selfishness it is implied that he was a monster of self-indulgence. He was not that--he was the opposite of that. He was in reality a monster of self-importance, and extreme personal importance is incompatible with gross personal indulgence. Self-indulgence is the failing of the impassioned, especially when the mental gifts are poor; while self-importance is the failing of the passionless, especially when the mental gifts are rich. Let there be given three factors, an unimpassioned temperament, a vigorous intellect, and circumstance favourable to public life--committee life, municipal, platform, Parliamentary, or pulpit life--and self-importance is rarely wanting. This price we must sometimes pay for often quite invaluable service. When Henry spoke--it is not infrequently so when the passionless and highly gifted individual speaks--the one unpardonable sin on the part of the listener was not to be convinced. A sin of a little less magnitude was to make a proposal to Henry. It implied that he was unable to cope with the problems which beset him and beset his time. He could not approve of what he himself did not originate; at any rate he put the alien proposal aside for the time--in a little time he _might_ approve of it and it might then seem to be his own. The temperament which censured a matter yesterday will often applaud it to-day and put it in action to-morrow. The unimpassioned are prone to imitation, but they first condemn what they afterwards imitate. When Cromwell made the grave proposal touching the headship of the Church, Henry hesitated--nay, was probably shocked--at first. Yet, for Henry's purposes at least, it was Cromwell (and not Cranmer with his University scheme) who had "caught the right sow by the ear." Henry had a boundless belief in the importance of the King; but this did not hinder, nay it helped him to believe in the importance of the people also--it helped him indeed to seek the more diligently their welfare, seeing that the more prosperous a people is, the more important is its King. True he always put himself first and the people second. How few leaders of men or movements do otherwise. Possibly William III. would have stepped down from his throne if it had been shown that another in his place could better curb the ambition of France abroad, or better secure the mutual toleration of religious parties at home. Possibly, nay probably, George Washington would have retired could he have seen that the attainment of American independence was more assured in other hands. Lloyd Garrison would have gladly retired into private life if another more quickly than he could have given freedom to the slave. John Bright would have willingly held his tongue if thereby another tongue could have spoken more powerfully for the good of his fellow-men. Such men can be counted on the fingers and Henry is not one of them. Henry would have denied (as would all his compeers in temperament) that he put himself first. He would have said; "I desire the people's good first and above all things;" but he would have significantly added; "Their good is safest in my hands." It is a moot point in history whether Henry was led by his high officials or was followed by them. Did he, for example, direct Wolsey or did Wolsey (as is the common view) in reality lead his King while appearing to follow him. To me the balance of evidence, as well as the natural proclivities of Henry's character, favour the view that he thought and willed and acted for himself. Do we not indeed know too well the fate of those whose thought and will ran counter to his? No man's opinion and conduct are independent of his surroundings and his time; for every man, especially every monarch, must see much through other eyes and hear much through other ears. But if other eyes and other ears are numerous enough they will also be conflicting enough, and will strengthen rather than diminish the self-confidence and self-importance of the self-confident and self-important ruler. Self-importance, as a rule, is built on a foundation of solid self-confidence, and Henry's confidence in himself was broad enough and deep enough to sustain any conceivable edifice. The Romish church was then, and had been for a thousand years, the strongest influence in Europe. It touched every event in men's bodily lives and decided also the fate of their immortal souls. Henry nevertheless had no misgiving as to his fitness to be the spiritual head of the Church in this country, or the spiritual head of the great globe itself, if the great globe had had one Church only. When I come to speak of the Reformation I shall have to remark that, had the great European religious movement reached our island in any other reign than Henry's, religion would not have been exactly what it now is. Of all our rulers Henry was the only one who was at the same time willing enough, educated enough (he had been trained to be an Archbishop), able enough, and pious enough to be at any rate the _first_ head of a great Church. Henry was so sagacious that he never forgot the superiority of sagacity over force. He delighted in reasoning, teaching, exhorting; and he believed that while any ruler could command, few could argue and very few could convince. It is true, alas, that when individuals or bodies were not convinced if he spoke, he became unreasonably petulant. When Scotland did not accept a long string of unwise proposals he laid Leith in ashes. When Ireland did not yield to his wishes, he knocked a castle to atoms with cannon, and thereby so astonished Ireland, be it noted, that it remained peaceful and prosperous during the remainder of his reign. Perhaps the happiest moments in Henry's life were those when he presided over courts of theological inquiry. To confute heresy was his chief delight; and his vanity was indulged to its utmost when the heretical Lambert was tried. Clothed in white silk, seated on a throne, surrounded by peers and bishops and learned doctors, he directed the momentous matters of this world and the next; he elucidated, expounded, and laid down the laws of both heaven and earth. It was a high day; one thing only marred its splendour--he, the first living defender of orthodoxy, had spoken and heterodoxy remained unconvinced. Heterodoxy must clearly be left to its just punishment, for bishops, peers, and learned doctors were astonished at the display of so much eloquence, learning, and piety. The physiological student of human nature who is much interested in the question of martyrdom finds, indeed, that the martyr-burner and the martyr (of whatever temperament) have much in common. Both believe themselves to possess assured and indisputable truth; both are infallible; both self-confident; both are prepared, in the interests of truth, to throw their neighbours into the fire if circumstance is favourable; both are willing to be themselves thrown into the fire if circumstance is adverse. One day they burn, the next day they are burnt. The feature in Henry's character which as we have seen amounted to mania was his love of popularity; it was a mania which saved him from many evils. Even unbridled self-will does little harm if it be an unbridled self-will to stand well with a progressive people. It has been a matter of surprise to those who contend that Henry, seeing that he possessed--it is said usurped--a lion's power, did not use it with lion-like licence. His ingrained love of applause is the physiological explanation. Let it be noted, too, that not everyone who thirsts for popularity succeeds in obtaining it, for success demands several factors: behind popular applause there must be action, behind action must be self-confidence, behind self-confidence must be large capability. Henry had all these. In such a chain love of applause is the link least likely to be missing. For, indeed, what is the use of being active, capable, confident and important in a closet? The crow sings as sweetly as the nightingale if no one is listening, and importance is no better than insignificance if there is no one "there to see." We shall gain further and not uninteresting knowledge of Henry's character if we look at certain side lights which history throws upon it. We turn therefore, in another note, to look for a few moments at the men, the movements, the drift, the institutions of his time, and observe how he bore himself towards them. HENRY AND HIS COMPEERS. NOTE VII. In Henry's time, and in every time, the art of judging women has been a very imperfect one. It is an imperfect art still and, as long as it takes for granted that women are radically unlike men, so long it will remain imperfect. But Henry was a good judge of one sex at any rate, for he was helped by the most capable men then living, and in reality he tolerated no stupidity--except in his wives. In an era of theological change it was perhaps an unfortunate circumstance that he was better helped in his politics than in his theology. Wolsey, although a Cardinal and even a candidate for the Papal chair, was to all intents and purposes a practical statesman. Had he succeeded in becoming a Pope he would nevertheless have remained a mere politician. Wolsey, then, and Cromwell and More were all distinctly abler men than Cranmer or Latimer or Gardiner. But Henry himself, looking at him in all that he was and in all that he did, was not unworthy of his helpers. There were then living in Europe some of the most enduring names in history. More, it is true, was made of finer clay than the king; Erasmus was not only the loftiest figure of his time--he is one of the loftiest of any time; but Henry was also a great personality and easily held his own in the front rank of European personalities. As a ruler no potentate of his time--royal, imperial or papal--could for a moment compare with him. Of all known Englishmen he was the fittest to be King of England. Had it been Henry's fortune to have had one or two or even three wives only, our school histories would have contained a chapter entitled "How 'Henry the Good' steered his country safely through its greatest storm." He played many parts with striking ability. He was probably as great a statesman as Wolsey or More or Cromwell. He would certainly have made a better archbishop than Cranmer; a better bishop than Latimer or Gardiner; he was a better soldier than Norfolk. What then might he have been had he been a statesman only, or a diplomatist or an ecclesiastic or a soldier only? In all the parts he played, save the part of husband, his unimpassioned temperament stood him in good stead. A man's attitudes to his fellow-men and to the movements of his time are, on the whole, determined more by his intellect than by his feeling. The emotions indeed are very disturbing elements. They have, it is true, made or helped to make a few careers; but they have destroyed many more. Very curiously, Henry's compeers were, most of them, like himself--unimpassioned men. Latimer, who was perhaps an exception, preached sermons at Paul's Cross brimful of a passion which Henry admired but did not understand. Cranmer too was a man of undoubted feeling and strong affection. It is said there is sometimes a magnetic charm between the unlike in temperament; strong friendships certainly exist between them; and it is to Henry's credit that to the last he kept near to him a man so unlike himself. Cranmer was a kindly, sympathetic, helpful, good soul, but not a saint. He was not one of those to whom Gracian refers as becoming bad out of pure goodness. Cranmer was a capable and a strong man, but he was not supremely capable or supremely strong. He was free from the worst of human evils--'cocksureness.' The acute Spaniard just named says that "every blockhead is thoroughly persuaded that he is in the right;" Cranmer was less of a blockhead than most of his compeers. Left to his own instincts, he preferred to live and let others live. Cranmer had not the loftiness (nor the hardness and inflexibility) of a More; not the genius and grace and scholarship of an Erasmus; not the definite purpose and iron will of a Cromwell; not the fire of a Latimer; not the clear sight and grasp of a Gardiner; not the sagacity and varied gifts of a Henry; but for my part I would have chosen him before all his fellows (certainly his English fellows) to advise with and to confide in. Of all the tables and the roofs of that time I should have preferred to sit at his table and sleep under his roof. The great luminaries who guide in revolutions are rare, and the smaller lights of smaller circumstance are not rare; but--the question is not easy to answer--which could we best spare, if we were compelled to choose, the towering lighthouse of exceptional storm or the cheery lamp of daily life? One figure of Henry's times which never fails to interest us is that of Sir Thomas More. More was clearly one of the unimpassioned class; but his commanding intellect, his quick response to high influences, his capability of forming noble friendships, and his lofty ideals seemed to dispense with the need of deep emotions. More and Henry, indeed, were much alike in many ways. Both were precocious in early life; both were quick, alert, practical; both were able; both, to the outside world at least, were genial, affable, attractive; both also, alas, were fitful, censorious, difficult to please; both were self-confident--one confident enough to kill, the other confident enough to be killed. Had they changed places in the greatest crisis of their lives Henry would have rejected More's headship of the Church and More would have sent Henry to the block. In order to understand More's character correctly we must recognise the changing waves of circumstance through which he passed. There were in fact two Mores, the earlier and the later. The earlier More was an unembittered and independent thinker; the seeming spirit of independence however was, in a great degree, merely the spirit of contradiction. He was a friend of education and the new learning. He advocated reform in religion; but reform, be it noted, before the Reformation, reform gently and from within; reform when kings and scholars and popes themselves all asked for it. History, unhappily, tells of much reform on the lips which doggedly refused to translate itself into practice. The earlier More was all for reform in principle, but he invariably disapproved of it in detail. The later and in some degree embittered More was thrown by temperament, by the natural bias of increasing years and by the exigencies of combat, into the ecclesiastical and reactionary camp, and in that camp his conduct was stained by cruel inquisitorial methods. The deteriorating effects of conflict (which happily grow less in each successive century) on individuals as well as on parties and peoples is seen in another notable though very different character of More's century. Savonarola, before his bitter fight with Florentine and Roman powers, was a large, clear-sighted, sane reformer; after the fight he became blind, fanatical, and insane. Why may we not combine all thankfulness for the early More and the early Savonarola, and all compassion for the later More and later Savonarola? Mary Stuart, Francis Bacon, Robert Burns, Napoleon Buonapart, and Lord Byron were notable personalities; they--some of them at least--did the world service which others did not and could not do. Yet how many of us are there who, if admitting to the full their greatness, do not belittle their follies? or, if freely admitting their follies, do not belittle their greatness? Wolsey, holding aloof from religious strife, remained simply the scholar and the politician--a politician moreover _before_ politics became in their turn also a matter of hostile camps. Being a politician only, he continued to be merciful while More drifted from politics and mercy into ecclesiasticism and cruelty. More's change was in itself evidence of a fitful and passionless temperament, of such evidence indeed there is no lack. His first public action was one of petulance and self-importance. He had been treated with continued and exceptional kindness by Cardinal Morton and Henry VII.; but when Morton, on behalf of his king, asked parliament for a subsidy, the newly-elected More, conscious of his powers, and thinking too, may we not say, much more of a people's applause than of a people's burdens, successfully urged its reduction to one half. More was by nature censorious, and never heartily approved of anything. When Wolsey, on submitting a proposal to him with the usual result, told him--told him it would seem in the unvarnished language of the time--that he stood alone in his disapproval, and that he was a fool, More, with ready wit and affected humility, rejoined that he thanked God that he was the only fool on the King's Council. More, we may be quite sure, was not conscious of a spirit of contradiction; he probably felt that his first duty was to suggest to everybody some improvement in everything. This spirit of antagonism nevertheless played a leading part in his changeful life. In his early years he found orthodoxy rampant and defiant, consequently he inclined to heresy; at a later period heresy became rampant and defiant, and as inevitably he returned to the older faith and views. A modern scholar and piquant censor, and--I gather from his own writings, the only knowledge I have of him--an extreme specimen of the unimpassioned temperament, Mark Pattison, says that he never saw anything without suggesting how it might have been better; and that every time he entered a railway carriage he worked out a better time table than the one in use. If More had lived in his own Utopia he would have found fault with it, and drawn in imagination another and a better land. The later More was, as all unimpassioned and censorious temperaments are, a prophet of evil; and as much evil did happen--was sure to happen--his wisdom has come down to us somewhat greater in appearance than it was in reality. The cruelty of the Tudor epoch has already been spoken of. Catholics and protestants, kings, popes, cardinals, ministers, Luthers, Calvins, Knoxes were all stained by it. Henry and More, we know, were no exceptions. But More's cruelty differed from Henry's in one important respect--there was nothing appertaining to self in it, except self-confidence. Henry's cruelty was in the interest of himself--his person, his family, and his throne; More's cruelty, although less limited perhaps, and more dangerous, was nevertheless in the interest of religion. HENRY AND HIS PEOPLE AND PARLIAMENT. NOTE VIII. It is in his attitude to his people and his parliament that we see Henry at his best. His sagacity did not show itself in any deliberate or deeply reasoned policy, certainly not, we may allow with Dr. Stubbs, in any great act of "constructive genius;" it showed itself in seeing clearly the difficulties of the hour and the day, and in the hourly and daily success with which they were met. Henry and his father presided over the introduction of a new order of things, which new order, however, was a step only, not a cataclysm. They themselves scarcely knew the significance of the step or how worthily they presided over it. The world, indeed, knows little--history says little--of great and sudden acts of constructive genius. These gradually emerge from the growth of peoples; they do not spring from the brains of individuals royal or otherwise. If the vision of a ruler is clear and his aims good, he, more than others, may help on organic and beneficent growth. Full-blown schemes and policies, even if marked by genius, are rarely helpful and not infrequently they end in hindrance or even in explosion. The Stuarts had a large "scheme" touching church and king. It was a scheme of "all in all or not at all;" for them and their dynasty it ended in "not at all." French history is brimful of "great acts of constructive genius" and has none of the products of development. For Celtic history is indeed a sad succession of fits, and not a process of quiet growth. How a succession of fits will end, and how growth will end, it is not difficult to foretel. The government of peoples is for the most part and in the long run that which they deserve, that which they are best fitted for, and not at all that which, it may be, they wish for and cry out for. A people ready--fairly and throughout all strata ready--for that which they demand will not long demand in vain. Our fathers, under the Tudor Henrys and the Tudor Elizabeth, had the rule which was best fitted for them, which they asked for, which they deserved--a significant morsel, by the bye, of racial circumstance. It by no means follows, let it be noted, that what people and king together approved of was the ideal or the wisest. It is with policies as with all things else, the fittest, not the best, continue to hold the field. Henry and Elizabeth had not only clearness of sight, but flexibility of mind also, and would doubtless have ruled over Puritan England with success; it lay in them to rule well over our modern England also. Charles I., by organisation and proclivity, would have fared badly at the hands of a Tudor parliament, and, again as a result of organisation and proclivity, Henry VIII. and the Long Parliament would have been excellent friends. Hand to mouth government, if it is also capable, is probably the best government for a revolutionary time. Conflicting parties are often kept quiet by mere suspense--by mingled hopes and fears. It has been well said of Henry of Navarre that he kept France, the home of political whirlwinds, tranquil for a time because the Protestants believed him to be a Protestant and the Catholics believed he was about to become a Catholic. The majority of historians and all the compilers of history tell us that Henry's parliaments were abject and servile. The statement is politically misleading and is also improbable on the grounds of organisation and race. It is one of many illustrations of the vice of purely literary judgments on men and movements; a vice which takes no account of physiology, of race, of organisation and proclivity. For we may be well assured that the grandsons of brave men and the grandfathers of brave men are never themselves cowards. One and the same people--especially a slow, steadfast, and growing people--does not put its neck under the foot of one king to-day and cut off the head of another king to-morrow. It is not difficult to see how the misconception arose: in a time of great trial the king and the people were agreed both in politics and in religion. The people held the king's views; they admired his sagacity; they trusted in his honour. If a brother is attached to his brother and does not quarrel with him, is he therefore poor-spirited? If by rare chance a servant sees, possibly on good grounds, a hero in his master, is he therefore a poltroon? If a parliament and a king see eye to eye, is it just to label the parliament throughout history as an abject parliament? Henry's epoch, moreover, was not one of marked political excitement, and therefore the hasty observer jumps to the conclusion that it was not one of political independence. In each individual, in each community, in each people there is a sum-total of nerve force. In a given amount of brain substance--one brain or many--in a given amount of brain nutriment of brain vitality, there is a given quantity of nerve power. This totality of power will show itself it may be in one way strongly or in several ways less strongly; it cannot be increased, it cannot be lessened. On purely physiological grounds it may be affirmed that Bacon could not have thought and written all his own work and at the same time have also thought and written the life-work of Shakspere. Shakspere could not have added Bacon's investigations to his own 'intuitions.' In our own time Carlyle could not have written "The French Revolution" and "The Descent of Man;" he could not have gone through the two trainings, gained the two knowledges, and lived the two lives which led to the two works. So it is with universities: when scholarship is robust, theology limps; and during the Tractarian excitement, so a great scholar affirms, learning in Oxford sank to a lower level. So with peoples: in a literary age religious feeling is less earnest; in a time of political excitement both religion and literature suffer. Henry's era was one of abounding theological activity: Luthers, Calvins, and (later) Knoxes came to the front, and the front could not, never can, hold many dominant and also differing spirits. In Elizabeth's time Marlowes and Shaksperes and Spensers were master spirits, and master spirits are never numerous. No doubt as civilisation goes on great men and great movements learn to move, never equally perhaps but more easily, side by side: more leaders come to the front--but is the front as brilliant? Choice spirits are more numerous--but are the spirits quite as choice? Another and a less partial generation must decide. "But," say the few observers and the crowd of compilers, "only a servile parliament would have given the king permission to issue proclamations having the authority of law." But the people, it cannot be too emphatically repeated, were neither creatures crawling in the mire nor red-tapists terrified at every innovation; they trusted the king, and he did not violate their trust. The proclamations, so it was stipulated, were not to tamper with existing laws; they were to meet exigencies in an epoch of exigencies, and they met them with a wisdom and a promptness which parliament could not come near. It is physiological proclivities--not red tape, not parchment clauses, not Magna Chartas--which keep a people free. It is rather red tape, and not the occasional snapping of red tape which enfeebles liberty. If the non-conformists, who by the bye detested Romanism more than they loved religion, had not rejected the declaration of indulgence of Charles II.--a declaration which gave to Romanists leave of worship as well as to non-conformists--does any sane person believe that English freedom would have been less than it now is? In our time a body of men who hate England more than they love Ireland have, of set purpose, tumbled parliament into the dust: now, if a capable and firm authority were entrusted for twelve months with exceptional yet absolute control over parliamentary procedure, does any sane person suppose that the English passion for free parliaments would be lulled to sleep? Rule has often to be cruel in order to be kind. Alas, the multitude is made up not of Cromwells, is indeed afraid of Cromwells. In total ignorance of racial proclivities, it foolishly believes that a Cromwellian speaker for twelve months would mean a Cromwellian speaker for ever. NOTE ON HENRY AND THE REFORMATION. NOTE IX. It is a singular misreading of history to say that Henry did much directly or indirectly to help on the Reformation of the Church in this country, although the part he played was not a small one. Neither was the Reformation itself, grave and critical as it was, so sudden and volcanic an upheaval as is generally believed. Luther himself did not put forward a single new idea. No man is thinker and fighter at once; at any rate, no man thinks and fights at the same moment. Luther struck his blows for already accomplished thought. Curious ideas of unknown dates--for history reveals mergings only, not beginnings, not endings, and the student of men and movements might well exclaim "nothing begins and nothing ends,"--ideas of unknown dates and unknown birth-places had slowly come into existence. In Teutonic Europe at least, the older ideas were becoming trivial and inadequate. It was the northern Europe, which from the earliest times had been dogged in its courage both bodily and mental; the Europe strong in that reverence for truth which rests on courage, which is inseparable from courage, which never exists apart from courage; the Europe strong in its respect for women; strong in its fearlessness of death, of darkness, of storm, of the sea-lion, the land monster, the unearthly ghost, and which was strong therefore in its fearlessness of hell-fire and priestly threats. Celtic Europe, especially Celtic Ireland, slept then and sleeps now the unbroken slumber of credulity. Credulity and fear are allied. Celtic Ireland was palsied then, and is palsied still, by the fear of what we may now call Father Furniss's hell. It is surely not difficult to recall and therefore not difficult to foretell the history of so widely differing races. Everywhere throughout Teutonic Europe, in castle and monastery, in mansion and cottage, the old-new ideas were talked over, drunk over, quarrelled over, shaken hands over, slept over. Everywhere the poets--the peoples' voices then, for the printed sheet, the coffee house, the club, were yet far off,--the poets, Lindsay, Barbour and others in Scotland; Langland, Skelton and others in England had, long before, pelted preachers and preaching with their bitterest gibes. Those poets little knew how narrowly they escaped with their lives; they escaped because they shouted their fierce diatribes just before not just after the strife of battle. They had flashed out the signals of undying warfare, but before the signals could be interpreted the signallers had died in their beds. Thought, inquiry, discussion, printing, poetry, the new learning, the older Lollardry had moved on with quiet steps. A less quiet step was at hand, but this also, if less quiet, was as natural and as inevitable as the stealthiest of preceding steps. Europe had gradually become covered with a network of universities, and students of every nationality were constantly passing from one to another. One common language, Latin, bound university to university and thinking men to thinking men. He who spoke to one spoke to all. The time was a sort of hot-house, and the growth of man was "forced." Reaction attends on action, but in the main, studious men made the universities--not universities the studious men; in like-manner good men have made religions, not religions so much good men. Ideas and opinions quickly became common property; sooner or later they filtered down from the Latin phrase to home-spun talk; filtered down also from the university to the town, village, and busy highway. The Papacy itself had made Papal rule impossible to vigorous peoples. With curiously narrow ambition Popes have always preferred even limited temporal importance to unlimited spiritual sway. Two Popes, nay at one time three, had struggled not for the supremacy of religion but for merely personal pre-eminence. Popes had fought Popes, councils had fought councils, and each had called in the friendly infidel to fight the catholic enemy. The catholic sack of catholic Rome had been accompanied by greater lust and more copious bloodshed than the sack of Rome in olden time by northern Infidels. The teachings, claims, and crimes native to Rome, nay, even the imported refinements of the arts and letters and elegancies of Paganism did what legions of full-blown Luthers could not have done. The Reformation, with its complex causes, its complex methods, its complex products, is, more than other great movements, brimful of matter for observation, thought, and inference. The French Revolution was but one of a series of fierce uprisings of a race which rises and slaughters whenever it has a chance. French history teems with slaughters both in time of peace and time of war. Mediæval French Kings dared not arm their peasants with bows and arrows, for otherwise not a nobleman or a gentleman would have been left alive. At the close of the eighteenth century in France the oppression was heavy, the opportunity was large, and the uprising was ferocious. No other people have ever shown such a spectacle, and it is therefore idle to compare other great national movements with it. French history stands alone: no oppressor can oppress like the French oppressor; no retaliator can retaliate like the French retaliator. It is a question much less of politics than of organisation and race. But to return. Mr. Carlyle, in his own rousing way and on a subject which deeply interests him--Luther and the Reformation--mingles fine literary vigour with an indifference to physiological teaching which is by no means habitual with him. The heaven-born hero tells us what has become false and unreal, and shows us--it is his special business--how we may _go back_ to truth and reality. The humbler student believes that we are constantly journeying _towards_ truth and reality--these lie not behind but in front of us. The school of prophets tells us that the hero alights in front of us and stands apart. The student declares that we all move together; that we partly make our heroes, and partly they make us; that we have grades of heroes; that they are not at all supernatural--we touch them, see them, know them, send them to the front, keep them and dismiss them at our will, or what seems our will. Carlyle affirms that modern civilisation took its rise from the great scene at Worms. The truths of organisation, of body, of brain, of race, of parentage would rather say that civilisation itself was not born of but in reality gave rise to Luther and the scene at Worms. The Reformation did not give private judgment; private judgment gave the Reformation. In all revolutions there is a mixture of the essential and the accidental. During the long succession of the ordinary efforts of growing peoples there are also from time to time unusual efforts to bring to an end whatever of accident is most at variance with essential truth and reason and sanity and honour. In the reformations of a growing people, whatever the age in which they happen, whatever the religion or policy or conduct of the age, leading spirits rebel against what is most oppressive and resent what is most arrogant in that age; they reject what is most false and laugh out of court what is most ridiculous. In the sixteenth century men felt no special or inherent resentment to arrogance because it lifted its head in Rome; they looked on the so-called miracle of transubstantiation with no special or peculiar incredulity; their sense of humour was not necessarily tickled by the idea that a soul leaped out of purgatory when a coin clinked in Tetzel's box. Those were matters of accident and circumstance; they were simply the most intolerable or incredible or preposterous items of the century. Given other preceding accidents--another Deity, or one appearing in another century or arising in another people; another emperor than Constantine; other soldiers than Constantine's--and the sixteenth-century items of oppression and falsehood would have been there, it is true, but they would have been other than they were. We are often told that great movements come quickly, and are the peculiar work of heroes. We are told, indeed, that from time to time mankind degenerates into a mass of dry fuel, and that at the fitting moment a hero descends, as a torch, and sets the mass on fire. Nay, moreover, if we doubt this teaching we are dead to poetic feeling and have lost our spiritual ideals. Happily, however, if phantasy dies, poetry still lives. Leaders and led, teachers and taught, are all changing and always changing; but no change brings a lessened poetic susceptibility or a lessened poetic impulse. If, in future, historians and critics come to see that the organisation and bodily proclivity and parentage of men have really much to do with men, let us nevertheless be comforted--the ether men breathe will be no less ample, the air no less divine. Every age is transitional--not this or that--and the ages are bound together by unbroken sequence. As with the movements so is it with the leaders: they are in touch with each other as well as in touch with their followers. All ages have some men who are bolder than others, or more reflective than others, or more courageous, or more active. At certain epochs in history there have been men who combined many high qualities, and who in several ways stood in front of their time. Wyclif was not separated from his fellows by any deep gulf, neither was he, as regards time, the first in his movement, but no leader ever sprang so far in front of the led. General leaders appear first, and afterwards, when the lines of cleavage are clearer, special leaders arise. Wyclif was a general leader, and therefore had many things to do. He did them all well. He was a scholar, a theologian, a writer, a preacher. It is his attitude to his age and to all ages, and to national growth, which interests us--not his particular writing, or his preaching, or his detailed views. He propounded, he defined, he lighted up, he animated, he fought. In one capacity or in two Wyclif might have soared to a loftier height and have shone a grander figure. But he did what was most needed to be done then and there. The time was not ripe, and it did not lie in Wyclif to make it ripe, for the Reformation, but he showed the way to the Reformation; he introduced its introducers and led its leaders. The special leaders appeared in due time, and they also were the product of their time. An Erasmus shed more light than others on burning problems; a Calvin formulated more incisively than his fellows; a Luther fought more defiantly; and, a little later, a Knox roused the laggards with fiercer speech. It is interesting to note that the fighters and the speakers in all movements and at all times come most quickly to the front; it is for them that the multitude shouts its loudest huzzas and the historian writes his brightest pages. But let us not forget this one lesson from history and physiology: it is not given--or but rarely given--to any one man to do all these things, to innovate, to illuminate, to formulate, to fight, to rouse; it is certainly not given to any one man to do all with equal power, and certainly not all at once. For there is a sum-total of brain-force, not in the individual only, but in the community and in the epoch. In one stream it is powerful; if it be divided in several streams each stream is weaker. It was a theological torrent at the beginning of the sixteenth century, a literary torrent at the century's close. We have (perhaps it is for our good) several streams, we have however, we all hope, a good total to divide. Curiously, too, the most clear-sighted of leaders never see the end, never indeed see far into the future of their movement. The matters and forces which go to form a revolution are many and complex, reformers when striving to improve a world often end in forming a party. If the leaders are clear-sighted, the party will be continuous, large, long-lived; dim-sighted enthusiasts, even when for the moment successful, lead a discontinuous, short-lived, spasmodic crowd. Sometimes a leader steps forth clear and capable, but the multitude continues to sleep. Wyclif, for example, called on his generation to follow him in a new and better path. He seemed to call in vain. In the sixteenth century men were awake, stirring, resolved; but no leaders were ready. Fortunately the people marched well although they had no captains to speak of. The age was heroic although it had no conspicuous heroes. Although in its forms, its beliefs, its opinions, its policy, its conduct, there was much that was accidental, it was nevertheless inevitable and essential that the Reformation should come. It mattered not whether this thing had been done or that; whether this particular leader led or that; whether this or that concession had been made at Rome. If Erasmus could not fight Luther could. If Rome could concede nothing, much could be torn from her. There is, indeed, much fighting and tearing in history: complacent persons, loftily indifferent to organisation, and race, and long antecedent, are astonished that men should fight, or should fight with their bodies, or that, when fighting they should actually kill each other. In all times, alas, the fittest, not the wisest, has prevailed--and the fittest, alas, has been cruel. In the seventeenth century Parliament and Charles Stuart fought each other by roughest bodily methods, and Parliament, proving victorious, killed Charles. Had Charles conquered, and could Parliament have been reduced to one neck or a dozen, we may be quite sure that the one neck or the dozen would have been severed on the block. When the thousand fermenting elements came together in the sixteenth century cauldron, no number of men, certainly no one man, certainly not Henry, could do much to hinder or to help on the seething process. This of course was not Henry's view. He believed himself to be--gave himself out to be--the fountain of truth. We know that he and an _admiring_ (not an _abject_) Parliament proposed an Act to abolish diversity of opinion on religious matters. We know too, that while he graciously permitted his subjects to read the Word of God, he commanded them to adopt the opinions of the king. It was indeed cheap compulsion, for he and the vast mass of his subjects held similar opinions. Nevertheless, it is true that Henry, with characteristic sagacity, turned to the right spot and at the right moment when the cauldron threatened to boil over, or possibly to explode. At a critical epoch he helped to avert bloodshed; for in this island there was no war of peasants, or princes, or theologians. Those who say that the great divorce question brought about or even accelerated the Reformation, are those who see or wish to see the bubbles only, and cannot, or will not see the stream--its depth and strength,--on which the bubbles float. For the six-wives matter was in reality a bubble, large it is true, prismatic, many-coloured, interesting, visible throughout Europe, minutely gossiped over on every hearth. If King Henry, however, had had no wife at all, the Reformation would have come no more slowly than it did; if he had had, like King Solomon, seven hundred wives, it would have come no more quickly. Henry was not himself a reformer, and but little likely to lead reformers. Under a fitful and petulant exterior the king was a cold, calculating, self-remembering man. The reformers were a self-forgetting, passionate, often a frenzied party, and as a rule, firebrands do not follow icebergs. If imperious circumstance loosened Henry's moorings to Rome, he had no more notion of drifting towards Augsburg or Geneva, than, a little later, his daughter Elizabeth had of drifting to Edinburgh and Knox. Henry had no deep attachment, but he clung to the old religion, chiefly perhaps because it was old, as much as he could cling to anything; he had no deep hatreds, but, as heartily as his nature permitted, he detested the new. He would have disliked it all the more, had that been possible, could he have looked with interpretative glance backward to the seed-time of Wyclif's era, or forward to the ripe harvest of the seventeenth century. Could it have been made plain to Henry that he was helping to put a sword into a Puritan's hand and bring a King's head to the block, he would have had himself whipped at the tomb of Catharine of Aragon, and would have thrown his crown at the Pope's feet. He assumed the headship of the English Church, it is true; but even good Catholics throughout Europe did not then so completely as now accept the supremacy of the Bishop of Rome, and central ideas had not then so completely swallowed up the territorial. If Henry had not taken the headship of the English Church when he did, the Church would probably have had no head at all, and religious teaching in this country would have fared much as it fared in Switzerland and Scotland and North Germany. As it was, Henry simply believed himself to be another Pope, and London to be another Rome. He, the English Pope, and the Pope at Rome would, for the most part, work together like brothers--work for the diffusion of the _one_ truth (which all sorts and conditions of Popes believe they possess), and work therefore for the good of all people. Had the great European religious movement reached our island in any other reign than Henry's it would not have run quite the same course it did. Of all the Kings who have ruled over us Henry VIII. was the only King who was at the same time willing enough, able enough, educated enough (he had been trained to be an Archbishop), and pious enough to be, at any rate, the first head of a great Church. But it is said: "Look at the destruction of the religious houses; surely that was the work of heresy and greed." Henry had no heresy in his nature, but he was not without greed, and as he was certainly extravagant, he had therefore the stronger incentives to exaction. But in our history the foible of a King avails but little when it clashes with the conscience, the ideal, the will of a people. Henry's greed, moreover, whatever its strength, was less strong than his conservatism, less strong than his piety. Stronger, too, than all these combined was his boundless love of popularity--a love which alone would have preserved the monasteries could the monasteries have been preserved by any single man. But new ideas and new religious ideals had come in, and the new religious ideals and the old religious houses could not flourish together. The existence of those houses had long been threatened. One hundred years before, Parliament had more than once seriously discussed the appropriation of ecclesiastical funds to military purposes. Cardinal Morton, after impartial inquiry, contemplated sweeping changes. Wolsey, a good Catholic, had suppressed numerous houses. It is interesting to know that at one period of his life Sir Thomas More thought of retiring into a religious house, but after carefully studying monastic life he gave up the project. It is not necessary to sift and resift the evidence touching the morality of the monasteries. Probably those institutions were not so black as their enemies, new or old, have painted them, nor so white as they appear in the eyes of their modern friends. But whether they were fragments of Hades thrust up from below, or fragments of the celestial regions let down from above, or whatever else they were, their end was come. Many causes were at work. They were coming into collision with the rapidly growing modern social life--a life more complex than at any time before, more complex in its roots, its growths, its products, and its needs. The newer social life had developed a passionate love of knowledge; it had formed a loftier ideal of domestic life. It pondered too over our economic problems, and disliked the ceaseless accumulation of land and wealth in ecclesiastical hands. Does any one imagine that a close network of institutions, which were at any rate not models of virtue; institutions which hated knowledge and thrust it out of doors; which directly or indirectly cast a slur on the growing domestic ideal; which told the awakening descendants of Scandinavian and Norseman and Saxon, that their women were unclean--that their mothers and daughters were "snares;" does anyone imagine that such a network could be permitted to entangle and strangle modern life? It has already been said that the newer social ideas were destined to arise, and that therefore the older religious houses were doomed to fall. It mattered little the particular year in which they fell; it mattered little who seemed to deal the final blow. Many centuries before, human nature being what it was, and social conditions what they were, quiet retreats had met a want--they were fittest to live and they lived. But a succession of centuries brought change--a little in human nature, much in social conditions, very much in thought and opinion, and the retreats, the inner life and opinions of which had not kept pace with life outside, were no longer needed, no longer fittest, and they fell. Henry did not destroy them. Catholicism, which neither made them pure nor made them impure, was unable to preserve them. Could the long buried bones of their founders have come to life again and have put on the newer flesh, thought, with newer brain, the newer thought, they would have found quite other outlets for their energy, leisure and wealth. It is so with all founders and all institutions. It is so at this moment with the institutions which were born of the Reformation itself. Naturalists tell us that the jelly-like mass, the amæba, embraces everything, both the useful and the useless, that comes in its way, but that in time it relaxes its embrace on the useless. So the civilisation of a growing people is like a huge amæba, which slowly enfolds men and ideas, and incidents, and systems, and then sooner or later it disenfolds the unsuitable and the worn-out. QUEEN ELIZABETH AND QUEEN MARY. NOTE X. Few rulers, few persons indeed, have ever been so much alike as our two rulers Henry VIII. and his daughter Elizabeth. No man was ever so like Henry as was the woman Elizabeth; no woman ever resembled Elizabeth so closely as did the man Henry. Both father and daughter were extreme examples of the intellectual and unimpassioned temperament. High capacity, acute perception, clear insight, correct inference were present in both. Both, too, were capricious, fault-finding, querulous and vain. Both, moreover, had their preferences and their dislikes. Both, too, felt and showed resentment when their vanity was wounded. But in neither of them, it may be truly affirmed, was there any consuming passion--any fervent love, or invincible hatred, or fierce jealousy, or overwhelming anger. Those who preach the doctrine of an essential difference between the sexes and who, with the injustice which so frequently accompanies the abounding self-importance of masculinity, would deprive women not only of "equality of sphere" but "equality of opportunity," may study the character of Henry and Elizabeth with great advantage. Human beings are first of all divided (I have elsewhere contended) into certain types of character and only afterwards into men and women. Many men are by nature devoted lovers and parents and friends; many women are not. Elizabeth was one of a number--a large number--of women who have, it may be, many of the qualities which tell in practical and public life, and but little of the emotion which wells up in true wifehood and motherhood and friendship. Henry and Elizabeth stand far above the average level of rulers. In sagacity, in tact and in statesmanship only two of their successors can compare with them. But the methods of Oliver Cromwell and William III. were very different from the Tudor methods. Cromwell and William strove to be guided by what they sincerely held to be lofty principles. Henry and Elizabeth were guided merely, though wisely guided, by the fineness of their instincts. Fine instincts were perhaps better fitted for the earlier time, and lofty principles for the later. It is easier, alas, to bungle in formulating and in applying principles than in trusting to adroitness and intuitions. All the elements of character which Henry possessed were found also in Elizabeth, and many of these elements, though not all, they possessed in equal degree. They were alike in capacity, courage, sincerity, versatility, industry; alike in their conservative proclivities and also in their love of pageantry--for Elizabeth, like Henry, revelled in public business and in public pleasures; she delighted in progresses, shows, masks and plays. They were alike, too, in their sense of duty, in their desire for the welfare of the people, and also in their thirst for the people's good opinion. But Elizabeth, although she had immense self-importance (she heartily approved of the queen and, heartily indeed, of nothing else), was perhaps less self-confident than her father. She was not quite comfortable in her headship of the Church--but then she had not been educated for the Church as her father had been, and she did not possess her father's devotional nature. Her conduct was however more decorous than her father's, notwithstanding that she was distinctly less religious than he--less religious in principle, in inward conviction and in outward worship. If she was less devout than Henry she had however a larger share of fitfulness than even he. The historian who more vividly than any other has placed the Tudor time before us speaks of Elizabeth's "ingrained insincerity;" the words "ingrained fitfulness" would perhaps be more correct, for she was in truth as sincere as her fitfulness permitted her to be. Although it is true she was not without--no one at that time was quite without--insincerity and intrigue and duplicity and falsehood in her diplomatic methods, she was fairly sincere in her views and aims and conduct. But unfortunately her views and aims and conduct were constantly changing. She was sincere too easily and too frequently. She had a dozen fits of sincerity in a dozen hours. Whenever she sent a message, no matter how carefully the message had been considered, a second was sent to recall or change it, and very shortly a third messenger would be despatched in pursuit of the second. Urgent and critical circumstance alone, and frequently not even this, forced upon her any conclusive action. I am compelled to agree with those who believe that the most distressing incident of her life was the final decision touching Mary Stuart's death: it was distressing on several grounds--she was not naturally cruel, or, like her father, cruel to those only who stood in her path; she did not like to kill a queen; and, above all, she hated to do anything which (like marriage, to wit) could not be undone. Elizabeth was compelled by temperament to be always doing something, but by temperament also she was always reluctant to get anything done. In her two bushels of occupation there were not two grains of performance. Her extreme fitfulness had at least one fortunate result--it saved many lives. Henry's frequent change of view and of policy was unquestionable, but the change was slow enough to give to the ever-watchful enemies of a fallen minister time enough to tear the fallen minister to pieces. But if a minister of Elizabeth's fell, his head was in little danger: if he fell from favour to-day, he was restored to-morrow. He might trip twenty times, and as many times his rivals would be on the alert; but twenty pardons would be granted all in good time. Touching the question of marriage the queen was far wiser than her father. Neither father nor daughter had the needful qualities which go to make marriage happy, and both had certain other qualities which in many cases make it an intolerable burden. Henry, unlike Elizabeth, did not discover this, for his perceptive powers generally were less acute than hers. She probably knew that in her inmost heart (her brain was sufficiently acute to gain a glimpse of what was in her heart and what was not) she was a stranger to the deep and sustained affections without which marriage is so often a cruel deception. She had admirers and favourites it is true; and, after the fashion of the time, was unseemly enough in her fits of romping and her fits of pettishness. But there has not yet been anywhere, or at any time, under the sun a healthful temperament which has objected to admiration and entertainment, and probably there never will be. Elizabeth's attitude to the religious condition of her people marks a decided movement, if not an onward movement: for we must never forget that a multitude of high-minded and capable souls believe that the several steps of the Reformation were downward steps. But what were the steps, and what especially was Elizabeth's step? The popes (and their times) had said, _in effect_, you need not read and you must not think or inquire; your duty is to obey and believe. Henry (and his time) said, you may think and you may read, especially if your reading enables you to understand the King, but you must believe what the King believes and worship as the King worships. Elizabeth (and her times), still more at the mercy of rising Teutonic waves, exclaimed, you may think and read and inquire and believe as you like--especially as you insist upon doing so--but you really must, all of you, go to church with me on Sunday mornings. Elizabeth's church-going act, by the bye, is still unrepealed. Long after, William III. (and his time, though William was before his time) said, you may think, read, believe, and publicly worship as you will, but you must believe something and you must worship somewhere. John Milton, before William in time and long before him in largeness of view, was the one colossal figure who fought bravely and single-handed for freedom in every domain of thought and speech and conduct. The Tudor time, more than any other in our history, lends itself to the study of character; a study which, although difficult, is the less difficult in that whatever of change may take place, old elements of character do not altogether disappear and entirely new elements do not make their appearance. These elements lie everywhere around us. A great writer and an acute observer of men declares indeed that we all contain the elements of a Luther and a Borgia (his ideal of the best and worst elements), and that if a man cannot see these near at hand he will not find them though he travel from Dan to Beersheba. The Tudor and the Stuart periods alike present remarkable persons and remarkable incidents; but in the earlier period the men and women were more striking than the events, while events attract our attention more than individuals in the later. With the Tudors men and women seemed to lead, for men and women were proportionately the stronger; circumstance seemed to be the stronger in the Stuart times. No century contains three royal figures so striking in themselves and so clearly revealed to us as are the figures of Henry and Elizabeth and Mary in the sixteenth. Their capability, their vitality and their attainments would have made them striking persons in any position of life. Each, indeed, possessed the three qualities which make a really interesting personality--and such personalities are but a small proportion of the neutral-tinted multitude who are good and kind and industrious--and nothing more. They, the three personalities, could all see facts for themselves; they could all see the relative value of facts (the rarest of the three qualities); and they could all draw sound inferences from the larger facts. The three individuals presented however but two types of character. Henry and Elizabeth were examples of one type and Mary of another. The Tudor father and daughter were, as we have already seen, not examples merely but _extreme_ examples of the unimpassioned, ever active, ever visible class. Mary was as extreme an example of the impassioned, meditative, persistent and tenacious class. It was a remarkable coincidence that pitted two such mental and bodily extremes against each other. All sane human beings have much more of that which is common to the character of the race than they have of that which is peculiar to the individual. There was not only this common basis of human nature in Elizabeth and Mary, there was something more: both were singularly capable, brilliant, witty and brave (Mary being the braver and her bravery being the more tried). The two queens had certain unusual advantages in common, for both were educated to the highest ideal of female education--very curiously a higher ideal then than at any other time before, or even since, until our own generation; both, too, had much experience of life--the larger and the less elevating share falling to Mary's lot. But here the resemblance ceases. What in Elizabeth Tudor were slight though shrill rivulets of love and hate and anger and scorn and jealousy, or of pity or gratitude, were mighty and rushing torrents in Mary Stuart. We have seen what Elizabeth was: in many ways Mary was the exact opposite, for she was not at all given to bustle or change or acrimony or captiousness or suspicion. She was not, it is true, without vanity; she had ample grounds for having it and she was deeply human, but (it was not so with Elizabeth) her pride was even greater than her vanity. The elements which met together in Mary were all of a finer quality than those which were found in Elizabeth; but in Mary some troublous elements were added to the choicer ones. In her high land there were ominous volcanic peaks, while in the decorous plain of Elizabeth's character there was a monotonous blending of vegetation and sand. In some of our greatest characters (the truism is well-worn) there have been grave defects. Burns' life never comes to any generous mind save with the deepest regret as well as the keenest admiration. Bacon's was a great mind with a great fault. Shakspere and Goethe--the two foremost spirits which time has yet given to us--are not held to have led altogether stainless lives. Now the Queen of Scots was not by any means one of the immortals, but she was nevertheless and in truth a great woman. Yet in the splendid block out of which the ever-pathetic figure of Mary was chiselled there came to light an ineradicable flaw. The good and evil of all these characters were mainly, though not wholly (for circumstance must not be forgotten), due to organisation and inheritance. A little difference in their organisation, and they would have been other individuals than they were, and would most likely have remained unknown to us; but having the parentage they had, and being what they were, a little difference in circumstance would probably have mattered little. What there was in each of organisation, what of circumstance, and what of volition, is a problem the solution of which is still far off. In all of them volition, whatever that may be, did its best; organisation, let us say, did its worst; circumstance looked on, helping here and hindering there,--the compromise is history. As the six-wives business clings to Henry's name, so does the Darnley matter, though curiously with less odium, cling to that of Mary. Henry has had no friends save those who lived in or near his time. In our time an inquirer, here or there, strives perhaps to gain for him something of impartial judgment. Mary has never been without warm friends, and her friends seem to grow in number and in warmth. The controversy still rages touching Mary's part in the tragic event which inflicted so deep a wound into her life. But although the controversy goes on at even fever heat, the public judgment remains cool and is probably just. It is kept cool and just by the weight of a few colossal truths which the deftest manipulation of a cloud of smaller truths cannot hide. At critical moments the physiological historian, who looks steadily at a few large incidents in the light of human nature, discovers clues which escape the vision of the purely literary historian, who is for ever diving--and usefully diving--into the wells of parchment detail. In reality it matters little whether this diver or that has dived most deeply; matters little whether certain documents are spurious or genuine. Mary Stuart accepted--she certainly did not reject--the passion of a certain man; that man was a leader among a number of men who murdered her husband; after the murder Mary Stuart married that particular man, and thereby most assuredly held a candle to murder. This was Mary. Now if everything that has been said in her favour could be proved, she would be but little better than this; if everything that has been said against her could be proved, she would be but little worse. The student of historic characters never forgets the time the country and the circumstance in which his characters lived. We are now looking at a time when not only noble and ignoble characters existed side by side, but when noble and less noble elements existed together in one and the same character. For indeed the good elements of a better time come in slowly, and the evil elements of a bad past die a lingering death. The active Scotland (there was, we know, a good quiet Scotland in the background), the active Scotland of Tudor times was given over to factions, fanatics, self-seekers and assassins. Life was taken and given with scant ceremony. The highest personages of that time contrived murder, or sanctioned it, or forgave it--the popes did, continental sovereigns did, Henry did, Elizabeth did. The murders thus contrived or sanctioned or condoned were, it is true, mainly on behalf of thrones or dominions or religions, while the murder which Mary assuredly forgave, if she did not sanction, was on behalf of her passions. The moral difference between murder for a crown and murder for a love we may not now discuss. It was to this Scotland, the active and factious Scotland just described, that the young queen of nineteen years was brought--brought from a different atmosphere and with an unpropitious training. The more favoured Elizabeth meanwhile was ruling over a quieter, a more united people, and was helped at her council-table by high-minded and unselfish men. It is useless now perhaps to ask if we may be allowed to admire the gifts, to deplore the faults, and to pity the fate of the more unfortunate queen. We can indeed, individually, do what we please, but the queen's posterity with no uncertain voice has declared that we may. Emerson says that the great soul of the world is just, and the great soul has kept Mary within the territory of its favour. It would seem that the affection and devotion which were given to Mary were not based on any single great or on any group of great actions; they were based (it is to her credit) on daily acts of kindliness and patience and unruffled grace. The sum of Mary's qualities, whatever they were, endowed her with the rare gift of making the world her friend; and the world does not, as a rule, make lasting friendships on insufficient grounds. Mary indeed, with all her faults, deserved a better country than Scotland; and England, it may be added, deserved a more gracious queen than Elizabeth. But whatever she deserved or whatever she was fitted for, Mary's fate was destined to be one of the saddest of recorded time. Inward force and outer circumstance are so commingled that mortal reason fails to disentangle them. To-day men _seem_ to put a curb on circumstance, and to-morrow circumstance _seems_ to run away with men. An ocean of complex and imperious circumstance surged around two queens, one it lifted up and kept afloat and carried into a secure haven, the other it tossed mercilessly to and fro and finally drew her underneath its waves. A number of leading Scottish nobles gave out and probably believed that the wretched Darnley's life was incompatible with the general good. Bothwell was but one of this number. Yet how clear it has ever been to all eyes, save to those of the blindly passionate actors themselves, that the Scottish queen's fatal error, even if there were no grave error before, was in marrying any one of the misguided band. But misguidance was in the ascendant. Could she by some magic web have concealed the husbands from each other and have married them all, she would at any rate have fared no worse than she did. But, to be serious, if a queen marries one of half a dozen ambitious assassins, the other five will assuredly make her life intolerable and her rule impossible. In no aspect of character did the two queens differ more than in their attitude to religion. Elizabeth's piety, like her father's, though less deep than his, was of a similar passionless, perceptive, unreflective order. Mary's religion, like Elizabeth's, like that of all individuals in all parts of the world, was no doubt at first the product of her early surroundings; but with the Scottish queen it was much more than this--it was a profoundly passionate conviction and a deeply revered ideal. A living writer, who is perhaps unrivalled in the historic art and who rarely errs in his historic judgments, is less happy than is his wont in his verdict on the catholic queen. He avers that she had no share "in the deeper and nobler emotions;" yet almost in the same breath he states that she had "a purpose fixed as the stars to trample down the Reformation." To have a purpose "fixed as the stars" to trample down _one_ religion was, in that age of the world, surely to have a purpose "fixed as the stars" to strengthen and protect _another_; to yearn to put down the Reformation was surely to yearn to bring in catholicism--catholic teaching and catholic rites and catholic rule. We may not be catholics, but we are not entitled to say that from an impassioned catholic woman's point of view this was not a high ideal; it had been the ideal of the judicial mind, Sir Thomas More, as well as the ideal of the enthusiast, Ignatius Loyola; it had been for a thousand years the ideal of a multitude of noble natures both men and women. Elizabeth, opportunely enough, had no ideals of any kind; ideals indeed are often inconvenient in a ruler; but she had, despite her acrimonious speech, plenty of sincerely good wishes and good intentions for all the world. If the Queen of England had no ideals she had many devices, and one was to check the flow of all sorts of zeal, especially Protestant zeal. In the two lives religion told in different ways--the difference was in the two natures, be it noted, not in the two religions. Elizabeth, with a skin-deep religion only, was evenly and enduringly virtuous. Mary had ardent and deep convictions, but her career was not one of unbroken virtue. Elizabeth was certainly unfortunate in her religious attitudes. She did not like the Protestants for she was not a good Protestant; the Catholics did not like her for she was not a good Catholic. In religion, indeed as in all things, she was greatly influenced by her inborn spirit of "contrariness." If the Catholics had intrigued less persistently against her throne and her life, and if (the idea is sufficiently ludicrous) the Queen of Scotland had chanced to run in harness with the hated John Knox (hated of both queens), she would gladly have given the rein to her Catholic impulses. The two queens differed as much in body as in mind. I have elsewhere sought to show not only that certain leading features of character tend to run together (in itself a distinct contribution to our knowledge), but also that these allied features are associated with a group of bodily peculiarities, a contribution, if it really is a contribution, of greatly additional interest. Elizabeth, large and pink-skinned like her father, was by no means without impressiveness and even stateliness. She carried her head a little forward and her chin a little downward, both these positions being due to a slightly curved upper spine. Her hair was scanty and her eyebrows were practically absent. All these bodily items, as well as her mental items, she inherited from her father. Mary had a wholly different figure and a different presence; her head was upright, her spine straight; in her back there was no convexity either vertically or transversely. Her eyebrows were abundant and her head of hair was long and massive. All these peculiarities, too, we may be quite sure, she derived from her parentage (not necessarily the nearest parents) on one side or the other. In my little work on body and parentage in character I urge--it is well to say here--that the bodily signs of certain classes of character (two more marked and one intervening) are now and then subject to the modifying influences of ailment and accident, and especially when these happen in early life. In Elizabeth and Mary, however, no such influences disturbed the development of two strongly-marked examples, both in body and in character, of two large classes of women and, with but little alteration, of two large classes of men also. [FOR INDEX SEE FULL TABLE OF CONTENTS.] HALL & ENGLISH, Printers, No. 71, High Street, Birmingham. 
26438	----	_NATURE SERIES_ ARE THE EFFECTS OF USE AND DISUSE INHERITED? _AN EXAMINATION OF THE VIEW HELD BY SPENCER AND DARWIN_ BY WILLIAM PLATT BALL LONDON MACMILLAN AND CO. AND NEW YORK 1890 _The Right of Translation and Reproduction is Reserved_ RICHARD CLAY AND SONS, LIMITED, LONDON AND BUNGAY. PREFACE. My warmest thanks are due to Mr. Francis Darwin, to Mr. E. B. Poulton (whose interest in the subject here discussed is shown by his share in the translation of Weismann's _Essays on Heredity_), and to Professor Romanes, for the help afforded by their kindly suggestions and criticisms, and for the advice and recommendation under which this essay is now published. Encouragement from Mr. Francis Darwin is to me the more precious, and the more worthy of grateful recognition, from the fact that my general conclusion that acquired characters are _not_ inherited is at variance with the opinion of his revered father, who aided his great theory by the retention of some remains of Lamarck's doctrine of the inherited effect of habit. I feel as if the son, as representative of his great progenitor, were carrying out the idea of an appreciative editor who writes to me: "We must say that if Darwin were still alive, he would find your arguments of great weight, and undoubtedly would give to them the serious consideration which they deserve." I hope, then, that I may be acquitted of undue presumption in opposing a view sanctioned by the author of the _Origin of Species_, but already stoutly questioned and firmly rejected by such followers of his as Weismann, Wallace, Poulton, Ray Lankester, and others, to say nothing of its practical rejection by so great an authority on heredity as Francis Galton. The sociological importance of the subject has already been insisted on in emphatic terms by Mr. Herbert Spencer, and this importance may be even greater than he imagined. Civilization largely sets aside the harsh but ultimately salutary action of the great law of Natural Selection without providing an efficient substitute for preventing degeneracy. The substitute on which moralists and legislators rely--if they think on the matter at all--is the cumulative inheritance of the beneficial effects of education, training, habits, institutions, and so forth--the inheritance, in short, of acquired characters, or of the effects of use and disuse. If this substitute is but a broken reed, then the deeper thinkers who gradually teach the teachers of the people, and ultimately even influence the legislators and moralists, must found their systems of morality and their criticisms of social and political laws and institutions and customs and ideas on the basis of the Darwinian law rather than on that of Lamarck. Looking forward to the hope that the human race may become consciously and increasingly master of itself and of its destiny, and recognizing the Darwinian principle of the selection of the fittest as the _only_ means of preventing the moral and physical degeneracy which, like an internal dry rot, has hitherto been the besetting danger of all civilizations, I desire that the thinkers who mould the opinions of mankind shall not be led astray from the true path of enduring progress and happiness by reliance on fallacious beliefs which will not bear examination. Such, at least, is the feeling or motive which has prompted me to devote much time and thought to a difficult but important inquiry in a debatable region of inference and conjecture, where (I am afraid) evidence on either side can never be absolutely conclusive, and where, especially, the absolute demonstration of a universal negative cannot reasonably be expected. CONTENTS. PAGE PREFACE v IMPORTANCE AND BEARING OF THE INQUIRY 1 SPENCER'S EXAMPLES AND ARGUMENTS 6-44 DIMINUTION OF THE JAWS 6 DIMINISHED BITING MUSCLES OF LAP-DOGS 12 CROWDED TEETH 14 BLIND CAVE-CRABS 17 NO CONCOMITANT VARIATION FROM CONCOMITANT DISUSE 17 THE GIRAFFE, AND NECESSITY FOR CONCOMITANT VARIATION 18 ALLEGED RUINOUS EFFECTS OF NATURAL SELECTION 23 ADVERSE CASE OF NEUTER INSECTS 24 ÆSTHETIC FACULTIES 29 LACK OF EVIDENCE 34 INHERITED EPILEPSY IN GUINEA-PIGS 35 INHERITED INSANITY AND NERVOUS DISORDERS 36 INDIVIDUAL AND TRANSMISSIBLE TYPE NOT MODIFIED ALIKE 40 DARWIN'S EXAMPLES 45-100 REDUCED WINGS OF BIRDS OF OCEANIC ISLANDS 49 DROOPING EARS AND DETERIORATED INSTINCTS 53 WINGS AND LEGS OF DUCKS AND FOWLS 55 PIGEONS' WINGS 62 SHORTENED BREAST-BONE IN PIGEONS 64 SHORTENED FEET IN PIGEONS 70 SHORTENED LEGS OF RABBITS 70 BLIND CAVE-ANIMALS 72 INHERITED HABITS 73 TAMENESS OF RABBITS 76 MODIFICATIONS OBVIOUSLY ATTRIBUTABLE TO SELECTION 82 SIMILAR EFFECTS OF NATURAL SELECTION AND USE-INHERITANCE 83 INFERIORITY OF SENSES IN EUROPEANS 85 SHORT-SIGHT IN WATCHMAKERS AND ENGRAVERS 85 LARGER HANDS OF LABOURERS' INFANTS 87 THICKENED SOLE IN INFANTS 88 A SOURCE OF MENTAL CONFUSION 91 WEAKNESS OF USE-INHERITANCE 94 INHERITED INJURIES 101-118 INHERITED MUTILATIONS 101 THE MOTMOT'S TAIL 110 OTHER INHERITED INJURIES MENTIONED BY DARWIN 111 QUASI-INHERITANCE 116 MISCELLANEOUS CONSIDERATIONS 119-143 TRUE RELATION OF PARENTS AND OFFSPRING 119 INVERSE INHERITANCE 123 EARLY ORIGIN OF THE OVA 124 MARKED EFFECTS OF USE AND DISUSE ON THE INDIVIDUAL 126 WOULD NATURAL SELECTION FAVOUR USE-INHERITANCE? 127 USE-INHERITANCE AN EVIL 128 VARIED EFFECTS OF USE AND DISUSE 134 USE-INHERITANCE IMPLIES PANGENESIS 137 PANGENESIS IMPROBABLE 138 SPENCER'S EXPLANATION OF USE-INHERITANCE 141 CONCLUSIONS 144-156 USE-INHERITANCE DISCREDITED AS UNNECESSARY, UNPROVEN, AND IMPROBABLE 144 MODERN RELIANCE ON USE-INHERITANCE MISPLACED 145 ARE THE EFFECTS OF USE AND DISUSE INHERITED? IMPORTANCE AND BEARING OF THE INQUIRY. The question whether the effects of use and disuse are inherited, or, in other words, whether acquired characters are hereditary, is of considerable interest to the general student of evolution; but it is, or should be, a matter of far deeper interest to the thoughtful philanthropist who desires to ensure the permanent welfare and happiness of the human race. So profoundly important, in fact, are the moral, social, and political conclusions that depend on the answer to this inquiry, that, as Mr. Herbert Spencer rightly says, it "demands, beyond all other questions whatsoever, the attention of scientific men." It is obvious that we can produce important changes in the individual. We can, for example, improve his muscles by athletics, and his brain by education. The use of organs enlarges and strengthens them; the disuse of parts or faculties weakens them. And so great is the power of habit that it is proverbially spoken of as "second nature." It is thus certain that we can modify the individual. We can strengthen (or weaken) his body; we can improve (or deteriorate) his intellect, his habits, his morals. But there remains the still more important question which we are about to consider. Will such modifications be inherited by the offspring of the modified individual? Does individual improvement transmit itself to descendants independently of personal teaching and example? Have artificially produced changes of structure or habit any inherent tendency to become congenitally transmissible and to be converted in time into fixed traits of constitution or character? Can the philanthropist rely on such a tendency as a hopeful factor in the evolution of mankind?--the only sound and stable basis of a higher and happier state of things being, as he knows or ought to know, the innate and constitutionally-fixed improvement of the race as a whole. If acquired modifications are impressed on the offspring and on the race, the systematic moral training of individuals will in time produce a constitutionally moral race, and we may hope to improve mankind even in defiance of the unnatural selection by which a spurious but highly popular philanthropy would systematically favour the survival of the unfittest and the rapid multiplication of the worst. But if acquired modifications do not tend to be transmitted, if the use or disuse of organs or faculties does not similarly affect posterity by inheritance, then it is evident that no innate improvement in the race can take place without the aid of natural or artificial selection. Herbert Spencer maintains that the effects of use and disuse _are_ inherited in kind, and in his _Factors of Organic Evolution_[1] he has supported his contention with a selection of facts and reasonings which I shall have the temerity to examine and criticize. Darwin also held the same view, though not so strongly. And here, to prevent misunderstanding, I may say that the admiration and reverence and gratitude due to Darwin ought not to be allowed to interfere in the slightest degree with the freest criticism of his conclusions. To perfect his work by the correction of really extraneous errors is as much a sacred duty as to study and apply the great truths he has taught. FOOTNOTES: [1] Which originally appeared in the _Nineteenth Century_ for April and May, 1886. SPENCER'S EXAMPLES AND ARGUMENTS. DIMINUTION OF THE JAWS IN CIVILIZED RACES. Mr. Spencer verified this by comparing English jaws with Australian and Negro jaws at the College of Surgeons.[2] He maintains that the diminution of the jaw in civilized races can _only_ have been brought about by inheritance of the effects of lessened use. But if English jaws are lighter and thinner than those of Australians and Negroes, so too is the rest of the skull. As the diminution in the weight and thickness of the walls of the cranium cannot well be ascribed to disuse, it must be attributed to some other cause; and this cause may have affected the jaw also. Cessation of the process by which natural selection[3] favoured strong thick bones during ages of brutal violence might bring about a change in this direction. Lightness of structure, facilitating agility and being economical of material, would also be favoured by natural selection so far as strength was not too seriously diminished. Sexual selection powerfully affects the human face, and so must affect the jaws--as is shown by the differences between male and female jaws, and by the relative lightness and smallness of the latter, especially in the higher races. Human preference, both sexual and social, would tend to eliminate huge jaws and ferocious teeth when these were no longer needed as weapons of war or organs of prehension, &c. We can hardly assume that the lower half of the face is specially exempt from the influence of natural and sexual selection; and the effects of these undoubted factors of evolution must be fully considered before we are entitled to call in the aid of a factor whose existence is questioned. After allowing for lost teeth and the consequent alveolar absorption, and for a reduction proportional to that shown in the rest of the skull, the difference in average weight in fifty European and fourteen Australian male jaws at the College of Surgeons turned out to be less than a fifth of an ounce, or about 5 per cent. This slight reduction may be much more than accounted for by such causes as disuse in the individual, human preference setting back the teeth, and partial transference of the much more marked diminution seen in female jaws. There is apparently no room for accumulated _inherited_ effects of ancestral disuse. The number of jaws is small, indeed; but weighing them is at least more decisive than Mr. Spencer's mere inspection. The differences between Anglo-Saxon male jaws and Australian and Tasmanian jaws are most easily explained as effects of human preference and natural selection. We can hardly suppose that disuse would maintain or develop the projecting chin, increase its perpendicular height till the jaw is deepest and strongest at its extremity, evolve a side flange, and enlarge the upper jaw-bone to form part of a more prominent nose, while drawing back the savagely obtrusive teeth and lips to a more pleasing and subdued position of retirement and of humanized beauty. If human preference and natural selection caused some of these differences, why are they incompetent to effect changes in the direction of a diminution of the jaw or teeth? And if use and disuse are the sole modifying agents in the case of the human jaw, why should men have any more chin than a gorilla or a dog? The excessive weight of the West African jaws at the College of Surgeons is partly _against_ Mr. Spencer's contention, unless he assumes that Guinea Negroes use their jaws far more than the Australians, a supposition which seems extremely improbable. The heavier skull and narrower molar teeth point however to other factors than increased use. The striking variability of the human jaw is strongly opposed to the idea of its being under the direct and dominant control of so uniform a cause as ancestral use and disuse. Mr. Spencer regards a variation of 1 oz. as a large one, but I found that the English jaws in the College of Surgeons varied from 1·9 oz. to 4·3 oz. (or 5 oz. if lost teeth were allowed for); Australian jaws varied from 2 oz. to 4·5 oz. (with _no_ lost teeth to allow for); while in Negro jaws the maximum rose to over 5-1/2 oz.[4] In spite of disuse some European jaws were twice as heavy as the lightest Australian jaw, either absolutely or (in some cases) relatively to the cranium. The uniformity of change relied upon by Mr. Spencer is scarcely borne out by the facts so far as male jaws are concerned. The great reduction in the weight of _female_ jaws _and skulls_ evidently points to sexual selection and to panmixia under male protection. I think, on the whole, we must conclude that the human jaws do not afford satisfactory proof of the inheritance of the effects of use and disuse, inasmuch as the differences in their weight and shape and size can be more reasonably and consistently accounted for as the result of less disputable causes. DIMINISHED BITING MUSCLES OF LAP-DOGS. The next example, the reduced biting muscles, &c., of lap-dogs is also unsatisfactory as a proof of the inheritance of the effects of disuse; for the change can readily be accounted for without the introduction of such a factor. The previous natural selection of strong jaws and teeth and muscles is reversed. The conscious or unconscious selection of lap-dogs with the least tendency to bite would easily bring about a general enfeeblement of the whole biting apparatus--weakness of the parts concerned favouring harmlessness. Mr. Spencer maintains that the dwindling of the parts concerned in clenching the jaw is certainly not due to artificial selection because the modifications offer no appreciable external signs. Surely hard biting is sufficiently appreciable by the person bitten without any visual admeasurement of the masseter muscles or the zygomatic arches. Disuse during lifetime would also cause some amount of degeneracy; and I am not sure that Mr. Spencer is right in _entirely_ excluding economy of nutrition from the problem. Breeders would not over-feed these dogs; and the puppies that grew most rapidly would usually be favoured. CROWDED TEETH. The too closely-packed teeth in the "decreasing" jaws of modern men (p. 13)[5] are also suggestive of other causes than use and disuse. Why is there not simultaneous variation in teeth and jaws, if disuse is the governing factor? Are we to suppose that the size of the human teeth is maintained by use at the same time that the jaws are being diminished by disuse? Mr. Spencer acknowledges that the crowding of bull-dogs' and lap-dogs' teeth is caused by the artificial selection of shortened jaws. If a similar change is really occurring in man, could it not be similarly explained by some factor, such as sexual selection, which might affect the outward appearance at the cost of less obvious defects or inconveniences? Mr. Spencer points to the decay of modern teeth as a sign or result of their being overcrowded through the diminution of the jaw by disuse.[6] But the teeth which are the most frequently overcrowded are the lower incisors. The upper incisors are less overcrowded, being commonly pressed outwards by the lower arc of teeth fitting inside them in biting. The lower incisors are correspondingly pressed inwards and closer together. Yet the upper incisors decay--or at least are extracted--about twenty times as frequently as the closely packed lower incisors.[7] Surely this must indicate that the cause of decay is not overcrowding. The lateness and irregularity of the wisdom teeth are sometimes supposed to indicate their gradual disappearance through want of room in a diminishing jaw. But a note on Tasmanian skulls in the _Catalogue of the College of Surgeons_ (p. 199) shows that this lateness and irregularity have been common among Tasmanians as well as among civilized races, so that the change can hardly be attributed to the effects of disuse under civilization. BLIND CAVE-CRABS. The cave-crabs which have lost their disused eyes but _not the disused eye-stalks_ appear to illustrate the effects of natural selection rather than of disuse. The loss of the exposed, sensitive, and worse-than-useless eye, would be a decided gain, while the disused eye-stalk, being no particular detriment to the crab, would be but slightly affected by natural selection, though open to the cumulative effects of disuse. The disused but better protected eyes of the blind cave-rat are still "of large size" (_Origin of Species_, p. 110). NO CONCOMITANT VARIATION FROM CONCOMITANT DISUSE. It is but fair to add that these instances of the cave-crab's eye-stalk and the closely-packed teeth are put forward by Mr. Spencer with the more immediate object of proving that there is "no concomitant variation in co-operative parts," even when "formed out of the same tissue, like the crab's eye and its peduncle" (pp. 12-14, 23, 33). It escapes his notice, however, that in two out of his three cases it is _disuse_, or _diminished use_, which fails to cause concomitant variation or proportionate variation. THE GIRAFFE, AND NECESSITY FOR CONCOMITANT VARIATION. Having unwittingly shown that lessened use of closely-connected and co-operative parts does not cause concomitant variation in these parts, Mr. Spencer concludes that the concomitant variation requisite for evolution can only be caused by altered degrees of use or disuse. He elaborately argues that the many co-ordinated modifications of parts necessitated by each important alteration in an animal are so complex that they cannot possibly be brought about except by the inherited effect of the use and disuse of the various parts concerned. He holds, for instance, that natural selection is inadequate to effect the numerous concomitant changes necessitated by such developments as that of the long neck of the giraffe. Darwin, however, on the contrary, holds that natural selection alone "would have sufficed for the production of this remarkable quadruped."[8] He is surprised at Mr. Spencer's view that natural selection can do so little in modifying the higher animals. Thus one of the chief arguments with which Mr. Spencer supports his theory is so poorly founded as to be rejected by a far greater authority on such subjects. All that is needed is that natural selection should preserve the tallest giraffes through times of famine by their being able to reach otherwise inaccessible stores of foliage. The continual variability of all parts of the higher animals gives scope for innumerable changes, and Nature is not in a hurry. Mr. Spencer, however, says that "the chances against any adequate readjustments fortuitously arising must be infinity to one." But he has also shown that altered degree of use does not cause the needed concomitant variation of co-operative parts. So the chances against a beneficial change in an animal must be, at a liberal estimate, infinity to two. Mr. Spencer, if he has proved anything, has proved that it is practically impossible that the giraffe can have acquired a long neck, or the elk its huge horns, or that any species has ever acquired any important modification. Mr. Wallace, in his _Darwinism_, answers Mr. Spencer by a collection of facts showing that "variation is the rule," that the range of variation in wild animals and plants is much greater than was supposed, and that "each part varies to a considerable extent independently" of other parts, so that "the materials constantly ready for natural selection to act upon are abundant in quantity and very varied in kind." While co-operative parts would often be more or less correlated, so that they would tend to vary together, coincident variation is not necessary. The lengthened wing might be gained in one generation, and the strengthened muscle at a subsequent period; the bird in the meanwhile drawing upon its surplus energy, aided (as I would suggest) by the strengthening effect of increased use in the individual. Seeing that artificial selection of complicated variations has modified animals in many points either simultaneously or by slow steps, as with otter-sheep, fancy pigeons, &c. (many of the characters thus obtained being clearly independent of use and disuse), natural selection must be credited with similar powers, and Mr. Wallace concludes that Mr. Spencer's insuperable difficulty is "wholly imaginary." The extract concerning a somewhat similar "class of difficulties," which Mr. Spencer quotes from his _Principles of Biology_, is faulty in its reasoning,[9] though legitimate in its conclusion concerning the increasing difficulty of evolution in proportion with the increasing number and complexity of faculties to be evolved. But this increasing difficulty of complex evolution is only overcome by _some_ favourably-varying individuals and species--not by all. And as the difficulty increases we find neglect and decay of the less-needed faculties--as with domesticated animals and civilized men, who lose in one direction while they gain in another. The increasing difficulty of complex evolution by natural selection is no proof whatever of use-inheritance[10] except to those who confound difficulty with impossibility. ALLEGED RUINOUS EFFECTS OF NATURAL SELECTION. Mr. Spencer further contends that natural selection, by unduly developing specially advantageous modifications without the necessary but complex secondary modifications, would render the constitution of a variety "unworkable" (p. 23). But this seems hardly feasible, seeing that natural selection must continually favour the most workable constitutions, and will only preserve organisms in proportion as they combine general workableness with the special modification. On the other hand, according to Mr. Spencer himself, use-inheritance must often disturb the balance of the constitution. Thus it tends to make the jaws and teeth unworkable through the overcrowding and decay of the teeth--there being, as his illustrations show, no simultaneous or concomitant or proportional variation in relation to altered degree of use or disuse. ADVERSE CASE OF NEUTER INSECTS. Mr. Spencer also holds that most mental phenomena, especially where complex or social or moral, can only be explained as arising from use-inheritance, which becomes more and more important as a factor of evolution as we advance from the vegetable world and the lower grades of animal life to the more complex activities, tastes, and habits of the higher organizations (preface, and p. 74). But there happens to be a tolerably clear proof that such changes as the evolution of complicated structures and habits and social instincts _can_ take place independently of use-inheritance. The wonderful instincts of the working bees have apparently been evolved (at least in all their later social complications and developments) without the aid of use-inheritance--nay, in spite of its utmost opposition. Working bees, being infertile "neuters," cannot as a rule transmit their own modifications and habits. They are descended from countless generations of queen bees and drones, whose habits have been widely different from those of the workers, and whose structures are dissimilar in various respects. In many species of ants there are two, and in the leaf-cutting ants of Brazil there are _three_, kinds of neuters which differ from each other and from their male and female ancestors "to an almost incredible degree."[11] The soldier caste is distinguished from the workers by enormously large heads, very powerful mandibles, and "extraordinarily different" instincts. In the driver ant of West Africa one kind of neuter is three times the size of the other, and has jaws nearly five times as long. In another case "the workers of one caste alone carry a wonderful sort of shield on their heads." One of the three neuter classes in the leaf-cutting ants has a single eye in the midst of its forehead. In certain Mexican and Australian ants some of the neuters have huge spherical abdomens, which serve as living reservoirs of honey for the use of the community. In the equally wonderful case of the termites, or so-called "white ants" (which belong, however, to an entirely different order of insect from the ants and bees) the neuters are blind and wingless, and are divided into soldiers and workers, each class possessing the requisite instincts and structures adapting it for its tasks. Seeing that natural selection can form and maintain the various structures and the exceedingly complicated instincts of ants and bees and wasps and termites in direct defiance of the alleged tendency to use-inheritance, surely we may believe that natural selection, unopposed by use-inheritance, is equally competent for the work of complex or social or mental evolution in the many cases where the strong presumptive evidence cannot be rendered almost indisputable by the exceptional exclusion of the modified animal from the work of reproduction. Ants and bees seem to be capable of altering their habits and methods of action much as men do. Bees taken to Australia cease to store honey after a few years' experience of the mild winters. Whole communities of bees sometimes take to theft, and live by plundering hives, first killing the queen to create dismay among the workers. Slave ants attend devotedly to their captors, and fight against their own species. Forel reared an artificial ant-colony made up of five different and more or less hostile species. Why cannot a much more intelligent animal modify his habits far more rapidly and comprehensively without the aid of a factor which is clearly unnecessary in the case of the more intelligent of the social insects? ÆSTHETIC FACULTIES. The modern development of music and harmony (p. 19) is undeniable, but why could it only have been brought about by the help of the inheritance of the effects of use? Why are we to suppose that "minor traits" such as the "æsthetic perceptions" cannot have been evolved by natural selection (p. 20) or by sexual selection? Darwin holds that our musical faculties were developed by sexual preference long before the acquisition of speech. He believes that the "rhythms and cadences of oratory are derived from previously developed musical powers"--a conclusion "exactly opposite" to that arrived at by Mr. Spencer.[12] The emotional susceptibility to music, and the delicate perceptions needed for the higher branches of art, were apparently the work of natural and sexual selection in the long past. Civilization, with its leisure and wealth and accumulated knowledge, perfects human faculties by artificial cultivation, develops and combines means of enjoyment, and discovers unsuspected sources of interest and pleasure. The sense of harmony, modern as it seems to be, must have been a latent and indirect consequence of the development of the sense of hearing and of melody. Use, at least, could never have called it into existence. Nature favours and develops enjoyments to a certain extent, for they subserve self-preservation and sexual and social preference in innumerable ways. But modern æsthetic advance seems to be almost entirely due to the culture of latent abilities, the formation of complex associations, the selection and encouragement of talent, and the wide diffusion and imitation of the accumulated products of the well-cultivated genius of favourably varying individuals. The fact that uneducated persons do not enjoy the higher tastes, and the rapidity with which such tastes are acquired or professed, ought to be sufficient proof that modern culture is brought about by far swifter and more potent influences than use-inheritance. Neither would this hypothetical factor of evolution materially aid in explaining the many other rapid changes of habit brought about by education, custom, and the changed conditions of civilization generally. Powerful tastes--as is incontestably shown in the cases of alcohol and tobacco--lie latent for ages, and suddenly become manifest when suitable conditions arise. Every discovery, and each step in social and moral evolution, produces its wide-spreading train of consequences. I see no reason why use-inheritance need be credited with any share in the cumulative results of the invention of printing and the steam-engine and gunpowder, or of freedom and security under representative government, or of science and art and the partial emancipation of the mind of man from superstition, or of the innumerable other improvements or changes that take place under modern civilization. Mr. Spencer suggests an inquiry whether the greater powers possessed by eminent musicians were not mainly due to the inherited effect of the musical practice of their fathers (p. 19). But these great musicians inherited far more than their parents possessed. The excess of their powers beyond their parents' must surely be attributed to spontaneous variation; and who shall say that the rest was in any way due to use-inheritance? If, too, the superiority of geniuses proves use-inheritance, why should not the inferiority of the sons of geniuses prove the existence of a tendency which is the exact opposite of use-inheritance? But nobody collects facts concerning the degenerate branches of musical families. Only the favourably varying branches are noticed, and a general impression of rapid evolution of talent is thus produced. Such cases might be explained, too, by the facts that musical faculty is strong in both sexes, that musical families associate together, and that the more gifted members may intermarry. Great musicians are often astonishingly precocious. Meyerbeer "played brilliantly" at the age of six. Mozart played beautifully at four. Are we to suppose that the effect of the _adult_ practice of parents was inherited at this early age? If use-inheritance was not necessary in the case of Handel, whose father was a surgeon, why is it needed to account for Bach? LACK OF EVIDENCE. The "direct proofs" of use-inheritance are not as plentiful as might be desired, it appears (pp. 24-28). This acknowledged "lack of recognized evidence" is indeed the weakest feature in the case, though Mr. Spencer would fain attribute this lack of direct proof to insufficient investigation and to the inconspicuous nature of the inheritance of the modification. But there is an almost endless abundance of conspicuous examples of the effects of use and disuse in the individual. How is it that the subsequent inheritance of these effects has not been more satisfactorily observed and investigated? Horse-breeders and others could profit by such a tendency, and one cannot help suspecting that the reason they ignore it must be its practical inefficacy, arising probably from its weakness, its obscurity and uncertainty or its non-existence. INHERITED EPILEPSY IN GUINEA-PIGS. Brown-Séquard's discovery that an epileptic tendency artificially produced by mutilating the nervous system of a guinea-pig is occasionally inherited may be a fact of "considerable weight," or on the other hand it may be entirely irrelevant. Cases of this kind strike one as peculiar exceptions rather than as examples of a general rule or law. They seem to show that certain morbid conditions may occasionally affect both the individual and the reproductive elements or transmissible type in a similar manner; but then we also know that such prompt and complete transmission of an artificial modification is widely different from the usual rule. Exceptional cases require exceptional explanations, and are scarcely good examples of the effect of a general tendency which in almost all other cases is so inconspicuous in its immediate effects. Further remarks on this inherited epilepsy can be most conveniently introduced later on in connection with Darwin's explanation of the inherited mutilation which it usually accompanies, but which Mr. Spencer does not mention. INHERITED INSANITY AND NERVOUS DISORDERS. Mr. Spencer infers that, because insanity is usually hereditary, and insanity can be artificially produced by various excesses, therefore this artificially-produced insanity must also be hereditary (p. 28). Direct evidence of this conclusion would be better than a mere inference which may beg the very question at issue. That the liability to insanity commonly runs in families is no proof that strictly non-inherited insanity will subsequently become hereditary. I think that theories should be based on facts rather than facts on theories, especially when those facts are to be the basis or proof of a further theory. Mr. Spencer also points out that he finds among physicians "the belief that nervous disorders of a less severe kind are inheritable"--a general belief which does not necessarily include the transmission of purely artificially-produced disorders, and so misses the point which is really at issue. He proceeds, however, to state more definitely that "men who have prostrated their nervous systems by prolonged overwork or in some other way, have children more or less prone to nervousness." The following observations will, I think, warrant at least a suspension of judgment concerning this particular form of use-inheritance. (1) The nervousness is seen in the _children_ at an early age, although the nervous prostration from which it is supposed to be derived obviously occurs in the parent at a much later period of life. This change in time is contrary to the rule of inheritance at corresponding periods; and, together with the unusual promptness and comparative completeness of the inheritance, it may indicate a special injury or deterioration of the reproductive elements rather than true inheritance. The healthy brain of early life has failed to transmit its robust condition. Is use-inheritance, then, only effective for evil? Does it only transfer the newly-acquired weakness, and not the previous long-continued vigour? (2) Members of nervous families would be liable to suffer from nervous prostration, and by the ordinary law of heredity alone would transmit nervousness to their children. (3) The shattered nerves or insanity resulting from alcoholic and other excesses, or from overwork or trouble, are evidently signs of a grave constitutional injury which may react upon the reproductive elements nourished and developed in that ruined constitution. The deterioration in parent and child may often display itself in the same organs--those probably which are hereditarily weakest. Acquired diseases or disorders thus appear to be transmitted, when all that was conveyed to the offspring was the exciting cause of a lowered vitality or disordered action, together with the ancestral liability to such diseases under such conditions. (4) Francis Galton says that "it is hard to find evidence of the power of the personal structure to react upon the sexual elements, that is not open to serious objection." Some of the cases of apparent inheritance he regards as coincidence of effect. Thus "the fact that a drunkard will often have imbecile children, although his offspring previous to his taking to drink were healthy," is an "instance of simultaneous action," and not of true inheritance. "The alcohol pervades his tissues, and, of course, affects the germinal matter in the sexual elements as much as it does that in his own structural cells, which have led to an alteration in the quality of his own nerves. Exactly the same must occur in the case of many constitutional diseases that have been acquired by long-continued irregular habits."[13] INDIVIDUAL AND TRANSMISSIBLE TYPE NOT MODIFIED ALIKE BY THE DIRECT EFFECT OF CHANGED HABITS OR CONDITIONS. Mr. Spencer finds it hard to believe that the modifications conveyed to offspring are not identical in tendency with the changes effected in the parent by altered use or habit (pp. 23-25, 34). But it is perfectly certain that the two sets of effects do not necessarily correspond. The effect of changed habits or conditions on the individual is often very far from coinciding with the effects on the reproductive elements or the transmissible type. The reproductive system is "extremely sensitive" to very slight changes, and is often powerfully affected by circumstances which otherwise have little effect on the individual (_Origin of Species_, p. 7). Various animals and plants become sterile when domesticated or supplied with too much nourishment. The native Tasmanians have already become extinct from sterility caused by greatly changed diet and habits. If, as Mr. Spencer teaches, continued culture and brain-work will in time produce lessened fertility or comparative sterility, we may yet have to be careful that intellectual development does not become a species of suicide, and that the culture of the race does not mean its extinction--or at least the extinction of those most susceptible of culture. The reproductive elements are also disturbed and modified in innumerable minor ways. Changed conditions or habits tend to produce a general "plasticity" of type, the "indefinite variability" thus caused being apparently irrelevant to the change, if any, in the individual.[14] A vast number of variations of structure have certainly arisen independently of similar parental modification as the preliminary. Whatever first caused these "spontaneous" congenital variations affected the reproductive elements quite differently from the individual. "When a new peculiarity first appears we can never predict whether it will be inherited." Many varieties of plants only keep true from shoots, and not from seed, which is by no means acted on in the same way as the individual plant. Seeing that such plants have _two_ reproductive types, both constant, it is evident that these cannot both be modified in the same way as the parent is modified. Many parental modifications of structure and habit are certainly not conveyed to neuter ants and bees; other modifications, which are not seen in the parents, being conveyed instead. Many other circumstances tend to show that the individual and the transmissible type are independent of each other so far as modifications of parts are concerned. It may seem natural to expect the transmission of an enlarged muscle or a cultivated brain, but, on the other hand, why should it be unreasonable to expect that a modification which was non-congenital in origin should still remain non-congenital? Why should the non-transmission of that which was not transmitted be surprising? Mr. Spencer thinks that the non-transmission of acquired modifications is incongruous with the great fact of atavism. But the great law of the inheritance of that which is a development of the transmissible type does not necessarily imply the inheritance of modifications acquired by the individual. Because English children may inherit blue eyes and flaxen hair from their Anglo-Saxon ancestors, it by no means follows that an Englishman must inherit his father's sunburnt complexion or smooth-shaven face. Of course atavism ultimately adopts many instances of revolt against its sway. But to assume that these changes of type _follow_ the personal change rather than cause it, is to assume the whole question at issue. That like begets like is true as a broad principle, but it has many exceptions, and the non-heredity of acquired characters may be one of them. FOOTNOTES: [2] _Principles of Biology_, § 166, footnote. The English jaws are somewhat lighter than the Australian jaws, though I could not undertake to affirm that they are really shorter and smaller. In the typical skulls depicted on p. 68 of the official guide to the mammalian galleries at South Kensington, the typical Caucasian jaw is very much larger than the Tasmanian jaw, although the repulsively obtrusive teeth of the latter convey the contrary idea to the imagination. Mr. Spencer's assumption that the ancient Britons had large jaws appears to me erroneous. (See Professor Rolleston's _Scientific Papers and Addresses_, i. p. 250.) [3] Romanes, Galton, and Weismann have made great use of this principle in explaining the diminution of disused organs. Weismann has given it the name of _Panmixia_,--_all_ individuals being equally free to survive and commingle their variations, and not merely selected or favoured individuals. See his _Essays on Heredity_, &c., p. 90 (Clarendon Press). [4] Inclusive in each case of fixed strengthening wire weighing about a sixteenth of an ounce or less. [5] References of course are to _Factors of Organic Evolution_. [6] P. 13; and _Nineteenth Century_, February, 1888, p. 211. [7] Tomes's _Dental Surgery_, pp. 273-275. Tomes observes that it is as yet uncertain in what way civilization predisposes to caries. But he shows that caries is caused by the lime salts in the teeth being attacked by _acids_ from decomposing food in crevices, from artificial drink such as cyder, from sugar, from medicine, and from vitiated secretions of the mouth. It is evident that in civilized races natural selection cannot so rigorously insist on sound teeth, sound constitutions, and _protective alkaline_ saliva. The reaction of the civilized mouth is often acid, especially when the system is disordered by dyspepsia or other diseases or forms of ill-health common under civilization. The main supply of saliva, which is poured from the cheeks opposite the upper molars, is often acid when in small quantities. But the submaxillary and sub-lingual saliva poured out at the foot of the lower incisors and held in the front part of the jaw as in a spoon, "differs from parotid saliva in being more alkaline" (Foster's _Text Book of Physiology_, p. 238; Tomes, pp. 284, 685). One observer says that the reaction near the lower incisors is "never acid." Hence (I conclude) the remarkable immunity of the lower incisors and canines from decay, an immunity which extends backwards in a lessening degree to the first and second bicuspids. The close packing of the lower incisors may assist by preventing the retention of decaying fragments of food. Sexual selection may promote caries by favouring white teeth, which are more prone to decay than yellow ones. Acid vitiation of the mucus might account both for caries and (possibly) for the strange infertility of some inferior races under civilization. [8] _Origin of Species_, pp. 198-9; _Variation of Animals and Plants under Domestication_, vol. ii. p. 328 footnote, also p. 206. [9] Mr. Spencer weakly argues that an advantageous attribute (such as swiftness, keen sight, courage, sagacity, strength, &c.) cannot be increased by natural selection unless it is "of greater importance, for the time being, than most of the other attributes"; and that natural selection cannot develop any one superiority when animals are equally preserved by "other superiorities." But as natural selection will simultaneously eliminate tendencies to slowness, blindness, deafness, stupidity, &c., it _must_ favour and improve many points simultaneously, although no one of them may be of greater importance than the rest. Of course the more complicated the evolution the slower it will be; but time is plentiful, and the amount of elimination is correspondingly vast. [10] I venture to coin this concise term to signify _the direct inheritance of the effects of use and disuse in kind_. Having a name for a thing is highly convenient; it facilitates clearness and accuracy in reasoning, and in this particular inquiry it may save some confusion of thought from double or incomplete meanings in the shortened phrases which would otherwise have to be employed to indicate this great but nameless factor of evolution. [11] _Origin of Species_, pp. 230-232; Bates's _Naturalist on the Amazons_. Darwin is "surprised that no one has hitherto advanced the demonstrative case of neuter insects, against the well-known doctrine of inherited habit, as advanced by Lamarck." As he justly observes, "it proves that with animals, as with plants, any amount of modification may be effected by the accumulation of numerous, slight, spontaneous variations, which are in any way profitable, without exercise or habit having been brought into play. For peculiar habits confined to the workers or sterile females, however long they might be followed, could not possibly affect the males and fertile females, which alone leave any descendants." Some slight modification of these remarks, however, may possibly be needed to meet the case of "factitious queens," who (probably through eating particles of the royal food) become capable of producing a few male eggs. [12] _Descent of Man_, pp. 573, 572, and footnote. [13] _Contemporary Review_, December, 1875, p. 92. [14] See _Origin of Species_, pp. 5-8. "Changed conditions induce an almost indefinite amount of fluctuating variability, by which the whole organization is rendered in some degree plastic" (_Descent of Man_, p. 30). It also appears that "the nature of the conditions is of subordinate importance in comparison with the nature of the organism in determining each particular form of variation;--perhaps of not more importance than the nature of the spark, by which a mass of combustible matter is ignited, has in determining the nature of the flames" (_Origin of Species_, p. 8). DARWIN'S EXAMPLES. The most formidable cases brought forward by Mr. Spencer are from Darwin. I shall endeavour to show, however, that Darwin was probably wrong in retaining the older explanation of these facts, and that the remains of the Lamarckian theory of use-inheritance need not any longer encumber the great explanation which has superseded that fallacious and unproven theory and has rendered it totally unnecessary. Meanwhile I think it is an excellent sign that Mr. Spencer has to complain that "Nowadays most naturalists are more Darwinian than Mr. Darwin himself"--inasmuch as they are inclined to say that there is "no proof" that the effects of use and disuse are inherited. Other excellent signs are the recent issue of a translation of Weismann's important essays on this and kindred subjects,[15] the strong support given to his views by Wallace in his _Darwinism_, and their adoption by Ray Lankester in his article on Zoology in the latest edition of the _Encyclopædia Britannica_. So sound and cautious an investigator as Francis Galton had also in 1875 concluded that "acquired modifications are barely, if at all, _inherited_, in the correct sense of that word." Darwin's belief in the inheritance of acquired characters was more or less hereditary in the family. His grandfather, Erasmus Darwin, anticipated Lamarck's views in his _Zoonomia_, which Darwin at one time "greatly admired." His father was "convinced" of the "inherited evil effects of alcohol," and to this extent at least he strongly impressed the belief in the inheritance of acquired characters upon his children's minds.[16] Darwin must also have been imbued with Lamarckian ideas from other sources, although Dr. Grant's enthusiastic advocacy entirely failed to convert him to a belief in evolution.[17] "Nevertheless," he says, "it is probable that the hearing rather early in life such views maintained and praised may have favoured my upholding them under a different form in my _Origin of Species_"--a remark which refers to Lamarck's views on the general doctrine of evolution, but might also prove equally true if applied to Darwin's partial retention of the Lamarckian explanation of that evolution. Professor Huxley has pointed out that in Darwin's earlier sketch of his theory of evolution (1844) he attached more weight to the inheritance of acquired habits than he does in his _Origin of Species_ published fifteen years later.[18] He appears to have acquired the belief in early life without first questioning and rigorously testing it as he would have done had it originated with himself. In later life it appeared to assist his theory of evolution in minor points, and in particular it appeared absolutely indispensable to him as the _only_ explanation of the diminution of disused parts in cases where, as in domestic animals, economy of growth seemed to be practically powerless. He failed to adequately notice the effect of panmixia, or the withdrawal of selection, in causing or allowing degeneracy and dwindling under disuse; and he hardly attached sufficient importance to the fact that rudimentary organs and other supposed effects of use or disuse are quite as marked features in neuter insects which cannot transmit the effects of use and disuse as they are in the higher animals. REDUCED WINGS OF BIRDS OF OCEANIC ISLANDS. Darwin himself has pointed out that the rudimentary wings of island beetles, at first thought to be due to disuse, are mainly brought about by natural selection--the best-winged beetles being most liable to be blown out to sea. But he says that in birds of the oceanic islands "not persecuted by any enemies, the reduction of their wings has probably been caused by disuse." This explanation may be as fallacious as it is acknowledged to have been in the case of the island beetles. According to Darwin's own views, natural selection _must_ at least have played an important part in reducing the wings; for he holds that "natural selection is continually trying to economize every part of the organization." He says: "If under changed conditions of life a structure, before useful, becomes less useful, its diminution will be favoured, for it will profit the individual not to have its nutriment wasted in building up an useless structure.... Thus, as I believe, natural selection will tend in the long run to reduce any part of the organization, as soon as it becomes, through changed habits, superfluous."[19] If, as Darwin powerfully urges (and he here ignores his usual explanation), ostriches' wings are insufficient for flight in consequence of the economy enforced by natural selection,[20] why may not the reduced wings of the dodo, or the penguin, or the apteryx, or of the Cursores generally, be wholly attributed to natural selection in favour of economy of material and adaptation of parts to changed conditions? The great principle of economy is continually at work shaping organisms, as sculptors shape statues, by removing the superfluous parts; and a mere glance at the forms of animals in general will show that it is well-nigh as dominant and universal a principle as is that of the positive development of useful parts. Other causes, moreover besides actual economy, would favour shorter and more convenient wings on oceanic islands. In the first place, birds that were somewhat weak on the wing would be most likely to settle on an island and stay there. Shortened wings would then become advantageous because they would restrain fatal migratory tendencies or useless and perilous flights in which the birds that flew furthest would be most often carried away by storms and adverse winds. Reduced wings would keep the birds near the shelter and the food afforded by the island and its neighbourhood, and in some cases would become adapted to act as fins or flappers for swimming under water in pursuit of fish. The reduced size of the wings of these island birds is paralleled by the remarkable thinness, &c., of the shell of the "gigantic land-tortoise" of the Galapagos Islands. The changes seen in the carapace can hardly have been brought about by the inherited effects of special disuse. Why then should not the reduction of equally useless, more wasteful, and perhaps positively dangerous wings be also due to an economy which has become advantageous to bird and reptile alike through the absence of the mammalian rivals whose places they are evidently being modified to fill? The _complete_ loss of the wings in neuter ants and termites can scarcely be due to the inherited effects of disuse; and as natural selection has abolished these wings in spite of the opposition of use-inheritance, it must clearly be fully competent to reduce wings without its aid. In considering the rudimentary wings of the apteryx, or of the moa, emu, ostrich, &c., we must not forget the frequent or occasional occurrence of hard seasons, and times of drought and famine, when Nature eliminates redundant, wasteful, and ill-adapted organisms in so severe and wholesale a fashion. Where enemies are absent there would be unrestrained multiplication, and this would greatly increase the severity of the competition for food, and so hasten the elimination of disused and useless parts. DROOPING EARS AND DETERIORATED INSTINCTS. Mr. Galton has pointed out that existing races and existing organs are only kept at their present high pitch of organic excellence by the stringent and incessant action of natural or artificial selection; and the simple relaxation or withdrawal of such selective influences will almost necessarily result in a certain amount of deterioration, independently even of the principle of economy.[21] I think that this cessation of a previous selective process will account for the drooping--but _not diminished_--ears of various domesticated animals (human preference and increased weight evidently aiding), and also for the inferior instincts seen in them and in artificially-fed caterpillars of the silk-moth, which now "often commit the strange mistake of devouring the base of the leaf on which they are feeding, and consequently fall down." Anyhow, I fail to see that anything is proved by this latter case, except that natural instinct may be perverted or aborted under unnatural conditions and a changed method of selection which abolishes the powerful corrective formerly supplied by natural selection. WINGS AND LEGS OF DUCKS AND FOWLS. The reduced wings and enlarged legs of domesticated ducks and fowls are attributed by Darwin and Spencer to the inheritance of the effects of use and disuse. But the inference by no means follows. Natural selection would usually favour these adaptive changes, and they would also have been aided by an artificial selection which is often unconscious or indirect. Birds with diminished power of flight would be less difficult to keep and manage, and in preserving and multiplying such birds man would be unconsciously bringing about structural changes which would easily be regarded as effects of use and disuse. "About eighteen centuries ago Columella and Varro speak of the necessity of keeping ducks in netted enclosures like other wild fowl, so that at this period there was danger of their flying away."[22] Is it not probable that the best fliers would escape most frequently, or would pine most if kept confined? On the other hand, birds with lessened powers of flight would not be eliminated as under natural conditions, but would be favoured; and natural selection, together with artificial selection of the most flourishing birds, would thicken and strengthen the legs to meet increased demands upon them. The diminution of the duck's wing is not great even in the birds that "never fly," and from this we must deduct the direct effect of disuse on the individual during its lifetime. As Weismann suggests, the _inherited_ portion of the change could only be ascertained by comparing the bones, &c., of wild and tame ducks _similarly reared_. If individual disuse diminished the weight of the duck's wing-bones by 9 per cent. there would be nothing left to account for. I suspect that investigation would reveal anomalies inconsistent with the theory of use-inheritance. Thus according to Darwin's tables of comparative weights and measurements[23] the leg-bones of the Penguin duck have slightly diminished in length, although they have increased 39 per cent. in weight. Relatively to the weight of the skeleton, the leg-bones have shortened in the tame breeds of ducks by over 5 per cent. (and in two breeds by over 8 per cent.) although they have increased more than 28 per cent. in proportional weight.[24] How can increased use simultaneously shorten and thicken these bones? If the relative shortening is attributed to a heavier skeleton, then the apparently reduced weight of the wing-bones is fully accounted for by the same circumstance, and disuse has had no inherited effect. Another strange circumstance is that the wing-bones have diminished _in length only_. The shortening is about 6 per cent. more than in the shortened legs, and it amounts to 11 per cent. as compared with the weight of the skeleton. Such a shortening should represent a reduction of 29 per cent. in weight, whereas the actual reduction in the weight of the wing-bones relatively to the weight of the skeleton is only 9 per cent. even in the breeds that never fly. Independently of shortening, the disused wing-bones have actually thickened or increased in weight. In the Aylesbury duck the disproportion caused by these conflicting changes is so great that the wing-bones are 47 per cent. heavier than they should be if their weight had varied proportionally with their length.[25] The reduction in weight on which Darwin relies seems to be entirely due to the shortening, and this shortening appears to be irrelevant to disuse, since the wings of the Call duck are similarly shortened in their proportions by 12 per cent., although this bird habitually flies to such an extent that Darwin partly attributes the greatly increased weight of its wing-bones to increased use under domestication. We find that _all_ the changes are in the direction of shorter and thicker bones--a tendency which must be largely dependent upon the suspension of the rigorous elimination which keeps the bones of the wild duck _long and light_. The used leg-bones and the disused wing-bones have alike been shortened and thickened, though in different proportions. Natural or artificial selection might easily thicken legs without lengthening them, or shorten wings without eliminating strong heavy bones, but it can hardly be contended that use-inheritance has acted in such conflicting ways. The thickening of the wing-bones has actually more than kept pace with any increase of weight in the skeleton, in spite of the effect of individual disuse and of the alleged cumulative effect of ancestral disuse for hundreds of generations. The case of the duck deserves special attention as a crucial one, if only from the fact that in this instance, and in this instance only, has Darwin given the weights of the skeletons, thus furnishing the means for a closer examination of his details than is usually possible. If we ignore such factors as selection, panmixia, correlation, and the effects of use and disuse during lifetime, and still regard the case of the domestic duck as a valid proof of the inheritance of the effects of use and disuse, we must also accept it as an equally valid proof that the effects of use and disuse are _not_ inherited. Nay, we may even have to admit that, in two points out of four, the _inherited_ effect of use and disuse on successive generations is exactly opposite to the immediate effect on the individual. Among fowls the wing-bones have lost much in weight but little or nothing in length--which is the reverse of what has occurred in ducks, although disuse is alleged to be the common cause in both cases. Some of the fowls which fly least have their wing-bones as long as ever. In the case of the Silk and Frizzled fowls--ancient breeds which "cannot fly at all"--and in that of the Cochins, which "can hardly fly up to a low perch," Darwin observes "how truly the proportions of an organ may be inherited although not fully exercised during many generations."[26] In four out of twelve breeds the wing-bones had become slightly heavier relatively to the leg-bones. Do not these facts tend to show that the changes in fowls' wings are due to fluctuating variability and selective influences rather than to a general law whereby the effects of disuse are cumulatively inherited? PIGEONS' WINGS. Concerning pigeons' wings Darwin says: "As fancy pigeons are generally confined in aviaries of moderate size, and as even when not confined they do not search for their own food, they must during many generations have used their wings incomparably less than the wild rock-pigeon ... but when we turn to the wings we find what at first appears a wholly different and unexpected result."[27] This unexpected increase in the spread of the wings from tip to tip is due to the feathers, which have lengthened in spite of disuse. Excluding the feathers, the wings were shorter in seventeen instances, and longer in eight. But as artificial selection has lengthened the wings in some instances, why may it not have shortened them in others? Wings with shortened bones would fold up more neatly than the long wings of the Carrier pigeon for instance, and so might unconsciously be favoured by fanciers. The selection of elegant birds with longer necks or bodies would cause a relative reduction in the wings--as with the Pouter, where the wings have been greatly lengthened but not so much as the body.[28] Slender bodies, too, and the lessened divergence of the furculum,[29] would slightly diminish the spread of the wings, and so would affect the measurements taken. As the wing-bones, moreover, are to some extent correlated with the beak and the feet, the artificial selection of shortened beaks might tend to shorten the wing as well as the feet. Under these circumstances how can we be sure of the actual efficacy of use-inheritance? Surely selection is as fully competent to effect slight changes in the direction of use-inheritance as it undoubtedly is to effect great changes in direct opposition to that alleged factor of evolution. SHORTENED BREAST-BONE IN PIGEONS. The shortening of the sternum in pigeons is attributed to disuse of the flight muscles attached to it. The bone is only shortened by a third of an inch, but this represents a very remarkable reduction in proportional length, which Darwin estimates at from one-seventh to one-eighth, or over 13 per cent. This marked reduction, too, quite unlike the slight reduction of the wing-bones to which the other ends of the muscles are attached, was universal in the eleven specimens measured by Darwin; and the bone, though acknowledged to have been modified by artificial selection in some breeds, is not so open to observation as wings or legs. Even, however, if this relative shortening of the sternum remained otherwise inexplicable, it might still be as irrelevant to use and disuse as is the fact that "many breeds" of fancy pigeons have lost a rib, having only seven where the ancestral rock-pigeon has eight.[30] But the excessive reduction in the sternum is far from being inexplicable. In the first place Darwin has somewhat over-estimated it. Instead of comparing the deficiency of length with the increased length which _should_ have been acquired (since the pigeons have increased in average size) he compares it with the length of the breast-bone in the rock-pigeon.[31] By this method if a pigeon had doubled in dimensions while its breast-bone remained unaltered, the reduction would be put down as 100 per cent., whereas obviously the true reduction would be one-half, or 50 per cent. of what the bone _should be_. Avoiding this error and a minor fallacy besides, a sound estimate reduces the supposed reduction of 13 or 14 per cent. to one of 11·7 per cent., which is still of course a considerable diminution. Part of this reduction must be due to the direct effect of disuse during the lifetime of the individual. Another and perhaps very considerable part of the relative change must be attributed to the lengthening of the neck or body by artificial selection, or to other modifications of shape and proportion effected directly or indirectly by the same cause.[32] The reduction is greatest in the Pouter (18-1/2 per cent.) and in the Pied Scanderoon (17-1/2 per cent.). In the former the body has been greatly elongated by artificial selection and three or four additional vertebræ have been acquired in the hinder part of the body.[33] In the latter a long neck increases the length of the bird, and so causes, or helps to cause, the relative shortening of the breast-bone. In the English Carrier--which experiences the effects of disuse, as it is too valuable to be flown--the relative reduction of 11 per cent. is apparently more than accounted for by the "elongated neck." The Dragon also has a long neck. In the Pouter, although the breast-bone has been shortened by 18-1/2 per cent. relatively to the length of the body, it has _lengthened_ by 20 per cent. relatively to the _bulk_ of the body.[34] Darwin forgot to ask whether allowance must not be made for a frequent, or perhaps general, elongation of the neck and the hinder part of the body, and the relative shortening or the throwing forward of the central portion containing the ribs (frequently one less in number) and the sternum. The whole body of the pigeon is so much under the control of artificial selection, that every precaution must be taken to guard against such possible sources of error.[35] Under domestication there would be a suspension of the previous elimination of reduced breast-bones by natural selection (Weismann's panmixia), and a diminution of the parts concerned in flying might even be favoured, as lessened powers of _continuous_ flight would prevent pigeons from straying too far, and would fit them for domestication or confinement. Such causes might reduce some of the less observed parts affected by flying, while still leaving the wing of full size for occasional flight, or to suit the requirements of the pigeon-fanciers. A change might thus be commenced like that seen in the rudimentary keel of the sternum in the owl-parrot of New Zealand, which has lost the power of flight although still retaining fairly-developed wings. SHORTENED FEET IN PIGEONS. Darwin thinks it highly probable that the short feet of most breeds of pigeons are due to lessened use, though he owns that the effects of correlation with the shortened beak are more plainly shown than the effects of disuse.[36] But why need the inherited effects of disuse be called in to explain an average reduction of some 5 per cent., when Darwin's measurements show that in the breeds where long beaks are favoured the principle of correlation between these parts has lengthened the foot by 13 per cent. in spite of disuse? SHORTENED LEGS OF RABBITS. In the case of the domestic rabbit Darwin notices that the bones of the legs have (relatively) become shorter by an inch and a half. But as the leg-bones have _not_ diminished in relative weight,[37] they must clearly have grown _thicker_ or denser. If disuse has shortened them, as Darwin supposes, why has it also thickened them? The ears and the tail have been lengthened in spite of disuse. Why then may not the ungainly hind-legs have been shortened by human preference independently of the inherited effects of disuse? By relying on apparently favourable instances and neglecting the others it would be easy to arrive at all manner of unsound conclusions. We might thus become convinced that vessels tend to sail northwards, or that a pendulum oscillates more often in one direction than in the other. It must not be forgotten that it would be easy to cite an enormous number of cases which are in direct conflict with the supposed law of use-inheritance. BLIND CAVE-ANIMALS. Weak or defective eyesight is by no means rare as a spontaneous variation in animals, "the great French veterinary Huzard going so far as to say that a blind race [of horses] could soon be formed." Natural selection evolves blind races whenever eyes are useless or disadvantageous, as with parasites. This may apparently be done independently of the effects of disuse, for certain neuter ants have eyes which are reduced to a more or less rudimentary condition, and neuter termites are blind as well as wingless. In one species of ant (_Eciton vastator_) the sockets have disappeared as well as the eyes. In deep caves not only would natural selection cease to maintain good eyesight but it would persistently favour blindness--or the entire removal of the eye when greatly exposed, as in the cave-crab--and as Dr. Ray Lankester has indicated,[38] there would have been a previous selection of animals which through spontaneous weakness, sensitiveness, or other affection of the eye found refuge and preservation in the cave, and a subsequent selection of the descendants whose fitness for relative darkness led them deeper into the cave or prevented them from straying back to the light with its various dangers and severer competition. Panmixia, however, as Weismann has shown, would probably be the most important factor in causing blindness. INHERITED HABITS. Darwin says: "A horse is trained to certain paces, and the colt inherits similar consensual movements."[39] But selection of the constitutional tendency to these paces, and imitation of the mother by the colt, may have been the real causes. The evidence, to be satisfactory, should show that such influences were excluded. Men acquire proficiency in swimming, waltzing, walking, smoking, languages, handicrafts, religious beliefs, &c., but the children only appear to inherit the innate abilities or constitutional proclivities of their parents. Even the songs of birds, including their call-notes, are no more inherited than is language by man (_Descent of Man_, p. 86). They are learned from the parent. Nestlings which acquire the song of a distinct species, "teach and transmit their new song to their offspring." If use-inheritance has not fixed the song of birds, why should we suppose that in a single generation it has transmitted a newly-taught method of walking or trotting? It is alleged that dogs inherit the intelligence acquired by association with man, and that retrievers inherit the effects of their training.[40] But selection and imitation are so potent that the additional hypothesis of use-inheritance seems perfectly superfluous. Where intelligence is not highly valued and carefully promoted by selection, the intelligence derivable from association with man does _not_ appear to be inherited. Lap-dogs, for instance, are often remarkably stupid. Darwin also instances the inheritance of dexterity in seal-catching as a case of use-inheritance.[41] But this is amply explained by the ordinary law of heredity. All that is needed is that the son shall inherit the suitable faculties which the father inherited before him. TAMENESS OF RABBITS. Darwin holds that in some cases selection alone has modified the instincts and dispositions of domesticated animals, but that in most cases selection and the inheritance of acquired habits have concurred in effecting the change. "On the other hand," he says, "habit alone in some cases has sufficed; hardly any animal is more difficult to tame than the young of the wild rabbit; scarcely any animal is tamer than the young of the tame rabbit; but I can hardly suppose that domestic rabbits have often been selected for tameness alone; so that we must attribute at least the greater part of the inherited change from extreme wildness to extreme tameness to habit and long-continued close confinement."[42] But there are strong, and to me irresistible, arguments to the contrary. I think that the following considerations will show that the greater part, if not the whole, of the change must be attributed to selection rather than to the direct inheritance of acquired habit. (1) For a period which may cover thousands of generations, there has been an entire cessation of the natural selection which maintains the wildness (or excessive fear, caution, activity, &c.) so indispensably essential for preserving defenceless wild rabbits of all ages from the many enemies that prey upon them. (2) During this same extensive period of time man has usually killed off the wildest and bred from the tamest and most manageable. To some extent he has done this consciously. "It is very conducive to successful breeding to keep only such as are quiet and tractable," says an authority on rabbits,[43] and he enjoins the selection of the handsomest and _best-tempered_ does to serve as breeders. To a still greater extent man has favoured tameness unconsciously and indirectly. He has systematically selected the largest and most prolific animals, and has thus doubled the size and the fertility of the domestic rabbit. In consciously selecting the largest and most flourishing individuals and the best and most prolific mothers, he _must_ have unconsciously selected those rabbits whose relative _tameness_ or placidity of disposition rendered it possible for them to flourish and to produce and rear large and thriving families, instead of fretting and pining as the wilder captives would do. When we consider how exceedingly delicate and easily disturbed yet all-important a function is that of maternity in the continually breeding rabbit, we see that the tamest and the least terrified would be the most successful mothers, and so would continually be selected, although man cared nothing for the tameness in itself. The tamest mothers would also be less liable to neglect or devour their offspring, as rabbits commonly do when their young are handled too soon, or even when merely frightened by mice, &c., or disturbed by changed surroundings. (3) We must remember the extraordinary fecundity of the rabbit and the excessive amount of elimination that consequently takes place either naturally or artificially. Where nature preserved only the wildest, man has preserved the tamest. If there is any truth in the Darwinian theory, this thorough and long-continued reversal of the selective process _must_ have had a powerful effect. Why should it not be amply sufficient to account for the tameness and mental degeneracy of the rabbit without the aid of a factor which can readily be shown to be far weaker in its normal action than either natural or artificial selection? Why may not the tameness of the rabbit be transferred to the group of cases in which Darwin holds that "habit has done nothing," and selection has done all? (4) If use-inheritance has tamed the rabbit, why are the bucks still so mischievous and unruly? Why is the Angora breed the only one in which the males show no desire to destroy the young? Why, too, should use-inheritance be so much more powerful in the rabbit than with other animals which are far more easily tamed in the first instance? Wild young rabbits when domesticated "remain unconquerably wild," and, although they may be kept alive, they pine and "rarely come to any good." Yet the animal which _acquires_ least tameness--or apparently, indeed, none at all--inherits most! It appears, in fact, to inherit that which it cannot acquire--a circumstance which indicates the selection of spontaneous variations rather than the inheritance of changed habits. Such variations occasionally occur in animals in a marked degree. Of a litter of wolf-cubs, all brought up in the same way, "one became tame and gentle like a dog, while the others preserved their natural savagery." Is it not probable that permanent domestication was rendered possible by the inevitable selection of spontaneous variations in this direction? The _excessive_ tameness, too, of the young rabbit, while easily explicable as a result of unconscious selection, is not easily explained as a result of acquired habit. No particular care is taken to tame or teach or domesticate rabbits. They are bred for food, or for profit or appearance, and they are left to themselves most of their time. As Sir J. Sebright notices with some surprise, the domestic rabbit "is not often visited, and seldom handled, and yet it is always tame." MODIFICATIONS OBVIOUSLY ATTRIBUTABLE TO SELECTION. Innumerable modifications in accordance with altered use or disuse, such as the enlarged udders of cows and goats, and the diminished lungs and livers in highly bred animals that take little exercise, can be readily and fully explained as depending on selection. As the fittest for the natural or artificial requirements will be favoured, natural or artificial selection may easily enlarge organs that are increasingly used and economize in those that are less needed. I therefore see no necessity whatever for calling in the aid of use-inheritance as Darwin does, to account for enlarged udders, or diminished lungs, or the thick arms and thin legs of canoe Indians, or the enlarged chests of mountaineers, or the diminished eyes of moles, or the lost feet of certain beetles, or the reduced wings of logger-headed ducks, or the prehensile tails of monkeys, or the displaced eyes of soles, or the altered number of teeth in plaice, or the increased fertility of domesticated animals, or the shortened legs and snouts of pigs, or the shortened intestines of tame rabbits, or the lengthened intestines of domestic cats, &c.[44] Changed habits and the requisite change of structure will usually be favoured by natural selection; for habit, as Darwin says, "almost implies that some benefit great or small is thus derived." SIMILAR EFFECTS OF NATURAL SELECTION AND USE-INHERITANCE. Here we perceive a difficulty which will equally trouble those who affirm use-inheritance and those who deny. Broadly speaking, the adaptive effects ascribed to use-inheritance coincide with the effects of natural selection. The individual adaptability (as shown in the thickening of skin, fur, muscle, &c., under the stimulus of friction, cold, use, &c.) is identical in kind and direction with the racial adaptability under natural selection. Consequently the alleged inheritance of the advantageous effects of use and disuse cannot readily be distinguished from the similarly beneficial effects of natural selection. The indisputable fact that natural selection imitates or simulates the beneficial effects ascribed to use-inheritance may be the chief source and explanation of a belief which may prove to be thoroughly fallacious. A similar simulation of course occurs under domestication, where natural selection is partly replaced by artificial selection of the best adapted and therefore most flourishing animals, while in disused parts panmixia or the comparative cessation of selection will aid or replace "economy of growth" in causing diminution.[45] INFERIORITY OF SENSES IN EUROPEANS. "The inferiority of Europeans, in comparison with savages, in eyesight and in the other senses," is attributed to "the accumulated and transmitted effect of lessened use during many generations."[46] But why may we not attribute it to the slackened and diverted action of the natural selection which keeps the senses so keen in some savage races? SHORT-SIGHT IN WATCHMAKERS AND ENGRAVERS. Darwin notices that watchmakers and engravers are liable to be short-sighted, and that short-sight and long-sight certainly tend to be inherited.[47] But we must be careful not to beg the question at issue by assuming that the frequent heredity of short sight necessarily covers the heredity of artificially-produced short-sight. Elsewhere, however, Darwin states more decisively that "there is ground for believing that it may often originate in causes acting on the individual affected, and may thence-forward become transmissible."[48] This impression may arise (1) from the facts of ordinary heredity--the ancestral liability being excited in father and son by similar artificial habits, such as reading, and viewing objects closely as among watchmakers and engravers--or by constitutional deterioration from indoor life, &c., acting upon a constitutional liability of the eye to the "something like inflammation of the coats, under which they yield" and so cause shortness of sight by altering the spherical shape of the eye-ball. (2) Panmixia, or the suspension of natural selection, together with altered habits, will account for an increase of short-sight among the population generally. (3) Long-sighted people could not work at watchmaking and engraving so comfortably and advantageously as at other occupations, and hence would be less likely to take to such callings. LARGER HANDS OF LABOURERS' INFANTS.[49] These are best explained as the result of natural selection and of the diminution of the hand by sexual selection in the gentry. If the larger hands of labourers' infants are really due to the inherited effects of ancestral use, why does the development occur so early in life, instead of only at a corresponding period, as is the rule? During the first few years of its life, at least, the labourer's infant does no more work than the gentleman's child. Why are not the effects of this disuse inherited by the labourer's infant? If the enlargement of the infant's hand illustrates the transference of a character gained later in life, it is evident that the transference must take place in spite of the inherited effects of disuse. THICKENED SOLE IN INFANTS. Darwin also attributes the thickened sole in infants, "long before birth," to "the inherited effects of pressure during a long series of generations."[50] But disuse should make the infant's sole _thin_, and it is this thinness that should be inherited. If we suppose the inheritance of the thickened soles of later life to be transferred to an earlier period, we have the anomaly of the inherited effects of disuse at that earlier period being overpowered by the untimely inheritance of the effects of use at another. On the other hand, it is clear that natural selection would favour thickened soles for walking on, and might also promote an early development which would ensure their being ready in good time for actual use; for variations in the direction of delay would be cut off, while variations in the other direction would be preserved. Anyhow, the mere transference of a character to an earlier period is no proof of use-inheritance. The real question is whether the thickened sole was gained by natural selection or by the inherited effects of pressure, and the mere transference or hastened appearance of the thickening does not in any degree solve this question. It merely excludes the effect of disuse during lifetime, and thus presents a fallacious appearance of being decisive. The thickened sole of the unborn infant, however, like the lanugo or hairy covering, is probably a result of the direct inheritance of ancestral stages of evolution, of which the embryo presents a condensed epitome. While the relative thinness of the infant's sole might be pointed to as the effect of _disuse_ during a long series of generations, its thickness is rather an illustration of atavism still resisting the effects of long-continued disuse. There is nothing to show that the inheritable portion of the full original thickness was not gained by natural selection rather than by the directly inherited effect of use; and the latter, being cumulative and indiscriminative in its action, would apparently have made the sole very much thicker and harder than it is. If natural selection were not supreme in such cases, how could we account for the effects of pressure resulting in hard hoofs in some cases and only soft pads in others? A SOURCE OF MENTAL CONFUSION. Of course in a certain sense this thickening of the sole has resulted from use. In one sense or other, most--or perhaps all--of the results of natural selection are inherited effects of use or disuse. Natural selection preserves that which is of use and which is used, while it eliminates that which is useless and is not used. The most confident assertions of the effects of use and disuse in modifying the heritable type, appear to rest on this indefeasible basis. Darwin's statements concerning the effects of use and disuse in evolution can frequently be read in two senses. They often command assent as undeniable truisms as they stand, but are of course written in another and more debatable sense. Thus in the case of the shortened wings and thickened legs of the domestic duck, I believe equally with Darwin and Spencer that "no one will dispute that they have resulted from the lessened use of the wings and the increased use of the legs." "Use" is at bottom the determining circumstance in evolution generally. The trunk of the elephant, the fin of the fish, the wing of the bird, the cunning hand of man and his complicated brain--and, in short, all organs and faculties whatsoever--can only have been moulded and developed by use--by usefulness and by using--but not necessarily by use-inheritance, not necessarily by directly inherited effects of use or disuse of parts in the individual. So, too, reduced or rudimentary organs are due to disuse, but it by no means follows that the diminution is caused by any direct tendency to the inheritance of the effects of disuse in the individual. The effects of natural selection are commonly expressible as effects of use and disuse, just as adaptation in nature is expressible in the language of teleology. But use-inheritance is no more proven by one of these necessary coincidences than special design is by the other. The inevitable simulation of use-inheritance may be entirely deceptive. Darwin thinks that "there can be no doubt that use in our domestic animals has strengthened and enlarged certain parts, and disuse diminished them; and that such modifications are inherited." Undoubtedly "such" or _similar_ modifications have often been inherited, but how can Darwin possibly tell that they are not due to the simulation of use-inheritance by natural or artificial selection acting upon general variability? Of the inevitability of selection and of its generally adaptive tendencies "there can be no doubt," and panmixia would tend to reduce disused parts; so that there _must always_ remain grave doubts of the alleged inheritance of the similar effects of use and disuse, unless we can accomplish the extremely difficult feat of excluding both natural and artificial selection as causes of enlargement, and panmixia and selection as causes of dwindling. WEAKNESS OF USE-INHERITANCE. Use-inheritance is normally so weak that it appears to be quite helpless when opposed to any other factor of evolution. Natural selection evolves and maintains the instincts of ants and termites in spite of use-inheritance to a more wonderful degree than it evolves the instincts of almost any other animal with the fullest help of use-inheritance. It develops seldom-used horns or natural armour just as readily as constantly-used hoofs or teeth. Sexual selection evolves elaborate structures like the peacock's tail in spite of disuse and natural selection combined. Artificial selection appears to enlarge or diminish used parts or disused parts with equal facility. The assistance of use-inheritance seems to be as unnecessary as its opposition is ineffective. The alleged inheritance of the effects of use and disuse in our domestic animals must be very slow and slight.[51] Darwin tells us that "there is no good evidence that this ever follows in the course of a single generation." "Several generations must be subjected to changed habits for any appreciable result."[52] What does this mean? One of two things. Either the tendency is very weak, or it is non-existent. If it is so weak that we cannot detect its alleged effects till several generations have elapsed, during which time the more powerful agency of selection has been at work, how are we to distinguish the effects of the minor factor from that of the major? Are we to conclude that use-inheritance _plus_ selection will modify races, just as Voltaire firmly held that incantations, together with sufficient arsenic, would destroy flocks of sheep? Is it not a significant fact that the alleged instances of use-inheritance so often prove to be self-conflicting in their details? For satisfactory proof of the prevalence of a law of use-inheritance we require normal instances where selection is clearly inadequate to produce the change, or where it is scarcely allowed time or opportunity to act, as in the immediate offspring of the modified individual. Of the first kind of cases there seems to be a plentiful lack. Of the latter kind, according to Darwin, there appears to be none--a circumstance which contrasts strangely and suspiciously with the many decisive cases in which variation from unknown causes has been inherited most strikingly in the immediate offspring. It must be expected, indeed, that among these innumerable cases some will accidentally mimic the alleged effects of use-inheritance. If Darwin had felt certain that the effects of habit or use tended in any marked degree to be conveyed directly and cumulatively to succeeding generations, he could hardly have given us such cautious, half-hearted encouragement of good habits as the following:--"It is not improbable that after long practice virtuous tendencies may be inherited." "Habits, moreover followed during many generations probably tend to be inherited."[53] This is probable, independently of use-inheritance. The "many generations" specified or implied, will allow time for the play of selective as well as of cumulatively-educative influences. There must apparently be a constitutional or inheritable predisposition or fitness for the habits spoken of, which otherwise would scarcely be continued for many generations, except by the favourably-varying branches of a family: which again is selection rather than use-inheritance. Where is the necessity for even the remains of the Lamarckian doctrine of inherited habit? Seeing how powerful the general principle of selection has shown itself in cases where use-inheritance could have given no aid or must even have offered its most strenuous opposition, why should it not equally be able to develop used organs or repress disused organs or faculties without the assistance of a relatively weak ally? Selection evolved the remarkable protective coverings of the armadillo, turtle, crocodile, porcupine, hedgehog, &c.; it formed alike the rose and its thorn, the nut and its shell; it developed the peacock's tail and the deer's antlers, the protective mimicry of various insects and butterflies, and the wonderful instincts of the white ants; it gave the serpent its deadly poison and the violet its grateful odour; it painted the gorgeous plumage of the Impeyan pheasant and the beautiful colours and decorations of countless birds and insects and flowers. These, and a thousand other achievements, it has evidently accomplished without the help of use-inheritance. Why should it be thought incapable of reducing a pigeon's wing or enlarging a duck's leg? Why should it be credited with the help of an officious ally in effecting comparatively slight changes, when great and striking modifications are effected without any such aid? FOOTNOTES: [15] Weismann's _Essays on Heredity_, &c. Clarendon Press, 1889. [16] _Life and Letters_, i. p. 16. Darwin's reverence for his father "was boundless and most touching. He would have wished to judge everything else in the world dispassionately, but anything his father had said was received with almost implicit faith; ... he hoped none of his sons would ever believe anything because he said it, unless they were themselves convinced of its truth--a feeling in striking contrast with his own manner of faith" (_Life and Letters_, i. pp. 10, 11). [17] _Ibid._, i. p. 38. [18] _Life and Letters_, ii. p. 14. [19] _Origin of Species_, pp. 117, 118. [20] _Ibid._, p. 180. [21] _Contemporary Review_, December, 1875, pp. 89, 93. [22] _Variation of Animals and Plants under Domestication_, i. 292. [23] _Variation of Animals and Plants under Domestication_, i. 299-301. [24] To keep pace with this lateral increase in weight, the leg-bones should have lengthened considerably so that their total deficiency in proportional length is 17 per cent.,--a changed proportion which being _linear_ is more excessive than the increase of weight by 28 per cent. So marked is the effect of the combined thickening and shortening that in the Aylesbury breed--which is the most typically representative one--the leg-bones have become 70 per cent. heavier than they should be if their thickness had continued to be proportional to their length. [25] This excessive thickening under disuse appears to be due partly to a positive lateral enlargement or increase of proportional weight of about 7-1/2 per cent., and partly to a shortening of about 15 per cent. Carefully calculated, the reduction of the weight of the wing-bones in this breed is only 8·3 per cent. relatively to the whole skeleton, or only 5 per cent. relatively to the skeleton _minus_ legs and wings. The latter method is the more correct, since the excessive weight of the leg-bones increases the weight of the skeleton more than the diminished weight of the wing-bones reduces it. [26] _Variation of Animals and Plants under Domestication_, i. 284. [27] _Variation of Animals and Plants under Domestication_, i. 184, 185. [28] _Ibid._, i. 144, 145. [29] _Ibid._, i. 185. [30] _Variation of Animals and Plants under Domestication_, i. 175. [31] _Variation of Animals and Plants under Domestication_, i. 184. I suspect that Darwin was in poor health when he wrote this page. He nods at least four times in it. Twice he speaks of "twelve" breeds where he obviously should have said eleven. [32] If a prominent breast is admired and selected by fanciers, the sternum might shorten in assuming a more forward and vertical position. If the shortening of the sternum is entirely due to disuse, it seems strange that Darwin has not noticed any similar shortening in the sternum of the duck. But selection has not tended to make the duck elegant, or "pigeon-breasted"; it has enlarged the abdominal sack instead, besides allowing the addition of an extra rib in various cases. [33] _Variation of Animals and Plants under Domestication_, 144, 175. [34] _Variation of Animals and Plants under Domestication_, i. 179. [35] In the six largest breeds the shortening of the sternum is nearly twice as great as in the three smaller breeds which remain nearest the rock-pigeon in size. We can hardly suppose that use-inheritance especially affects the eight breeds that have varied most in size. If we exclude these, there is only a total shortening of 7 per cent. to be accounted for. [36] _Variation of Animals and Plants under Domestication_, i. 183, 186. [37] _Variation of Animals and Plants under Domestication_, i. 130, 135; ii. 288. [38] _Encyclopædia Britannica_, article "Zoology." [39] _Variation of Animals and Plants under Domestication_, ii. 367. [40] _Variation of Animals and Plants under Domestication_, ii. 367. Why then does the cheetah inherit ancestral habits so inadequately that it is useless for the chase unless it has first learned to hunt for itself before being captured? (ii. 133). [41] _Descent of Man_, p. 33. [42] _Origin of Species_, pp. 210, 211. [43] E. S. Delamer on _Pigeons and Rabbits_, pp. 132, 103. For other points referred to, see pages 133, 102, 100, 95, 131. [44] _Origin of Species_, pp. 188, 110; _Descent of Man_, pp. 32-35; _Variation of Animals and Plants under Domestication_, ii. 289, 293. Use or disuse during lifetime of course co-operates, and in some cases, as in that of the canoe Indians, may be the principal or even perhaps the _sole_ cause of the change. [45] For the importance of panmixia as invalidating Darwin's strongest evidence for use-inheritance--namely, that drawn from the effects of disuse in highly-fed domestic animals where there is supposed to be no economy of growth--see Professor Romanes on Panmixia, _Nature_, April 3, 1890. [46] _Descent of Man_, p. 33. [47] _Descent of Man_, p. 33. [48] _Variation of Animals and Plants under Domestication_, i., 453. [49] _Descent of Man_, p. 33. [50] _Descent of Man_, p. 33. [51] Wallace shows that the changes in our domestic animals, if spread over the thousands of years since the animals were first tamed, must be extremely insignificant in each generation, and he concludes that such infinitesimal effects of use and disuse would be swallowed up by the far greater effects of variation and selection (_Darwinism_, p. 436). Professor Romanes has replied to him in the _Contemporary Review_ (August 1889), showing that this is no disproof of the existence of the minor factor, inasmuch as slight changes in each generation need not necessarily be matters of life and death to the individual, although their cumulative development by use-inheritance might eventually become of much service. But selection would favour spontaneous variations of a similarly serviceable character. The slightest tendency to eliminate the extreme variations in either direction would proportionally modify the average in a breed. Use-inheritance appears to be so relatively weak a factor that probably neither proof nor disproof of its existence can ever be given, owing to the practical impossibility of disentangling its effects (if any) from the effects of admittedly far more powerful factors which often act in unsuspected ways. Thus wild ducklings, which can easily be reared by themselves, invariably "die off" if reared with tame ones (_Variation_, &c., i. 292, ii. 219). They cannot get their fair share in the competition for food, and are completely eliminated. Professor Romanes fully acknowledges that there is the "gravest possible doubt" as to the transmission of the effects of disuse (Letter on Panmixia, _Nature_, March 13, 1890). [52] _Variation of Animals and Plants under Domestication_, ii. 287-289. [53] _Descent of Man_, pp. 612, 131. INHERITED INJURIES. INHERITED MUTILATIONS. The almost universal _non-inheritance_ of mutilations seems to me a far more valid argument _against_ a general law of modification-inheritance than the few doubtful or abnormal cases of such inheritance can furnish in its favour. No inherited effect has been produced by the docking of horses' tails for many generations, or by a well-known mutilation which has been practised by the Hebrew race from time immemorial. As lost or mutilated parts are reproduced in offspring independently of the existence of those parts in the parent, there is the less reason to suppose that the particular condition of parental parts transmits itself, or tends to transmit itself, to the offspring. So unsatisfactory is the argument derivable from inherited mutilations that Mr. Spencer does not mention them at all, and Darwin has to attribute them to a special cause which is independent of any general theory of use-inheritance.[54] Darwin's most striking case--and to my mind the only case of any importance--is that of Brown-Séquard's epileptic guinea-pigs, which inherited the mutilated condition of parents who had gnawed off their own gangrenous toes when anæsthetic through the sciatic nerve having been divided.[55] Darwin also mentions a cow that lost a horn by accident, followed by suppuration, and subsequently produced three calves which had on the same side of the head, instead of a horn, a bony lump attached merely to the skin. Such cases may seem to prove that mutilation _associated with morbid action_ is occasionally inherited or repeated with a promptitude and thoroughness that contrast most strikingly with the imperceptible nature of the immediate inheritance of the effects of use and disuse; but they by no means prove that mutilation in general is inheritable, and they are absolutely no proof whatever of a _normal_ and non-pathological tendency to the inheritance of acquired characters. Those who accept Darwin's special explanation of the supposed inheritance of mutilations, ought to notice that his explanation applies equally well under a theory which is strongly adverse to use-inheritance--namely, Galton's idea of the sterilization and complete "using up" of otherwise reproductive matter in the growth and maintenance of the personal structure. Darwin's explanation of inherited mutilations--which, as he notes, occur "especially or perhaps exclusively" when the injury has been followed by disease[56]--is that all the representative gemmules which would develop or repair or reproduce the injured part are attracted to the diseased surface during the reparative process and are there destroyed by the morbid action.[57] Hence they cannot reproduce the part in offspring. This explanation by no means implies that mutilation would _usually_ affect the offspring. On the contrary, in all ordinary cases of mutilation the purely atavistic elements or gemmules would be set free from any modifying influence of the non-existent or mutilated part. The gemmules--as in Galton's theory of heredity and with neuter insects--might be perfectly independent of pangenesis and the normal inheritance of acquired characters. Such self-multiplying gemmules without pangenesis would enable us to understand both the excessive weakness or non-existence of normal use-inheritance, and the excessive strength and abruptness of the effect of their partial destruction under special pathological conditions. The series of epileptic phenomena that can be excited by tickling a certain part of the cheek and neck of the adult guinea-pig during the growth and rejoining of the ends of the severed nerve, are said to be repeated with striking accuracy of detail in the young who inherit mutilated toes; but as epilepsy is often due to some _one_ exciting cause or morbid condition, the single transmission of a highly morbid condition of the system might easily reproduce the whole chain of consequences and might also have caused the loss of toes. The particulars of the guinea-pig cases are very inadequately recorded,[58] but the results are so anomalous[59] that Brown-Séquard's own conclusion is that the epilepsy and the inherited injuries are _not_ directly transmitted, but that "what is transmitted is the morbid state of the nervous system." He thinks that the missing toes may "possibly" be exceptions to this conclusion, "but the other facts only imply the transmission of a morbid state of the sympathetic or sciatic nerve or of a part of the medulla oblongata." Until we can tell what is transmitted, we are not in a position to determine whether there is any true inheritance or only an exaggerated simulation of it under peculiar circumstances. When the actual observers believe that the mutilations and epilepsy are not the cause of their own repetition, and when these observers guard themselves by such phrases as, "if any conclusion can at present be drawn from those facts," we who have only incomplete reports to guide us may well be excused if we preserve an even more pronounced attitude of caution and reserve.[60] The morbid state of the system may be wholly due to general injury of the germs rather than to specific inheritance. Weismann suggests that the morbid condition of the nervous system may be due to some infection such as might arise from microbes, which find a home in the mutilated and disordered nervous system in the parent, and subsequently transmit themselves to the offspring through the reproductive elements, as the infections of various diseases appear to do--the muscardine silkworm disease in particular being known to be conveyed to offspring in this manner. But whether we can discover the true explanation or not, inherited mutilations can hardly be accounted for as the result of a general tendency to inherit acquired modifications. How could a factor which seems to be totally inoperative in cases of ordinary mutilation, and only infinitesimally operative in transmitting the normal effects of use and disuse, suddenly become so powerful as to completely overthrow atavism, and its own tendency to transmit the non-mutilated type of one of the parents and of the non-mutilated type presented by the injured parent in earlier life? Does not so striking and abrupt an intensification of its usually insignificant power demand an explanation widely different from that which might account for the extremely slow and slight inheritance of the normal effects of use and disuse? Surely it would be better to suspend one's judgment as to the true explanation of highly exceptional and purely pathological cases rather than resort to an hypothesis that creates more difficulties than it solves. THE MOTMOT'S TAIL. The narrowing of the long central tail feathers of the motmot is attributed to the inherited effects of habitual mutilation (_Descent of Man_, pp. 384, 603). But in the specimens at South Kensington[61] the narrowness extends upwards much beyond the habitually denuded part, and the broadened end is the broadest part of the whole feather. If the inherited effect of an inch or two of denudation extends from three to six inches upwards, why has it not also extended two inches downwards so as to narrow the broadened end? The narrowness seems to be a mainly relative or negative effect produced by the broadening out of a long tapering feather at its end under the influence of sexual selection. Several other birds have similarly narrowed or spoon-shaped feathers and do not bite them. Is it not more feasible to suppose that this attractive peculiarity first suggested its artificial intensification, than to suppose that the bird began nibbling without any definite cause? Sexual selection would then encourage the habit. Anyhow, it is as impossible to show that the mutilation preceded the narrowing as it is to show that tonsure preceded baldness. OTHER INHERITED INJURIES MENTIONED BY DARWIN. Darwin quotes some cases from Dr. Prosper Lucas's "long" but weak and unsatisfactory "list of inherited injuries."[62] But Lucas was somewhat credulous. One of his cases is that many girls were born in London without mammæ through the injurious effect of certain corsets on the mothers. He also gives a long account of a Jew who could read through the thick covers of a book, and whose son inherited this "hyperæsthesia" of the sense of sight in a still more remarkable degree (i. 113-119). Evidently Lucas's cases cannot be accepted without some amount of reserve. The cases of the three calves which inherited the one-horned condition of the cow, the two sons who inherited a father's crooked finger, and the two sons who were microphthalmic on the same side as their father had lost an eye, may be due to mere coincidence; or an inherited constitutional tendency or liability might lead to somewhat similar results in parent and offspring[63]--just as the tendency to certain fatal diseases or to suicide may produce similar results in father and son, although the artificially-produced hanging or apoplexy obviously cannot be directly transmitted. That more than one of the offspring was affected does not render the chances against coincidence "almost infinitely great," as Darwin mistakenly supposes. It "frequently occurs" that a man's sons or daughters may _all_ exhibit either a latent or a newly-developed congenital peculiarity previously unknown;[64] and the coincidence may merely be that one of the parents accidentally suffered a similar kind of injury--a kind of coincidence which must of course occasionally occur, and which may have been partly caused by a latent tendency. The chances against coincidence are indeed great, but the cases appear to be correspondingly rare. Darwin acknowledges that many supposed instances of inherited mutilation may be due to coincidence; and there is apparently no more reason for attributing inherited scars, &c., to any special form of heredity than to the effect of the mother's imagination on the unborn babe--a popular but fallacious belief in corroboration of which far more alleged instances could be collected than of the inheritance of injuries. As an instance of the coincidences that occur, I may mention that a friend of mine has a daughter who was born with a small hole in one ear, just as if it were already pierced for the earring which she has since worn in it. I suppose, however, that no one will venture to claim this as an instance of the inheritance of a mutilation practised by female ancestors, especially as such holes are not altogether unknown or inexplicable, though very rarely occurring low down in the lobe of the ear.[65] Many cases are known of the inheritance of mutilations or malformations arising congenitally from some abrupt variation in the reproductive elements. In such cases as the one-eared rabbits, the two-legged pigs, the three-legged dogs, the one-horned stags, hornless bulls, earless rabbits, lop-eared rabbits, tailless dogs, &c., if the father or the mother or the embryo had suffered from some accident or disease which might plausibly have been assigned as the cause of the original malformation, these transmitted defects would readily be cited as instances of the inheritance of an accidentally-produced modification. The inheritance of exostoses on horses' legs may be the inheritance of a constitutional tendency rather than of the effect of the parents' hard travelling. Horses congenitally liable to such formations would transmit the liability,[66] and this might readily be mistaken for inheritance of the results of the liability. An apparent increase in this liability might arise from greater attention being now paid to it, or from increased use of harder roads; or a real increase might be due to panmixia and some obscure forms of correlation. QUASI-INHERITANCE. Of course artificially-caused ill-health or weakness in parents will tend in a general way to injure the offspring. But deterioration thus caused is only a form of quasi-inheritance, as I should prefer to call it. Semi-starvation in a new-born babe is _not_ truly inherited from its half-starved mother, but is the direct result of insufficient nourishment. The general welfare of germs--as of parasites--is necessarily bound up with that of the organism which feeds and shelters them, but this is not heredity, and is quite irrelevant to the question whether particular modifications are transmitted or not. Another form of quasi-inheritance is seen in the communication of certain infections to offspring. Not being transmitted by the action of the organism so much as in defiance of it, such diseases are not truly hereditary, though for convenience' sake they are usually so described. A perversion or prevention of true inheritance is also seen in the action of alcohol, or excessive overwork, or any other cause which by originating morbid conditions in individuals may also injure the reproductive elements. These forms of quasi-inheritance are, of course, highly important so far as the improvement of the race is concerned. So, too, is the fact that improved or deteriorated habits and thoughts are transmitted by personal teaching and influence and are cumulative in their effect. But all this must not be confounded with the inheritance of acquired characters. Cases of quasi-inheritance may perhaps be most readily distinguished from cases of true inheritance by the time test. When a modification acquired in adult life is promptly communicated to the child in early life or from birth, it may rightly be suspected that the inheritance, like that of money or title, is not truly congenital, but is extraneous or even anti-congenital in its nature. Judged by such a standard, the inherited injuries in Brown-Séquard's guinea-pigs are only exceptional cases of quasi-inheritance, and are not necessarily indicative of any general rule affecting true inheritance. FOOTNOTES: [54] A very able anatomist of my acquaintance denies the inheritance of mutilations and injuries, although he strongly believes in the inheritance of the effects of use and disuse. [55] _Variation of Animals and Plants under Domestication_, i. 467-469. Lost toes were only seen by Dr. Dupuy in three young out of two hundred. Obersteiner found that most of the offspring of his epileptic guinea-pigs were injuriously affected, being weakly, small, paralysed in one or more limbs, and so forth. Only two were epileptic, and both were weakly and died early (Weismann's _Essays_, p. 311). A morbid condition of the spinal cord might affect the hind limbs especially (as in paraplegia) and might occasionally cause loss of toes in the embryo by preventing development or by ulceration. Brown-Séquard does not say that the defective feet were on the same side as in the parents (_Lancet_, Jan., 1875, pp. 7, 8). [56] _Variation of Animals and Plants under Domestication_, ii. 57. [57] _Ibid._, ii. 392. Perhaps it might be better to suppose that the _best_ gemmules were sacrificed in repairing the injured _nerve_, and hence only inferior substitutes were left to take their place, and could only imperfectly reproduce the injured part of the nervous system in offspring. [58] Hence perhaps Mr. Spencer's error in representing the epileptic liability as permanent and as coming on _after_ healing (_Factors of Organic Evolution_, p. 27). [59] It is not claimed that the imperfect foot was on the same side of the body as in the parent, and where parents had lost _all_ the toes of a foot, or the whole foot, the few offspring affected usually had lost only two toes out of the three, or only a part of one or two or three toes. Sometimes the offspring had toes missing on _both_ hind feet, although the parent was only affected in _one_. _One_ diseased ear and eye in the parent was "generally" or "always" succeeded by _two_ equally affected ears and eyes in the offspring (cf. _Pop. Science Monthly_, New York, xi. 334). The important law of inheritance at corresponding periods was also set aside. Gangrene or inflammation commenced in both ears and both eyes soon after birth (pointing possibly to infection of some kind); the epileptic period commenced "perhaps two months or more after birth," while the loss of toes had occurred before birth. In no case, as Weismann points out, is the original mutilation of the nervous system ever transmitted. Even where an extirpated ganglion was never regenerated in the parent, the offspring always regained the part in an apparently perfect condition. On the whole the conflicting results ought to be as puzzling to those who may attribute them to a universal tendency to inherit the exact condition of parents as they are to those who, like myself, are sceptical as to the existence of such a law or tendency. [60] The various results need to be fully and impartially recorded, and they should also be well tested and confirmed in proportion as they appear improbable and contrary to general experience. Professor Romanes has been carrying out the necessary experiments for some time past. [61] Natural History Museum, central hall, third recess on the left. [62] _Traité de l'Hérédité_, ii. 489; _Variation of Animals and Plants under Domestication_, i. 469. If injuries are inherited, why has the repeated rupture of the hymen produced no inherited effect? [63] Compare the three cases of crooked fingers given in _Variation of Animals and Plants under Domestication_, ii. 55, 240. [64] _Ibid._, i. 460. Thus, where two brothers married two sisters all the seven children were perfect albinos, although none of the parents or their relatives were albinos. In another case the nine children of two sound parents were all born blind (ii. 322). [65] See pp. 179-182, _Evolution and Disease_, by J. Bland Sutton, to whom and to our mutual friend Dr. D. Thurston I am indebted for information on various points. [66] _Variation of Animals and Plants under Domestication_, ii. 290; i. 454. MISCELLANEOUS CONSIDERATIONS. TRUE RELATION OF PARENTS AND OFFSPRING. It is difficult to entirely free ourselves from the flattering and almost universal idea that parents are true originators or creators of copies of themselves. But the main truth, if not the whole truth, is that they are merely the transmitters of types of which they and their offspring are alike more or less similarly moulded resultants. A parent is a trustee. He transmits, not himself and his own modifications, but the stock, the type, the representative elements, of which he is a product and a custodian in one. It seems probable that he has no more definite or "particulate" influence over the reproductive elements within him than a mother over the embryo or a vessel over its cargo. Parent and offspring are like successive copies of books printed from the same "type." A battered letter in the "type" will display its effects in both earlier and later copies alike, but a purely extraneous or acquired flaw in the first copy is not necessarily repeated in subsequent copies. Unlike printer's type, however, the material source of heredity is of a fluctuating nature, consisting of competing elements derived from two parents and from innumerable ancestors. Galton compares parent and child to successive pendants on the same chain. Weismann likens them to successive offshoots thrown up by a long underground root or sucker. Such comparisons indicate the improbability of acquired modifications being transmitted to offspring. That parts are developed in offspring independently of those parts in parents is clear. Mutilated parents transmit parts which they do not possess. The offspring of young parents cannot inherit the later stages of life from parents who have not passed through them. Cases of remote reversion or atavism show that ancestral peculiarities can transmit themselves in a latent or undeveloped condition for hundreds or thousands of generations. Many obvious facts compelled Darwin to suppose that vast numbers of the reproductive gemmules in an individual are not thrown off by his own cells, but are the self-multiplying progeny of ancestral gemmules. Galton restricts the production of gemmules by the personal structure to a few exceptional cases, and would evidently like to dispense with pangenesis altogether, if he could only be sure that acquired characters are never inherited. Weismann entirely rejects pangenesis and the inheritance of acquired characters. This enables him to explain heredity by his theory of the "Continuity of the Germ-plasm."[67] Parent and offspring are alike successive products or offshoots of this persistent germ-substance, which obviously would not be correspondingly affected by modifications of parts in parents, and so would render the transmission of acquired characters impossible. INVERSE INHERITANCE. Mr. Galton contends that the reproductive elements become sterile when used in forming and maintaining the individual, and that only a small proportion of them are so used.[68] He holds that the next generation will be formed entirely, or almost entirely, from the residue of undeveloped germs, which, not having been employed in the structure and work of the individual, have been free to multiply and form the reproductive elements whence future individuals are derived. Hence the singular inferiority not infrequently displayed by the children of men of extraordinary genius, especially where the ancestry has been only of a mediocre ability. The valuable germs have been used up in the individual, and rendered sterile in the structure of his person. Hence, too, the "strong tendency to deterioration in the transmission of every exceptionally gifted race." Mr. Galton's hypothesis "explains the fact of certain diseases skipping one or more generations," and it "agrees singularly well with many classes of fact;" and it is strongly opposed to the theory of use-inheritance. The elements which are used die almost universally without germ progeny: the germs which are _not_ used are the great source of posterity. Hence, when the germs or gemmules which achieve development are either better or worse than the residue, the qualities transmitted to offspring will be of an inverse character. If brain-work attracts, develops _and sterilizes_ the best gemmules, the ultimate effect of education on the intellect of posterity may differ from its immediate effect. EARLY ORIGIN OF THE OVA. As the ova are formed at as early a period as the rest of the maternal structure, Galton notices that it seems improbable that they would be correspondingly affected by subsequent modifications of parental structure. Of course it is not certain that this is a valid argument. We know that the paternal half of the reproductive elements does not enter the ovum till a comparatively late stage in its history, and it is quite possible that maternal elements or gemmules may also enter the ovum from without. If reproductive elements were confined to one special part or organ, we should be unable to explain the reproduction of lost limbs in salamanders, and the persistent effect of intercrossing on subsequent issue by the same mother, and the propagation of plants from shoots, or of the begonia from minute fragments of leaves, or the development of small pieces of water-worms into complete animals. MARKED EFFECTS OF USE AND DISUSE ON THE INDIVIDUAL. These are, to some extent, an argument against the cumulative inheritance of such effects. When a nerve atrophies from disuse, or a duct shrivels, or bone is absorbed, or a muscle becomes small or flabby, it proves, so far, that the average effect of use through enormous ages is _not_ transmitted. When the fibula of a dog's leg thickens by 400 per cent. to a size "equal to or greater than" that of the removed tibia which previously did the work,[69] it shows that in spite of disuse for countless generations, the "almost filiform" bone has retained a potentiality of development which is fully equal to that possessed by the larger one which has been constantly used. When, after being reared on the ailanthus, the caterpillars of the _Bombyx hesperus_ die of hunger rather than return to their natural food, the inherited effect of ancestral habit does not seem to be particularly strong. Neither is there any strongly-inherited effect of long-continued ancestral wildness in many animals which are easily tamed. WOULD NATURAL SELECTION FAVOUR USE-INHERITANCE? If use-inheritance is really one of the factors of evolution, it is certainly a subordinate one, and an utterly helpless one, whenever it comes into conflict with the great ruling principle of Selection. Would this dominant cause of evolution have favoured a tendency to use-inheritance if such had appeared, or would it have discouraged and destroyed it? We have already seen that use-inheritance is unnecessary, since natural selection will be far more effective in bringing about advantageous modifications; and if it can be shown that use-inheritance would often be an evil, it then becomes probable that on the whole natural selection would more strongly discourage and eliminate it as a hostile factor than it might occasionally favour such a tendency as a totally unnecessary aid. USE-INHERITANCE AN EVIL. Use-inheritance would crudely and indiscriminately proportion parts to actual work done--or rather to the varying _nourishment and growth_ resulting from a multiplicity of causes--and this in its various details would often conflict most seriously with the real necessities of the case, such as occasional passive strength, or appropriate shape, lightness and general adaptation. If its accumulated effects were not corrected by natural or sexual selection, horns and antlers would disappear in favour of enlarged hoofs. The elephant's tusks would become smaller than its teeth. Men would have callosities for sitting on, like certain monkeys, and huge corns or hoofs for walking on. Bones would often be modified disastrously. Thus the condyle of the human jaw would become larger than the body of the jaw, because as the fulcrum of the lever it receives more pressure. Some organs (like the heart, which is always at work) would become inconveniently or unnecessarily large. Other absolutely indispensable organs, which are comparatively passive or are very seldom used, would dwindle until their weakness caused the ruin of the individual or the extinction of the species. In eliminating various evil results of use-inheritance, natural selection would be eliminating use-inheritance itself. The displacement of Lamarck's theory by Darwin's shows that the effects of use-inheritance often differ from those required by natural selection; and it is clear that the latter factor must at least have reduced use-inheritance to the very minor position of comparative feebleness and harmlessness assigned to it by Darwin. Use-inheritance would be ruinous through causing unequal variation in co-operative parts--of which Mr. Spencer may accept his own instances of the jaws and teeth, and the cave-crab's lost eyes and persistent eye-stalks, as typical examples. That the variation would be unequal seems almost self-evident from the varying rapidity and extent of the effects of use and disuse on different tissues and on different parts of the general structure. The optic nerve may atrophy in a few months from disuse consequent on the loss of the eye. Some of the bones of the rudimentary hind legs of the whale are still in existence after disuse for an enormous period. Evidently use-inheritance could not equally modify the turtle and its shell, or the brain and its skull; and in minor matters there would be the same incongruity of effect. Thus, if the molar teeth lengthened from extra use the incisors could not meet. Unequal and indiscriminate variation would throw the machinery of the organism out of gear in innumerable ways. Use-inheritance would perpetuate various evils. We are taught, for instance, that it perpetuates short-sight, inferior senses, epilepsy, insanity, nervous disorders, and so forth. It would apparently transmit the evil effects of over-exertion, disuse, hardship, exposure, disease and accident, as well as the defects of age or immaturity. Would it not be better on the whole if each individual took a fresh start as far as possible on the advantageous typical lines laid down by natural selection? Through the long stages of evolution from primæval protoplasm upwards, such species as were least affected by use-inheritance would be most free to develop necessary but seldom-used organs, protective coverings such as shells or skulls, and natural weapons, defences, ornaments, special adaptations, and so forth; and this would be an advantage--for survival would obviously depend on the _importance_ of a structure or faculty in deciding the struggle for existence and reproduction, and not on the total amount of its using or nourishment. If natural selection had on the whole favoured this officious ally and frequent enemy, surely we should find better evidence of its existence. Without laying undue stress upon the evil effects of use-inheritance, a careful examination of them in detail may at least serve to counter-balance the optimistic _a priori_ arguments for belief in that plausible but unproven factor of evolution. The benefits derivable from use-inheritance are largely illusory. The effects of _use_, indeed, are generally beneficial up to a certain point; for natural selection has sanctioned or evolved organs which possess the property or potentiality of developing to the right extent under the stimulus of use or nourishment. But use-_inheritance_ would cumulatively alter this individual adaptability, and would tend to fix the size of organs by the average amount of ancestral use or disuse rather than by the actual requirements of the individual. Of course under changed conditions involving increased or lessened use of parts it might become advantageous; but even here it may prove a decided hindrance to adaptive evolution in some respects as well as an unnecessary aid in others. Thus in the case of animals becoming heavier, or walking more, it would _lengthen_ the legs although natural selection might require them to be shortened. In the Aylesbury duck and the Call duck, if use-inheritance has increased the dimensions of the bones and tendons of the leg, natural selection has had to counteract this increase so far as length is concerned, and to effect 8 per cent. of shortening besides. If use-inheritance thickens bones without proportionally lengthening them, it would hinder rather than help the evolution of such structures as the long light wings of birds, or the long legs and neck of the giraffe or crane. VARIED EFFECTS OF USE AND DISUSE. The changes which we somewhat roughly and empirically group together as the effects of "use and disuse" are of widely diverse character. Thus bone, as the physiological fact, thickens under _alternations_ of pressure (and the consequent increased flow of nourishment), but atrophies under a steadily continued pressure; so that if the use of a bone involved continuous pressure, the effect of such use would be a partial or total absorption of that bone. Darwin shows that bone lengthens as well as thickens from carrying a greater weight, while tension (as seen in sailors' arms, which are used in pulling) appears to have an equally marked effect in shortening bones (_Descent of Man_, p. 32). Thus different kinds of use may produce opposite results. The cumulative inheritance of such effects would often be mischievous. The limbs of the sloth and the prehensile tail of the spider monkey would continually grow shorter, while the legs of the evolving elephant or rhinoceros might lengthen to an undesirable extent. Such cumulative tendencies of use-inheritance, if they exist, are obviously well kept under by natural selection. Although the ultimate effect of use is generally growth or enlargement through increased flow of blood, the first effect usually is a loss of substance, and a consequent diminution of size and strength. When the loss exceeds the growth, use will diminish or deteriorate the part used, while disuse would enlarge or perfect it. Teeth, claws, nails, skin, hair, hoofs, feathers, &c., may thus be worn away faster than they can renew themselves. But this wearing away usually stimulates the repairing process, and so increases the rate of growth; that is, it will increase the size produced, if not the size retained. Which effect of use does use-inheritance transmit in such cases--the increased rate of growth, or the dilapidation of the worn-out parts? We can hardly suppose that both these effects of use will be inherited. Would shaving destroy the beard in time or strengthen it? Will the continued shearing of sheep increase or lessen the growth of wool? What will be the ultimate effect of plucking geese's quills, and of the eider duck's abstraction of the down from her breast? If the mutilated parts grow stronger or more abundantly, why were the motmot's feathers alleged to be narrowed by the inherited effects of ancestral nibbling? The "use" or "work" or "function" of muscles, nerves, bones, teeth, skin, tendon, glands, ducts, eyes, blood corpuscles, cilia, and the other constituents of the organism, is as widely different as the various parts are from each other, and the effects of their use or disuse are equally varied and complicated. USE-INHERITANCE IMPLIES PANGENESIS. How could the transmission of these varied effects to offspring be accounted for? Is it possible to believe, with Mr. Spencer, that the effects of use and disuse on the parts of the personal structure are simultaneously registered in corresponding impressions on the seminal germs? Must we not feel, with Darwin apparently,[70] that the _only_ intelligible explanation of use-inheritance is the hypothesis of Pangenesis, according to which each modified cell, or physiological unit, throws off similarly-modified gemmules or parts of itself, which ultimately reproduce the change in offspring? If we reject pangenesis, it becomes difficult to see how use-inheritance can be possible. PANGENESIS IMPROBABLE. The more important and best-known phenomena of heredity do not require any such hypothesis, and leading facts (such as atavism, transmission of lost parts, and the general non-transmission of acquired characters) are so adverse to it that Darwin has to concede that many of the reproductive gemmules are atavistic, and that by continuous self-multiplication they may preserve a practical "continuity of germ-substance," as Weismann would term it. The idea that the relationship of offspring to parent is one of direct descent is, as Galton tells us, "wholly untenable"; and the only reason he admits some supplementary traces of pangenesis into his "Theory of Heredity,"[71] is that he may thus account for the more or less questionable cases of the transmission of acquired characters. But there appears to be no necessity even for this concession. We ought therefore to dispense with the useless and gratuitous hypothesis that cells multiply by throwing off minute self-multiplying gemmules, as well as by the well-known method of self-division. If pangenesis occurs, the transmission of acquired characters ought to be a prominent fact. The size, strength, health and other good or evil qualities of the cells could hardly fail to exercise a marked and corresponding effect upon the size and quality of the reproductive gemmules thrown off by those cells. The direct evidence tends to show that these free gemmules do not exist. Transfusion of blood has failed to affect inheritance in the slightest degree. Pangenesis, with its attraction of gemmules from all parts of the body into the germ-cells, and the free circulation of gemmules in the offspring till they hit upon or are attracted by the particular cell or cells, with which alone they can readily unite, seems a less feasible theory and less in conformity with the whole of the facts than an hypothesis of germ-continuity which supposes that the development of the germ-plasm and of the successive self-dividing cells of the body proceeds from within. Darwin's keen analogy of the fertilization of plants by pollen renders development from without conceivable, but as there are no insects to convey gemmules to their destination, each kind of gemmule would have to be exceedingly numerous and easily attracted from amongst an inconceivable number of other gemmules. Arguments against pangenesis can also be drawn from the case of neuter insects--a fact which seems to have escaped Darwin's notice, although he had seen how strongly that case was opposed to the doctrine which is the essential basis of the theory of pangenesis. SPENCER'S EXPLANATION OF USE-INHERITANCE. Mr. Spencer's explanation of the inheritance of the effects of use and disuse (p. 36) is that "while generating a modified _consensus_ of functions and of structures, the activities are at the same time impressing this modified _consensus_ on the sperm-cells and germ-cells whence future individuals are to be produced"--a proposition which reads more like metaphysics than science. Difficult to understand or believe in ordinary instances, such _consensus_-inheritance seems impossible in cases like that of the hive-bee. Can we suppose that the _consensus_ of the activities of the working bee impresses itself on the sperm-cells of the drones and on the germ-cells of the carefully secluded queen? Büchner thinks so, for he says: "Although the queens and drones do not now work, yet the capacities inherited from earlier times still remain to them, especially to the former, and are kept alive and fresh by the impressions constantly made upon them during life, and they are thus in a position to transmit them to posterity." Surely it is better to abandon a cherished theory than to be compelled to defend it by explanations which are as inconsistent as they are inadequate. New capacities are developed as well as old ones kept fresh. The massacre or expulsion of the drones would have to impress itself on the germ-cells of an onlooking queen, and the imprisonment of the queen on the sperm-cells of the drones--and in such a way, moreover, as to be afterwards developed into action in the neuters only. And use-inheritance all the while is being thoroughly overpowered by impression-inheritance--by the full transmission of that which is merely seen in others! If such a law prevails, one may feel cold because an ancestor thought of the frosty Caucasus. None of this absurdity would arise if it were clearly seen that a parent is only a trustee--that transmission and development are perfectly distinct--that parental modifications are irrelevant to those transmitted to offspring. FOOTNOTES: [67] _Essays on Heredity_, p. 104. Weismann's theory is clear, simple and convenient, but incomplete; for, unlike Darwin's theory of pangenesis, it scarcely attempts any real explanation of the extremely complex potentialities possessed by the reproductive elements. Perhaps we might retain Darwin's self-multiplying gemmules without supposing them to be thrown off by the cells, which will no longer be credited with _two_ modes of multiplication. These minute germs or gemmules may have been evolved by natural selection playing upon the sample germs that achieve development; and they may exist either separately, or (preferably but perhaps not invariably) in aggregates to form Weismann's germ-plasm. [68] _Contemporary Review_, Dec., 1875, p. 88. [69] _Variation of Animals and Plants under Domestication_, ii. 286. [70] _Variation of Animals and Plants under Domestication_, ii. 388, 398, 367; _Life and Letters_, iii. 44. [71] _Contemporary Review_, Dec., 1875, pp. 94, 95. CONCLUSIONS. USE-INHERITANCE DISCREDITED AS UNNECESSARY, UNPROVEN, AND IMPROBABLE. General experience teaches that acquired characters are not usually inherited; and investigation shows that the apparent exceptions to this great rule are probably fallacious. Even the alleged instances of use-inheritance culled by such great and judicious selectors as Darwin and Spencer break down upon examination; for they can be better explained without use-inheritance than with it. On the other hand, the adverse facts and considerations are almost strong enough to prove the actual non-existence of such a law or tendency. There is no need to undertake the apparently impossible task of demonstrating an absolute negative. It will be enough to ask that the Lamarckian factor of use-inheritance shall be removed from the category of accredited factors of evolution to that of unnecessary and improbable hypotheses. The main explanation or source of the fallacy may be found in the fact that natural selection frequently imitates some of the more obvious effects of use and disuse. MODERN RELIANCE ON USE-INHERITANCE MISPLACED. Modern philanthropy--so far at least as it ever studies ultimate results--constantly relies on this ill-founded belief as its justification for ignoring the warnings of those who point out the ultimately disastrous results of a systematic defiance or reversal of the great law of natural selection. This reliance finds strong support in Mr. Spencer's latest teachings, for he holds that the inheritance of the effects of use and disuse takes place universally, and that it is now "the chief factor" in the evolution of civilized man (pp. 35, 74, iv)--natural selection being quite inadequate for the work of progressive modification. Practically he abandons the hope of evolution by natural selection, and substitutes the ideal of a nation being "modified _en masse_ by transmission of the effects" of its institutions and habits. Use-inheritance will "mould its members far more rapidly and comprehensively" than can be effected by the survival of the fittest alone. But could we rely upon the aid of use-inheritance if it really were a universal law and not a mere simulation of one? Let us consider some of the features of this alleged factor of evolution, seeing that it is henceforth to be our principal means of securing the improvement of our species and our continued adaptation to the changing conditions of a progressive civilization. It is curiously uncertain and irregular in its action. It diminishes or abolishes some structures (such as jaws or eyes) without correspondingly diminishing or abolishing other equally disused and closely related parts (such as teeth, or eye-stalks). It thickens ducks' leg-bones while allowing them to shorten. It shortens the disused wing-bones of ducks and the leg-bones of rabbits while allowing them to thicken; and yet in other cases it greatly reduces the thickness of bones without shortening them. It transmits tameness most powerfully in an animal which usually cannot acquire it. It aids in webbing the feet of water-dogs, but fails to web the feet of the water-hen or to remove the web in the feet of upland geese.[72] It allows the disused fibula to retain a potentiality of development fully equal to that possessed by the long-used tibia. It lengthens legs because they are used in supporting the body, and shortens arms because they are used in pulling. Whether it enlarges brain if used in one way and diminishes it if used in another, we cannot tell; but it must obviously deaden nervous sensibilities in some cases and intensify them in others. It enlarges hands long before they are used, and thickens soles long before the time for walking on them. At the same time, as if by an oversight, it so delays its transmission of the habit of walking on these thickened soles, that the gradual and tedious acquisition of the non-transmitted habit costs the infant much time and trouble and often some pain and danger. Yet where aided by natural selection, as with chickens and foals, it transmits the habit in wonderful perfection and at a remarkably early date. It transmits new paces in horses in a single generation, but fails to perpetuate the songs of birds. It modifies offspring like parents, and yet allows the formation of two reproductive types in plants, and of two or more types widely different from the parents in some of the higher insects. It is said to be indispensable for the co-ordinated development of man and the giraffe and the elk, but appears to be unnecessary for the evolution and the maintenance of wonderful structures and habits and instincts in a thousand species of ants and bees and termites. It is the only possible means of complex evolution and adaptation of co-operative parts, and yet in Mr. Spencer's most representative case it renders such important parts as teeth and jaws unsuited for each other, and is said to ruin the teeth by the consequent overcrowding and decay. It survives amidst a general "lack of recognised evidence," and only seems to act usefully and healthily and regularly in quarters where it can least easily be distinguished from other more powerful and demonstrable factors of evolution. So little does it care to display its powers where they would be easily verifiable as well as useful that practical breeders ignore it. So slight is its independent power that it seems to allow natural selection or sexual selection or artificial selection to modify organisms in sheer defiance of its utmost opposition, just as readily as they modify organisms in other directions with its utmost help. If it partially perpetuates and extends the pecked-out indentations in the motmot's tail feathers, it on the other hand fails to transmit the slightest trace of mutilation in an almost infinite number of ordinary cases, and even where the mutilation is repeated for a hundred generations; and it apparently repairs rather than transmits the ordinary and oft-repeated losses caused by plucking hair, down and feathers, and the wear and tear of claws, teeth, hoofs and skin. It is often mischievous as well as anomalous in its action. Under civilization with its division of labour, the various functions of mind and body are very unequally exercised. There is overwork or misuse of one part and disuse and neglect of others, leading to the partial breakdown or degeneration of various organs and to general deterioration of health through disturbed balance of the constitution. The brain, or rather particular parts of it, are often over-stimulated, while the body is neglected. In many ways education and civilization foster nervousness and weakness, and undermine the rude natural health and spirits of the human animal. Alcohol, tobacco, tea, coffee, extra brain work, late hours, dissipation, overwork, indoor life, division of labour, preservation of the weak, and many other causes, all help to injure the modern constitution; so that the prospect of cumulative intensification of these evils by the additional influence of use-inheritance is not an encouraging one. It is true that modern progress and prosperity are improving the people in various respects by their direct action; but if use-inheritance has any share in effecting this improvement it must also transmit increased wants and more luxurious habits, together with such evils as have already been referred to. As depicted by its defenders, use-inheritance transmits evils far more powerfully and promptly than benefits. It transmits insanity and shattered nerves rather than the healthy brain which preceded the breakdown. It perpetuates, and cumulatively intensifies, a deterioration in the senses of civilized men, but it fails to perpetuate the rank vigour of various plants when too well nourished, or the flourishing condition of various animals when too fat or when tamed. It already transmits the short-sight caused by so modern an art as watchmaking, but so fails to transmit the long-practised art of seeing (as it does of walking and talking) that vision is worse than useless to a man until he gradually acquires the necessary but non-transmitted associations of sensation and idea by his own experience. In a well-known case, a blind man on gaining his sight by an operation said that "all objects seemed to touch his eyes, as what he felt did his skin"--so little had the universal experience of countless ages impressed itself on his faculties. Under normal healthy conditions use-inheritance is so slow in its action that "several generations" must elapse before it produces any appreciable effect, and then that effect is only precisely what selection might be expected to bring about without its aid. Strong for evil and slow for good, it can convey epilepsy promptly in guinea pigs, but transmits the acquirements of genius so poorly that our best student of the heredity of genius has to account for the frequent and remarkable deterioration of the offspring by a theory which is strongly hostile to use-inheritance. It would tend to make organisms unworkable by the excessive differences in its rate and manner of action on co-operative parts, and by adapting these parts to the total amount of nourishment received rather than to occasional necessity or actual usefulness. It would tend to stereotype habits and convert reason into instinct. How then can we rely upon use-inheritance for the improvement of the race? Even if it is not a sheer delusion, it may be more detrimental as a positive evil than it is advantageous as an unnecessary benefit; and as a normal modifying agent it is miserably weak and untrustworthy in comparison with the powerful selective influences by which nature and society continually and inevitably affect the species for good or for evil. The effects of use and disuse--rightly directed by education in its widest sense--must of course be called in to secure the highly essential but nevertheless _superficial, limited, and partly deceptive_ improvement of individuals and of social manners and methods; but as this artificial development of already existing potentialities does not directly or readily tend to become congenital, it is evident that some considerable amount of natural or artificial selection of the more favourably varying individuals will still be the only means of securing the race against the constant tendency to degeneration which would ultimately swallow up all the advantages of civilization. The selective influences by which our present high level has been reached and maintained may well be modified, but they must not be abandoned or reversed in the rash expectation that State education, or State feeding of children, or State housing of the poor, or any amount of State socialism or public or private philanthropy, will prove permanently satisfactory substitutes. If ruinous deterioration and other more immediate evils, are to be avoided, the race must still be to the swift and the battle to the strong. The healthy Individualism so earnestly championed by Mr. Spencer must be allowed free play. Open competition, as Darwin teaches, with its survival and multiplication of the fittest, must be allowed to decide the battle of life independently of a foolish benevolence that prefers the elaborate cultivation and multiplication of weeds to the growth of corn and roses. We are trustees for the countless generations of the future. 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34368	----	Transcriber's note: A few typographical errors have been corrected: they are listed at the end of the text. * * * * * Page numbers enclosed by curly braces (example: {25}) have been incorporated to facilitate the use of the Table of Contents. * * * * * Tables which have been divided into two parts widthwise are marked with a double ~ on the original common edge. * * * * * SEX-LINKED INHERITANCE IN DROSOPHILA BY T. H. MORGAN AND C. B. BRIDGES [Illustration] WASHINGTON PUBLISHED BY THE CARNEGIE INSTITUTION OF WASHINGTON 1916 CARNEGIE INSTITUTION OF WASHINGTON PUBLICATION NO. 237. PRESS OF GIBSON BROTHERS, INC. WASHINGTON, D. C. * * * * * {3} CONTENTS. PAGE. PART I. INTRODUCTORY 5 Mendel's law of segregation 5 Linkage and chromosomes 5 Crossing-over 7 The Y chromosome and non-disjunction 8 Mutation in _Drosophila ampelophila_ 10 Multiple allelomorphs 11 Sex-linked lethals and the sex ratio 14 Influence of the environment on the realization of two sex-linked characters 16 Sexual polymorphism 17 Fertility and sterility in the mutants 18 Balanced inviability 19 How the factors are located in the chromosomes 20 The sex-linked factors of _Drosophila_ 21 Map of chromosome X 22 Nomenclature 24 PART II. NEW DATA 25 White 25 Rudimentary 25 Miniature 26 Vermilion 27 Yellow 27 Abnormal abdomen 27 Eosin 28 Bifid 28 Linkage of bifid with yellow, with white, and with vermilion 29 Linkage of cherry, bifid, and vermilion 30 Reduplicated legs 31 Lethal 1 31 Lethal 1a 32 Spot 33 Sable 34 Linkage of yellow and sable 35 Linkage of cherry and sable 37 Linkage of eosin, vermilion, and sable 37 Linkage of miniature and sable 40 Linkage of vermilion, sable, and bar 40 Dot 44 Linkage of vermilion and dot 44 Bow 46 Bow by arc 47 Lemon body-color 48 Linkage of cherry, lemon, and vermilion 48 Lethal 2 49 Cherry 51 A system of quadruple allelomorphs 51 Linkage of cherry and vermilion 51 Compounds of cherry 52 Fused 53 Linkage of eosin and fused 54 Linkage of vermilion, bar, and fused 56 {4} Forked 58 Linkage of vermilion and forked 59 Linkage of cherry and forked 59 Linkage of forked, bar, and fused 60 Linkage of sable, rudimentary, and forked 61 Linkage of rudimentary, forked, and bar 62 Shifted 63 Linkage of shifted and vermilion 63 Linkage of shifted, vermilion, and bar 64 Lethals _sa_ and _sb_ 64 Bar 66 Notch 66 Depressed 67 Linkage of depressed and bar 67 Linkage of cherry, depressed, and vermilion 68 Club 69 Genotypic club 70 Linkage of club and vermilion 70 Linkage of yellow, club, and vermilion 70 Linkage of cherry, club, and vermilion 72 Green 73 Chrome 74 Lethal 3 74 Lethal 3_a_ 75 Lethal 1_b_ 76 Facet 76 Linkage of facet, vermilion, and sable 77 Linkage of eosin, facet, and vermilion 78 Lethal _sc_ 79 Lethal _sd_ 79 Furrowed 80 Additional data for yellow, white, vermilion, and miniature 80 New data contributed by A. H. Sturtevant and H. J. Muller 82 Summary of the previously determined cross-over values 83 Summary of all data upon linkage of gens in chromosome I. 84 BIBLIOGRAPHY. 86 * * * * * {5} PART I. INTRODUCTORY. MENDEL'S LAW OF SEGREGATION. Although the ratio of 3 to 1 in which contrasted characters reappear in the second or F_2 generation is sometimes referred to as Mendel's Law of Heredity, the really significant discovery of Mendel was not the 3 to 1 ratio, but the segregation of the characters (or rather, of the germinal representatives of the characters) which is the underlying cause of the appearance of the ratio. Mendel saw that the characters with which he worked must be represented in the germ-cells by specific producers (which we may call factors), and that in the fertilization of an individual showing one member of a pair of contrasting characters by an individual showing the other member, the factors for the two characters meet in the hybrid, and that _when the hybrid forms germ-cells the factors segregate from each other without having been contaminated one by the other._ In consequence, half the germ-cells contain one member of the pair and the other half the other member. When two such hybrid individuals are bred together the combinations of the pure germ-cells give three classes of offspring, namely, two hybrids to one of each of the pure forms. Since the hybrids usually can not be distinguished from one of the pure forms, the observed ratio is 3 of one kind (the dominant) to 1 of the other kind (the recessive). There is another discovery that is generally included as a part of Mendel's Law. We may refer to this as the _assortment_ in the germ-cells of the products of the segregation of two or more pairs of factors. If assortment takes place according to chance, then definite F_2 ratios result, such as 9:3:3:1 (for two pairs) and 27:9:9:9:3:3:3:1 (for three pairs), etc. Mendel obtained such ratios in peas, and until quite recently it has been generally supposed that free assortment is the rule when several pairs of characters are involved. But, as we shall try to show, the emphasis that has been laid on these ratios has obscured the really important part of Mendel's discovery, namely, _segregation_; for with the discovery in 1906 of the fact of linkage the ratios based on free assortment were seen to hold only for combinations of certain pairs of characters, not for other combinations. But the principle of segregation still holds for each pair of characters. Hence segregation remains the cardinal point of Mendelism. Segregation is to-day Mendel's Law. LINKAGE AND CHROMOSOMES. It has been found that when _certain_ characters enter a cross together (_i. e._, from the same parent) their factors tend to pass into the same gamete of the hybrid, with the result that other ratios than the chance ratios described by Mendel are found in the F_2 generation. {6} Such cases of linkage have been described in several forms, but nowhere on so extensive a scale as in the pomace fly, _Drosophila ampelophila_. Here, over a hundred characters that have been investigated as to their linkage relations are found to fall into four groups, the members of each group being linked, in the sense that they tend to be transmitted to the gametes in the same combinations in which they entered from the parents. The members of each group give free assortment with the members of any of the other three groups. A most significant fact in regard to the linkage shown by the _Drosophila_ mutants is that _the number of linked groups corresponds to the number of pairs of the chromosomes._ If the gens for the Mendelian characters are carried by the chromosomes we should expect to find demonstrated in _Drosophila_ that there are as many groups of characters that are inherited together as there are pairs of chromosomes, provided the chromosomes retain their individuality. The evidence that the chromosomes are structural elements of the cell that perpetuate themselves at every division has continually grown stronger. That factors have the same distribution as the chromosomes is clearly seen in the case of sex-linked characters, where it can be shown that any character of this type appears in those individuals which from the known distribution of the X chromosomes must also contain the chromosome in question. For example, in _Drosophila_, as in many other insects, there are two X chromosomes in the cells of the female and one X chromosome in the cells of the male. There is in the male, in addition to the X, also a Y chromosome, which acts as its mate in synapsis and reduction. After reduction each egg carries an X chromosome. In the male there are two classes of sperm, one carrying the X chromosome and the other carrying the Y chromosome. Any egg fertilized by an X sperm produces a female; any egg fertilized by a Y sperm produces a male. The scheme of inheritance is as follows. +------------------------------+ | | | Eggs X--X | | Sperm X--Y | +------------------------------+ | Daughter XX | | Son XY | | | +------------------------------+ The sons get their single X chromosome from their mother, and should therefore show any character whose gen is carried by such a chromosome. In sex-linked inheritance all sons show the characters of their mother. A male transmits his sex-linked character to his daughters, who show it if dominant and conceal it if recessive. But any daughter will transmit such a character, whether dominant or recessive, to half of her sons. The path of transmission of the gen is the same as the path followed by the X chromosome, received here {7} from the male. Many other combinations show the same relations. In the case of non-disjunction, to be given later, there is direct experimental evidence of such a nature that there can no longer be any doubt that the X chromosomes are the carriers of certain gens that we speak of as sex-linked. This term (sex-linked) is intended to mean that such characters are carried by the X chromosome. It has been objected that this use of the term implies a knowledge of a factor for sex in the X chromosome to which the other factors in that chromosome are linked; but in fact we have as much knowledge in regard to the occurrence of a sex factor or sex factors in the X chromosome as we have for other factors. It is true we do not know whether there is more than one sex-factor, because there is no crossing-over in the male (the heterozygous sex), and crossing-over in the female does not influence the distribution of sex, since like parts are simply interchanged. It follows from this that we are unable as yet to locate the sex factor or factors in the X chromosome. The fact that we can not detect crossing-over under this condition is not an argument against the occurrence of linkage. We are justified, therefore, in speaking of the factors carried by the X chromosome as sex-linked. CROSSING-OVER. When two or more sex-linked factors are present in a male they are always transmitted together to his daughters, as must necessarily be the case if they are carried by the unpaired X chromosome. If such a male carrying, let us say, two sex-linked factors, is mated to a wild female, his daughters will have one X chromosome containing the factors for both characters, derived from the father, and another X chromosome that contains the factors that are normal for these two factors (the normal allelomorphs). The sons of such a female will get one or the other of these two kinds of chromosomes, and should be expected to be like the one or the other grandparent. In fact, most of the sons are of these two kinds. But, in addition, there are sons that show one only of the two original mutant characters. Clearly an interchange has taken place between the two X chromosomes in the female in such a way that a piece of one chromosome has been exchanged for the homologous piece of the other. The same conclusion is reached if the cross is made in such a way that the same two sex-linked characters enter, but, one from the mother and the other from the father. The daughter gets one of her sex chromosomes from her mother and the other from her father. She should produce, then, two kinds of sons, one like her mother and one like her father. In fact, the majority of her sons are of these two kinds, but, in addition, there are two other kinds of sons, one kind showing both mutant characters, the other kind showing normal characters. Here again the results must be due to interchange between the two X's in the hybrid female. _The number of_ {8} _the sons due to exchange in the two foregoing crosses is always the same, although they are of contrary classes._ Clearly, then, the interchange takes place irrespective of the way in which the factors enter the cross. We call those classes that arise through interchange between the chromosomes "cross-over classes" or merely "cross-overs." The phenomenon of holding together we speak of as linkage. By taking a number of factors into consideration at the same time it has been shown that _crossing-over involves large pieces of the chromosomes_. The X chromosomes undergo crossing-over in about 60 per cent of the cases, and the crossing-over may occur at any point along the chromosome. When it occurs once, whole ends (or halves even) go over together and the exchange is always equivalent. If crossing-over occurs twice at the same time a middle piece of one chromosome is intercalated between the ends of the other chromosome. This process is called double crossing-over. It occurs not oftener than in about 10 per cent of cases for the total length of the X chromosome. Triple crossing-over in the X chromosome is extremely rare and has been observed only about a half dozen times. While the genetic evidence forces one to accept crossing-over between the sex chromosomes in the female, that evidence gives no clue as to how such a process is brought about. There are, however, certain facts familiar to the cytologist that furnish a clue as to how such an interchange might take place. When the homologous chromosomes come together at synapsis it has been demonstrated, in some forms at least, that they twist about each other so that one chromosome comes to lie now on the one side now on the other of its partner. If at some points the chromosomes break and the pieces on the same side unite and pass to the same pole of the karyokinetic spindle, the necessary condition for crossing-over will have been fulfilled. THE Y CHROMOSOME AND NON-DISJUNCTION. Following Wilson's nomenclature, we speak of both X and Y as sex chromosomes. Both the cytological and the genetic evidence shows that when two X chromosomes are present a female is produced, when one, a male. This conclusion leaves the Y chromosome without any observed relation to sex-determination, despite the fact that the Y is normally present in every male and is confined to the male line. The question may be asked, and in fact has been asked, why may not the presence of the Y chromosome determine that a male develop and its absence that a female appear? The only answer that has yet been given, outside of the work on _Drosophila_, is that since in some insects there is no Y chromosome, there is no need to make such an assumption. But in _Drosophila_ direct proof that Y has no such function is furnished by the evidence discovered by Bridges in the case of non-disjunction. (Bridges, 1913, 1914, 1916, and unpublished results.) {9} Ordinarily all the sons and none of the daughters show the recessive sex-linked characters of the mother when the father carries the dominant allelomorph. The peculiarity of non-disjunction is that sometimes a female produces a daughter like herself or a son like the father, although the rest of the offspring are perfectly regular. For example, a vermilion female mated to a wild male produces vermilion sons and wild-type daughters, but rarely also a vermilion daughter or a wild-type son. The production of these exceptions (primary exceptions) by a normal XX female must be due to an aberrant reduction division at which the two X chromosomes fail to disjoin from each other. In consequence both remain in the egg or both pass into the polar body. In the latter case an egg without an X chromosome is produced. Such an egg fertilized by an X sperm produces a male with the constitution XO. These males received their single X from their father and therefore show the father's characters. While these XO males are exceptions to sex-linked inheritance, the characters that they do show are perfectly normal, that is, the miniature or the bar or other sex-linked characters that the XO male has are like those of an XY male, showing that the Y normally has no effect upon the development of these characters. But that the Y does play some positive rôle is proved by the fact that all the XO males have been found to be absolutely sterile. While the presence of the Y is necessary for the fertility of the male, it has no effect upon sex itself. This is shown even more strikingly by the phenomenon known as secondary non-disjunction. If the two X chromosomes that fail to disjoin remain in the egg, and this egg is fertilized by a Y sperm, an XXY individual results. This is a female which is like her mother in all sex-linked characters (a matroclinous exception), since she received both her X chromosomes from her mother and none from her father. As far as sex is concerned this is a perfectly normal female. The extra Y has no effect upon the appearance of the characters, even in the case of eosin, where the female is much darker than the male. The only effect which the extra Y has is as an extra wheel in the machinery of synapsis and reduction; for, on account of the presence of the Y, both X's of the XXY female are sometimes left within the ripe egg, a process called secondary non-disjunction. In consequence, an XXY female regularly produces exceptions (to the extent of about 4 per cent). A small percentage of reductions are of this XX-Y type; the majority are X-XY. The XY eggs, produced by the X-XY reductions, when fertilized by Y sperm, give XYY males, which show no influence of the extra Y except at synapsis and reduction. By mating an XXY female to an XYY male, XXYY females have been produced and these are perfectly normal in appearance. We may conclude from the fact that visibly indistinguishable males have been produced with the formulas XO, XY, and XYY, and {10} likewise females with the formulas XX, XXY, and XXYY, that the Y is without effect either on the sex or on the visible characters (other than fertility) of the individual. The evidence is equally positive that sex is quantitatively determined by the X chromosome--that two X's determine a female and one a male. For in the case of non-disjunction, a zero or a Y egg fertilized by an X sperm produces a male, while conversely an XX egg fertilized by a Y sperm produces a female. It is thus impossible to assume that the X sperms are normally female-producing because of something else than the X or that the Y sperm produce males for any other reason than that they normally fertilize X eggs. Both the X and the Y sperm have been shown to produce the sex opposite to that which they normally produce when they fertilize eggs that are normal in every respect, except that of their X chromosome content. These facts establish experimentally that sex is determined by the combinations of the X chromosomes, and that the male and female combinations are the causes of sex differentiation and are not simply the results of maleness and femaleness already determined by some other agent. Cytological examination has demonstrated the existence of one XXYY female, and has checked up the occurrence in the proper classes and proportions of the XXY females. Numerous and extensive breeding-tests have been made upon the other points discussed. The evidence leaves no escape from the conclusion that the genetic exceptions are produced as a consequence of the exceptional distribution of the X chromosomes and that the gens for the sex-linked characters are carried by those chromosomes. MUTATION IN DROSOPHILA AMPELOPHILA. The first mutants were found in the spring of 1910. Since then an ever-increasing series of new types has been appearing. An immense number of flies have come under the scrutiny of those who are working in the Zoological Laboratory of Columbia University, and the discovery of so many mutant types is undoubtedly due to this fact. But that mutation is more frequent in _Drosophila ampelophila_ than in some of the other species of _Drosophila_ seems not improbable from an extensive examination of other types. It is true a few mutants have been found in other _Drosophilas_, but relatively few as compared with the number in _D. ampelophila_. Whether _ampelophila_ is more prone to mutate, or whether the conditions under which it is kept are such as to favor this process, we have no knowledge. Several attempts that we have made to produce mutations have led to no conclusive results. The mutants of _Drosophila_ have been referred to by Baur as "mutations through loss," but inasmuch as they differ in no respect that we can discover from other mutants in domesticated animals and plants, there is no particular reason for putting them into this category unless {11} to imply that new characters have not appeared, or that those that have appeared must be due to loss in the sense of absence of something from the germ-plasm. In regard to the first point, several of the mutants are characterized by what seem to be additions. For example, the eye-color sepia is darker than the ordinary red. At least three new markings have been added to the thorax. A speck has appeared at the base of the wing, etc. These are recessive characters, it is true, but the character "streak," which consists of a dark band added to the thorax, is a dominant. If dominance is supposed to be a criterion as to "presence," then it should be pointed out that among the mutants of _Drosophila_ a number of dominant types occur. But clearly we are not justified by these criteria in inferring anything whatever in regard to the nature of the change that takes place in the germ-plasm. Probably the only data which give a basis for attempting to decide the nature of the change in the germ-plasm are from cases where multiple allelomorphs are found. Several such cases are known to us, and two of these are found in the X chromosome group, namely, a quadruple system (white, eosin, cherry, red), and a triple system (yellow, spot, gray). In such cases each member acts as the allelomorph of any other member, and only two can occur in any one female, and only one in any male. If the normal allelomorph is thought of as the positive character, which one of the mutants is due to its loss or to its absence? If each is produced by a loss it must be a different loss that acts as an allelomorph to the other loss. This is obviously absurd unless a different idea from the one usually promulgated in regard to "absence" is held. MULTIPLE ALLELOMORPHS. It appears that Cuénot was the first to find a case (in mice) in which the results could be explained on the basis that more than two factors may stand in the relation of allelomorphs to each other. In other words, a given factor may become the partner of more than one other factor, although, in any one individual, no more than two factors stand in this relation. While it appears that his evidence as published was not demonstrative, and that, at the time he wrote, the possibility of such results being due to very close linkage could not have been appreciated as an alternative explanation, nevertheless it remains that Cuénot was right in his interpretation of his results and that the factors for yellow, gray, gray white-belly, and black in mice form a system of quadruple allelomorphs. There are at least two such systems among the factors in the first chromosome in _Drosophila_. The first of these includes the factor for white eyes, that for eosin eyes, and that for cherry eyes, and of course that allelomorph of these factors present in the wild fly and which when present gives the red color. In this instance the normal {12} allelomorph dominates all the other three, but in mice the mutant factor for yellow dominates the wild or "normal" allelomorph. The other system of multiple allelomorphs in the first chromosome is a triple system made up of yellow (body-color), spot (on abdomen), and their normal allelomorph--the factor in the normal fly that stands for "gray." In general it may be said that there are two principal ways in which it is possible to show that certain factors (more than two) are the allelomorphs of each other. First, if they are allelomorphs only two can exist in the same individual; and, in the case of sex-linked characters, while two may exist in the same female, only one can exist in the male, for he contains but one X chromosome. Second, all the allelomorphs should give the same percentages of crossing-over with each other factor in the same chromosome. It is a question of considerable theoretical importance whether these cases of multiple allelomorphs are only extreme cases of linkage or whether they form a system quite apart from linkage and in relation to normal allelomorphism. It may be worth while, therefore, to discuss this question more at length, especially because _Drosophila_ is one of the best cases known for such a discussion. The factors in the first chromosome are linked to each other in various degrees. When they are as closely linked as yellow body-color and white eyes crossing-over takes place only once in a hundred times. If two factors were still nearer together it is thinkable that crossing-over might be such a rare occurrence that it would require an enormous number of individuals to demonstrate its occurrence. In such a case the factors might be said to be completely linked, yet each would be supposed to have its normal allelomorph in the homologous chromosome of the wild type. Imagine, then, a situation in which one of these two mutant factors (a) enters from one parent and the other mutant factor (b) from the other parent. The normal allelomorph of a may be called A. It enters the combination with b, while the normal allelomorph B of b enters the combination with a. Since b is completely linked to A and a to B, the result will be the same as though a and b were the allelomorphs of each other, for in the germ-cells of the hybrid aBAb the assortment will be into aB and Ab, which is the same as though a and b acted as segregating allelomorphs. There is no way from Mendelian data by which this difference between a true case of multiple allelomorphs and one of complete linkage (as just illustrated) can be determined. There is, however, a different line of attack which, in a case like that of _Drosophila_, will give an answer to this question. The answer is found in the way in which the mutant factors arise. This argument has been fully developed in the book entitled "The Mechanism of Mendelian Inheritance," and will therefore not be repeated here. It must suffice to say that if two mutant {13} types that behave as allelomorphs of each other arise separately from the wild form, one of them must have arisen as a double mutation of two factors so close to each other as to be completely linked--a highly improbable occurrence when the infrequency of mutations is taken into consideration.[1] The evidence opposed to such an interpretation is now so strong that there can be little doubt that multiple allelomorphs have actually appeared. On _a priori_ grounds there is no reason why several mutative changes might not take place in the same locus of a chromosome. If we think of a chromosome as made up of a chain of chemical particles, there may be a number of possible recombinations or rearrangements within each particle. Any change might make a difference in the end-product of the activity of the cell, and give rise to a new mutant type. It is only when one arbitrarily supposes that the only possible change in a factor is its loss that any serious difficulty arises in the interpretation of multiple allelomorphs. One of the most striking facts connected with the subject of multiple allelomorphs is that the same kind of change is effected in the same organ. Thus, in the quadruple system mentioned above, the color of the eye is affected. In the yellow-spot system the color of the body is involved. In mice it is the coat-color that is different in each member of the series. While this is undoubtedly a striking relation and one which seems to fit well with the idea that such effects are due to mutative changes in the same fundamental element that affects the character in question, yet on the other hand it would be dangerous to lay too much emphasis on this point, because any given organ may be affected by other factors in a similar manner, and also because a factor frequently produces more than a single effect. For instance, the factor that when present gives a white eye affects also the general yellowish pigment of the body. If red-eyed and white-eyed flies are put for several hours into alcohol, the yellowish body-color of the white-eyed flies is freely extracted, but not that of the red-eyed flies. In the living condition the difference between the body-colors of the red- and of the white-eyed flies is too slight to be visible, but after extraction in alcohol the difference is striking. There are other effects also that follow in the wake of the white factor. Now, it is quite conceivable that in some specific case one of the effects might be more striking than the one produced in that organ more markedly affected by the other factor of the allelomorphic series. In such a case the relation mentioned above might seemingly disappear. For this reason it is well not to insist too strongly on the idea that multiple allelomorphs affect the same part in the same way, even although at present that appears to be the rule for all known cases. {14} SEX-LINKED LETHALS AND THE SEX RATIO. Most of the mutant types of _Drosophila_ show characteristics that may be regarded as superficial in so far as they do not prevent the animal from living in the protected life that our cultures afford. Were they thrown into open competition with wild forms, or, better said, were they left to shift for themselves under natural conditions, many or most of the types would no doubt soon die out. So far as we can see, there is no reason to suppose that the mutations which can be described as superficial are disproportionally more likely to occur than others. Of course, superficial mutations are more likely to survive and hence to be seen; while if mutations took place in important organs some of them would be expected to affect injuriously parts essential to the life of the individual and in consequence such an individual perishes. The "lethal factors" of _Drosophila_ may be supposed to be mutations of some such nature; but as yet we have not studied this side of the question sufficiently, and this supposed method of action of the lethals is purely speculative. Whatever the nature of the lethals' action, it can be shown that from among the offspring obtained from certain stocks expected classes are missing, and the absence of these classes can be accounted for on the assumption that there are present mutant factors that follow the Mendelian rule of segregation and which show normal linkage to other factors, but whose only recognizable difference from the normal is the death of those individuals which receive them. The numerical results can be handled in precisely the same way as are other linkage results. There are some general relations that concern the lethals that may be mentioned here, while the details are left for the special part or are found in the special papers dealing with these lethals. A factor of this kind carried by the X chromosome would be transmitted in the female line because the female, having two X chromosomes, would have one of them with the normal allelomorph (dominant) of the lethal factor carried by the other X chromosome. Half of her sons would get one of her X's, the other half the other. Those sons that get the lethal X will die, since the male having only one X lacks the power of containing both the lethal and its normal allelomorph. The other half of the sons will survive, but will not transmit the lethal factor. In all lethal stocks there are only half as many sons as daughters. The heterozygous lethal-bearing female, fertilized by a normal male, will give rise to two kinds of daughters; one normal in both X's, the other with a normal X and a lethal-bearing X chromosome. The former are always normal in behavior, and the latter repeat in their descendants the 2:1 sex-ratio. Whether a female bearing the same lethal twice (_i.e._, one homozygous for a given lethal) would die, can not be stated, for no such females are obtainable, because the lethal males, which alone could bring about {15} such a condition, do not exist. The presumption is that a female of this kind would also die if the lethal acts injuriously on some vital function or structure. Since only half of the daughters of the lethal-bearing females carry the lethal, the stock can be maintained by breeding daughters separately in each generation to insure obtaining one which repeats the 2:1 ratio. There is, however, a much more advantageous way of carrying on the stock--one that also confirms the sufficiency of the theory. In carrying on a stock of a lethal, advantage can be taken of linkage. A lethal factor has a definite locus in the chromosome; if, then, a lethal-bearing female is crossed to a male of another stock with a recessive character whose factor lies in the X chromosome very close to the lethal factor, half the daughters will have lethal in one X and the recessive in the other. The lethal-bearing females can be picked out from their sisters by the fact that they give a 2:1 sex-ratio, and by the fact that nearly all the sons that do survive show the recessive character. If such females are tested by breeding to the recessive males, then the daughters which do not show the recessive carry the lethal, except in the few cases of crossing-over. Thus in each generation the normal females are crossed to the recessive males with the assurance that the lethal will not be lost. If instead of the single recessive used in this fashion, a double recessive of such a sort that one recessive lies on each side of the lethal is used, then in each generation the females which show neither recessive will almost invariably contain the lethal, since a double cross-over is required to remove the lethal. It is true that females carrying two _different_ lethals might arise and not die, because the injurious effect of each lethal would be dominated by its allelomorph in the other X chromosome. Such females can not be obtained by combining two existing lethals, since lethal males do not survive. They can occur only through a new lethal arising through mutation in the homologous chromosome of a female that already carries one lethal. Rare as such an event must be, it has occurred in our cultures thrice. The presence of a female of this kind will be at once noticed by the fact that she produces no sons, or very rarely one, giving in consequence extraordinary sex-ratios. The rare appearance of a son from such a female can be accounted for in the following way: If crossing-over occurs between her X chromosomes the result will be that one X will sometimes contain two lethals, the other none. The latter, if it passes into a male, will lead to the development of a normal individual. The number of such males depends on the distance apart of the two lethals in the chromosome. There is a crucial test of this hypothesis of two lethals in females giving extraordinary ratios. This test has been applied to the cases in which such females were found, by Rawls (1913), by Morgan (1914_c_), and again by Stark (1915), and it has been found to confirm the explanation. The daughters of {16} such a female should all (excepting a rare one due to crossing-over) give 2:1 ratios, because each daughter must get one or the other X chromosome of her mother, that is, one or the other lethal. Although the mother was fertilized by a normal male, every daughter is heterozygous for one or the other of the lethal factors. The daughters of the two-lethal females differ from the daughters of the one-lethal female in that the former mother, as just stated, gives all lethal-bearing daughters; the latter transmits her lethal to only half of her daughters. INFLUENCE OF THE ENVIRONMENT ON THE REALIZATION OF TWO SEX-LINKED CHARACTERS. The need of a special environment in order that certain mutant characters may express themselves has been shown for abnormal abdomen (Morgan, 1912_d_, 1915_b_) and for reduplication of the legs (Hoge, 1915). In a third type, club, described here (page 69), the failure of the unfolding of the wing which occurs in about 20 per cent of the flies is also without much doubt an environmental effect, but as yet the particular influence that causes the change is unknown. A very extensive series of observations has been made on the character called abnormal abdomen. In pure cultures kept moist with abundance of fresh food all the flies that hatch for the first few days have the black bands of the abdomen obliterated or made faint and irregular. As the bottles get dry and the food becomes scarce the flies become more and more normal, until at last they are indistinguishable from the normal flies. Nevertheless these normal-looking flies will give rise in a suitable environment to the same kind of flies as the very abnormal flies first hatched. By breeding from the last flies of each culture, and in dry cultures, flies can be bred from normal ancestors for several generations, and then by making the conditions favorable for the appearance of the abnormal condition, the flies will be as abnormal as though their ancestors had always been abnormal. Here, then, is a character that is susceptible to the variations in the environment, yet whatever the realized condition of the soma may be, that condition has no effect whatever on the nature of the germ-plasm. A more striking disproof of the theory of the inheritance of acquired characters would be hard to find. A demonstration is given in this instance of the interaction between a given genotypic constitution and a special environment. The character abnormal is a sex-linked dominant. Therefore, if an abnormal male is mated to a wild female the daughters are heterozygous for abnormal, while the sons, getting their X chromosome from their mother, are entirely normal. In a wet environment all the daughters are abnormal and the sons normal. As the culture dries out the daughters' color becomes normal in appearance. But while the sons {17} will never transmit abnormality to any of their descendants in any environment, the daughters will transmit (if bred to normal males) in a suitable environment their peculiarity to half of their daughters and to half of their sons. The experiment shows convincingly that the abnormal abdomen appears in a special environment only in those flies that have a given genotypic constitution. As the cultures dry out the abnormal males are the first to change over to normal, then the heterozygous females, and lastly the homozygous females. It is doubtful if any far-reaching conclusion can be drawn from this series, because the first and second classes differ from each other not only in the presence of one or of two factors for abnormal, but also by the absence in the first case (male) of an entire X chromosome with its contained factors. The second and third classes differ from each other only by the abnormal factor. Similar results were found in the mutant type called reduplicated legs, which is a sex-linked recessive character that appears best when the cultures are kept at about 10° C. As Miss M. A. Hoge has shown, this character then becomes realized in nearly all of the flies that have the proper constitution, but not in flies of normal constitution placed in the same environment. Here the effect is produced by cold. SEXUAL POLYMORPHISM. Outside the primary and secondary sexual differences between the male and the female, there is a considerable number of species of animals with more than one kind of female or male. Darwin and his followers have tried to explain such cases on the grounds that more than one kind of female (or male) might arise through natural selection, in consequence of some individuals mimicking a protected species. It is needless to point out here how involved and intricate such a process would be, because the mutation theory has cut the Gordian knot and given a simpler solution of the origin of such diandromorphic and digynomorphic conditions. In _Drosophila_ a mutant, eosin eye-color, appeared in which the female has darker eyes than the male. If such stock is crossed with cherry (another sex-linked recessive mutant, allelomorphic to eosin) the females in the F_2 generation are alike (for the pure eosin and the eosin-cherry compound are not separable), but the cherry males and the eosin males are quite different in appearance. Here we have a simulation, at least, of a diandromorphic species. Such a group perpetuates itself, giving one type of female (inasmuch as eosin and cherry females are very closely similar) and two types of males, only one of which is like the females. A population of this kind is very directly comparable to certain polymorphic types that occur in nature. In _Colias philodice_ there is one type of male, yellow, and two types of females, yellow and {18} white. In _Colias eurydice_ the male is orange and the females are orange or white. In _Papilio turnus_ the male is yellow and the females either yellow or black. Those cases are directly comparable to an eosin-cherry population, except that in Lepidoptera the female is heterozygous for the sex differential, in Diptera the male. Since in _Drosophila_ the results are explicable on a sex-linked basis, a similar explanation may apply to polymorphism in butterflies. By suitable combinations of eosin and cherry most of the cases of polymorphism in butterflies may be simulated. To simulate the more complex cases, such as that of _Papilio polytes_ and _memnon_, another allelomorph like eosin would have to be introduced. A population of mixed cherry and white would give three somatic types of females (cherry, cherry-white, and white) and two of males (cherry and white). FERTILITY AND STERILITY IN THE MUTANTS. Aside from the decrease in fertility that occurs in certain stocks (a question that need not be treated here), there are among the types described in the text two cases that call for special comment. When the mutant type called "rudimentary" was first discovered, it was found that the females were sterile but the males were fully fertile. Later work has revealed the nature of the sterility of the female. The ovaries are present and in the young flies appear normal, but while in the normal flies the eggs in the posterior portion enlarge rapidly during the first few days after hatching, in the rudimentary females only a very few (about 15) eggs enlarge. The other eggs in the ovary remain at a lower stage of their development. Rarely the female lays a few eggs; when she does so some of the eggs hatch, and if she has been mated to a rudimentary male, the offspring are rudimentary females and males. The rudimentary females mate in the normal time with rudimentary or with normal males, and their sexual behavior is normal. Their sterility is therefore due to the failure of the eggs to develop properly. Whether in addition to this there is some incompatibility between the sperm and the eggs of this type (as supposed to be the case at one time) is not conclusively disproved, but is not probable from the evidence now available. In the mutant called "fused" the females are sterile both with wild males and with males from their own stock. An examination of the ovaries of these females, made by Mr. C. McEwen, shows clearly that there are fewer than the normal number of mature eggs, recalling the case of rudimentary. It should be noticed that there is no apparent relation between the sterility of these two types and the occurrence of the mutation in the X chromosome, because other mutations in the X do not cause sterility, and there is sterility in other mutant types that are due to factors in other chromosomes. {19} BALANCED INVIABILITY. The determination of the cross-over values of the factors was at first hindered because of the poor viability of some of the mutants. If the viability of each mutant type could be determined in relation to the viability of the normal, "coefficients of viability" could serve as corrections in working with the various mutant characters. But it was found (Bridges and Sturtevant, 1914) that viability was so erratic that coefficients might mislead. At the same time it was becoming more apparent that poor viability is no necessary attribute of a character, but depends very largely on the condition of culture. Competition among larvæ was found to be the chief factor in viability. Mass cultures almost invariably have extremely poor viability, even though an attempt is made to supply an abundance of food. Special tests (Morgan and Tice, 1914) showed that even those mutants which were considered the very poorest in viability were produced in proportions fairly close to the theoretical when only one female was used for each large culture bottle and the amount and quality of food was carefully adjusted. For the majority of mutants which did well even under heavy competition in mass cultures the pair-breeding method reduced the disturbances due to viability to a point where they were negligible. Later a method was devised (Bridges, 1915) whereby mutations of poor viability could be worked with in linkage experiments fairly accurately and whereby the residual inviability of the ordinary characters could be largely canceled. This method consists in balancing the data of a certain class with poor viability by means of an equivalent amount of data in which the same class occurs as the other member of the ratio. Thus in obtaining data upon any linkage case it is best to have the total number of individuals made up of approximately equal numbers derived from each of the possible ways in which the experiment may be conducted. In the simplest case, in which the results are of the form AB:Ab:aB:ab, let us suppose that the class ab has a disproportionately low viability. If, then, ab occurs in an experiment as a cross-over class, that class will be too small and a false linkage value will be calculated. The remedy is to balance the preceding data by an equal amount of data in which ab occurs as a non-cross-over. In these latter the error will be the opposite of the previous one, and by combining the two experiments the errors should be balanced to give a better approximation to the true value. When equal amounts of data, secured in these two ways, are combined, all four classes will be balanced in the required manner by occurring both as non-cross-overs and as cross-overs. The error, therefore, should be very small. For three pairs of gens there are eight classes, and in order that each of them may appear as a non-cross-over, as each single cross-over, and as the double cross-over, four experiments must be made. {20} HOW THE FACTORS ARE LOCATED IN THE CHROMOSOMES. A character is in the first chromosome if it is transmitted by the grandfather to half of his grandsons, while, in the reciprocal cross, the mother transmits her character to all her sons (criss-cross inheritance) and to half of her granddaughters and to half of her grandsons; in other words, if the factor that differentiates the character has the same distribution as the X chromosome. If, however, a new mutant type does not show this sex-linked inheritance, its chromosome is determined by taking advantage of the fact that in _Drosophila_ there is no crossing-over in the male between factors in the same chromosome. For instance, if a new mutant type is found not to be sex-linked, its group is determined by the following tests: It is crossed to black, whose factor is known to be in the second chromosome, and to pink, whose factor lies in the third chromosome. If the factor of the new form should happen to be in the second chromosome, then, in the cross with black, no double recessive can appear, so that the F_{2} proportion is 2:1:1:0; but with pink, the mutant type should give the proportion 9:3:3:1, typical of free assortment. If, however, the factor of the new form is in the third chromosome, then, when crossed to black, the double recessive and the 9:3:3:1 proportion appear in F_{2}. But when crossed to pink no double recessive appears in F_{2}, and the proportion 2:1:1:0 occurs. If these tests show that the new mutant does not belong to either the second or third chromosome, that is, if both with black and with pink the 9:3:3:1 ratio is obtained, then by exclusion the factor lies in the fourth chromosome, in which as yet only two factors have been found. We propose to give in a series of papers an account of the mutant races of _Drosophila_ and the linkage shown in their inheritance. In this paper we shall consider only the members of the first chromosome, describing a large number of new mutants with their linkage relations and summarizing to date all the linkage data relating to the first chromosome. In later papers we propose to consider the members of the second, third, and fourth chromosomes. The list at the top of page 21 gives the names of the factors dealt with in this paper. They stand in the order of their discovery, the mutant forms reported here for the first time being starred. In each experiment the percentage of crossing-over is found by dividing the number of the cross-overs by the sum of the non-cross-overs and the cross-overs, and multiplying this quotient by 100. The resulting percentages, or cross-over values, are used as measures of the distances between loci. Thus if the experiments give a cross-over value of 5 per cent for white and bifid, we say that white and bifid lie 5 units apart in the X chromosome. Other experiments show that yellow and white are about 1 unit apart, and that yellow and bifid are about 6 units apart. We can therefore construct a diagram with yellow as {21} the zero, with white at 1, and with bifid at 6. If we know the cross-over values given by a new mutant with any two mutants of the same chromosome whose positions are already determined, then we can locate the new factor with accuracy, and be able to predict the cross-over value which the new factor will give with any other factor whose position is plotted. _The sex-linked factors of Drosophila._ +------------+----------+-------+-------+--------+------------+---------+ | Gen. | Part |Figure.|Symbol.| Locus. | Date found.|Found by.| | |affected. | | | | | | +------------+----------+-------+-------+--------+------------+---------+ |White |Eye-color | 11 | w | 1.1 | May 1910 |Morgan. | |Rudimentary |Wings | A | r | 55.1 | June 1910 |Morgan. | |Miniature |Wings | 7-8 | m | 36.1 | Aug. 1910 |Morgan. | |Vermilion |Eye-color | 10 | v | 33.0 | Nov. 1910 |Morgan. | |Yellow |Body-color| 5 | y | 0.0 | Jan. 1911 |Wallace. | |Abnormal |Abdomen | 4 | A' | 2.4 | July 1911 |Morgan. | |Eosin |Eye-color | 7-8 | w^e | 1.1 | Aug. 1911 |Morgan. | |Bifid |Wings | B | b_i | 6.3 | Nov. 1911 |Morgan. | |Reduplicated|Legs | | | 34.7 | Nov. 1911 |Hoge. | |Lethal 1 |Life | | l_1 | 0.7 | Feb. 1912 |Rawls. | |Lethal 1_a_*|Life | | l_1a | 3.3 | Mar. 1912 |Rawls. | |Spot* |Body-color| 14-17 | y^s | 0.0 | April 1912 |Cattell. | |Sable* |Body-color| 2 | s | 43.0 | July 1912 |Bridges. | |Dot* |Thorax | | | 33 ± | July 1912 |Bridges. | |Bow* |Wings | C | | | Aug. 1912 |Bridges. | |Lemon* |Body-color| 3 | l_m | 17.5 | Aug. 1912 |Wallace. | |Lethal 2 |Life | | l_2 | 12.5± | Sept. 1912 |Morgan. | |Cherry |Eye-color | 9 | w^c | 1.1 | Oct. 1912 |Safir. | |Fused* |Venation | D | f_u | 59.5 | Nov. 1912 |Bridges. | |Forked* |Bristles | E | f | 56.5 | Nov. 1912 |Bridges. | |Shifted* |Venation | F | s_h | 17.8 | Jan. 1913 |Bridges. | |Lethal sa |Life | | l_sa | 23.7 | Jan. 1913 |Stark. | |Bar |Eye-shape | 12-13 | B' | 57.0 | Feb. 1913 |Tice. | |Notch |Wing | | N' | 2.6 | Mar. 1913 |Dexter. | |Depressed* |Wing | G | d_p | 18.0 | April 1913 |Bridges. | |Lethal sb |Life | | l_sb | 16.7 | April 1913 |Stark. | |Club* |Wings | H | c_l | 14.6 | May 1913 |Morgan. | |Green* |Body-color| | | | May 1913 |Bridges. | |Chrome* |Body-color| | | | Sept. 1913 |Bridges. | |Lethal 3 |Life | | l_3 | 26.5 | Dec. 1913 |Morgan. | |Lethal 3_a_ |Life | | l_3a | 19.5 | Jan. 1914 |Morgan. | |Lethal 1_b_*|Life | | l_1b | 1.1- | Feb. 1914 |Morgan. | |Facet* |Eye | | f_a | 2.2 | Feb. 1914 |Bridges. | |Lethal _sc_ |Life | | l_sc | 66.2 | April 1914 |Stark. | |Lethal _sd_ |Life | | l_sd | | May 1914 |Stark. | |Furrowed |Eye | | f_w | 38.0 | Nov. 1914 |Duncan. | +------------+----------+-------+-------+--------+------------+---------+ The factors are located preferably by short distances (_i.e._, by those cases in which the amount of crossing-over is small), because when the amount of crossing-over is large a correction must be made for double crossing-over, and the correction can be best found through breaking up the long distances into short ones, by using intermediate points. Conversely, when a long distance is indicated on the chromosome diagram, the actual cross-over value found by experiment (_i.e._, the percentage of cross-overs) will be less than the diagram indicates, because the diagram has been corrected for double crossing-over. {22} 0.0 | Yellow, spot 0.7 | Lethal I 1.1-| Lethal Ib 1.1 | White, eosin, cherry 2.2 | Facet 2.4 | Abnormal 2.6 | Notch 3.3 | Lethal Ia | 6.3 | Bifid | | | | | | 12.5 | Lethal II 14.6 | Lethal sb 16.7 | Club 17.5 | Lemon 17.8 | Shifted 18.0 | Depressed 19.5 | Lethal IIIa | | 23.7 | Lethal sa | 26.5 | Lethal III | | | 33.0 | Vermilion 33.± | Dot 34.7 | Reduplicated 36.1 | Miniature 38.0 | Furrowed | | 43.0 | Sable | | | | | | 55.1 | Rudimentary 56.5 | Forked 57.0 | Bar 59.5 | Fused | | | 66.2 | Lethal sc DIAGRAM I. {23} Diagram I has been constructed upon the basis of all the data summarized in table 65 (p. 84) for the first or X chromosome. It shows the relative positions of the gens of the sex-linked characters of _Drosophila_. One unit of distance corresponds to 1 per cent of crossing-over. Since all distances are corrected for double crossing-over and for coincidence, the values represent the _total_ of crossing-over between the loci. The uncorrected value obtained in any experiment with two loci widely separated will be smaller than the value given in the map. It may be asked what will happen when two factors whose loci are more than 50 units apart in the same chromosome are used in the same experiment? One might expect to get more than 50 per cent of cross-overs with such an experiment, but double crossing-over becomes disproportionately greater the longer the distance involved, so that in experiments the observed percentage of crossing-over does not rise above 50 per cent. For example, if eosin is tested against bar, somewhat under 50 per cent of cross-overs are obtained, but if the distance of bar from eosin is found by summation of the component distances the interval for eosin bar is 56 units. In calculating the loci of the first chromosome, a system of weighting was used which allowed each case to influence the positions of the loci in proportion to the amount of the data. In this way advantage was taken of the entire mass of data. The factors (lethal 1, white, facet, abnormal, notch, and bifid) which lie close to yellow were the first to be calculated and plotted. The next step was to determine very accurately the position of vermilion with respect to yellow. There are many separate experiments which influence this calculation and all were proportionately weighted. Then, using vermilion as the fixed point the factors (dot, reduplicated, miniature, and sable) which lie close to vermilion were plotted. The same process was repeated in locating bar with respect to vermilion and the factors about bar with reference to bar. The last step was to interpolate the factors (club, lethal 2, lemon, depressed, and shifted), which form a group about midway between yellow and vermilion. Of these, club is the only one whose location is accurate. The apparent closeness of the grouping of these loci is not to be taken as significant, for they have been placed only with reference to the distant points yellow and vermilion and not with respect to each other; furthermore, the data available in the cases of lemon and depressed are very meager. The factors which are most important and are most accurately located are yellow, white (eosin), bifid, club, vermilion, miniature, sable, forked, and bar. Of these again, white (eosin), vermilion, and bar are of prime importance and will probably continue to claim first rank. Of the three allelomorphs, white, eosin, and cherry, eosin is the most useful. {24} NOMENCLATURE. The system of symbols used in the diagrams and table headings is as follows: The factor or gen for a recessive mutant character is represented by a lower-case letter, as v for vermilion and m for miniature. The symbols for the dominant mutant characters bar, abnormal, and notch are B', A', and N'. There are now so many characters that it is impossible to represent all of them by a single letter. We therefore add a subletter in such cases, as bifid (b_i), fused (f_u), and lethal 2 (l_2). In the case of multiple allelomorphs we usually use as the base of the symbol the symbol of that member of the system which was first found and add a letter as an exponent to indicate the particular member, as y^s for spot, w^e for eosin, and w^c for cherry. The normal allelomorphs of the mutant gens are indicated by the converse letter, as V for not-vermilion, B_i for not-bifid, and b' for not-bar. In the table headings the normal allelomorphs are indicated by position alone without the use of a symbol. Thus the symbol [draw] indicates that the female in question carried eosin, not-vermilion, and bar in one chromosome and not-eosin, vermilion, and not-bar in the other. The symbol [draw] when used in the heading of a column in a table indicates that the flies classified under this heading are the result of single crossing-over between eosin and vermilion in a mother which was the composition [draw]; the symbol tells at the same time that the flies that result from a single cross-over between eosin and vermilion in the mother are of the two contrary classes, eosin bar and vermilion. When a fly shows two or more non-allelomorphic characters the names are written from left to right in the order of their positions from the zero end of the map. * * * * * {25} PART II. NEW DATA. WHITE. (Plate II, figure 11.) The recessive character white eye-color, which appeared in May 1910, was the first sex-linked mutation in _Drosophila_ (Morgan, 1910_a_, 1910_b_). Soon afterwards (June 1910) rudimentary appeared, and the two types were crossed (Morgan, 1910_c_). Under the conditions of culture the viability of rudimentary was extremely poor, but the data demonstrated the occurrence of recombination of the factors in the ovogenesis so that white and rudimentary, though both sex-linked, were brought together into the same individual. The results were not fully recognized as linkage, because white and rudimentary are so far apart in the chromosome that they seemed to assort freely from each other. Owing to the excellent viability and the perfect sharpness of separation, white was extensively used in linkage experiments, especially with miniature and yellow (Morgan, 1911_a_; Morgan and Cattell, 1912 and 1913). White has been more extensively used than any other character in _Drosophila_, though it is now being used very little because of the fact that the double recessives of white with other sex-linked eye-colors, such as vermilion, are white, and consequently a separation into the true genetic classes is impossible. The place of white has been taken by eosin, which is an allelomorph of white and which can be readily used with any other eye-color. The locus of white and its allelomorphs is only 1.1 units from that of yellow, which is the zero of the chromosome. Yellow and white are very closely linked, therefore giving only about one cross-over per 100 flies. All the published data upon the linkage of white with other sex-linked characters have been collected into table 65. RUDIMENTARY. Rudimentary, which appeared in June 1910, was the second sex-linked character in _Drosophila_ (Morgan, 1910_c_). Its viability has always been very poor; in this respect it is one of the very poorest of the sex-linked characters. The early linkage data (Morgan, 1911_a_) derived from mass cultures have all been discarded. By breeding from a single F_1 female in each large culture bottle it has been possible to obtain results which are fairly trustworthy (Morgan, 1912_g_; Morgan and Tice, 1914). These data appear in table 65, which summarizes all the published data. {26} The locus of rudimentary is at 55.1, for a long time the extreme right end of the known chromosome, though recently several mutants have been found to lie somewhat beyond it. [Illustration: Fig. A. _a._ rudimentary wing; _b._ the wild fly for comparison.] The rudimentary males are perfectly fertile, but the rudimentary females rarely produce any offspring at all, and then only a very few. The reason for this is that most of the germ-cells cease their development in the early growth stage of the eggs (Morgan, 1915_a_). MINIATURE. (Plate II. figures 7 and 8.) The recessive sex-linked mutant miniature wings appeared in August 1910 (Morgan, 1911b and 1912a). The viability of miniature is fair, and this stock has been used in linkage experiments more than any {27} other, with the single exception of white. While the wings of miniature usually extend backwards, they are sometimes held out at right angles to the body, and especially in acid bottles the miniature flies easily become stuck to the food or the wings become stringy, so that other wing characters are not easy to distinguish in those flies which are also miniature. At present vermilion, whose locus is at 33, in being used more frequently in linkage work. The locus of miniature at 36.1 is slightly beyond the middle of the chromosome. VERMILION. (Plate II. figure 10.) The recessive sex-linked mutant vermilion eye-color (Morgan, 1911_c_ and 1912_a_) appeared in November 1910, and has appeared at least twice since then (Morgan and Plough, 1915). This is one of the best of the sex-linked characters, on account of its excellent viability, its sharp distinction from normal with very little variability, its value as a double recessive in combination with other sex-linked eye-colors, and because of its location at 33.0, very near to the middle of the known chromosome. YELLOW. (Plate I. figure 5.) The recessive sex-linked mutant yellow body and wing-color appeared in January 1911 (Morgan, 1911_c_ and 1912_a_). Its first appearance was in black stock; hence the fly was a double recessive, then called brown. Later the same mutation has appeared independently from gray stock. Yellow was found to be at the end of the X chromosome, and this end was arbitrarily chosen as the zero or the "left end," while the other gens are spoken of as lying at various distances to the right of yellow. Recently a lethal gen has been located less than one-tenth of a unit (-0.04) to the left of yellow, but yellow is still retained as the zero-point. The viability of yellow is fairly good and the character can be separated from gray with great facility, and in consequence yellow has been used extensively, although at present it is being used less than formerly, since eosin lies only 1.1 units distant from yellow and is generally preferred. ABNORMAL ABDOMEN. (Plate I. figure 4.) The dominant sex-linked character abnormal abdomen appeared in July 1911 (Morgan, 1911_d_). It was soon found that the realization of the abnormal condition depended greatly upon the nature of the environment (Morgan, 1912). Recently a very extensive study of this character has been published (Morgan, 1915). As this case has been reviewed in the introduction, there is little further to be said here. {28} Because of the change that takes place as the culture grows older (the abnormal changing to normal), this character is not of much value in linkage work. The location of the factor in the X chromosome at 2.4 has been made out from the data given by Morgan (1915_b_). These data, which in general include only the abnormal classes, are summarized in table 1. TABLE 1.--_Linkage data, from Morgan, 1915b._ +------------------+-----------+-----------+------------+ | Gens. | Total. | Cross- | Cross-over | | | | overs. | values. | +------------------+-----------+-----------+------------+ | Yellow white | 28,018 | 334 | 1.2 | | Yellow abnormal | 15,314 | 299 | 2.0 | | White abnormal | 16,300 | 277 | 1.7 | +------------------+-----------+-----------+------------+ EOSIN. (Plate II, figures 7 and 8.) The recessive sex-linked mutation eosin eye-color appeared in August 1911 in a culture of white-eyed flies (Morgan 1912_a_). The eye-color is different in the male and female, the male being a light pinkish yellow, while the female is a rather dark yellowish pink. Eosin is allelomorphic to white and the white-eosin compound or heterozygote has the color of the eosin male. There is probably no special significance in this coincidence of color, since similar dilutions to various degrees have been demonstrated for all the other eye-colors tested (Morgan and Bridges, 1913). Since eosin is allelomorphic to white, its locus is also at 1.1. Eosin is the most useful character among all those in the left end of the chromosome. BIFID. The sex-linked wing mutant bifid, which appeared in November 1911, is characterized by the fusion of all the longitudinal veins into a heavy stalk at the base of the wing. The wing stands out from the body at a wide angle, so that the fusion is easily seen. At the tip of the wing the third longitudinal vein spreads out into a delta which reaches to the marginal vein. The fourth longitudinal vein reaches the margin only rarely. There is very often opposite this vein a great bay in the margin, or the whole wing is irregularly truncated. The stock of bifid was at first extremely varied in the amount of this truncation. By selection a stock was secured which showed only very greatly reduced wings like those shown in figures _a_, b. Another stock (figs. _c_, _d_) was secured by outcrossing and selection which showed wings of nearly normal size and shape, which always had the bifid stalk, generally the spread positions (not as extreme), and often the delta and the shortened fourth longitudinal vein. We believe that the extreme reduction in size seen in the one stock was due to an added modifier of {29} the nature of beaded, since this could be eliminated by outcrossing and selection. [Illustration: FIG. B.--Bifid wing. _c_ and _d_ show the typical condition of bifid wings. All the longitudinal veins are fused into a heavy stalk at the base of the wing. _a_ shows the typical position in which the bifid wings are held. The small size of the wings in _a_ and _b_ is due to the action of a modifier of the nature of "beaded" which has been eliminated in _c_, d.] LINKAGE OF BIFID WITH YELLOW, WITH WHITE, AND WITH VERMILION. The stock of the normal (not-beaded) bifid was used by Dr. R. Chambers, Jr., for determining the chromosome locus of bifid by means of its linkage relations to vermilion, white, and yellow (Chambers, 1913). We have attempted to bring together in table 2 the complete data and to calculate the locus of bifid. TABLE 2.--_Linkage data, from Chambers, 1913._ +-----------------+------------+-------------+--------------+ | Gens. | Total. | Cross- | Cross-over | | | | overs. | values. | +-----------------+------------+-------------+--------------+ | Yellow bifid | 3,175 | 182 | 5.8 | | White bifid | 20,800 | 1,127 | 5.3 | | Bifid vermilion | 2,509 | 806 | 32.1 | +-----------------+------------+-------------+--------------+ {30} In the crosses between white and bifid there were 1,127 cross-overs in a total of 20,800 available individuals, which gives a cross-over value of 5.3. In the crosses between yellow and bifid there were 182 cross-overs in a total of 3,175 available individuals, which gives a cross-over value of 5.8. In crosses between bifid and vermilion there were 806 cross-overs in a total of 2,509, which gives a cross-over value of 32.1. On the basis of all the data summarized in table 65, bifid is located at 6.3 to the right of yellow. LINKAGE OF CHERRY, BIFID, AND VERMILION. In a small experiment of our own, three factors were involved--cherry, bifid, and vermilion. A cherry vermilion female was crossed to a bifid male. Two daughters were back-crossed singly to white bifid males. The female offspring will then give data for the linkage of cherry white with bifid, while the sons will show the linkage of the three gens, cherry, bifid, and vermilion. The results are shown in table 3. TABLE 3.--_P_1 cherry vermilion [female] [female] � bifid [male] [male]. B. C.[2] F_1 wild-type [female] � white bifid [male] [male]._ |----------------------------------- | | F_2 females. | | |---------------------------+ | | | |Refer-| Non-cross- |Cross-overs. | |ence. | overs. | | | |-------------+-------------+ | |White-|Bifid.|White-|Wild- ~ | |cherry| |cherry|type. ~ | | | |bifid.| | |------+------+------+------+------+ | 262 | 40 | 46 | 1 | 2 | | 263 | 47 | 45 | 3 | 3 | | |------+------+------+------+ |Total.| 87 | 91 | 4 | 5 | |----------------------------------- |----------------------------------------------------------------------| | | F_2 males. | | |-----------------------------+---------------------------------| | | w^c v | w^c b | w^c | w^c b_i v | |Refer-| ------------ | ---+-------- | ---------+--- | ---+-----+--- | |ence. | b_i | v | b_i v | | | |--------------+--------------+---------------+-----------------| ~ |Cherry |Bifid.|Cherry| Ver- |Cherry.|Bifid | Cherry |Wild- | ~ | ver- | |bifid.|milion.| | ver- | bifid |type. | | |milion.| | | | |milion.|vermilion.| | |------+-------+------+------+-------+-------+-------+----------+------| | 262 | 45 | 38 | 3 | 2 | 11 | 13 | .. | .. | | 263 | 30 | 50 | 1 | 3 | 8 | 10 | 1 | .. | | |-------+------+------+-------+-------+-------+----------+------| |Total.| 75 | 88 | 4 | 5 | 19 | 23 | 1 | 0 | |----------------------------------------------------------------------| Both males and females give a cross-over value of 5 units for cherry bifid, which is the value determined by Chambers. The order of the factors, viz, cherry, bifid, vermilion, is established by taking advantage of the double cross-over classes in the males. The male classes give a cross-over value of 20 for bifid vermilion and 24 for cherry vermilion, which are low compared with values given by other experiments. The locus of bifid at 6.3 is convenient for many linkage problems, but this advantage is largely offset by the liability of the bifid flies to become stuck in the food and against the sides of the bottle. Bifid flies can be separated from the normal with certainty and with great ease. {31} REDUPLICATED LEGS. In November 1912 Miss Mildred Hoge found that a certain stock was giving some males whose legs were reduplicated, either completely or only with respect to the terminal segments (described and figured, Hoge, 1915). Subsequent work by Miss Hoge showed that the condition was due to a sex-linked gen, but that at room temperature not all the flies that were genetically reduplicated showed reduplication. However, if the flies were raised through the pupa stage in the ice-box at a temperature of about 10° to 12° a majority of the flies which were expected to show reduplication did so. The most extremely reduplicated individual showed parts of 14 legs. In studying the cross-over values of reduplicated, only those flies that have abnormal legs are to be used in calculation, as in the case of abnormal abdomen where the phenotypically normal individuals are partly genetically abnormal. Table 4 gives a summary of the data secured by Miss Hoge. TABLE 4.--_Summary of linkage data upon reduplicated legs, from Hoge, 1915._ +---------------------------+---------+---------+------------+ | Gens. | Total. | Cross- | Cross-over | | | | overs. | values. | |---------------------------+---------+---------|------------| | | | | | |White reduplicated | 418 | 121 | 29.0 | |Reduplicated vermilion | 667 | 11 | 1.7 | |Reduplicated bar | 583 | 120 | 20.6 | | | | | | +---------------------------+---------+---------+------------+ The most accurate data, those upon the value for reduplicated and vermilion, give for reduplicated a distance of 1.7 from vermilion, either to the right or to the left. The distance from white is 29, which would place the locus for reduplication to the left of vermilion, which is at 33. The data for bar give a distance of 21, but since bar is itself 24 units from vermilion, this distance of 21 would seem to place the locus to the right of vermilion. The evidence is slightly in favor of this position to the right of vermilion at 34.7, where reduplicated may be located provisionally. In any case the locus is so near to that of vermilion that final decision must come from data involving double crossing-over, _i. e._, from a three-locus experiment. LETHAL 1. In February 1912 Miss E. Rawls found that certain females from a wild stock were giving only about half as many sons as daughters. Tests continuing through five generations showed that the sons that appeared were entirely normal, but that half of the daughters gave again 2 : 1 sex-ratios, while the other half gave normal 1 : 1 sex-ratios. {32} The explanation of this mode of transmission became clear when it was found that the cause of the death of half of the males was a particular factor that had as definite a locus in the X chromosome as have other sex-linked factors (Morgan, 1912_e_). Morgan mated females (from the stock sent to him by Miss Rawls) to white-eyed males. Half of the females, as expected, gave 2 : 1 sex-ratios, and daughters from these were again mated to white males. Here once more half of the daughters gave 2 : 1 sex-ratios, but in such cases the sons were nearly all white-eyed and only rarely a red-eyed son appeared, when under ordinary circumstances there should be just as many red sons as white sons. The total output for 11 such females was as follows (Morgan, 1914_b_): white [female], 457; red [female], 433; white [male], 370; red [male], 2. It is evident from these data that there must be present in the sex-chromosome a gen that causes the death of every male that receives this chromosome, and that this lethal factor lies very close to the factor for white eyes. The linkage of this lethal (now called lethal 1) to various other sex-linked gens was determined (Morgan 1914_b_), and is summarized in table 5. On the basis of these data it is found that the gen lethal 1 lies 0.4 unit to the left of white, or at 0.7. TABLE 5.--_Summary of linkage data upon lethal 1, from Morgan, 1914b, pp. 81-92._ +------------------------+---------+--------+-------------+ | Gens. | Total. | Cross- | Cross-over | | | | overs. | values. | +------------------------+---------+--------+-------------+ | | | | | | Yellow lethal 1 | 131 | 1 | 0.8 | | Yellow miniature | 131 | 45 | 34.4 | | Lethal 1 white | 1,763 | 7 | 0.4 | | Lethal 1 miniature | 814 | 323 | 39.7 | | White miniature | 994 | 397 | 39.9 | | | | | | +------------------------+---------+--------+-------------+ LETHAL 1a. In the second generation of the flies bred by Miss Rawls, one female gave (March 1912) only 3 sons, although she gave 312 daughters. It was not known for some time (see lethals 3 and 3_a_) what was the cause of this extreme rarity of sons. It is now apparent, however, that this mother carried lethal 1 in one X and in the other X a new lethal which had arisen by mutation. The new lethal was very close to lethal 1, as shown by the rarity of the surviving sons, which are cross-overs between lethal 1 and the new lethal that we may call lethal 1a. There is another class of cross-overs, namely, those which have lethal 1 and get lethal 1_a_ by crossing-over. These doubly lethal males must also die, but since they are theoretically as numerous as the males (3) free from both lethals, we must double this number (3 � 2) to get the total number of cross-overs. There were 312 daughters, but as the sons are normally about 96 per cent of the number of the females, {33} we may take 300 as the number of the males which died. There must have been, then, about 2 per cent of crossing-over, which makes lethal 1_a_ lie about 2 units from lethal 1. This location of lethal 1_a_ is confirmed by a test that Miss Rawls made of the daughters of the high-ratio female. Out of 98 of these daughters none repeated the high sex-ratio and only 2 gave 1 [female] : 1 [male] ratios. The two daughters which gave 1 : 1 ratios are cross-overs. There should be an equal number of cross-overs which contain both lethals. These latter would not be distinguishable from the non-cross-over females, each of which carries one or the other lethal. In calculation, allowance can be made for them by doubling the number of observed cross-overs (2 � 2) and taking 98 - 2 as the number of non-cross-overs. The cross-over fraction {6 + 4}/{300 + 96} gives 2.6 as the distance between the two lethals. Lethal 1_a_ is probably to the right of lethal 1 at 0.7 + 2.6 = 3.3. SPOT. (Plate II, figures 14 to 17.) In April 1912 there was found in the stock of yellow flies a male that differed from yellow in that it had a conspicuous light spot on the upper surface of the abdomen (Morgan, 1914_a_). In yellow flies this region is dark brown in color. In crosses with wild flies the spot remained with the yellow, and although some 30,000 flies were raised, none of the gray offspring showed the spot, which should have occurred had crossing-over taken place. The most probable interpretation of spot is that it was due to another mutation in the yellow factor, the first mutation being from gray to yellow and the second from yellow to spot. Spot behaves as an allelomorph to yellow in all crosses where the two are involved and is completely recessive to yellow, _i. e._, the yellow-spot hybrid is exactly like yellow. A yellow-spot female, back-crossed to a spot male, produces yellows and spots in equal numbers. In a cross of spot to black it was found that the double recessive, spot black, flies that appear in F_2 have, in addition to the spot on the abdomen, another spot on the scutellum and a light streak on the thorax. These two latter characters ("dot and dash") are very sharply marked and conspicuous when the flies are young, but they are only juvenile characters and disappear as the flies become older. The spot flies never show the "dot and dash" clearly, and it only comes out when black acts as a developer. These characters furnish a good illustration of the fact that mutant gens ordinarily affect many parts of the body, though these secondary effects often pass unnoticed. In the F_2 of the cross of spot by black one yellow black fly appeared, although none are expected, on the assumption that spot and yellow {34} are allelomorphic. Unless due to crossing-over it must have been a mutation from spot back to yellow. Improbable as this may seem to those who look upon mutations as due to losses from the germ-plasm, yet we have records of several other cases where similar mutations "backwards" have taken place, notably in the case of eosin to white, under conditions where the alternative interpretation of crossing-over is excluded. SABLE. (Plate I, figure 2.) In an experiment involving black body-color[3] a fly appeared (July 19, 1912) whose body-color differed slightly from ordinary black in that the trident mark on the thorax was sharper and the color itself was brighter and clearer. This fly, a male, was mated to black females and gave some black males and females, but also some gray (wild body-color) males and females, showing not only that he was heterozygous for ordinary recessive black, but at the same time that his dark color must be due to another kind of black. The gray F_1 flies when mated together gave a series of gray and dark flies in F_2 about as follows: In the females 3 grays to 1 dark; in the males 3 grays to 5 dark in color. The result indicated that the new black color, which we call sable, was due to a sex-linked factor. It was difficult to discover which of the heterogeneous F_2 males were the new blacks. Suspected males were bred (singly) to wild females, and the F_2 dark males, from those cultures that gave the closest approach to a 2 gray [female] : 1 gray [male] : 1 dark [male], were bred to their sisters in pairs in order to obtain sable females and males. Thus stock homozygous for sable but still containing black as an impurity was obtained. It became necessary to free it from black by successive individual out-crossings to wild flies and extractions. This account of how sable was purified shows how difficult it is to separate two recessive factors that give closely similar somatic effects. If a character like sable should be present in any other black stock, or if a character like black should be present in sable, very erratic results would be obtained if such stocks were used in experiments, before such a population had been separated into its component races. Sable males of the purified stock were mated to wild females and gave wild-type (gray) males and females. These inbred gave the results shown in table 6. No sable females appeared in F_2, as seen in table 6. The reciprocal cross gave the results shown in table 7. {35} The F_1 males were sable like their mother. The evidence thus shows that sable is a sex-linked recessive character. Our next step was to determine the linkage relations of sable to certain other sex-linked gens, namely, yellow, eosin, cherry, vermilion, miniature, and bar. TABLE 6.--_P_1 wild [female] [female] � sable [male]. F_1 wild-type [female] [female] � F_1 wild-type [male] [male]._ +---------------+-------------------+-------------------+---------------+ | | | | | | Reference.[4] |Wild-type [female].| Wild-type [male]. | Sable [male]. | | | | | | +---------------+-------------------+-------------------+---------------+ | | | | | | 88 C | 218 | 100 | 70 | | 143 C | 245 | 108 | 72 | | 146 C | 200 | 115 | 82 | | +-------------------+-------------------+---------------+ | Total | 663 | 323 | 224 | | | | | | +---------------+-------------------+-------------------+---------------+ TABLE 7.--_P_1 sable [female] � wild [male] [male]. F_1 wild-type [female] � F_1 sable [male]._ +--------------+-------------+-------------+-------------+-------------+ | | | | | | | Reference. | Wild-type | Wild-type | Sable | Sable | | | [female]. | [male]. | [female]. | [male]. | +--------------+-------------+-------------+-------------+-------------+ | | | | | | | 4 I | 10 | 10 | 6 | 10 | | | | | | | +--------------+-------------+-------------+-------------+-------------+ LINKAGE OF YELLOW AND SABLE. The factor for yellow body-color lies at one end of the known series of sex-linked gens. As already stated, we speak of this end as the left end of the diagram, and yellow as the zero in locating factors. When yellow (not-sable) females were mated to (not-yellow) sable males they gave wild-type (gray) daughters and yellow sons. These inbred gave in F_2 two classes of females, namely, yellow and gray, and four classes of males, namely, yellow and sable (non-cross-overs), wild type and the double recessive yellow sable (cross-overs). From off-spring (F_3) of the F_2 yellow sable males by F_2 yellow females, pure stock of the double recessive yellow sable was made up and used in the crosses to test linkage. In color the yellow sable is quite similar to yellow black, that is, a rich brown with a very dark brown trident pattern on the thorax. Yellow sable is easier to distinguish from yellow than is yellow black, even when the flies have not yet acquired their adult body-color. Yellow sable males were bred to wild females and F_1 consisted of wild-type males and females. These inbred gave the results shown in table 8. {36} TABLE 8.--_P_1 wild [female] [female] � yellow sable [male] [male]. F_1 wild-type [female] [female] � F_1 wild-type [male] [male]._ +-----------+---------+--------------+--------------+-------+-----------+ | | |Non-cross-over| Cross-over | | | | | Wild- | [male]. | [male]. | | | | Reference.| type +-------+------+-------+------+ Total |Cross-over | | |[female].| Yellow| Wild-| | | males.| value. | | | | sable.| type.|Yellow.|Sable.| | | +-----------+---------+-------+------+-------+------+-------+-----------+ | | | | | | | | | | 44 I | 292 | 110 | 43 | 75 | 36 | 264 | 42 | | 45 I | 384 | 104 | 58 | 71 | 60 | 293 | 45 | | +---------+--------------+-------+------+-------+-----------+ | Total | 676 | 214 | 101 | 146 | 96 | 557 | 43 | | | | | | | | | | +-----------+---------+-------+------+-------+------+-------+-----------+ Some of the F_1 females were back-crossed to yellow sable males and gave the data for table 9. TABLE 9.--_P_1 wild-type [female] [female] � yellow sable [male] [male]. B. C. F_1 wild-type [female] � yellow sable [male] [male]._ +----------+-------------------------+---------------+-------+----------+ | | | | | | | | Non-cross-overs. | Cross-overs. | | | | | | | | | |Reference.+-----------+-------------+-------+-------+ Total.|Cross-over| | | | | | | | value. | | | Wild-type.|Yellow sable.|Yellow.| Sable.| | | | | | | | | | | +----------+-----------+-------------+-------+-------+-------+----------+ | | | | | | | | | 31 I | 108 | 51 | 58 | 56 | 273 | 42 | | 49 I | 265 | 175 | 161 | 169 | 770 | 43 | | +-----------+-------------+-------+-------+-------+----------+ | Total | 373 | 226 | 219 | 225 | 1,043 | 43 | | | | | | | | | +----------+-----------+-------------+-------+-------+-------+----------+ In these tables the last column (to the right) shows for each culture the amount of crossing-over between yellow and sable. These values are found by dividing the number of cross-overs by the total number of individuals which might show crossing-over, that is, males only or both males and females, as the case may be. Free assortment would give 50 per cent of cross-overs and absolute linkage 0 per cent of cross-overs. Except where the percentage of crossing-over is very small these values are expressed to the nearest unit, since the experimental error might make a closer calculation misleading. The combined data of tables 8 and 9 give 686 cross-overs in a total of 1,600 individuals in which crossing-over might occur. The females of table 8 are all of one class (wild type) and are useless for this calculation except as a check upon viability. The cross-over value of 43 per cent shows that crossing-over is very free. We interpret this to mean that sable is far from yellow in the chromosome. Since yellow is at one end of the known series, sable would then occupy a locus somewhere near the opposite end. This can be checked up by finding its linkage relations to the other sex-linked factors. {37} LINKAGE OF CHERRY AND SABLE. The origin of cherry eye-color (Plate II, fig. 9) has been given by Safir (Biol. Bull., 1913). From considerations which will be discussed later in this paper we regard cherry as allelomorphic to white in a quadruple allelomorph system composed of white, eosin, cherry, and their normal red allelomorph. Cherry will then occupy the same locus as white, which is one unit to the right of yellow, and will show the same linkage relations to other factors as does white. A slightly lower cross-over value should be given by cherry and sable than was given by yellow and sable. When cherry (gray) females were crossed to (red) sable males the daughters were wild type and the sons cherry. Inbred these gave the results shown in table 10. TABLE 10.--_P_1 cherry [female][female] � sable [male][male]. F_1 wild-type [female] � F_1 cherry [male] [male]._ +---------+---------+---------+--------------+------------+------+------+ | | | | Non-cross- | Cross-over | | | | | Wild- | Cherry | over [male]. | [male]. | |Cross-| | Refer- | type |[female].+-------+------+------+-----+Total | over | | ence. |[female].| |Cherry.|Sable.|Cherry|Wild-|males.|value.| | | | | | |sable.|type.| | | +---------+---------+---------+-------+------+------+-----+------+------+ | | | | | | | | | | | 24 I | 94 | 105 | 51 | 42 | 20 | 43 | 156 | 40 | | 55 I | 101 | 131 | 63 | 52 | 38 | 48 | 201 | 43 | | 55' I | 96 | 94 | 52 | 31 | 29 | 30 | 142 | 42 | | +---------+---------+-------+------+------+-----+------+------+ | Total | 291 | 330 | 166 | 125 | 87 | 121 | 499 | 42 | | | | | | | | | | | +---------+---------+---------+-------+------+------+-----+------+------+ The percentage of crossing-over between cherry and sable is 42. Since cherry is one point from yellow, this result agrees extremely well with the value 43 for yellow and sable. Since yellow and eosin lie at the left end of the first chromosome, the high values, namely, 43 and 42, agree in making it very probable that sable lies near the other end (_i. e._, to the right). Sable will lie farther to the right than vermilion, for vermilion has been shown elsewhere to give 33 per cent of crossing-over with eosin. The location of sable to the right of vermilion has in fact been substantiated by all later work. LINKAGE OF EOSIN, VERMILION, AND SABLE. Three loci are involved in the next experiment. Since eosin is an allelomorph of cherry, it should be expected to give with sable the same cross-over value as did cherry. When eosin (red) sable females were crossed to (red) vermilion (gray) males, the daughters were wild type and the males were eosin sable. Inbred these gave the classes shown in table 11. {38} TABLE 11.--_P_1 eosin sable [female] � vermilion [male][male]. F_1 wild-type [female][female] � F_1 eosin sable [male][male]._ +------+--------------------------+ | | | | | F_2 females. | | | | | +------------+-------------+ | | w^e s | w^e | |Refer-| ---------- | -----+----- | | | | s | |ence. +------+-----+------+------+ | | | | | | | | | | | | | |Eosin |Wild-|Eosin.|Sable.~ | |sable.|type.| | ~ | | | | | | +------+------+-----+------+------+ | | | | | | | 26 I | 132 | 171 | 113 | 109 | | 26'I | 96 | 146 | 86 | 78 | | +------+-----+------+------+ |Total.| 228 | 317 | 199 | 187 | +------+------+-----+------+------+ +------+---------------------------------------------------------+ | | | | | F_2 males. | | | | | +---------------+--------------+-------------+------------+ | | w^e s | w^e v | w^e | w^e v s | |Refer-| ----------- | -----+----- | --------+-- | ---+---+-- | | | v | s | v s | | |ence. +-------+-------+-------+------+------+------+------+-----+ | | | | | | | | | | | | | |Eosin | | |Ver- |Eosin | | ~ | Eosin |Ver- |ver- |Sable.|Eosin.|milion|ver- |Wild-| ~ | sable.|milion.|milion.| | |sable.|milion|type.| | | | | | | | |sable.| | +------+-------+-------+-------+------+------+------+------+-----+ | | | | | | | | | | | 26 I | 127 | 163 | 75 | 76 | 37 | 14 | 2 | 5 | | 26'I | 74 | 128 | 76 | 59 | 18 | 21 | 4 | 3 | | +-------+-------+-------+------+------+------+------+-----+ |Total.| 201 | 291 | 151 | 135 | 55 | 35 | 6 | 8 | +------+-------+-------+-------+------+------+------+------+-----+ If we consider the male classes of table 11, we find that the smallest classes are eosin vermilion sable and wild type, which are the expected double cross-over classes if sable lies to the right of vermilion, as indicated by the crosses with eosin and with yellow. The classes which represent single crossing-over between eosin and vermilion are eosin vermilion, and sable, and those which represent single crossing-over between vermilion and sable are eosin and vermilion sable. These relations are seen in diagram II. w^e V s --+--------------------------------------------------+--------------+ X X --+--------------------------------------------------+--------------+ W v S DIAGRAM II.--The upper line represents an X chromosome, the lower line its mate. The cross connecting lines indicate crossing-over between pairs of factors. w^e s {Eosin sable. Non-cross-overs -------------------------- { v {Vermilion. w^e v {Eosin vermilion. Single cross-overs ------------+------------- { s {Sable. w {Eosin. -----------------------+-- { v s {Vermilion sable. w^e v s {Eosin vermilion sable. Double cross-overs ------------+----------+-- { {Wild-type. If we consider the female classes of table 11, we get information as to the cross-over value of eosin and sable, namely, 42 units. The male classes will be considered in connection with the cross that follows. The next experiment involves the same three gens which now enter in different relations. A double recessive, eosin vermilion (gray) female {39} was mated to (red red) sable males and gave 202 wild-type[5] females and 184 eosin vermilion males. Two F_1 pairs gave the results shown in table 12 (the four classes of females not being separated). TABLE 12.--_P_1 eosin vermilion F_1 wild-type [female] � F_1 eosin vermilion [male] [male]._ +------+--------+-------------------------------------------------------+ | | | F_2 males. | | | +-------------+-------------+-------------+-------------+ | | | w^e v | w^e s | w^e v s | w^e | | | | ----------- | -----+----- | --------+-- | ----+---+-- | |Refer-| F_2 | s | v | | v s | | ence.|females.+------+------+------+------+------+------+------+------+ | | | | | | |Eosin | | | | | | |Eosin | | | |verm- |Wild- | |Verm- | | | |verm- |Sable.|Eosin |Verm- |ilion |type. |Eosin.|ilion | | | |ilion.|[male]|sable.|ilion.|sable.|[male]|[male]|sable.| | | |[male]| |[male]|[male]|[male]| | |[male]| +------+--------+------+------+------+------+------+------+------+------+ | 59 C | 133 | 40 | 33 | 7 | 16 | 5 | 5 | 2 | 1 | | 61 C | 101 | 34 | 26 | 8 | 11 | 3 | 7 | 1 | 0 | | +--------+------+------+------+------+------+------+------+------+ |Total | 234 | 74 | 59 | 15 | 27 | 8 | 12 | 3 | 1 | +------+--------+------+------+------+------+------+------+------+------+ If we combine the data for males given in table 12 with those of table 11, we get the following cross-over values. Eosin vermilion, 32; vermilion sable, 12; eosin sable, 41. {40} LINKAGE OF MINIATURE AND SABLE. The miniature wing has been described (Morgan, Science, 1911) and the wing figured (Morgan, Jour. Exp. Zool., 1911). The gen for miniature lies about 3 units to the right of vermilion, so that it is still closer to sable than is vermilion. The double recessive, miniature sable, was made up, and males of this stock were bred to wild females (long gray). The wild-type daughters were back-crossed to double recessive males and gave the results (mass cultures) shown in table 13. TABLE 13.--_P_1 wild [female] [female] � miniature sable [male] [male]. B. C. F_1 wild-type [female] [female] � miniature sable [male] [male]._ +-----------+---------------------+-----------------+-------+-------+ | | | | | | | | Non-cross-overs. | Cross-overs. | | | | | | | | Cross-| | Reference.+----------+----------+----------+------+ Total.| over | | | | | | | | value.| | |Miniature |Wild-type.|Miniature.|Sable.| | | | | sable. | | | | | | +-----------+----------+----------+----------+------+-------+-------+ | | | | | | | | | 38 I | 245 | 283 | 15 | 17 | 560 | 6 | | 43 I | 191 | 236 | 13 | 18 | 458 | 7 | | 46 I | 232 | 274 | 24 | 21 | 551 | 8 | | +----------+----------+----------+------+-------+-------+ | Total | 668 | 793 | 52 | 56 | 1,569 | 7 | | | | | | | | | +-----------+----------+----------+----------+------+-------+-------+ Since the results for the male and the female classes are expected to be the same, the sexes were not separated. The combined data give 7 per cent of crossing-over between miniature and sable. LINKAGE OF VERMILION, SABLE, AND BAR. Bar eye has been described by Mrs. S. C. Tice (1914). It is a dominant sex-linked character, whose locus, lying beyond vermilion and sable, is near the right end of the chromosome series, that is, at the end opposite yellow. In the first cross of a balanced series of experiments for the gens vermilion, sable, and bar, vermilion (gray not-bar) entered from one side ([female]) and (red) sable bar from the other ([male]). The daughters were bar and the sons vermilion. The daughters were back-crossed singly to the triple recessive males vermilion sable (not-bar), and gave the data included in table 14. In the second cross, vermilion sable (not-bar) went in from one side ([female]) and (red, gray) bar from the other. The daughters were bar and the sons were vermilion sable. Since these sons have the three recessive factors, inbreeding of F_1 is equivalent to a triple back-cross. The results are given by pairs in table 15. {41} TABLE 14.--_P_1 vermilion [female] [female] � sable bar [male] [male]. B. C. F_1 bar [female] � vermilion sable [male] [male]._ +------+------------+-----------+------------+-----------+ | | v | v s B' | v B' | v s | | | ---------- | ---+----- | -----+---- | --+--+--- | | | s B' | | s | B' | | +------+-----+-----+-----+-----+------+------+----+ |Refer-| | |Verm-| | | | | | |ence. |Verm- |Sable|ilion|Wild-|Verm-| |Ver- | | | |ilion.| bar.|sable|type.|ilion|Sable.|milion|Bar.| | | | | bar.| | bar.| |sable.| | +------+------+-----+-----+-----+-----+------+------+----+ | | | | | | | | | | |147 I | 81 | 66 | 12 | 15 | 15 | 18 | | ~ |148 I | 103 | 108 | 4 | 19 | 11 | 11 | | ~ |149 I | 97 | 88 | 10 | 8 | 17 | 17 | 1 | 1 | |150 I | 95 | 75 | 10 | 11 | 21 | 22 | 1 | 1 | |151 I | 116 | 96 | 11 | 15 | 23 | 26 | | 2 | | 89 | 89 | 94 | 10 | 19 | 15 | 11 | 1 | | | 90 | 49 | 50 | 4 | 8 | 15 | 14 | | | | 91 | 104 | 88 | 13 | 15 | 12 | 12 | | | | +------+-----+-----+-----+-----+------+------+----+ |Total.| 734 | 665 | 74 | 110 | 129 | 131 | 3 | 4 | | | | | | | | | | | +------+------+-----+-----+-----+-----+------+------+----+ +------+------+------------------+ | | | | | | |Cross-over values.| | | | | | | +------+-----+-----+ |Refer-|Total.| | | | |ence. | |Verm- | |Verm-| | | |ilion |Sable|ilion| | | |sable.| bar.|bar. | +------+------+------+-----+-----+ | | | | | | ~147 I | 207 | 13 | 16 | 29 | ~148 I | 256 | 9 | 9 | 18 | |149 I | 239 | 8 | 15 | 22 | |150 I | 236 | 10 | 19 | 27 | |151 I | 289 | 10 | 18 | 26 | | 89 | 239 | 13 | 11 | 23 | | 90 | 140 | 9 | 21 | 29 | | 91 | 244 | 11 | 10 | 21 | | +------+------+-----+-----+ |Total.|1,850 | 10 | 14 | 24 | | | | | | | +------+------+------+-----+-----+ TABLE 15.--_P_1 vermilion sable [female] [female] � bar [male] [male]. B. C. F_1 bar [female] � vermilion sable [male] [male]._ +------+----------+------------+-----------+------------+ | | v s | v B' | v s B' | v | | | -------- | ---+------ | -----+--- | --+---+--- | | | B' | s | | s B' | | +------+---+-----+------+-----+-----+------+-----+ |Refer-| | | | |Verm-| | | | |ence. |Verm- | |Verm-| |ilion|Wild-|Verm- |Sable| | |ilion |Bar|ilion|Sable.|sable|type.|ilion.| bar.| | |sable.| | bar.| | bar.| | | | +------+------+---+-----+------+-----+-----+------+-----+ |105 I | 41 | 75| 10 | 4 | 5 | 11 | | ~ |106 I | 59 |122| 16 | 13 | 11 | 17 | | ~ |107 I | 92 | 98| 8 | 12 | 16 | 10 | | | |116 I | 111 |149| 19 | 16 | 20 | 19 | | 1 | |117 I | 92 |117| 16 | 14 | 15 | 18 | | | |126 I | 96 |160| 13 | 13 | 17 | 35 | | | |127 I | 117 |124| 13 | 25 | 24 | 30 | 1 | | | +------+---+-----+------+-----+-----+------+-----+ |Total | 608 |845| 95 | 97 | 108 | 140 | 1 | 1 | +------+------+---+-----+------+-----+-----+------+-----+ +------+------+------------------+ | | | | | | |Cross-over values.| | | | | | | +------+-----+-----+ |Refer-|Total.| | | | |ence. | |Verm- | |Verm-| | | |ilion.|Sable|ilion| | | |sable.| bar.|bar. | +------+------+------+-----+-----+ ~105 I | 146 | 10 | 11 | 21 | ~106 I | 238 | 12 | 12 | 24 | |107 I | 236 | 9 | 11 | 20 | |116 I | 335 | 11 | 12 | 22 | |117 I | 272 | 11 | 12 | 23 | |126 I | 334 | 8 | 15 | 23 | |127 I | 334 | 12 | 16 | 28 | | +------+------+-----+-----+ |Total |1,895 | 10 | 13 | 23 | +------+------+------+-----+-----+ {42} In the third cross, vermilion (gray) bar entered from one side ([female]) and (red) sable (not-bar) from the other ([male]). The daughters are bar and the sons vermilion bar. The daughters were back-crossed singly to vermilion sable males and gave the data in table 16. TABLE 16.--_P_1 vermilion bar_ [female] [female] � _sable_ [male] [male]. _B. C. F_1 bar_ [female] � _vermilion sable_ [male] [male]. +-----------+--------------+------------+-------------+---------------+ | | v B' | v s | v | v s B' | | | ----- | -+------ | -----+-- | -+---+-- | |Reference. | s | B' | s B' | | | +-------+------+------+-----+-------+-----+---------+-----+ | | Ver- |Sable.| Ver- | Bar.| Ver- |Sable|Vermilion|Wild-| | | milion| |milion| |milion.|bar. | sable |type.| | | bar. | |sable.| | | | bar. | | +-----------+-------+------+------+-----+-------+-----+---------+-----+ | 129 I | 132 | 147 | 15 | 15 | 19 | 21 | 1 | 1 ~ | 130 I | 194 | 168 | 21 | 17 | 28 | 25 | .. | 1 ~ | 131 I | 121 | 89 | 10 | 20 | 26 | 11 | 1 | 1 | | 137 I | 139 | 113 | 19 | 12 | 33 | 14 | .. | 1 | | 138 I | 131 | 128 | 11 | 11 | 28 | 24 | 1 | .. | | 139 I | 83 | 79 | 4 | 12 | 17 | 12 | .. | .. | | +-------+------+------+-----+-------+-----+---------+-----+ | Total. | 800 | 724 | 80 | 87 | 151 | 107 | 3 | 4 | +-----------+-------+------+------+-----+-------+-----+---------+-----+ +-----------+-------+-------------------------+ | | | | | | | | |Reference. | Total.| Cross-over values. | | | +---------+-----+---------+ | | |Vermilion|Sable|Vermilion| | | |sable. |bar. |bar. | +-----------+-------+---------+-----+---------+ ~ 129 I | 351 | 9 | 12 | 20 | ~ 130 I | 454 | 9 | 12 | 20 | | 131 I | 279 | 12 | 14 | 24 | | 137 I | 331 | 10 | 15 | 24 | | 138 I | 334 | 7 | 16 | 22 | | 139 I | 207 | 8 | 14 | 22 | | +-------+---------+-----+---------+ | Total. | 1,956 | 9 | 14 | 22 | +-----------+-------+---------+-----+---------+ In the fourth cross, vermilion sable bar entered from one side, and (red gray not-bar) wild type from the other. The daughters were bar and the sons vermilion sable bar. The daughters were back-crossed singly to vermilion sable males, with the results shown in table 17. TABLE 17.--_P_1 vermilion sable bar_ [female] [female] � _wild_ [male] [male]. _B. C. F_1 bar_ [female] � _vermilion sable_ [male] [male]. +-----------+---------------+--------------+------------+--------------+ | | v s B' | v | v s | v B' | | | -------- | -+----- | -----+-- | -+-+-- | | Reference.| | s B' | B' | s | | +---------+-----+--------+-----+-------+----+-------+------+ | |Vermilion|Wild-| Ver- |Sable| Ver- |Bar.| Ver- |Sable.| | | sable |type | milion.|bar. | milion| | milion| | | | bar. | | | | sable.| | bar. | | +-----------+---------+-----+--------+-----+-------+----+-------+------+ | 132 I | 95 | 108 | 10 | 13 | 24 | 22 | .. | .. ~ | 133 I | 112 | 150 | 18 | 16 | 26 | 16 | 1 | 2 ~ | 134 I | 84 | 95 | 14 | 7 | 15 | 16 | .. | 1 | | 135 I | 100 | 86 | 16 | 17 | 19 | 22 | .. | 1 | | 152 I | 73 | 88 | 12 | 8 | 14 | 18 | .. | .. | | 153 I | 114 | 138 | 12 | 12 | 17 | 17 | .. | .. | | 154 I | 63 | 90 | 10 | 8 | 8 | 15 | .. | .. | | | | | | | | | | | | Total. | 641 | 755 | 92 | 81 | 123 |126 | 1 | 4 | +-----------+---------+-----+--------+-----+-------+----+-------+------+ +-----------+------+-------------------------+ | | | | | | | | | Reference.|Total.| Cross-over values. | | | +---------+-----+---------+ | | |Vermilion|Sable|Vermilion| | | |sable. |bar. |bar. | +-----------+------+---------+-----+---------+ ~ 132 I | 272 | 9 | 17 | 25 | ~ 133 I | 341 | 11 | 13 | 22 | | 134 I | 232 | 10 | 14 | 22 | | 135 I | 261 | 13 | 16 | 28 | | 152 I | 213 | 9 | 15 | 24 | | 153 I | 310 | 8 | 11 | 19 | | 154 I | 194 | 9 | 12 | 21 | | | | | | | | Total. |1,823 | 10 | 14 | 23 | +-----------+------+---------+-----+---------+ {43} In tables 14 to 17 the calculations for the three cross-over values for vermilion, sable, and bar are given for the separate cultures and for the totals. The latter are here repeated. +-----------+-----------+---------+-----------+ | From-- | Vermilion | Sable | Vermilion | | | sable. | bar. | bar. | +-----------+-----------+---------+-----------+ | Table 14 | 10 | 14 | 24 | | 15 | 10 | 13 | 23 | | 16 | 9 | 14 | 22 | | 17 | 10 | 14 | 23 | +-----------+-----------+---------+-----------+ The results of the different experiments are remarkably uniform. There can be no doubt that the cross-over value is independent of the way in which the experiment is made, whether any two recessives enter from the same or from opposite sides. TABLE 18.--_Linkage of vermilion, sable, and bar with balanced viability._ +---------------------+---------+---------+---------+---------+-------+ | | ------- | --+---- | ----+-- | --+-+-- | Total.| +---------------------+---------+---------+---------+---------+-------+ | Wild-type | 755 | 110 | 140 | 4 | | | Vermilion | 734 | 92 | 151 | 1 | | | Sable | 724 | 97 | 131 | 4 | | | Bar | 845 | 87 | 126 | 4 | | | Vermilion sable | 608 | 80 | 123 | 3 | | | Vermilion bar | 800 | 95 | 129 | 1 | | | Sable bar | 665 | 81 | 107 | 1 | | | Vermilion sable bar | 641 | 74 | 108 | 3 | | | +---------+---------+---------+---------+-------+ | Total | 5,772 | 716 | 1,015 | 21 | 7,524 | | Percentage | 76.7 | 9.53 | 13.49 | 0.28 | | +---------------------+---------+---------+---------+---------+-------+ In table 18 the data from each of the four separate experiments have been combined in the manner explained, so that viability is canceled to the greatest extent. The amount of each kind of cross-over appears at the bottom of the table. The total amount of crossing-over between vermilion and sable is the sum of the single (9.53) and of the double (0.28) cross-overs, which value is 9.8. Likewise the cross-over value for sable bar is 13.49 + 0.28 (= 14), and for vermilion bar is 9.53 + 13.49 (= 23). By means of these cross-over values we may calculate the coincidence involved, which is in this case 0.0028 � 100 --------------------------------- = 20.8 0.0953 + 0.0028 � 0.1349 + 0.0028 This value shows that there actually occurs only about 21 per cent of the double cross-overs which from the values of the single cross-overs are expected to occur in this section of the chromosome. This is the result which is to be anticipated upon the chromosome view, for if crossing-over is connected with loops of the chromosomes, and if these loops have an average length, then if the chromosomes cross over at one {44} point it is unlikely they will cross over again at another point nearer than the average length of the loop. The calculation of the locus for sable gives 43.0. DOT. In the F_2, from a cross of a double recessive (white vermilion) female by a triple recessive (eosin vermilion pink) male, there appeared, July 21, 1912, three white-eyed females which had two small, symmetrically placed, black, granular masses upon the thorax. These "dots" appeared to be dried exudations from pores. It did not seem possible that such an effect could be inherited, but as this condition had never been observed before, it seemed worth while to mate the three females to their brothers. In the next generation about 1 per cent of the males were dotted. From these females and males a stock was made up which in subsequent generations showed from 10 to 50 per cent of dot. Selection seemed to have no effect upon the percentage of dot. Although the stock never showed more than 50 per cent of dot, yet it was found that the normal individuals from the stock threw about the same per cent as did those that were dotted, so that the stock was probably genetically pure. The number of males which showed the character was always much smaller than the number of dotted females; in the hatches which produced nearly 50 per cent of dot, nearly all the females but very few of the males were dotted. Quite often the character showed on only one side of the thorax. Since this character arose in an experiment involving several eye-colors an effort was made by crossing to wild and extracting to transfer the dot to flies normal in all other respects. This effort succeeded only partly, for a stock was obtained which differed from the wild type only in that it bore dot (about 30 per cent) and in that the eyes were vermilion. Several attempts to get the dot separated from vermilion failed. Since this was only part of the preliminary routine work necessary to get a mutant stock in shape for exact experimentation, no extensive records were kept. LINKAGE OF VERMILION AND DOT. When a dot male with vermilion eyes was bred to a wild female the offspring were wild-type males and females. These inbred gave the data shown in table 19. TABLE 19.--_P_1 vermilion dot [male] � wild [female] [female]. F_1 wild-type [female] [female] � F_1 wild-type [male] [male]._ +------------+----------+-----------+-----------+-------------+---------+ | Reference. | F_2 | Wild-type | Vermilion | Vermilion | Dot | | | females. | [male]. | [male]. | dot [male]. | [male]. | +------------+----------+-----------+-----------+-------------+---------+ | 7 | 345 | 151 | 130 | 0 | 0 | | 8 | 524 | 245 | 220 | 3 | 0 | | +----------+-----------+-----------+-------------+---------+ | Total. | 869 | 396 | 350 | 3 | 0 | +------------+----------+-----------+-----------+-------------+---------+ {45} Only three dot individuals appeared in F_2, but since these were males the result indicates that the dot character is due to a sex-linked gen. These three males had also vermilion eyes, indicating linkage of dot and vermilion. The males show no deficiency in numbers, therefore the non-appearance of the dot can not be due to its being semi-lethal. It appears, therefore, that the expression of the character must depend on the presence of an intensifying factor in one of the autosomes, or more probably, like club, it appears only in a small percentage of flies that are genetically pure for the character. The reciprocal cross (dot female with vermilion eyes by wild male) was made (table 20). The daughters were wild type and the sons vermilion. Not one of the 272 sons showed dot. If the gen is sex-linked the non-appearance of dot in the F_1 males can be explained on the ground that males that are genetically dot show dot very rarely, or that its appearance is dependent upon the intensification by an autosomal factor of the effect produced by the sex-linked factor for dot. TABLE 20.--_P_1 vermilion dot [female] � wild [male]._ A = Wild-type [female]. B = Vermilion [male]. C = Wild-type [male]. D = Wild-type [female]. E = Vermilion [male]. F = Vermilion [female]. G = Vermilion dot [male]. H = Vermilion dot [female]. I = Dot [male]. J = Dot [female]. +--------------------++-----------------------------------------------+ | First generation. || Second generation. | +----------+----+----++----------+----+----+----+----+----+---+---+---+ |Reference.| A | B ||Reference.| C | D | E | F | G | H | I | J | +--------------------++----------+----+----+----+----+----+---+---+---+ | 137 C. | 44 | 45 || 19 |211 |198 |228 |206 | 20 | 3 | 0 | 0 | | 138 C. | 77 | 62 || 22 |266 |220 |227 |227 | 16 | 0 | 0 | 0 | | |124 |124 || 28 |143 |149 |125 |124 | 14 | 1 | 0 | 0 | | | 57 | 41 || +----+----+----+----+----+---+---+---+ | |----|----|| Total.|620 |567 |570 |557 | 50 | 4 | 0 | 0 | | Total.|291 |272 || | | | | | | | | | +--------------------++----------+----+----+----+----+----+---+---+---+ The F_2 generation is given in table 20. The dot reappeared in F_2 both in females and in males, but instead of appearing in 50 per cent of both sexes, as expected if it is simply sex-linked, it appeared in 4.0 per cent in the females and in only 0.4 per cent in the males. The failure of the character to be fully realized is again apparent, but here, where it is possible for it to be realized equally in males and females, we find that there are 50 females with dot to only 4 dot males. This would indicate that the character is partially "_sex-limited_" (Morgan, 1914_d_) in its realization. The dot appeared only in flies with vermilion eyes, indicating extremely strong linkage between vermilion and dot. The evidence from the history of the stock, together with these experiments, shows that the character resembles club (wing) in that it is not expressed somatically in all the flies which are homozygous for it. In the case of club we were fortunate enough to find a constant feature {46} which we could use as an index, but, so far as we have been able to see, there is no such constant accessory character in the case of the dot. Unlike club, dot is markedly sex-limited in its effect; that is, there is a difference of expression of the gen in the male and female. This difference recalls the sexual dimorphism of the eosin eye. BOW. In an F_2 generation from rudimentary males by wild females there appeared, August 15, 1912, a single male whose wings instead of being flat were turned down over the abdomen (fig. c). The curvature was uniform throughout the length of the wing. A previous mutation, arc, of this same type had been found to be a recessive character in the second group. The new mutation, bow, is less extreme than arc and is more variable in the amount of curvature. When the bow male was mated to wild females the offspring had straight wings. [Illustration: FIG. C.--Bow wing.] TABLE 21.--_P_1 bow [male][male] � wild [female][female]._ +------------------------------------------+ | First generation. | +----------+-----------------+-------------+ |Reference.| Wild-type | Wild-type ~ | |[female][female].|[male][male].~ +----------+-----------------+-------------+ | 169 C. | 17 | 17 | +----------+-----------------+-------------+ +--------------------------------------------------------+ | Second generation. | +----------+-----------------+-------------+-------------+ ~Reference.| Wild-type | Wild-type | Bow | ~ |[female][female].|[male][male].|[male][male].| +----------+-----------------+-------------+-------------+ | 18 I. | 193 | 145 | 67 | | 21 I | 182 | 100 | 49 | | +-----------------+-------------+-------------+ | Total.| 375 | 245 | 116 | +----------+-----------------+-------------+-------------+ {47} The F_2 ratio in table 21 is evidently the 2:1:1 ratio typical of sex-linkage, but with the bow males running behind expectation. This deficiency is due in part to viability but more to a failure to recognize all the bow-winged individuals, so that some of them were classified among the not-bow or straight wings. In favor of the view that the classification was not strict is the fact that the sum of the two male classes about equals the number of the females. BOW BY ARC. When this mutant first appeared its similarity to arc led us to suspect that it might be arc itself or an allelomorph of arc. It was bred, therefore, to arc. The bow male by arc females gave straight (normal) winged males and females. The appearance of straight wings shows that bow is not arc nor allelomorphic to arc. When made later, the reciprocal cross of bow female by arc male gave in F_1 straight-winged females but bow males. This result is in accordance with the interpretation that bow is a sex-linked recessive. Further details of these last two experiments may now be given. The F_1 (wild-type) flies from bow male by arc female were inbred. The data are given in table 22. TABLE 22.--_P_1 bow [male] � arc [female]._ +--------------------------------------------+ | First generation. | +----------+------------------+--------------+ |Reference.| Wild-type | Wild-type ~ | |[female] [female].|[male] [male].~ +----------+------------------+--------------+ | 71 C. | 48 | 43 | | 75 C. | 28 | 27 | | +------------------+--------------+ | Total.| 76 | 70 | +----------+------------------+--------------+ +------------------------------+ | Second generation. | +----------+---------+---------+ ~Reference.|Straight.| Not- | ~ | |straight.| +----------+---------+---------+ | 71 C. | 179 | 133 | +----------+---------+---------+ Bow and arc are so much alike that they give a single rather variable phenotypic class in F_2. Therefore the F_2 generation is made up of only two separable classes--flies with straight wings and flies with not-straight wings. The ratio of the two should be theoretically 9:7, which is approximately realized in 179:133. If the distribution of the characters according to sex is ignored, the case is similar to the case of the two white races of sweet peas, which bred together gave wild-type or purple peas in F_1 and in F_2 gave 9 colored to 7 white. If sex is taken into account, the theoretical expectation for the F_2 females is 6 straight to 2 arc, and for the F_2 males 3 straight to 1 arc to 3 bow to 1 bow-arc. The F_1 from bow females by arc male and their F_2 offspring are given in table 23. {48} TABLE 23.--_P_1 bow [female] � arc [male]._ +--------------------------------------------+ | First generation. | |----------+------------------+--------------+ |Reference.| Wild-type | Bow | | |[female] [female].|[male] [male].| |----------+------------------+--------------+ | 72 C. | 22 | 19 ~ | 73 C. | 12 | 10 ~ | 5 I. | 22 | 21 | | 74 C. | 56 | 52 | | |------------------+--------------+ | Total.| 112 | 102 | +----------+------------------+--------------+ +------------------------------+ | Second generation. | +----------+---------+---------+ |Reference.|Straight.| Not- | | | |straight.| +----------+---------+---------+ ~ 3 I. | 56 | 69 | ~ 3.1 I. | 46 | 62 | | 5 I. | 56 | 68 | | 5.1 I. | 90 | 108 | +----------+---------+---------+ | Total.| 248 | 307 | +----------+---------+---------+ In this case the F_2 expectation is 6 straight to 10 not-straight. Since the sex-linked gen bow entered from the female, half the F_2 males and females are bow. The half that are not-bow consist of 3 straight to 1 arc, so that both in the female classes and in the male classes there are 3 straight to 5 not-straight or in all 6 straight to 10 not-straight. The realized result, 248 straight to 307 not-straight, is more nearly a 3:4 ratio, due probably to a wrong classification of some of the bow as straight. LEMON BODY-COLOR. (Plate I, figure 3.) A few males of a new mutant with a lemon-colored body and wings appeared in August 1912. The lemon flies (Plate II, fig. 3) resemble quite closely the yellow flies (Plate II, fig. 4). They are paler and the bristles, instead of being brown, are black. These flies are so weak that despite most careful attention they get stuck to the food, so that they die before mating. The stock was at first maintained in mass from those cultures that gave the greatest percentage of lemon flies. In a few cases lemon males mated with their gray sisters left offspring, but the stock obtained in this way had still to be maintained by breeding heterozygotes, as stated above. But from the gray sisters heterozygous for lemon (bred to lemon males) some lemon females were also produced. LINKAGE OF CHERRY, LEMON, AND VERMILION. In order to study the linkage of lemon, the following experiment was carried out. Since it was impracticable to breed directly from the lemon flies, virgin females were taken from stock throwing lemon, and were mated singly to cherry vermilion males. Only a few of the females showed themselves heterozygous for lemon by producing lemon as well as gray sons. Half the daughters of such a pair are expected to be heterozygous for lemon and also for cherry and vermilion, which went in from the father. These daughters were mated singly to cherry vermilion males, and those that gave some lemon sons were continued, {49} and are recorded in table 24. The four classes of females were not separated from each other, but the total of females is given in the table. TABLE 24.--_P_1 lemon (het.) [female] � cherry vermilion [male] [male]. F_1 wild-type [female] � cherry vermilion [male] [male]._ +-------+--------------+-------------+-------------+-------------+------+ | | W^c V | W^c l_m | W^c | W^c l_m V | | | | ---------- | ---+------ | ------+--- | ---+----+---| | | | l_m | V | l_m V | | | |Females+-------+------+------+------+------+------+-------+-----+ Total| | |Cherry | |Cherry| Ver- |Cherry|Lemon |Cherry |Wild |[male]| | | ver- |Lemon.|lemon.|milion| | ver- |lemon |type.|[male]| | |milion.| | | | |milion| ver- | | | | | | | | | | |milion.| | | +-------+-------+------+------+------+------+------+-------+-----+------+ | 71 | 42 | 19 | 2 | 6 | 3 | 6 | 0 | 0 | 78 | | 88 | 26 | 19 | 2 | 8 | 8 | 4 | 0 | 0 | 67 | | 36 | 28 | 7 | 0 | 2 | 1 | 0 | 0 | 0 | 38 | | 51 | 12 | 22 | 0 | 4 | 4 | 4 | 0 | 0 | 46 | | 98 | 29 | 35 | 0 | 8 | 5 | 1 | 0 | 0 | 78 | | 47 | 17 | 11 | 0 | 1 | 3 | 2 | 0 | 0 | 34 | | 46 | 23 | 20 | 1 | 6 | 5 | 2 | 0 | 0 | 57 | +-------+-------+------+------+------+------+------+-------+-----+------+ | 437 | 177 | 133 | 5 | 35 | 29 | 19 | 0 | 0 | 398 | +-------+-------+------+------+------+------+------+-------+-----+------+ There are three loci involved in this cross, namely, cherry, lemon, and vermilion. Of these loci two were known, cherry and vermilion. The data are consistent with the assumption that the lemon locus is between cherry and vermilion, for the double cross-over classes (the smallest classes) are cherry lemon vermilion and wild type. The number of single cross-overs between cherry and lemon and between lemon and vermilion are also consistent with this assumption. Since lemon flies fail to emerge successfully, depending in part upon the condition of the bottle, the classes involving lemon are worthless in calculating crossing-over and are here ignored. In other words, lemon may be treated as though it did not appear at all, _i. e._, as a lethal. The not-lemon classes--cherry, vermilion, cherry vermilion, and wild type--give the following approximate cross-over values for the three loci involved: Cherry lemon, 15; lemon vermilion, 12; cherry vermilion, 27. The locus of lemon, calculated by interpolation, is at about 17.5. LETHAL 2. In September 1912 a certain wild female produced 78 daughters and only 16 sons (Morgan, 1914_b_); 63 of these daughters were tested and 31 of them gave 2 females to 1 male, while 32 of them gave 1:1 sex-ratios. This shows that the mother of the original high sex-ratio was heterozygous for a recessive sex-linked lethal. In order to determine the position of this lethal, a lethal-bearing female was bred to an eosin (or white) miniature male, and those daughters that were heterozygous for eosin, lethal, and miniature were then back-crossed to {50} eosin miniature males. The daughters that result from such a cross give only the amount of crossing-over between eosin and miniature (as 29.7), but the males give the cross-over values for eosin lethal (9.9), lethal miniature (15.4), and eosin miniature (25.1). The data for this cross are given in table 25. TABLE 25.--_Total data upon linkage of eosin, lethal 2, and miniature, from Morgan, 1914b._ +------------------------------------+ | Females. | +--------+--------------+------------+ | | | | | Total. | Cross-overs. | Cross-over | | | | value. ~ | | | ~ +--------+--------------+------------+ | 15,904 | 4,736 | 29.7 | +--------+--------------+------------+ +-----------------------------------------------------------------------+ | Males. | +--------+--------+--------+---------+----------------------------------+ |w^e m|w^e l_2 |w^e |w^e l_2 m| Cross-over values. | |--------|---+----|------+-|---+---+-+----------+-----------+-----------+ ~ l_2 | m| l_2 m| | Eosin | Lethal 2 | Eosin | ~ | | | | lethal 2.| miniature.| miniature.| +--------+--------+--------+---------+----------+-----------+-----------+ | 5,045 | 653 | 1,040 | 14 | 9.9 | 15.4 | 25.1 | +--------+--------+--------+---------+----------+-----------+-----------+ A similar experiment, in which eosin and vermilion were used instead of eosin and miniature, is summarized in table 26. TABLE 26.--_Total data upon the linkage of eosin, lethal 2, and vermilion, from Morgan, 1914b._ +------------------------------------+ | Females. | +--------+--------------+------------+ | | | | | Total. | Cross-overs. | Cross-over | | | | value. ~ | | | ~ +--------+--------------+------------+ | 2,656 | 729 | 27.5 | +--------+--------------+------------+ +-----------------------------------------------------------------------+ | Males. | +--------+--------+--------+---------+----------------------------------+ |w^e v|w^e l_2 |w^e |w^e l_2 v| Cross-over values. | |--------|---+----|------+-|---+---+-+----------+-----------+-----------+ ~ l_2 | v| l_2 v| | Eosin | Lethal 2 | Eosin | ~ | | | | lethal 2.| vermilion.| vermilion.| +--------+--------+--------+---------+----------+-----------+-----------+ | 902 | 124 | 227 | 6 | 10.3 | 18.5 | 27.9 | +--------+--------+--------+---------+----------+-----------+-----------+ Considerable data in which lethal was not involved were also obtained in the course of these experiments and are included in the summary of the total data given in table 27. TABLE 27.--_Summary of all data upon lethal 2, from Morgan, 1914b._ +--------------------+--------+--------------+------------+ | Gens. | Total. | Cross-overs. | Cross-over | | | | | values. | +--------------------+--------+--------------+------------+ | White lethal 2 | 8,011 | 767 | 9.6 | | White vermilion | 6,023 | 1,612 | 26.8 | | White miniature | 36,021 | 11,048 | 30.7 | | Lethal 2 vermilion | 1,400 | 248 | 17.7 | | Lethal 2 miniature | 6,752 | 1,054 | 15.4 | +--------------------+--------+--------------+------------+ The amount of crossing-over between eosin and lethal is about 10 per cent and the amount of crossing-over between lethal and miniature is about 18 per cent. Since the amount of crossing-over between eosin {51} and miniature is over 30 per cent, the lethal factor must lie between eosin and miniature, somewhat nearer to eosin. It is impossible at present to locate lethal 2 accurately because of a real discrepancy in the data, which makes it appear that lethal 2 extends for a distance of about 5 units along the chromosome from about 10 to about 15. Work is being done which it is hoped will make clear the reason for this. For the present we may locate lethal 2 at the midpoint of its range, or at 12.5. CHERRY. (Plate II, figure 9.) The origin of the eye-color cherry has been given by Safir (Biol. Bull., 1913). Cherry appeared (October 1912) in an experiment involving vermilion eye-color and miniature wings. This is the only time the mutant has ever come up, and although several of this mutant (males) appeared in Safir's experiment, they may have all come from the same mother. It is probable that the mutation occurred in the vermilion stock only a generation or so before the experiment was made, for otherwise cherry would be expected to be found also in the vermilion stock from which the mothers were taken; however, it was not found. A SYSTEM OF QUADRUPLE ALLELOMORPHS. Safir has described crosses between this eye-color and red, white, eosin, and vermilion. We conclude for reasons similar to those given by Morgan and Bridges (Jour. Exp. Zool., 1913) for the case of white and eosin, that cherry is an allelomorph of white and of eosin. This is not the interpretation followed in Safir's paper, where cherry is treated as though absolutely linked to white or to eosin. Both interpretations give, however, the same numerical result for each cross considered by itself. Safir's data and those which appear in this paper show that white, eosin, cherry, and a normal (red) allelomorph form a system of quadruple allelomorphs. If this interpretation is correct, then the linkage relations of cherry should be identical with those of white or of eosin. LINKAGE OF CHERRY AND VERMILION. The cross-over value for white (eosin) and vermilion, based on a very large amount of data, is about 31 units. An experiment of our own in which cherry was used with vermilion gave a cross-over value of 31 units, which is a close approximation to the cross-over value of white and vermilion. The cross which gave this data was that of a cherry vermilion (double recessive) male by wild females. The F_{1} wild-type flies inbred gave a single class of females (wild-type) and the males in four classes which show by the deviation from a 1:1:1:1 ratio the amount of crossing-over involved. {52} In one of the F_{2} male classes of table 28 the simple eye-color cherry appeared for the first time (since the original mutant was vermilion as well as cherry). Safir has recorded a similar cross with like results. TABLE 28.--_P_{1} cherry vermilion [male] [male] � wild [female] [female]. F_{1} wild-type [female] [female] � F_{1} wild-type [male] [male]._ +----------+---------+----------------+---------------+-------+------+ | | | Non-cross-over | Cross-over | | | | | | [male]. | [male]. | | | | |Wild-type+----------+-----+-------+-------+Total |Cross-| |Reference.|[female] | Cherry |Wild-|Cherry.| Ver- |[male] |over | | |[female].|vermilion.|type.| |milion.|[male].|value.| +----------+---------+----------+-----+-------+-------+-------+------+ | 160 C | 188 | 57 | 61 | 32 | 34 | 184 | 36 | | 161 C | 256 | 85 | 93 | 40 | 52 | 270 | 34 | | 162 C | 251 | 78 | 78 | 20 | 37 | 213 | 26 | | 163 C | 229 | 76 | 95 | 34 | 33 | 238 | 28 | +----------+---------+----------+-----+-------+-------+-------+------+ | Total | 924 | 296 | 327 | 126 | 156 | 905 | 31 | +----------+---------+----------+-----+-------+-------+-------+------+ Some cherry males were bred to wild females. The F_{1} wild-type males and females inbred gave the results shown in table 29. Some of the cherry males thus produced were bred to their sisters. Cherry females as well as males resulted; and it was seen that the eye-color is the same in the males and females, in contradistinction to the allelomorph eosin, where there is a marked bicolorism (figs. 7, 8, Plate II). The cherry eye-color is almost identical with that of the eosin female, but is perhaps slightly more translucent and brighter. TABLE 29.--_P_{1} cherry [male] [male] � wild [female] [female]. F_{1} wild-type [female] [female] � F_{1} wild-type [male] [male]._ +------------+---------------------+-------------------+----------------+ | Reference. | Wild-type [female]. | Wild-type [male]. | Cherry [male]. | +------------+---------------------+-------------------+----------------+ | 15 I | 266 | 120 | 100 | +------------+---------------------+-------------------+----------------+ +------------+-------------------------------------+ | | First generation. | | Reference. +--------------------+----------------+ | | White-cherry | | | | compound [female]. | Cherry [male]. | +------------+--------------------+----------------+ | 9 M | 321 | 302 | +------------+--------------------+----------------+ Eosin-cherry compound was also made. An eosin female was mated to a cherry male. The eosin-cherry daughters were darker than their eosin brothers. Inbred they gave the results shown in table 31. TABLE 31.--_P_1 eosin [female] � cherry [male]._ +------------------------------------------+ | First generation. | +------------+-------------------+---------+ | | Eosin-cherry | Eosin | | Reference. | compound | [male] | | | [female][female]. | [male]. ~ | | | ~ +------------+-------------------+---------+ | 43C | 71 | 58 | +------------+-------------------+---------+ +----------------------------------------------------+ | Second generation. | +------------+-------------------+---------+---------+ | | Eosin and | | | | Reference. | eosin-cherry | Cherry | Eosin | ~ | compound | [male]. | [male]. | ~ | [female][female]. | | | +------------+-------------------+---------+---------+ | 1I | 154 | 99 | 62 | | 2I | 174 | 74 | 77 | | +-------------------+---------+---------+ | | 328 | 173 | 139 | +------------+-------------------+---------+---------+ Although in the F_2 results there are two genotypic classes of females, namely, pure eosin and eosin-cherry compound, the eye-colors are so nearly the same that they can not be separated. The two classes of males can be readily distinguished; of these, one class, cherry, has the same color as the females, while the other class, eosin, is much lighter. Such an F_2 group will perpetuate itself, giving one type of female (of three possible genotypic compositions, but somatically practically homogeneous) and two types of males, only one of which is like the females. FUSED. In a cross between purple-eyed[6] males and black females there appeared in F_2 (Nov. 4, 1912) a male having the veins of the wing arranged as shown in text-figure D b. It will be seen that the third and the fourth longitudinal veins are fused from the base to and beyond the {53} point at which in normal flies the anterior cross-vein lies. The cross-vein and the cell normally cut off by it are absent. There are a number of other features (see fig. D _c_) characteristic of this mutation: the wings are held out at a wide angle from the body, the ocelli are very much reduced in size or entirely absent, the bristles around the ocelli are usually small. The females are absolutely sterile, not only with their own, but with any males. Fused males by wild females gave wild-type males and females. Inbred these gave the results shown in table 32. The fused character reappeared only in the F_2 males, showing that it is a recessive sex-linked character. TABLE 32.--_P_1 fused [male] � wild [female][female]._ +-------------------------------------------------+ | First generation. | +------------+-------------------+----------------+ | Reference. | Wild-type | Wild-type ~ | | [female][female]. | [male][male]. ~ +------------+-------------------+----------------+ | 4I | 66 | 43 | | | | | +------------+-------------------+----------------+ +------------------------------------------------------------------+ | Second generation. | +------------+-------------------+----------------+----------------+ ~ Reference. | Wild-type | Wild-type | Fused | ~ | [female][female]. | [male][male]. | [male][male]. | +------------+-------------------+----------------+----------------+ | 190C | 258 | 96 | 115 | | 14I | 239 | 105 | 90 | | +-------------------+----------------+----------------+ | Total | 497 | 201 | 205 | +------------+-------------------+----------------+----------------+ The reciprocal cross was tried many times, but is impossible, owing to the sterility of the females. Since the fused females are sterile to fused males, the stock is kept up by breeding heterozygous females to fused males. By means of the following experiments the position of fused in the X chromosome was determined. A preliminary test was made by mating with eosin, whose factor lies near the left end of the X chromosome series. LINKAGE OF EOSIN AND FUSED. Fused (red-eyed) males mated to eosin (not-fused) females gave wild-type daughters and eosin sons, which inbred gave the classes shown in table 33. TABLE 33.--_P_1 eosin [female][female] � fused [male][male]. F_1 wild-type [female][female] � F_1 eosin [male][male]._ +----------+--------+-----------------+----------------+-------+--------+ | | | Non-cross-over | Cross-over | | | | | | [male][male]. | [male][male]. | Total | Cross- | |Reference.|Females.+--------+--------+--------+-------+ males.| over | | | | Eosin. | Fused. | Eosin | Wild- | | value. | | | | | | fused. | type. | | | +----------+--------+--------+--------+--------+-------+-------+--------+ | 56I | 496 | 131 | 113 | 82 | 104 | 430 | 43 | +----------+--------+--------+--------+--------+-------+-------+--------+ {54} The data give 43 per cent of crossing-over, which places fused far to the right or to the left of eosin. The latter position is improbable, since eosin already lies very near the extreme left end of the known series. Therefore, since 43 per cent would place the factor nearly at the right end of the series, the next step was to test its relation to a factor like bar that lies at the right end of the chromosome. By mating to bar alone we could only get the linkage to bar without discovering on which side of bar the new factor lies, but by mating to a fly that carries still another sex-linked factor, known to lie to the left of bar, the information gained should show the relative order of the factors involved. Furthermore, since, by making a back-cross, both males and females give the same kind of data (and need not be separated), the experiment was made in this way. In order to have material for such an experiment double mutant stocks of vermilion fused and also of bar fused were made up. [Illustration: Fig. D.--_a_, normal wing; _b_ and _c_, fused wings. _c_ shows a typical fused wing. The most striking feature is the closure of the cell between the third and fourth longitudinal veins with the elimination of the cross-vein; the veins at the base of the wing differ from those in the normal shown in a. _b_ shows the normal position in which the fused wings are held. The fusion of the veins in _b_ is unusually complete.] {55} LINKAGE OF VERMILION, BAR, AND FUSED. Males from the stock of (red) bar fused were mated to vermilion (not-bar, not-fused) females, and produced bar females and vermilion males. The bar F_1 daughters were back-crossed to vermilion fused males and produced the classes of offspring shown in table 34. TABLE 34.--P_1 _vermilion_ [female] [female] � _bar fused_ [male] [male]. _B. C. F_1 bar_ [female] � _vermilion fused_ [male] [male]. +----------+-------------------+---------------------+------------------+ | | v | v B' f_u | v f_u | | | ----------------- | ----+-------------- | -----------+---- | | | B' f_u | | B' | |Reference.+----------+--------+----------+----------+-----------+------+ | | | | Vermilion| | | | | |Vermilion.| Bar | bar |Wild-type.| Vermilion | Bar. | | | | fused. | fused. | | fused. | | +----------+----------+--------+----------+----------+-----------+------+ |140 I | 137 | 130 | 35 | 40 | 5 | 8 ~ |141 I | 144 | 137 | 38 | 41 | 4 | 2 ~ |142 I | 153 | 120 | 43 | 58 | 6 | 7 | |143 I | 153 | 92 | 44 | 41 | 3 | 7 | |145 I | 69 | 62 | 29 | 19 | 1 | .. | |146 I | 96 | 103 | 30 | 34 | 7 | 3 | |156 I | 62 | 45 | 25 | 27 | 1 | 4 | |157 I | 93 | 57 | 11 | 31 | 2 | 2 | | +----------+--------+----------+----------+-----------+------+ | Total. | 907 | 746 | 255 | 291 | 29 | 33 | +----------+----------+--------+----------+----------+-----------+------+ +--------------------+--------+--------------------------------+ | v B' | | | | ----+--------+---- | | Cross-over values. | | f_u | | | +-----------+--------+ +-----------+--------+-----------+ | | | Total. | | | | | Vermilion | Fused. | | Vermilion | Bar | Vermilion | | bar. | | | bar. | fused. | fused. | +-----------+--------+--------+-----------+--------+-----------+ ~ .. | .. | 355 | 21 | 4 | 25 | ~ .. | .. | 366 | 22 | 2 | 23 | | 1 | .. | 388 | 26 | 4 | 29 | | 3 | 1 | 344 | 26 | 4 | 28 | | 1 | .. | 181 | 27 | 1 | 27 | | .. | .. | 273 | 23 | 4 | 26 | | .. | .. | 164 | 32 | 3 | 35 | | .. | 2 | 198 | 22 | 3 | 23 | +-----------+--------+--------+-----------+--------+-----------+ | 5 | 3 | 2,269 | 24 | 3 | 27 | +-----------+--------+--------+-----------+--------+-----------+ The data show that the factor for fused lies about 3 units to the right of bar. This is the furthest point yet obtained to the right. The reasons for locating fused to the right of bar are that, if it occupies such a position, then the double cross-over classes (which are expected to be the smallest classes) should be vermilion bar and fused, and these are, in fact, the smallest classes. The order of factors is, then, vermilion, bar, fused. This order is confirmed by the result that the number of cross-overs between fused and vermilion is greater than that between bar and vermilion. In order to obtain data to balance viability effects, the following experiment was made: Vermilion (not-bar) fused males were bred to (red) bar (not-fused) females. The daughters and sons were bar. The daughters were back-crossed, singly, to vermilion fused males and gave the results shown in table 35. Each female was also transferred to a second culture bottle, so that for each female there are two broods given consecutively (82, 82', etc.) in table 35. The results given by the two broods of the same female are similar. The values are very near to those given in the last experiment, and confirm the conclusions there drawn. The combined data give the results shown in table 36. {56} TABLE 35.--_P_1 bar [female] [female] � vermilion fused [male] [male]. B. C. F_1 bar [female] � vermilion fused [male] [male]._ A - Vermilion fused. B - Bar. C - Vermilion bar. D - Fused. E - Vermilion. F - Bar fused. G - Vermilion bar fused. H - Wild type. ------------------------------------------------------------------------- | v f_u | v B' |v |v B' f_u| | Cross- | -------- |----+----|----+----|-+---+---| | over | B' | f_u | B' f_u | |Total.| values. Reference +-------------+---------+---------+---------+ +----------- | A | B | C | D | E | F | G | H | | C | F | A ----------+------+------+----+----+----+----+----+----+------+---+---+--- | | | | | | | | | | | | 82 | 165 | 165 | 63 | 57 | 8 | 7 | 1 | .. | 466 | 26|3 | 29 82' | 104 | 87 | 26 | 24 | .. | 4 | .. | .. | 245 | 20|2 | 22 83 | 128 | 164 | 51 | 39 | 6 | 4 | .. | .. | 392 | 23|3 | 26 83' | 100 | 94 | 28 | 30 | 4 | 4 | .. | .. | 260 | 22|3 | 25 89 | 85 | 105 | 23 | 24 | 5 | 2 | .. | .. | 244 | 19|3 | 22 89' | 78 | 91 | 21 | 27 | 1 | 2 | .. | 1 | 221 | 22|2 | 23 90 | 86 | 85 | 30 | 28 | 5 | .. | .. | .. | 234 | 25|2 | 27 90' | 33 | 38 | 22 | 14 | 4 | 1 | .. | 1 | 113 | 33|5 | 36 91 | 125 | 107 | 41 | 31 | 1 | 1 | .. | .. | 306 | 24|1 | 24 91' | 91 | 95 | 31 | 25 | 5 | 1 | .. | 2 | 250 | 23|3 | 25 92 | 109 | 136 | 41 | 24 | 4 | 2 | .. | .. | 316 | 21|2 | 23 92' | 100 | 105 | 29 | 29 | .. | 1 | .. | 1 | 265 | 22|1 | 22 93 | 75 | 67 | 19 | 20 | .. | 1 | .. | .. | 182 | 21|1 | 22 93' | 68 | 94 | 31 | 17 | 1 | 1 | .. | .. | 212 | 23|1 | 24 94 | 84 | 96 | 31 | 35 | 8 | 1 | .. | .. | 255 | 26|4 | 29 94' | 61 | 73 | 20 | 22 | 5 | 4 | .. | .. | 185 | 23|5 | 28 95 | 84 | 102 | 27 | 26 | 3 | 3 | .. | .. | 245 | 22|2 | 24 96 | 144 | 148 | 43 | 34 | 1 | 2 | .. | 1 | 373 | 21|1 | 21 97 | 81 | 96 | 25 | 20 | 5 | 3 | .. | .. | 230 | 20|4 | 23 98 | 107 | 112 | 39 | 33 | 1 | 2 | .. | .. | 294 | 25|1 | 26 Firsts |1,273 |1,383 |433 |371 | 47 | 28 | 1 | 1 |3,537 | 23|2 | 25 Seconds | 635 | 677 |208 |188 | 20 | 18 | .. | 5 |1,751 | 23|3 | 25 ----------+------+------+----+----+----+----+----+----+------+---+---+--- Total.|1,908 |2,060 |641 |559 | 67 | 46 | 1 | 6 |5,288 | 23|2.3| 25 ----------+------+------+----+----+----+----+----+----+------+---+---+--- TABLE 36.--_Linkage of vermilion, bar, and fused with balanced viability._ +------------+----------+-----------+-----------+-----------+--------+ | | v B' f_u | v | v B' | v f_u | | | | -------- | --+------ | -----+--- | -+---+--- | Total. | | | | B' f_u | f_u | B' | | +------------+----------+-----------+-----------+-----------+--------+ | | | | | | | | | 5,621 | 1,756 | 175 | 15 | 7,567 | | Percentage | 74.3 | 23.19 | 2.31 | 0.2 | | | | | | | | | +------------+----------+-----------+-----------+-----------+--------+ Some additional data bearing on the linkage of vermilion and fused were obtained. Males of (red) fused stock were bred to vermilion (not-fused) females, and gave wild-type females and vermilion males, which inbred gave the results shown in table 37. The percentage of cross-overs between vermilion and fused is here 27, which is in agreement with the 26 per cent of the preceding experiment. The converse experiment, namely, red (not-fused) females by vermilion fused males also gave, when the wild-type daughters were {57} back-crossed to vermilion fused males, a linkage value of 27 units. Two 10-day broods were reared from each female. The data given in table 38 show that the percentage of crossing-over does not change as the flies get older. The locus of fused on the basis of all of the data is at 59.5. TABLE 37.--P_1 vermilion [female] [female] � fused [male] [male]. F_1 wild-type [female] [female] � F_1 vermilion [male] [male]. KEY: A: Non-cross-over [male] [male]. B: Cross-over [male] [male]. C: Females. D: Vermilion. E: Fused. F: Vermilion fused. G: Wild-type. H: Total [male] [male]. I: Cross-over values. +------------+-----+-----------+----------+-----+----+ | | | A | B | | | | | +-----+-----+----+-----+ | | | Reference. | C | D | E | F | G | H | I | +------------+-----+-----+-----+----+-----+-----+----+ | 79 I | 299 | 93 | 96 | 37 | 36 | 262 | 28 | | 80 I | 245 | 93 | 60 | 28 | 27 | 208 | 26 | | 81 I | 263 | 101 | 63 | 22 | 40 | 226 | 27 | | +-----+-----+-----+----+-----+-----+----+ | Total. | 807 | 287 | 219 | 87 | 103 | 696 | 27 | +------------+-----+-----+-----+----+-----+-----+----+ TABLE 38.--P_1 wild [female] [female] � vermilion fused [male] [male]. F_1 wild-type [female] � F_1 wild-type [male] [male]. KEY: A: Wild-type [female] [female]. B: Non-Cross-over [male]. C: Cross-over [male]. D: Vermilion fused. E: Wild-type. F: Vermilion. G: Fused. H: Total [male] [male]. I: Cross-over values. +------------+-------+------------+-----------+-----+----+ | | | B | C | | | | | +-----+------+-----+-----+ | | | Reference. | A | D | E | F | G | H | I | +------------+-------+-----+------+-----+-----+-----+----+ | 52 | 96 | 25 | 30 | 16 | 11 | 82 | 33 | | 52' | 176 | 59 | 64 | 24 | 19 | 166 | 26 | | 53 | 60 | 20 | 22 | 9 | 6 | 57 | 26 | | 53' | 76 | 21 | 27 | 11 | 10 | 69 | 31 | | 54 | 88 | 35 | 38 | 14 | 16 | 103 | 29 | | 54' | 60 | 22 | 20 | 8 | 9 | 59 | 29 | | 57 | 61 | 22 | 20 | 7 | 11 | 60 | 30 | | 57' | 170 | 47 | 54 | 24 | 19 | 144 | 30 | | 58 | 128 | 37 | 55 | 14 | 10 | 116 | 21 | | 58' | 144 | 38 | 64 | 16 | 15 | 133 | 23 | | Firsts | 433 | 139 | 165 | 60 | 54 | 418 | 27 | | Seconds | 626 | 187 | 229 | 83 | 72 | 571 | 27 | | +-------+-----+------+-----+-----+-----+----+ | Total | 1,059 | 326 | 394 | 143 | 126 | 989 | 27 | +------------+-------+-----+------+-----+-----+-----+----+ FORKED. On November 19, 1912 there appeared in a stock of a double recessive eye-color, vermilion maroon, a few males which showed a novel form of the large bristles (macrochætæ) upon the head and thorax. In this mutation (text-fig. E) the first of several which affect the shape and distribution of the bristles, the macrochætæ, instead of {58} being long, slender, and tapered (see Plate 1, fig. I), are greatly shortened and crinkled as though scorched. The ends are forked or branched, bent sharply, or merely thickened. The bristles which are most distorted are those upon the scutellum, where they are sometimes curled together into balls. LINKAGE OF VERMILION AND FORKED. [Illustration: FIG. E.--Forked bristles.] Since forked arose in vermilion stock, the double recessive for these two sex-linked factors could be used in testing the linkage relations of the mutation. Vermilion forked males were crossed to wild females and gave wild-type males and females, which inbred gave in F_2 the results shown in table 39. Forked reappeared only in the males in the following proportion: not-forked [female], 742; not-forked [male], 346; forked [male], 301. The result shows that the character is a sex-linked recessive. TABLE 39.--_P_1 wild_ [female] [female] � _vermilion-forked_ [male] [male]. _F_1 wild-type_ [female] [female] � _F_1 wild-type_ [male] [male]. +----------+----------+----------------+---------------+--------+-------+ | | | Non-cross-over | Cross-over | | | | |Wild-type | [male] [male]. | [male] [male].| Total |Cross- | |Reference.|[female] +--------+-------+-------+-------+ [male] | over | | |[female]. | Ver- |Wild- | Ver- |Forked.| [male].|values.| | | | milion |type. |milion.| | | | | | | forked.| | | | | | +----------+----------+--------+-------+-------+-------+--------+-------+ | 9 I | 366 | 113 | 123 | 49 | 41 | 326 | 28 | | 11 I | 376 | 116 | 150 | 42 | 31 | 339 | 22 | | +----------+--------+-------+-------+-------+--------+-------+ | Total.| 742 | 229 | 273 | 91 | 72 | 665 | 25 | +----------+----------+--------+-------+-------+-------+--------+-------+ In table 39 vermilion forked and wild-type are non-cross-overs, and vermilion and forked are cross-overs, giving a cross-over value of 25 units. The locus, therefore, is 25 units to the right or to the left of vermilion, that is, either about 58 or 8 units from the yellow locus. LINKAGE OF CHERRY AND FORKED. Forked males were crossed to cherry females (cherry has the same locus as white, which is about 1 unit from yellow) and gave wild-type females and cherry males. These gave in F_2 the results shown in table 40. The non-cross-overs (cherry and forked) plus the cross-overs (cherry forked and wild type) divided into the cross-overs give a cross-over value of 46 units, which shows that the locus lies to the right of vermilion, because if it had been to the left, the value would have been 8 (_i. e._, 33-25) instead of 33+25=58. The difference between 58 {59} and 46 is due to the expected amount of double crossing-over. In fact, for a distance as long as 58 an almost independent behavior of linked gens is to be expected. TABLE 40.--_P_{1} cherry_ [female] [female] � _forked_ [male] [male]. _F_{1} wild-type_ [female] [female] � _F_{1} cherry_ [male] [male]. +----------+--------------+---------------+-------------+-------+-------+ |Reference.| Females. | Non-cross-over| Cross-over | | | | | | [male] [male].|[male] [male]| Total |Cross- | | +-------+------+-------+-------+-------+-----+[male] | over | | |Cherry.| Wild-|Cherry.|Forked.|Cherry |Wild-|[male].|values.| | | | type.| | |forked.|type.| | | +----------+-------+------+-------+-------+-------+-----+-------+-------+ | 25 | 129 | 145 | 73 | 70 | 65 | 68 | 276 | 48 | | 25' | 167 | 148 | 74 | 82 | 66 | 88 | 310 | 50 | | 36 | 96 | 88 | 52 | 52 | 35 | 51 | 190 | 45 | | 36' | 57 | 76 | 41 | 32 | 24 | 30 | 127 | 43 | | 84 | 76 | 86 | 40 | 34 | 38 | 26 | 138 | 46 | | 84' | 62 | 71 | 24 | 39 | 25 | 28 | 116 | 46 | | 85 | 114 | 86 | 43 | 78 | 41 | 53 | 215 | 44 | | 85' | 98 | 95 | 48 | 63 | 52 | 46 | 209 | 47 | | 86 | 307 | 323 | 152 | 144 | 118 | 165 | 579 | 49 | | 87 | 351 | 341 | 183 | 213 | 160 | 147 | 703 | 45 | | 88 | 244 | 246 | 142 | 142 | 107 | 104 | 495 | 43 | +----------+-------+------+-------+-------+-------+-----+-------+-------+ |Total. | 1,701 |1,705 | 872 | 949 | 731 | 806 |3,358 | 46 | +----------+-------+------+-------+-------+-------+-----+-------+-------+ LINKAGE OF FORKED, BAR, AND FUSED. This value of 58 gave the furthest locus to the right obtained up to that time, since forked is slightly beyond rudimentary. Later, the locus for bar-eye was found still farther to the right, and the locus for fused even farther to the right than bar. A cross was made involving these three gens. A forked (not-bar) fused male was bred to a (not-forked) bar (not-fused) female and gave bar females and males. The F_1 females were back-crossed singly to forked fused males with the result shown in table 41. TABLE 41.--_P_1 bar_ [female] [female] � _forked fused_ [male] [male]. _B. C. F_1 bar_ [female] � _forked fused_ [male] [male]. +-------+------------+-------------+--------------+-------------+-------+ | | f f_u | f B' | f | f B' f_u | | |Refer- | ------ | --+----- | ---+--- | -+--+--- | | | ence. | B' | f_u | B' f_u | | | | +------+-----+------+------+-------+------+-------+-----+ Total.| | |Forked| Bar.|Forked|Fused.|Forked.| Bar |Forked |Wild-| | | |fused.| | bar. | | |fused.|bar |type.| | | | | | | | | |fused. | | | +-------+------+-----+------+------+-------+------+-------+-----+-------+ | 163 | 45 | 55 | .. | 1 | 4 | 2 | .. | .. | 108 | | 164 | 71 | 90 | .. | .. | 4 | 1 | .. | .. | 166 | | 165 | 97 | 106 | .. | .. | 2 | 4 | .. | .. | 209 | | 11 | 21 | 35 | .. | .. | 1 | 2 | .. | .. | 59 | | 33 | 15 | 23 | .. | .. | .. | 1 | .. | .. | 39 | | +------+-----+------+------+-------+------+-------+-----+-------+ | Total.| 250 | 309 | .. | 1 | 11 | 10 | .. | .. | 581 | +-------+------+-----+------+------+-------+------+-------+-----+-------+ {60} The same three points were combined in a different way, namely, by mating forked females to bar fused males. The bar daughters were back-crossed to forked fused males and gave the results shown in table 42. TABLE 42.--_P_1 forked_ [female] [female] � _bar fused_ [male] [male]. _B.C. F_1 bar_ [female] � _forked fused_ [male] [male]. +------+--------------+-------------+-------------+--------------+------+ | | f | f B' f_u | f f_u | f B' | | | | ------ | -+------ | --+--- | -+--+-- | | |Refer-| B' f | | B' | f_u |Total.| | ence.+-------+------+------+------+------+------+------+-------+ | | |Forked.| Fused|Forked| Wild-|Forked| Bar. |Forked| Fused.| | | | | bar. | bar | type.|fused.| |bar. | | | | | | |fused.| | | | | | | +------+-------+------+------+------+------+------+------+-------+------+ |158 | 131 | 124 | 1 | .. | 3 | 3 | .. | .. | 262 | |159 | 31 | 45 | .. | .. | .. | .. | .. | .. | 76 | |160 | 29 | 23 | .. | .. | 1 | 2 | .. | .. | 55 | |161 | 24 | 11 | 1 | .. | .. | .. | .. | .. | 36 | |162 | 96 | 91 | 2 | .. | 1 | 1 | .. | .. | 191 | | +-------+------+------+------+------+------+------+-------+------+ |Total.| 311 | 294 | 4 | .. | 5 | 6 | .. | .. | 620 | +------+-------+------+------+------+------+------+------+-------+------+ By combining the results of tables 41 and 42 data are obtained for cross-over values from which (by balancing the inviable classes, as explained in table 43) the element of inviability is reduced to a minimum. TABLE 43. +----------+------------+------------+------------+------------+--------+ | | | | | | | | | ------ | -+---- | ----+- | -+--+- | Total. | | | | | | | | +----------+------------+------------+------------+------------+--------+ | | | | | | | | | 1,164 | 5 | 32 | 0 | 1,201 | |Per cent. | 96.9 | 0.42 | 2.7 | 0 | | +----------+------------+------------+------------+------------+--------+ The linkages involved in these data are very strong. The cross-overs between forked and bar number only 5 in a total of 1,201, which gives less than 0.5 per cent of crossing-over. There are 32 cross-overs or 2.7 per cent between bar and fused. The value for forked fused is the sum of the two other values, or 3.1 per cent. LINKAGE OF SABLE, RUDIMENTARY, AND FORKED. Rudimentary, forked, bar, and fused form a rather compact group at the right end of the chromosome, as do yellow, lethal 1, white, abnormal, etc., at the zero end. The following two experiments were made to determine more accurately the interval between rudimentary and the other members of this group. A sable rudimentary forked {61} male mated to a wild female gave wild-type sons and daughters. These inbred give the results shown in table 44. TABLE 44.--_P_{1} sable rudimentary forked_ [male] � _wild_ [female]. _F_{1} wild-type_ [female] � _F_{1} wild-type_ [male] [male]. +----------+---------+-----------------+-------------------+ | | | s r f | s | | | | ------ | -+---- | | | | | r f | | | +-----------+-----+-------+-----------+ |Reference.|Wild-type| Sable |Wild-| Sable.|Rudimentary| | |[female] |rudimentary|type.| | forked. | | |[female].| forked. | | | | +----------+---------+-----------+-----+-------+-----------+ | 264 | 98 | 28 | 17 | 2 | 5 ~ | 265 | 97 | 29 | 54 | 4 | 9 ~ | 266 | 114 | 42 | 49 | 11 | 11 | +----------+---------+-----------+-----+-------+-----------+ |Total | 309 | 99 |120 | 17 | 25 | +----------+---------+-----------+-----+-------+-----------+ +----------+--------------------+--------------------+ | | s r | s f | | | ---+- | -+--+- | | | f | r | | +------------+-------+-------+------------+ |Reference.| Sable |Forked.|Sable |Rudimentary.| | |rudimentary.| |forked.| | | | | | | | +----------+------------+-------+-------+------------+ ~ 264 | 1 | 1 | .. | .. | ~ 265 | .. | .. | .. | .. | | 266 | .. | 2 | .. | .. | +----------+------------+-------+-------+------------+ |Total | 1 | 3 | .. | .. | +----------+------------+-------+-------+------------+ There were 265 males, of which 42 were cross-overs between sable and rudimentary and 4 between rudimentary and forked. The values found are: sable rudimentary, 16; rudimentary forked, 1.5; sable forked, 17. LINKAGE OF RUDIMENTARY, FORKED, AND BAR. The three gens, rudimentary, forked, and bar, form a very compact group. A rudimentary forked male was crossed to bar females and the daughters (bar) were back-crossed singly to rudimentary forked males, the results being shown in table 45. TABLE 45.--_P_1 rudimentary forked_ [male] � _bar_ [female]. _B.C. F_1 bar_ [female] � _rudimentary forked_ [male] [male]. +----------+---------------+---------------+-------------+--------------+ | | r f | r B' | r f B' | r | | | ------ | -+---- | ----+- | -+--+- | | | B' | f | | f B' | | +---------+-----+-------+-------+-------+-----+-------+------+ |Reference.| Rudim- | Bar.| Rudim-|Forked.| Rudim-|Wild-| Rudim-|Forked| | | entary | | entary| | entary|type.| entary| bar. | | | forked. | | bar. | | forked| | | | | | | | | | bar. | | | | +----------+---------+-----+-------+-------+-------+-----+-------+------+ |267 | 56 | 104 | .. | 2 | 1 | 1 | .. | .. | |268 | 82 | 86 | 1 | 2 | .. | .. | .. | .. | |269 | 68 | 101 | .. | .. | .. | 1 | .. | .. | +----------+---------+-----+-------+-------+-------+-----+-------+------+ |Total | 206 | 291 | 1 | 4 | 1 | 2 | .. | .. | +----------+---------+-----+-------+-------+-------+-----+-------+------+ The cross-over values are: rudimentary forked, 1; forked bar, 0.6; rudimentary bar, 1.6. The order of factors is rudimentary, forked, bar. On the basis of the total data the locus of forked is at 56.5. {62} SHIFTED. Shifted appeared (January 1913) in a stock culture of vermilion dot. The chief characteristic of this mutant is that the third longitudinal vein (see text-fig. F) does not reach the margin as it does in the normal fly. The vein is displaced toward the fourth throughout its length, and only very rarely does it extend far enough to join the marginal vein. The cross-vein between the third and the fourth veins is often absent because of the shifting. The flies themselves are smaller than normal. The wings are held out from the body at a wide angle. The two posterior bristles of the scutellum are much reduced in size and stick straight up--a useful landmark by which just-hatched shifted flies may be recognized, even though the wings are not expanded. LINKAGE OF SHIFTED AND VERMILION. Since shifted arose in vermilion, the double recessive shifted vermilion was available for the following linkage experiment: shifted vermilion males by wild females gave wild-type males and females which inbred gave the data shown in table 46. [Illustration: FIG. F.--Shifted venation. The third longitudinal vein is shifted toward the fourth and fails to reach the margin. Cross-vein between third and fourth longitudinal veins is lacking.] Disregarding the eye-color, the following is a summary of the preceding results: wild-type [female], 1,001; wild-type [male], 437; shifted [male], 328. The result shows that shifted is a sex-linked recessive. The data of table 46 show that the locus of shifted lies about 15 units on one side or the other of vermilion, which from the calculated position of vermilion at 33 would give a position for shifted at either 18 or 48 from yellow. TABLE 46.--_P_1 shifted vermilion [male] [male] � wild [female] [female]. F_1 wild-type [female] � F_1 wild-type [male] [male]._ Key to columns: A: Wild-type [female] [female]. B: Non-cross-over [male] [male], Shifted. C: Non-cross-over [male] [male], Wild-type. D: Cross-over [male] [male], Shifted. E: Cross-over [male] [male], Wild-type. F: Total [male] [male]. G: Cross-over values. +--------------+---------+------+------+-------+-------+-------+------+ | Reference. | A | B | C | D | E | F | G | +--------------+---------+------+------+-------+-------+-------+------+ | 13 | 345 | 79 | 115 | 8 | 25 | 227 | 15 | | 29 | 68 | 20 | 32 | 3 | 4 | 59 | 12 | | 30 | 191 | 37 | 54 | 5 | 13 | 109 | 17 | | 31 | 151 | 41 | 65 | 17 | 13 | 136 | 22 | | 33 | 133 | 49 | 40 | 4 | 6 | 99 | 10 | | 34 | 113 | 56 | 59 | 9 | 11 | 135 | 15 | +--------------+---------+------+------+-------+-------+-------+------+ | Total. | 1,001 | 282 | 365 | 46 | 72 | 765 | 15 | +--------------+---------+------+------+-------+-------+-------+------+ {63} LINKAGE OF SHIFTED, VERMILION, AND BAR. In order to determine on which side of vermilion shifted lies, a shifted vermilion (not-bar) female was crossed to a (not-shifted red) bar male. Three factors are involved, of which one, bar, is dominant. The shifted vermilion (not-bar) stock is a triple recessive, and a three-point back-cross was therefore possible. The daughters were bar and the sons were shifted vermilion (the triple recessive). Inbred these gave the results shown in table 46. The smallest classes (double cross-overs) are shifted and vermilion bar, which places shifted to the left of vermilion at approximately 17.8 units from yellow. TABLE 47.--_P_1 shifted vermilion_ [female] � _bar_ [male] [male]. _F_1 bar_ [female] � _F_1 shifted vermillion_ [male] [male]. +-------+---------------+---------------+---------------+---------------+ | | s_h v | s_h B' | s_h v B' | s_h | | Refer-| ------ | --+---- | -----+- | --+-+-- | | ence. | B' | v | | v B' | | +----------+----+--------+------+---------+-----+--------+------+ | |Shifted |Bar.|Shifted |Verm- |Shifted |Wild-|Shifted.| Verm-~ | |vermilion.| | bar. |ilion.|vermilion|type.| | ilion~ | | | | | |bar. | | | bar. | +-------+----------+----+--------+------+---------+-----+--------+------+ | 65 | 56 |108 | 15 | 20 | 8 | 33 | 1 | 1 | +-------+----------+----+--------+------+---------+-----+--------+------+ +----------+------+----------------------------+ | | | | |Reference.|Total.| Cross-over values. | | | | | | | +----------+---------+-------+ ~ | |Shifted |Vermilion|Shifted| ~ | |vermilion.|bar. |bar. | | | | | | | +----------+------+----------+---------+-------+ | 65 | 242 | 15 | 18 | 31 | +----------+------+----------+---------+-------+ The stock of shifted has been thrown away, since too great difficulty was encountered in maintaining it, because, apparently, of sterility in the females. LETHALS SA AND SB. The first lethal found by Miss Rawls was in a stock that had been bred for about 3 years. While there was no _a priori_ reason that could be given to support the view that lethal mutations would occur more frequently among flies inbred in confinement, nevertheless a hundred females from each of several newly caught and from each of several confined stocks were examined for lethals (Stark, 1915). No lethals were found among the wild stocks, but 4 were found among the confined stocks. Whether this difference is significant is perhaps open to question. The first lethal was found in January 1913, in a stock that had been caught at Falmouth, Massachusetts, in 1911, and had been inbred for 18 months, _i.e._, for about 50 generations. This lethal, lethal _sa_, was recessive and behaved like the former lethals, being transmitted by half the females and causing the death of half the sons. The position of this lethal to the X chromosome was found as follows, by means of the cross-over value white lethal _sa_. Lethal-bearing females were mated to white males and the lethal-bearing daughters were again mated to white males. The white sons (894) were non-cross-overs and the red sons (256) were cross-overs. The percentage of crossing-over {64} is 22.2. A correction of 0.4 unit should be added for double crossing-over, indicating that the locus is 22.6 units from white, or at 23.7. When the work on lethal _sa_ had been continued for 3 months, the second lethal, lethal _sb_, was found (April 1913) to be present in a female which was already heterozygous for lethal _sa_. It is probable that this second lethal arose as a mutation in the father, and that a sperm whose X carried lethal _sb_ fertilized an egg whose X carried lethal _sa_. As in the cases of lethals 1 and 1_a_ and lethals 3 and 3_a_, this lethal, lethal _sb_, was discovered from the fact that only a very few sons were produced, there being 82 daughters and only 3 sons. If, as in the other cases, the number of daughters is taken as the number of non-cross-overs and twice the number of sons as the cross-overs, it is found that the two lethals are about 7 units apart. Since the two lethals were in different X chromosomes, all the daughters should receive one or the other lethal, except in those few cases in which crossing over had taken place. Of the daughters 19 were tested and every one was found to carry a lethal. Again, if the cross-over values of the lethals with some other character, such as white eyes, be found and plotted, the curve should show two modes corresponding to the two lethals. This test was applied, but the curve failed to show two modes clearly,[7] the two lethals being too close together to be differentiated by the small number of determinations that were made. It seems probable that lethal _sa_ and lethal _sb_ are about 5 units apart. The position of lethal _sb_ was accurately found by continuing the determinations with a white lethal cross-over. A white female was found which had only one of the two lethals and the linkage of this lethal with eosin and miniature was found as follows: A female carrying white and lethal in one chromosome and no mutant factor in the homologous chromosome was bred to an eosin miniature male. The white eosin daughters carried lethal, and their sons show the amount of crossing-over between white and lethal (15.6), between lethal and miniature (19.9), and between white and miniature (32.9). The data on which these calculations are based are given in table 48. TABLE 48.--_Data on the linkage of white, lethal sb, and miniature, from Stark, 1915_. +-----------+------------+------------+--------------+ | w^e m | w^e l_{sb} | w^e | w^e l_{sb} m | | --------- | ---+------ | -------+-- | ---+-----+-- | | w l_{sb} | w m | w l_{sb} m | w | | | | | | +-----------+------------+------------+--------------+ | Eosin | White | Eosin. | White. ~ | miniature | miniature. | | ~ | | | | | +-----------+------------+------------+--------------+ | 2,421 | 524 | 685 | 48 | +-----------+------------+------------+--------------+ +--------+--------------------------------+ | | | | | Cross-over values. | | | | | | | | Total. +----------+----------+----------+ ~ |White |Lethal |White | ~ |lethal |_sb_ |miniature.| | |_sb_. |miniature.| | +--------+----------+----------+----------+ | 3,678 | 15.6 | 19.9 | 32.9 | +--------+----------+----------+----------+ {65} The locus of this lethal is at 16.7; the locus of lethal _sa_ was found to be at 23.7, so that the lethal at 16.7 is evidently the second lethal or lethal _sb_ whose advent gave rise to the high sex-ratio. This interpretation is in accord with the curve which Miss Stark published, for although the mode which corresponds to lethal _sa_ is weak, the mode at 15-16 is well marked. The two other lethals, lethals _sc_ and _sd_, which came up in the course of these experiments by Miss Stark, are treated in other sections of this paper. BAR. (Plate II, figures 12 and 13.) The dominant sex-linked mutant called bar-eye (formerly called barred) appeared in February 1913 in an experiment involving rudimentary and long-winged flies (Tice, 1914). A female that is heterozygous for bar has an eye that is intermediate between the rounded eye of the wild fly and the narrow band of the bar stock. This heterozygous bar female is always readily distinguishable from the normal, but can not always be separated from the pure bar. Bar is therefore nearly always used as a dominant and back-crosses are made with normal males. Bar is the most useful sex-linked character so far discovered, on account of its dominance, the certainty of its classification, and its position near the right end of the X chromosome. The locus of bar at 57 was determined on the basis of the data of table 65. NOTCH. A sex-linked dominant factor that brings about a notch at the ends of the wings appeared in March 1913, and has been described and figured by Dexter (1914, p. 753, and fig. 13, p. 730). The factor acts as a lethal for the male. Consequently a female heterozygous for notch bred to a wild male gives a 2:1 sex-ratio; half of her daughters are notch and half normal; the sons are only normal. The actual figures obtained by Dexter were 235 notch females, 270 normal females, and 235 normal males. The location of notch in the X chromosome was not determined by Dexter, but the mutant has appeared anew three or four times and the position has been found by Bridges to be approximately at 2.6. {66} DEPRESSED. Several mutations have appeared in which the wings are not flat. Of these the first that appeared was curved (second chromosome), in which the wings are curved downward throughout their length, but are elevated and held out sidewise from the body; the texture is thinner than normal. The second of these wing mutants to appear was jaunty (second chromosome), in which the wings turn up sharply at the tip; they lie in the normal position. The third mutant, arc (second chromosome), has, as its name implies, its wings curved like the arc of a circle. The fourth mutant, bow (first chromosome, fig. C), is like arc, but the amount of curvature is slightly less. The fifth mutant, depressed (first chromosome, fig. G), has the tip of its wings turned down instead of up, as in jaunty, but, as in jaunty, the wing is straight, except near the tip, where it bends suddenly. These stocks have been kept separate since their origin, and flies from them have seldom been crossed to each other, because in the succeeding generations it would be almost impossible to make a satisfactory classification of the various types. But that they are genetically different mutations is at once shown on crossing any two, when wild-type offspring are produced. For instance, bow and arc are the two most nearly alike. Mated together (bow [male] by arc [female]), they give in F_1 straight-winged flies which inbred give in F_2 9 straight to 7 not-straight (_i.e._, bow, arc, and bow arc together). Depressed wings first appeared (April 1913) among the males of a culture of black flies. They were mated to their sisters and from subsequent generations both males and females with depressed wings were obtained which gave a pure stock. This new character proved to be another sex-linked recessive. LINKAGE OF DEPRESSED AND BAR. Depressed (not-bar) males mated to (not-depressed) bar females gave bar daughters. Two of these were back-crossed singly to depressed males and gave the results shown in table 49. Males and females were not separated, since they should give the same result. TABLE 49.--_P_1 depressed_ [female] [female] � _bar_ [female] [female]. _B.C. F_1 bar_ [female] � _depressed_ [male] [male]. +----------+--------------------+-------------------+-------+-----------+ | | Non-cross-overs. | Cross-overs. | | | +----------+-------------+------+-----------+-------+ | | |Reference.| Depressed. | Bar. | Depressed | Wild- | Total.| Cross-over| | | | | bar. | type. | | values. | +----------+-------------+------+-----------+-------+-------+-----------+ | 66 I | 48 | 51 | 21 | 41 | 161 | 39 | | 67 I | 85 | 104 | 44 | 70 | 303 | 38 | +----------+-------------+------+-----------+-------+-------+-----------+ | Total.| 133 | 155 | 65 | 111 | 464 | 38 | +----------+-------------+------+-----------+-------+-------+-----------+ {67} [Illustration: FIG. G.--Depressed wing.] LINKAGE OF CHERRY, DEPRESSED, AND VERMILION. The linkage value 38 (see table 49) indicates that depressed is somewhere near the opposite end of the series of sex-linked factors from bar. The locus could be more accurately determined by finding the linkage relations of depressed with gens at its end of the chromosome. Accordingly, depressed females were crossed to cherry vermilion males. F_1 gave wild-type females and depressed males. The daughters bred again to cherry vermilion males gave the results shown in table 50. The data only suffice to show that the locus of depressed is about midway between cherry and vermilion, or at about 15 units from yellow. The F_1 males in the last experiment did not have their wings as much depressed as is the condition in stock males, and in F_2 most of the depressed winged males were of the F_1 type, although a few were like those of stock. This result suggests that the stock is a double recessive, _i. e._, one that contains, in addition to the sex-linked depressed, an autosomal factor that intensifies the effect of the primary sex-linked factor. TABLE 50.--_P_1 depressed [female] � cherry vermilion [male] [male]._ +-------------------++---------------------------------------+ | || Second generation. | | First |+----------+--------+-------------------+ | generation. || | | w^c v | +---------|---------+| | | ------- | | | || | | d_p | | Wild- |Depressed|| | +---------+---------+ | type | [male] ||Reference.| | | ~ |[female] | [male]. || |[female]|Cherry | ~ |[female].| || |[female]|vermilion|Depressed| | | || | | | | | | || | | [male]. | [male]. | +---------+---------++----------+--------+---------+---------+ | 21 | 31 || 19 I | 59 | 23 | 24 | +---------+---------++----------+--------+---------+---------+ +---------------------------------------------------------+ | Second generation. | +-------------------+-------------------------------------+ | w^c d_p | w^c | w^c d_p v | | --+----- | -----+-- | --+----+--- | | v | d_p v | | +---------+---------+--------+---------+---------+--------| ~ | | | | | | ~ Cherry | | Cherry |Depressed|Cherry | Wild- | |depressed|Vermilion| |vermilion|depressed| type | | | | | |vermilion| | | [male]. |[male]. |[male]. | [male]. | [male]. | [male].| +---------+---------+--------+---------+---------+--------+ | 6 | 6 | 5 | 5 | 0 | 0 | +---------+---------+--------+---------+---------+--------+ {68} CLUB. In May 1913 there were observed in a certain stock some flies which, although mature, did not unfold their wings (text-fig. H_a_). This condition was at first found only in males and suspicion was aroused that the character might be sex-linked. When these males were bred to wild females the club-shaped wings reappeared only in the F_2 males, but in smaller number than expected for a recessive sex-linked character. The result led to the further suspicion that not all those individuals that are genetically club show club somatically. These points are best illustrated and proven by the following history of the stock: [Illustration: FIG. H.--Club wing. _a_ shows the unexpanded wings of club flies; _c_ shows the absence of the two large bristles from the side of the thorax present in the normal condition of the wild, b.] Club females were obtained by breeding F_2 club males to their F_2 long-winged sisters, half of which should be heterozygous for club. {69} 5,352; wild-type [male], 4,181; club [male], 236. The wild-type males include, of course, those club males that have expanded wings (potential clubs). Club females by wild males gave in the F_2 generation (mass cultures): wild-type [female], 1,131; wild-type [male], 897; club [female], 57; club [male], 131. It is noticeable that there were fewer club females than club males, equality being expected, which might appear to indicate that the club condition is more often realized by the male than by the female, but later crosses show that the difference here is not a constant feature of the cross. Long-winged males from club stock (potential clubs) bred to wild females gave in F_2 the following: wild-type [female], 521; wild-type (and potential club) [male], 403; club [male], 82. Club females by club males of club stock gave in F_2: potential club [female], 126; potential club [male], 78; club [female], 95; club [male], 81. These results are from 8 pairs. The high proportion of club is noticeable. Potential club females and males from pure club stock (_i. e._, stock derived originally from a pair of club) gave in F_2 the following: potential club [female], 1,049; potential club [male], 666; club [female], 450; club [male], 453. GENOTYPIC CLUB. Accurate work with the club character was made possible by the discovery of a character that is a constant index of the presence of homozygous club. This character is the absence of the two large bristles (text-fig. H_c_) that are present on each side of the thorax of the wild fly as shown in figure Hb. All club flies are now classified by this character and no attention is paid to whether the wings remain as pads or become expanded. LINKAGE OF CLUB AND VERMILION. The linkage of club and vermilion is shown by the cultures listed in table 51, which were obtained as controls in working with lethal III. The cross-over value is shown in the male classes by the cross-over fraction 276/1463 or 19 per cent. LINKAGE OF YELLOW, CLUB, AND VERMILION. The data just given in table 51 show that club is 19 units from vermilion, but in order to determine in which direction from vermilion it lies, the crossing-over of club to one other gen must be tested. For this test we used yellow, which lies at the extreme left of the chromosome series. At the same time we included vermilion, so that a three-point experiment was made. Females that were (gray) club vermilion were bred to yellow (not-club red) and gave wild-type daughters and club vermilion sons. These inbred gave the results of table 52. The data from the males show that the locus of club is about midway between yellow and vermilion. This conclusion is based on the {70} evidence that yellow and club give 18 per cent of crossing-over, club and vermilion 20 per cent, and yellow and vermilion 35 per cent. The double cross-overs on this view are yellow club (3) and vermilion (3). The females furnish additional data for the linkage of club and vermilion. The value calculated from the female classes alone is 20 units, which is the same value as that given by the males. TABLE 51.--_P_1 club_ [female] [female] � _vermilion_ [male] [male]. _F_1 wild-type_ [female] � _F_1 club_ [male]. +----------+--------+-----------------+-----------------+-------+-------+ | | | Non-cross-over | Cross-over | | | | | | [male] [male]. | [male] [male]. | | | | | +------+----------+----------+------+ Total |Cross- | |Reference.|Females.| Club.|Vermilion.|Club |Wild- |[male] | over | | | | | |Vermilion.|type. |[male].|values.| | | | | | | | | | +----------+--------+------+----------+----------+------+-------+-------+ | 137 | 75 | 17 | 39 | 6 | 11 | 73 | 23 | | 138 | 64 | 24 | 32 | 6 | 8 | 70 | 20 | | 139 | 56 | 10 | 31 | 4 | 3 | 48 | 15 | | 140 | 74 | 13 | 39 | 3 | 5 | 60 | 13 | | 144 | 97 | 30 | 40 | 10 | 13 | 93 | 25 | | 145 | 63 | 15 | 29 | 4 | 6 | 54 | 19 | | 146 | 126 | 44 | 46 | 9 | 9 | 108 | 15 | | 106 | 92 | 33 | 34 | 6 | 10 | 83 | 19 | | 107 | 55 | 31 | 25 | 7 | 3 | 66 | 15 | | 108 | 86 | 29 | 32 | 7 | 10 | 78 | 22 | | 109 | 103 | 25 | 36 | 4 | 9 | 74 | 18 | | | 83 | 30 | 34 | 6 | 9 | 79 | 19 | | | 77 | 18 | 26 | 7 | 8 | 59 | 25 | | | 67 | 20 | 21 | 6 | 7 | 54 | 24 | | | 126 | 32 | 60 | 15 | 13 | 120 | 23 | | | 63 | 21 | 28 | 7 | 10 | 66 | 26 | | | 114 | 45 | 71 | 9 | 7 | 132 | 12 | | | 46 | 18 | 18 | 3 | 3 | 42 | 14 | | | 111 | 35 | 56 | 6 | 7 | 104 | 13 | | +--------+------+----------+----------+------+-------+-------+ | Total.| 1,578 | 490 | 697 | 125 | 151 | 1,463 | 19 | +----------+--------+------+----------+----------+------+-------+-------+ TABLE 52.--_P_1 club vermilion_ [female] [female] � _yellow_ [male] [male]. _F_1 wild-type_ [female] [female] � _F_1 club vermilion_ [male] [male]. +------------+-----------------------------------+ | | F_2 females. | | +-----------------+-----------------+ | | Non-cross-overs.| Cross-overs. | | | | | | | | | |Reference. +-----------+-----+------+----------+ | | Club |Wild-| Club.|Vermilion.~ | | vermilion.|type.| | ~ +------------+-----------+-----+------+----------+ | 99 | 44 | 52 | 13 | 7 | | 100 | 38 | 58 | 6 | 12 | | 101 | 30 | 32 | 6 | 12 | | 102 | 44 | 55 | 20 | 13 | | 103 | ... |... | ... | ... | | +-----------+-----+------+----------+ | Total. | 156 |197 | 45 | 44 | +------------+-----------+-----+------+----------+ +-----------------------------------------------------------------------+ | F_2 males. | +------------------+-----------------+----------------+-----------------+ | y | y c_l v | y v | y c_l | | ------ | -+----- | ---+- | -+--+- | | c_l v | | c_l | v | +-------+----------+-----------+-----+----------+-----+------+----------+ ~Yellow.|Club |Yellow club|Wild-|Yellow |Club.|Yellow|Vermilion.| ~ |vermilion.|vermilion. |type.|vermilion.| |club. | | +-------+----------+-----------+-----+----------+-----+------+----------+ | 35 | 27 | 2 | 9 | 8 | 11 | 0 | 1 | | 43 | 23 | 1 | 15 | 11 | 14 | 0 | 0 | | 19 | 24 | 6 | 5 | 10 | 3 | 1 | 0 | | 48 | 38 | 12 | 14 | 8 | 15 | 1 | 1 | | 43 | 32 | 7 | 16 | 13 | 7 | 1 | 1 | +-------+----------+-----------+-----+----------+-----+------+----------+ | 188 | 144 | 28 | 59 | 50 | 50 | 3 | 3 | +-------+----------+-----------+-----+----------+-----+------+----------+ {71} LINKAGE OF CHERRY, CLUB, AND VERMILION. The need for a readily workable character whose gen should lie in the long space between cherry and vermilion has long been felt. Cherry and vermilion are so far apart that there must be considerable double crossing-over between them. But with no favorably placed character which is at the same time viable and clearly and rapidly distinguishable, we were unable to find the exact amount of double crossing-over, and hence could not make a proper correction in plotting the chromosome. Club occupies just this favorable position nearly midway between cherry and vermilion. The distances from cherry to club and from club to vermilion are short enough so that no error would be introduced if we ignored the small amount of double crossing-over within each of these distances. It thus becomes important to know very exactly the cross-over values for cherry club and club vermilion. The experiment has the form of the yellow club vermilion cross of table 52, except that cherry is used instead of yellow. Cherry is better than yellow because it is slightly nearer club than is yellow and because the bristles of yellow flies are very inconspicuous. In yellow flies the bristles on the side of the thorax are yellowish brown against a yellow background, while in gray-bodied flies the bristles are very black against a light yellowish-gray background. For the time being we are able to present only incomplete results upon this cross. In the first experiment cherry females were crossed to club vermilion males and the wild-type daughters were back-crossed to cherry club vermilion, which triple recessive had been secured for this purpose. Table 53 gives the results. TABLE 53.--_P_{1} cherry_ [female] [female] � _club vermilion_ [male] [male]. _B. C. F__{1} _wild-type_ [female] � _cherry club vermilion_ [male] [male]. +--------+-------------------+-------------------+-------------------+ | | w^c | w^c c_l v | w^c v | | | --------------- | ----+---------- | -----------+--- | | Refer- | c_l v | | c_l | | ence. +-------------------+---------+---------+-------------------+ | | | | | | | | | | | Club | Cherry | | Cherry | | | | Cherry. | ver- | club | Wild- | ver- | Club. | | | | milion. | ver- | type. | milion. | | | | | | milion. | | | | +--------+---------+---------+---------+---------+---------+---------+ | | | | | | | ~ | 163 | 68 | 68 | 4 | 10 | 21 | 13 ~ | 164 | 99 | 67 | 13 | 21 | 21 | 12 | | 165 | 23 | 37 | 9 | 7 | 15 | 2 | | 166 | 107 | 86 | 14 | 28 | 31 | 43 | | 167 | 42 | 49 | 7 | 11 | 12 | 11 | | 168 | 40 | 30 | 6 | 15 | 16 | 8 | | +---------+---------+---------+---------+---------+---------+ | Total. | 379 | 337 | 53 | 92 | 116 | 89 | +--------+---------+---------+---------+---------+---------+---------+ +-------------------+---------+----------------------------+ | w^c c_l | | | | ----+------+--- | | Cross-over values. | | v | | | +---------+---------+ +----------------------------+ | | | | | | | | | | Total. | | Club. | Cherry | | Cherry | Ver- | | Cherry | ver- | ver- | | club. | milion. | | club. | milion. | milion. | | | | | | | | +---------+---------+---------+--------+---------+---------+ ~ | | | | | | ~ 1 | 0 | 185 | 8 | 19 | 26 | | 1 | 0 | 234 | 15 | 15 | 29 | | 0 | 2 | 95 | 19 | 25 | 35 | | 3 | 3 | 315 | 15 | 25 | 37 | | 2 | 2 | 136 | 16 | 20 | 30 | | 0 | 0 | 115 | 18 | 21 | 39 | +---------+---------+---------+--------+---------+---------+ | 7 | 7 | 1,080 | 15 | 20 | 32 | +---------+---------+---------+--------+---------+---------+ {72} A complementary experiment was made by crossing cherry club vermilion females to wild males and inbreeding the F_1 in pairs. Table 54 gives the results of this cross. TABLE 54.--_P_{1} cherry club vermilion_ [male] [male]. [female] [female] � _wild_ [male] [male]. _F_{1} wild-type_ [female] � _F_{1} cherry club vermilion_ [male] [male]. +----------+-----------------+------------------+-----------------+ | | w^c c_l v | w^c | w^c c_l | | | ------------- | ----+-------- | ---------+--- | | | | c_l v | v | | +-----------+-----+-------+----------+------+----------+ |Reference.|Cherry club|Wild-|Cherry.| Club |Cherry|Vermilion.| | |vermilion. |type.| |vermilion.| club.| | +----------+-----------+-----+-------+----------+------+----------+ | 188 | 60 | 76 | 12 | 8 | 12 | 29 ~ | 189 | 228 | 314 | 48 | 44 | 50 | 60 ~ | 197 | 68 | 81 | 23 | 13 | 9 | 22 | +----------+-----------+-----+-------+----------+------+----------+ |Total. | 356 | 471 | 83 | 65 | 71 | 111 | +----------+-----------+-----+-------+----------+------+----------+ +----------------+------+----------------------------+ | w^c v | | | | ----+----+--- | | Cross-over values. | | c_l | | | +----------+-----+Total.+------+----------+----------+ | Cherry |Club.| |Cherry|Club |Cherry | |vermilion.| | |club. |vermilion.|vermilion.| +----------+-----+------+------+----------+----------+ ~ 2 | 1 | 200 | 11 | 22 | 30 | ~ 1 | 8 | 753 | 13 | 16 | 27 | | 2 | 0 | 218 | 17 | 15 | 31 | +----------+-----+------+------+----------+----------+ | 5 | 9 |1,171 | 14 | 17 | 28 | +----------+-----+------+------+----------+----------+ The combined data of tables 53 and 54 give 14.2 as the value for cherry club. All the data thus far presented upon club vermilion (886 cross-overs in a total of 4,681), give 19.2 as the value for club vermilion. The locus of club on the basis of the total data available is at 14.6. GREEN. In May 1913 there appeared in a culture of flies with gray body-color a few males with a greenish-black tinge to the body and legs. The trident pattern on the thorax, which is almost invisible in many wild flies, was here quite marked. A green male was mated to wild females and gave in F_2 a close approach to a 2:1:1 ratio. The green reappeared only in the F_2 males, but the separation of green from gray was not as easy or complete as desirable. From subsequent generations a pure stock of green was made. A green female by wild male gave 138 wild-type females and 127 males which were greenish. This green color varies somewhat in depth, so that some of these F_1 males could not have been separated with certainty from a mixed culture of green and gray males. The results of these two experiments show that green is a sex-linked melanistic character like sable, but the somatic difference produced is much less than in the case of sable, so that the new mutation, although genetically definite, is of little practical value. We have found several eye-colors which differed from the red color of the wild fly by very small differences. With some of these we have worked successfully by using another eye-color as a developer. For example, the double recessive vermilion "clear" is far more easily distinguished from vermilion than is clear from red. But it is no small task to make up the stocks {73} necessary for such a special study. In the case of green we might perhaps have employed a similar method, performing all experiments with a common difference from the gray in all flies used. CHROME. In a stock of forked fused there appeared, September 15, 1913, three males of a brownish-yellow body-color. They were uniform in color, without any of the abdominal banding so striking in other body-colors. Even the tip of the abdomen lacked the heavy pigmentation which is a marked secondary sexual character of the male. About 20 or more of these males appeared in the same culture. This appearance of many males showing a mutant character and the non-appearance of corresponding females is usual for sex-linked characters. In such cases females appear in the next generation, as they did in this case when the chrome males were mated to their sisters in mass cultures. Since both females and males of chrome were on hand, it should have been an easy matter to continue the stock, but many matings failed, and it was necessary to resort to breeding in heterozygous form. The chrome, however, gradually disappeared from the stock. Such a difficult sex-linked mutation as this could be successfully handled (like a lethal) if it could be mated to a double recessive whose members lie one on each side of the mutant, but in the case of chrome this was not attempted soon enough to save the stock. LETHAL 3. In the repetition of a cross between a white miniature male and a vermilion pink male (December 1913), the F_2 ratios among the males were seen to be very much distorted because of the partial absence of certain classes (Morgan 1914_c_). While it was suspected that the disturbance was due to a lethal, the data were useless for determining the position of such a lethal, from the fact that more than one mother had been used in each culture. From an F_2 culture that gave practically a 2:1 sex-ratio, vermilion females were bred to club males. Several such females gave sex-ratios. Their daughters were again mated to vermilion males. Half of these daughters gave high female sex-ratios and showed the linkage relations given in table 55. TABLE 55.--_Linkage data on club, lethal 3, and vermilion, from Morgan, 1914c_. +----------+-----------------------------------------------------------+ | | Males. | | +-----------+--------------+------------------+-------------+ | | c_1 | c_1 l_3 v | c_1 v | c_1 l_3 | | Females. | ------- | --+------ | ----+- | --+--+-- | | | l_3 v | | l_3 | v | | +-----------+--------------+------------------+-------------+ | | Club. | Wild-type. | Club vermilion. | Vermilion. | +----------+-----------+--------------+------------------+-------------+ | 588 | 182 | 28 | 11 | 1 | +----------+-----------+--------------+------------------+-------------+ {74} Lethal 3 proved to lie between club and vermilion, 13 units from club and 5 from vermilion. The same locus was indicated by the data from the cross of vermilion lethal-bearing females by eosin miniature males. The complete data bearing on the position of lethal 3 is summarized in table 56. On the basis of this data lethal 3 is located at 26.5. TABLE 56.--_Summary of linkage data on lethal 3, from Morgan, 1914c_. +---------------------+--------+--------+------------+ | Gens. | Total. | Cross- | Cross-over | | | | overs. | values. | +---------------------+--------+--------+------------+ | Eosin lethal 3 | 1,327 | 268 | 20.2 | | Eosin vermilion | 1,327 | 357 | 27.0 | | Eosin miniature | 3,374 | 967 | 29.0 | | Club lethal 3 | 222 | 29 | 13.0 | | Club vermilion | 877 | 161 | 18.4 | | Lethal 3 vermilion | 1,549 | 105 | 6.8 | | Lethal 3 miniature | 1,481 | 138 | 9.3 | | Vermilion miniature | 1,327 | 31 | 2.3 | +---------------------+--------+--------+------------+ LETHAL 3a. In January 1914 a vermilion female from a lethal 3 culture when bred to a vermilion male gave 71 daughters and only 3 sons; 34 of these daughters were tested, and every one of them gave a 2:1 sex-ratio. The explanation advanced (Morgan 1914_c_) was that the mother of the high ratio was heterozygous for lethal 3, and also for another lethal that had arisen by mutation in the X chromosome brought in by the sperm. On this interpretation the few males that survived were those that had arisen through crossing-over. The rarity of the sons shows that the two lethals were in loci near together, although here of course in different chromosomes, except when one of them crossed over to the other. As explained in the section on lethal 1 and 1_a_ the distance between the two lethals can be found by taking twice the number of the surviving males (2+3) as the cross-overs and the number of the females as the non-cross-overs. But the 34 daughters tested were also non-cross-overs, since none of them failed to carry a lethal. The fractions (6+0)/(71+34) = 6/105 give 5.7 as the distance between the lethals in question. In the case of lethals 3 and 3_a_ another test was applied which showed graphically that two lethals were present. Each of the daughters tested showed, by the classes of her sons, the amount of crossing-over between white and that lethal of the two that she carried. These cross-over values were plotted and gave a bimodal curve with modes 7 units apart. It had already been shown that the locus of one of the two lethals was at 26.5, and since the higher of the two modes was at about 23, it corresponds to lethal 3. The data and the curve show that the lethals 3 and 3_a_ are about 7 units apart, _i. e._, lethal 3_a_ lies at about 19.5. {75} LETHAL 1b. A cross between yellow white males and abnormal abdomen females gave (February 1914) regular results in 10 F_2 cultures, but three cultures gave 2 [female] : 1 [male] sex-ratios (Morgan, 1914_b_, p. 92). The yellow white class, which was a non-cross-over class in these 10 cultures, had disappeared in the 3 cultures. Subsequent work gave the data summarized in table 57. At the time when the results of table 57 were obtained it did not seem possible that two different lethals could be present in the space of about 1 unit between yellow and white, and this lethal was thought to be a reappearance of lethal 1 (Morgan, 1912_b_, p. 92). Since then a large number of lethals have arisen, one of them less than 0.1 unit from yellow, and at least one other mutation has taken place between yellow and white, so that the supposition is now rather that the lethal in question was not lethal 1. Indeed, the linkage data show that this lethal, which may be called lethal 1_b_, lies extraordinarily close to white, for the distance from yellow was 0.8 unit and of white from yellow on the basis of the same data 0.8. There was also a total absence of cross-overs between lethal 1_b_ and white in the total of 846 flies which could have shown such crossing-over. On the basis of this linkage data alone we should be obliged to locate lethal 1_b_ at the point at which white itself is situated, namely, 1.1, but on _a priori_ grounds it seems improbable that a lethal mutation has occurred at the same locus as the factor for white eye-color. Farther evidence against this supposition is that females that have one X chromosome with both yellow and white and the other X chromosome with yellow, lethal, and white are exactly like regular stock yellow white flies. The lethal must have appeared in a chromosome which was already carrying white and yet did not affect the character of the white. We prefer, therefore, to locate lethal 1_b_ at 1.1-. TABLE 57.--_Summary of all linkage data upon lethal 1b, from Morgan, 1914b_. +-------------------------+---------+--------+---------------+ | Gens. | Total. | Cross- | Cross-over | | | | overs. | values. | +-------------------------+---------+--------+---------------+ | Yellow lethal 1_b_ | 744 | 6 | 0.81 | | Yellow white | 2,787 | 23 | 0.82 | | Lethal 1_b_ white | 846 | 0 | 0.0 | +-------------------------+---------+--------+---------------+ FACET. Several autosomal mutations had been found in which the facets of the compound eye are disarranged. One that was sex-linked appeared in February 1914. Under the low power of the binocular microscope the facets are seen to be irregular in arrangement, instead of being arranged in a strictly regular pattern. The ommatidia are more nearly circular than hexagonal in outline, and are variable in size, some being considerably larger than normal. The large ones are also darker than {76} the smaller, giving a blotched appearance to the eye. The short hairs between the facets point in all directions instead of radially, as in the normal eye. The irregular reflection breaks up the dark fleck which is characteristic of the normal eye. The shape of the eye differs somewhat from the normal; it is more convex, smaller, and is encircled by a narrow rim destitute of ommatidia. Facet arose in a back-cross to test the independence of speck (second chromosome) and maroon (third chromosome). One of the cultures produced, among the first males to hatch, some males which showed the facet disarrangement. None of the females showed this character. The complete output was that typical of a female heterozygous for a recessive sex-linked character: not-facet [female] [female] (2), 112; not-facet [male] [male] (1), 57; facet [male] [male] (1), 51. Of the three characters which were shown by the F_2 males, one, facet, is sex-linked, another, speck, is in the second chromosome, and maroon is in the third chromosome. All eight F_2 classes are therefore expected to be equal in size, and each pair of characters should show free assortment, that is, 50 per cent. The assortment value for facet speck is 48, for speck maroon 52, and for facet maroon 48, as calculated from the F_2 males of table 58. TABLE 58.--_P_1 speck maroon_ [male] � _wild_ [female] [female]. _B.C. F_1 wild-type_ [female] � _speck maroon_ [male]. +----------+----------------------------+ | | F_2 females. | |Reference.+-------+-----+------+-------+ | |Speck |Wild-|Speck.|Maroon.| | |maroon.|type.| | ~ | | | | | ~ +----------+-------+-----+------+-------+ | 66 | 31 | 30 | 26 | 25 | +----------+-------+-----+------+-------+ +----------------------------------------------------------+ | F_2 males. | +------+-------+-------+-----+-------+------+------+-------+ |Facet.|Speck |Facet |Wild-|Facet |Speck.|Facet |Maroon.| ~ |maroon.|speck |type.|maroon.| |speck.| | ~ | |maroon.| | | | | | +------+-------+-------+-----+-------+------+------+-------+ | 14 | 14 | 14 | 10 | 11 | 17 | 12 | 17 | +------+-------+-------+-----+-------+------+------+-------+ LINKAGE OF FACET, VERMILION AND SABLE. In order to determine the location of facet in the first chromosome, one of the facet males which appeared in culture 66 was crossed out to vermilion sable females. Three of the wild-type daughters were back-crossed to vermilion sable males. The females of the next generation should give data upon the linkage of vermilion and sable, while the males should show the linkage of all three gens, facet, vermilion, and sable. The offspring of these three females are classified in table 59. The cross-over fraction for vermilion sable as calculated from the females is 19/194. The cross-over value corresponding to this fraction is 10 units, which was the value found in the more extensive experiments given in the section on sable. It will be noticed that the results in the males of culture 150 are markedly different from those of the other two pairs. While the sable males are fully represented, their opposite classes, the gray males, are {77} entirely absent. This result is due to a lethal factor, lethal 5, which appeared in this culture for the first time. The males of the two cultures 149 and 151 give the order of gens as facet, vermilion, sable; that is, facet lies to the left of vermilion and toward yellow. The cross-over values are: facet vermilion 40; vermilion sable 12; facet sable 42. Since yellow and vermilion usually give but 34 per cent of crossing-over, this large value of 40 for facet vermilion shows that facet must lie very near to yellow. TABLE 59.--_P_1 facet_ [male] � _vermilion sable_ [female] [female]. _B.C. F_1 wild-type_ [female] � _vermilion sable_ [male] [male]. +----------+----------------------------------+ | | F_2 females. | | +----------------+-----------------+ | | | | | |Non-cross-overs.| Cross-overs. | | | | | |Reference.+---------+------+----------+------+ | |Vermilion|Wild- |Vermilion.|Sable.| | |sable. |type. | | ~ | | | | | ~ +----------+---------+------+----------+------+ | 149 | 16 | 29 | 3 | 3 | | 150 | 13 | 17 | 2 | 2 | | 151 | 37 | 63 | 7 | 2 | | +---------+------+----------+------+ | Total. | 66 | 109 | 12 | 8 | +----------+---------+------+----------+------+ +--------------------------------------------------------------------+ | F_2 males. | +----------------+---------------+-----------------+-----------------+ | f_a | f_a v s | f_a s | f_a v | | ------ | --+---- | ----+- | --+--+-- | | v s | | v | s | +------+---------+---------+-----+------+----------+----------+------+ |Facet.|Vermilion|Facet |Wild-|Facet |Vermilion.|Facet |Sable.| ~ |sable. |vermilion|type.|sable.| |vermilion.| | ~ | |sable. | | | | | | +------+---------+---------+-----+------+----------+----------+------+ | 17 | 10 | 8 | 12 | 2 | .. | 2 | 1 | | .. | 10 | 9 | .. | 1 | .. | .. | .. | | 38 | 23 | 12 | 26 | 2 | 8 | 4 | 1 | +------+---------+---------+-----+------+----------+----------+------+ | 55 | 43 | 29 | 38 | 5 | 8 | 6 | 2 | +------+---------+---------+-----+------+----------+----------+------+ LINKAGE OF EOSIN, FACET, AND VERMILION. In order to obtain more accurate information on the location of facet, a facet male was mated to an eosin vermilion female. The F_1 females were mated singly to wild males and they gave the results shown in table 60. The F_2 females were not counted, since they do not furnish any information. The evidence of table 60 places facet at 1.1 units to the right of eosin, or at 2.2. TABLE 60.--_P_1 eosin vermilion_ [female] � _facet_ [male]. _F_1 wild-type_ [female] � _wild_ [male]. +----------+-----------------+-----------------+-----------------+ | | w^c v | w^c f_a | w^c | | | ------- | --+---- | ----+- | | | f_a | v | f_a v | |Reference.+----------+------+------+----------+------+----------+ | |Eosin |Facet.|Eosin |Vermilion.|Eosin.|Facet | | |vermilion.| |facet.| | |vermilion.| | | | | | | | | +----------+----------+------+------+----------+------+----------+ | 512 | 43 | 43 | .. | 1 | 13 | 16 ~ | 513 | 28 | 35 | .. | 2 | 19 | 5 ~ | 514 | 18 | 31 | 1 | .. | 17 | 11 | | 515 | 18 | 60 | .. | .. | 20 | 15 | | 516 | 10 | 31 | .. | .. | 7 | 12 | | 517 | 24 | 34 | .. | .. | 10 | 12 | | 518 | 44 | 38 | 1 | 1 | 23 | 22 | +----------+----------+------+------+----------+------+----------+ | Total.| 185 | 272 | 2 | 4 | 109 | 93 | +----------+----------+------+------+----------+------+----------+ +----------------+------+----------------------------+ | w^c f_a v | | | | --+---+-- | | Cross-over values. | | | | | +----------+-----+Total.+------+----------+----------+ |Eosin |Wild-| |Eosin |Facet |Eosin | |facet |type.| |facet.|vermilion.|vermilion.| |vermilion.| | | | | | +----------+-----+------+------+----------+----------+ ~ .. | .. | 116 | .... | .... | .... | ~ .. | .. | 89 | .... | .... | .... | | .. | .. | 78 | .... | .... | .... | | .. | .. | 113 | .... | .... | .... | | .. | .. | 60 | .... | .... | .... | | .. | .. | 80 | .... | .... | .... | | .. | 1 | 130 | .... | .... | .... | +----------+-----+------+------+----------+----------+ | .. | 1 | 666 | 1.05 | 30.5 | 31.3 | +----------+-----+------+------+----------+----------+ {78} LETHAL SC. The third of the lethals which Miss Stark found (Stark, 1915) while she was testing the relative frequency of occurrence of lethals in fresh and inbred wild stocks arose in April 1914 in stock caught in 1910. Females heterozygous for this lethal, lethal _sc_, were mated to white males and the daughters were back-crossed to white males. Half of the daughters gave lethal sex-ratio, and these gave 1,405 cross-overs in a total of 3,053 males, from which the amount of crossing-over between white and lethal _sc_ has been calculated as 46 per cent. By reference to table 65 it is seen that white and bar normally give only about 44 per cent of crossing-over in a two-locus experiment; lethal _sc_ then is expected to be situated at least as far to the right as bar. Females heterozygous for lethal _sc_ were therefore crossed to bar males, and their daughters were tested. The lethal-bearing daughters gave 144 cross-overs in a total of 1,734 males, that is, bar and lethal _sc_ gave 8.3 per cent of crossing-over. Lethal _sc_ therefore lies 8.3 units beyond bar or at about 66.5. The cross-over value sable lethal _sc_ was found to be 23.5 (387 cross-overs in a total of 1,641 males) which places the lethal at 43+23.5, or at 66.5. We know from other data that there is enough double crossing-over in the distance which gives an experimental value of 23.5 per cent, so that the true distance is a half unit longer or the locus at 67.0 is indicated by the 1,641 males of the sable lethal experiment. In a distance so short that the experimental value is only 8.3 per cent there is, as far as we have been able to determine, no double crossing-over at all, or at most an amount that is entirely negligible, so that a locus at 57+8.3 or 65.3 is indicated by the 1,734 males of the bar lethal experiment. To get the value indicated by the total data the cases may be weighted, that is, the value 65.3 may be multiplied by 1,734, and 67.0 may be multiplied by 1,641. The sum of these two numbers divided by the sum of 1,734 and 1,641 gives 66.2 as the locus indicated by all the data available. This method has been used in every case where more than one experiment furnishes data upon the location of a factor. In constructing the map given in diagram I rather complex balancings were necessary. LETHAL SD. The fourth lethal which Miss Stark found (May 1914) in the inbred stocks of _Drosophila_ has not been located by means of linkage experiments. It is interesting in that the males which receive the lethal factor sometimes live long enough to hatch. These males are extremely feeble and never live more than two days. There is, as far as can be seen, no anatomical defect to which their extreme feebleness and early death can be attributed. {79} FURROWED. In studying the effect of hybridization upon the production of mutations in _Drosophila_, F. N. Duncan found a sex-linked mutation which he called "furrowed eye" (Duncan 1915). The furrowed flies are characterized by a foreshortening of the head, which causes the surface of the eye to be thrown into irregular folds with furrows between. The spines of the scutellum are stumpy, a character which is of importance in classification, since quite often flies occur which have no noticeable disturbance of the eyes. The locus of furrowed was determined to be at 38.0 on the basis of the data given in table 61. TABLE 61.--_Data on the linkage of furrowed, from Duncan, 1915_. +------------+-------------------------------------------+------+ | Gens. | F_2 males. | | +------------+---------+---------+-----------+-----------+ + | | w^e m | w^e f_w | w^e m f_w | w^e |Total.| | | ------- | --+---- | -----+--- | --+--+-- | | | | f_w | m | | m f_w | | | +---------+---------+-----------+-----------+------+ |Eosin, | | | | | | | miniature,| | | | | | | furrowed | 142 | 59 | 4 | 3 | 208 | | +=========+=========+===========+===========+======+ | | f_w | f_w s f | f_w f | f_w s | | | | ------- | --+---- | ----+- | --+--+-- | | | | s f | | s | f | | | |---------+---------+-----------+-----------+------+ |Furrowed, | | | | | ~ | sable, | | | | | ~ | forked | 166 | 9 | 31 | 3 | 209 | | +=========+=========+===========+===========+======+ | | v B' | v f_w | v | v f_w B' | | | | ------- | -+----- | ----+-- | -+---+-- | | | | f_w | B' | f_w B' | | | | +---------+---------+-----------+-----------+------+ |Vermilion, | | | | | | | furrowed, | | | | | | | bar | 188 | 9 | 43 | 0 | 240 | +------------+---------+---------+-----------+-----------+------+ +------------------------------+ | Cross-over values. | +----------+---------+---------+ |Eosin |Miniature|Eosin | |miniature.|furrowed.|furrowed.| | | | | +----------+---------+---------+ | | | | | | | | | 29.8 | 30.4 | 30.3 | +==========+=========+=========+ |Furrowed |Sable |Furrowed | |sable. |forked. |forked. | | | | | +----------+---------+---------+ ~ | | | ~ | | | | 5.7 | 16.3 | 19.1 | +==========+=========+=========+ |Vermilion |Furrowed |Vermilion| |furrowed. |bar. |bar. | | | | | +----------+---------+---------+ | | | | | | | | | 3.8 | 21.6 | 17.9 | +----------+---------+---------+ ADDITIONAL DATA FOR YELLOW, WHITE, VERMILION, AND MINIATURE. Considerable new work has been done by various students upon the linkage of the older mutant characters, namely, yellow, white, vermilion, and miniature. We have summarized these new data, and they give values very close to those already published. We have included in the white miniature data those published by P. W. Whiting (Whiting 1913). {80} TABLE 62.--_Data upon the linkage of yellow, white, vermilion, and miniature_ (_contributed by students_). +--------------------+-----------------+-------------+-------+----------+ | Gens. | Non-cross-overs.| Cross-overs.| | | +--------------------+-----------------+-------------+ | | | | w m | w |Total. |Cross-over| | | ------------- | -----+----- | |values. | | | | m | | | | +-----------------+-------------+-------+----------+ |White miniature. | 6,219[8] 7,378 | 3,754 3,337 |20,688 | 34.2 | | +=================+=============+=======+==========+ | | w | w m | | | | | ------------- | -----+----- | | | | | m | | | | | +-----------------+-------------+-------+----------+ | | 1,651 1,116 | 671 1,047 | 4,485 | 38.3 | | +=================+=============+=======+==========+ | | y | y m | | | | | ------------- | -----+----- | | | | | m | | | | | +-----------------+-------------+-------+----------+ |Yellow miniature. | 761 923 | 421 653 | 2,758 | 39 | | +=================+=============+=======+==========+ | | v | v m | | | | | ------------- | -----+----- | | | | | m | | | | | +-----------------+-------------+-------+----------+ |Vermilion miniature.| 1,685 1,460 | 32 36 | 3,213 | 2.1 | | +=================+=============+=======+==========+ | | y w | y | | | | | ------------- | -----+----- | | | | | | w | | | | +-----------------+-------------+-------+----------+ |Yellow white. | 1,600 1,807 | 10 7 | 3,424 | 0.5 | | +=================+=============+=======+==========+ | | y v | y | | | | | ------------- | -----+----- | | | | | | v | | | | +-----------------+-------------+-------+----------+ |Yellow vermilion. | 509 587 | 328 284 | 1,708 | 35.8 | | +=================+=============+=======+==========+ | | w B' | w | | | | | ------------- | -----+----- | | | | | | B' | | | | +-----------------+-------------+-------+----------+ |White bar. | 198 272 | 168 166 | 804 | 42 | | +=================+=============+=======+==========+ | | b_1 | b_1 r | | | | | ------------- | -----+----- | | | | | r | | | | | +-----------------+-------------+-------+----------+ |Bifid rudimentary. | 142 15 | 12 116 | 285 | 45 | | +=================+=============+=======+==========+ | | r | r f | | | | | ------------- | -----+----- | | | | | f | | | | | +-----------------+-------------+-------+----------+ |Rudimentary forked. | 73 211 | ... 4 | 288 | 1.4 | +--------------------+-----------------+-------------+-------+----------+ {81} NEW DATA CONTRIBUTED BY A. H. STURTEVANT AND H. J. MULLER. Data from several experiments upon sex-linked characters described in this paper have been contributed by Dr. A. H. Sturtevant and Mr. H. J. Muller, and are given in table 63. TABLE 63.--_Data contributed by A. H. Sturtevant and H. J. Muller._ +---------------------+-----------------------------------+------+ |Gens. | Classes. | | +---------------------+--------+--------+--------+--------+ | | | y w | y b_1| y w b_1| y |Total.| | | -------| -+-----| ---+---| -+--+--| | | | b_1| w | | w b_1 | | | +--------+--------+--------+--------+------+ |Yellow white � bifid.| 233 254| 1 2 | 10 6 | .. .. | 506 | | +========+========+========+========+======+ | | y | y v B' | y B'| y v | | | | -------| -+-----| ---+---| -+--+--| | | | v B'| | v | B'| | |Yellow � vermilion +--------+--------+--------+--------+------+ |bar. | 99 101 | 60 55 | 49 48 | 9 14 | 435 | | +========+========+========+========+======+ | | w b_1 | w f| w b_1 f| w | | | | -------| -+-----| ---+---| -+--+--| | | | f| b | | b_1 f| | | +--------+--------+--------+--------+------+ |White bifid � forked.| 84 77 | 9 6 | 65 59 | 1 5 | 306 | | +========+========+========+========+======+ | | v m | v s| v m s| v | | | | -------| -+-----| ---+---| -+--+--| | | | s| m | | m s| | |Vermilion miniature +--------+--------+--------+--------+------+ |� sable. | 152 111| 4 2 | 5 12 | .. ..| 286 | | +========+========+========+========+======+ | | s r | s f| s r f| s | ~ | | -------| -+-----| ----+--| -+--+--| ~ | | f| r | | r f| | |Sable rudimentary � +--------+--------+--------+--------+------+ |forked. | 143 195| 26 27 | 4 3 | .. ..| 398 | +---------------------+--------+--------+--------+--------+------+ | WHITE BIFID � RUDIMENTARY. | +---------------------+-----------------------------------+------+ | F_{2} females. | F_{2} males. | | +--------+------------+--------+--------+--------+--------+ | |w b_1 | w | w b_1 | w r | w b_1 r| w |Total.| |------- | --+--- | -------| -+--- | -----+-| +---+- | | | | b_1 | r | b_1 | | b_1 r | | +--------+------------+--------+--------+--------+--------+------+ |228 335 | 15 11 | 150 66 | 2 10 | 29 135| 2 1 | 395 | +--------+------------+--------+--------+--------+--------+------+ | WHITE BIFID � MINIATURE RUDIMENTARY. | +--------+------------+--------+--------+--------+--------+------+ |w b_1 | w | | | | | | |------- | --+--- | ------ | -+--- | ---+---| -----+-|-+-+--| | | b_1 | | | | | | +--------+------------+--------+--------+--------+--------+------+ | 344 | 31 | 109 | 2 | 58 | 41 | 2 | +--------+------------+--------+--------+--------+--------+------+ +--------------------------------------+ | Cross-over values. | +------------+------------+------------+ | Yellow | White | Yellow | | white. | bifid. | bifid. | | | | | +------------+------------+------------+ | 0.6 | 3.2 | 3.8 | +============+============+============+ | Yellow |Vermilion | Yellow | |vermilion. | bar. | bar. | | | | | +------------+------------+------------+ | 32 | 28 | 49 | +============+============+============+ | White | Bifid | White | | bifid. | forked. | forked. | | | | | +------------+------------+------------+ | 7 | 42 | 45 | +============+============+============+ | Vermilion |Miniature |Vermilion | | miniature. | sable. | sable. | | | | | +------------+------------+------------+ | 2.1 | 6 | 8.1 | +============+============+============+ ~ Sable |Rudimentary | Sable | ~rudimentary.| forked. | forked. | | | | | +------------+------------+------------+ | 13.3 | 1.8 | 15 | +------------+------------+------------+ | WHITE BIFID � RUDIMENTARY. | +--------------------------------------+ | Cross-over values. | +------------+------------+------------+ | White | Bifid | White | | bifid. |rudimentary.|rudimentary.| | | | | +------------+------------+------------+ | 3.8 | 42.3 | 44.5 | +------------+------------+------------+ | WHITE BIFID � MINIATURE RUDIMENTARY. | +------------+------------+------------+ | | | | | -+--+- | ---+-+- | -+-+-+- | | | | | +------------+------------+------------+ | 0 | 6 | 1 | +------------+------------+------------+ {82} SUMMARY OF THE PREVIOUSLY DETERMINED CROSS-OVER VALUES. The data of the earlier papers, namely, Dexter, 1912; Morgan, 1910_c_, 1911_a_, 1911_f_, 1912_f_, 1912_g_; Morgan and Bridges, 1913; Morgan and Cattell, 1912 and 1913; Safir, 1913; Sturtevant, 1913 and 1915; and Tice, 1914, have been summarized in a recent paper by Sturtevant (Sturtevant, 1915) and are given here in table 64. Our summary combines three summaries of Sturtevant, viz, that of single crossing-over and two of double crossing-over. TABLE 64.--_Previously published data summarized from Sturtevant, 1915_. +------------------------+--------+-------------+------------+ | Factors. | Total. | Cross-overs.| Cross-over | | | | | values. | +------------------------+--------+-------------+------------+ | Yellow white. | 46,564 | 498 | 1.07 | | Yellow vermilion. | 10,603 | 3,644 | 33.4 | | Yellow miniature. | 18,797 | 6,440 | 34.3 | | Yellow rudimentary. | 2,563 | 1,100 | 42.9 | | Yellow bar. | 191 | 88 | 46.1 | | White vermilion. | 15,257 | 4,910 | 32.1 | | White miniature. | 41,034 | 13,513 | 32.8 | | White rudimentary. | 5,847 | 2,461 | 42.1 | | White bar. | 5,151 | 2,267 | 44.0 | | Vermilion miniature. | 5,329 | 212 | 4.0 | | Vermilion rudimentary. | 1,554 | 376 | 24.1 | | Vermilion bar. | 7,514 | 1,895 | 25.2 | | Miniature rudimentary. | 12,567 | 2,236 | 17.8 | | Miniature bar. | 3,112 | 636 | 20.4 | | Rudimentary bar. | 159 | 7 | 4.4 | +------------------------+--------+-------------+------------+ {83} SUMMARY OF ALL DATA UPON LINKAGE OF GENS IN CHROMOSOME I. In table 65 all data so far secured upon the sex-linked characters are summarized. These data include the experiments previously published in the papers given in the bibliography and the experiments given here. The data from experiments involving three or more loci are calculated separately for each value and included in the totals. TABLE 65.--_A summary of all linkage data upon chromosome I_. +----------------------------+----------+--------------+------------+ | Gens. | Total. | Cross-overs. | Cross-over | | | | | values. | +----------------------------+----------+--------------+------------+ | Yellow lethal 1. | 131 | 1 | 0.8 | | Yellow lethal 1_b_. | 744 | 6 | 0.8 | | Yellow white. | 81,299 | 875 | 1.1 | | Yellow abnormal. | 15,314 | 299 | 2.0 | | Yellow bifid. | 3,681 | 201 | 5.5 | | Yellow club. | 525 | 93 | 17.7 | | Yellow vermilion. | 13,271 | 4,581 | 34.5 | | Yellow miniature. | 21,686 | 7,559 | 34.3 | | Yellow sable. | 1,600 | 686 | 42.9 | | Yellow rudimentary. | 2,563 | 1,100 | 42.9 | | Yellow bar. | 626 | 300 | 47.9 | | Lethal 1 white. | 1,763 | 7 | 0.4 | | Lethal 1 miniature. | 814 | 323 | 39.7 | | Lethal 1_b_ white. | 846 | 0 | 0.0 | | White facet. | 666 | 7 | 1.1 | | White abnormal. | 16,300 | 277 | 1.7 | | White bifid. | 23,595 | 1,260 | 5.3 | | White lethal 2. | 8,011 | 767 | 9.6 | | White club. | 2,251 | 321 | 14.3 | | White lethal _sb_. | 3,678 | 572 | 15.6 | | White lemon. | 241 | 35 | 14.5 | | White depressed. | 59 | 12 | 20.3 | | White lethal _sa_. | 1,150 | 256 | 22.2 | | White vermilion. | 27,962 | 8,532 | 30.5 | | White reduplicated. | 418 | 121 | 28.9 | | White miniature. | 110,701 | 31,071 | 33.2 | | White furrowed. | 208 | 63 | 30.3 | | White sable. | 2,511 | 1,032 | 41.2 | | White rudimentary. | 6,461 | 2,739 | 42.4 | | White forked. | 3,664 | 1,676 | 45.7 | | White bar. | 5,955 | 2,601 | 43.6 | | White fused. | 430 | 186 | 43.3 | | White lethal _sc_. | 3,053 | 1,406 | 46.0 | | Facet vermilion. | 852 | 278 | 32.6 | | Facet sable. | 186 | 80 | 43.0 | | Bifid vermilion. | 2,724 | 849 | 31.1 | | Bifid miniature. | 219 | 67 | 30.6 | | Bifid rudimentary. | 899 | 384 | 42.7 | | Bifid forked. | 306 | 130 | 42.5 | | Lethal 2 vermilion. | 1,400 | 248 | 17.7 | | Lethal 2 miniature. | 6,752 | 1,054 | 15.4 | | Club lethal 3. | 222 | 29 | 13.0 | | Club vermilion. | 5,558 | 1,047 | 18.8 | | Lethal _sb_ miniature. | 3,678 | 733 | 19.9 | | Lemon vermilion. | 241 | 29 | 12.0 | {84} | Shifted vermilion. | 1,007 | 155 | 15.5 | | Shifted bar. | 242 | 76 | 31.4 | | Depressed vermilion. | 59 | 10 | 17.0 | | Depressed bar. | 464 | 176 | 38.0 | | Lethal 3 vermilion. | 1,549 | 105 | 6.8 | | Lethal 3 miniature. | 1,481 | 138 | 9.3 | | Vermilion dot. | 57 | 0 | 0.0 | | Vermilion reduplicated. | 667 | 11 | 1.7 | | Vermilion miniature. | 10,155 | 317 | 3.1 | | Vermilion furrowed. | 240 | 9 | 3.8 | | Vermilion sable. | 9,209 | 929 | 10.1 | | Vermilion rudimentary. | 1,554 | 376 | 24.1 | | Vermilion forked. | 665 | 163 | 24.5 | | Vermilion bar. | 23,522 | 5,612 | 23.9 | | Vermilion fused. | 9,252 | 2,390 | 25.8 | | Reduplicated bar. | 583 | 120 | 20.6 | | Miniature furrowed. | 208 | 7 | 3.4 | | Miniature sable. | 1,855 | 125 | 6.7 | | Miniature rudimentary. | 12,786 | 2,284 | 17.9 | | Miniature bar. | 3,112 | 636 | 20.5 | | Furrowed sable. | 209 | 12 | 5.7 | | Furrowed forked. | 209 | 40 | 19.1 | | Furrowed bar. | 240 | 43 | 17.9 | | Sable rudimentary. | 663 | 95 | 14.3 | | Sable forked. | 872 | 140 | 16.0 | | Sable bar. | 7,524 | 1,036 | 13.8 | | Sable lethal _sc_. | 1,641 | 387 | 23.6 | | Rudimentary forked. | 1,456 | 20 | 1.4 | | Rudimentary bar. | 664 | 15 | 2.3 | | Forked bar. | 1,706 | 8 | 0.5 | | Forked fused. | 1,201 | 37 | 3.1 | | Bar fused. | 8,768 | 222 | 2.5 | | Bar lethal _sc_. | 1,734 | 144 | 8.3 | +----------------------------+----------+--------------+------------+ * * * * * {85} BIBLIOGRAPHY. BRIDGES, CALVIN B. 1913. Non-disjunction of the sex-chromosomes of _Drosophila_. Jour. Exp. Zool., 15, p. 587, Nov. 1913. 1914. Direct proof through non-disjunction that the sex-linked gens of _Drosophila_ are borne by the X chromosome. Science, 40, p. 107, July 17, 1914. 1915. A linkage variation in _Drosophila_. Jour. Exp. Zool., 19, p. 1. July 1915. 1916. Non-disjunction as proof of the chromosome theory of heredity. First instalment, Genetics I, p. 1-52; second instalment, Genetics I, No. 2, 107-164. CHAMBERS, R. 1914. Linkage of the factor for bifid wing. Biol. Bull. 27, p. 151, Sept. 1914. DEXTER, JOHN S. 1912. On coupling of certain sex-linked characters in _Drosophila_. Biol. Bull. 23, p. 183, Aug. 1912. 1914. The analysis of a case of continuous variation in _Drosophila_ by a study of its linkage relations. Am. Nat., 48, p. 712, Dec. 1914. DUNCAN, F. N. 1915. An attempt to produce mutations through hybridization. Am. Nat., 49, p. 575, Sept. 1915. HOGE, M. A. 1915. The influence of temperature on the development of a Mendelian character. Jour. Exp. Zool., 18, p. 241. MORGAN, T. H. 1910a. Hybridization in a mutating period in _Drosophila_. Proc. Soc. Exp. Biol. and Med., p. 160, May 18, 1910. 1910b. Sex-limited inheritance in _Drosophila_. Science 32, p. 120, July 22, 1910. 1910c. The method of inheritance of two sex-limited characters in the same animal. Proc. Soc. Exp. Biol. and Med., 8, p. 17. 1911a. An alteration of the sex-ratio induced by hybridization. Proc. Soc. Exp. Biol. and Med., 8, No. 3. 1911b. The origin of nine wing mutations in _Drosophila_. Science, 33, p. 496, Mar. 31, 1911. 1911c. The origin of five mutations in eye-color in _Drosophila_, and their mode of inheritance. Science, April 7, 1911, 33, P. 534. 1911d. A dominant sex-limited character. Proc. Soc. Exp. Biol. and Med., Oct. 1911. 1911e. Random segregation _versus_ coupling in Mendelian inheritance. Science, 34, p. 384, Sept. 22, 1911. 1911_f_. An attempt to analyze the constitution of the chromosomes on the basis of sex-linked inheritance in _Drosophila_. Jour. Exp. Zool., 11, p. 365, Nov. 1911. 1912a. Eight factors that show sex-linked inheritance in _Drosophila_. Science, Mar. 22, 1912. 1912c. Heredity of body-color in _Drosophila_. Jour. Exp. Zool., 13, p. 27, July 1912. 1912d. The masking of a Mendelian result by the influence of the environment. Proc. Soc. Exp. Zool. and Med., 9, p. 73. 1912e. The explanation of a new sex-ratio in _Drosophila_. Science, 36, p. 718, No. 22, 1912. 1912_f_. Further experiments with mutations in eye-color of _Drosophila_. Jour. Acad. Nat. Sci. Phil., Nov. 1912. 1912_g_. A modification of the sex-ratio and of other ratios through linkage. Z. f. ind. Abs. u. Veterb. 1912. 1914a. Another case of multiple allelomorphs in _Drosophila_. Biol. Bull. 26, p. 231, Apr. 1914. 1914b. Two sex-linked lethal factors in _Drosophila_ and their influence on the sex-ratio. Jour. Exp. Zool., 17, p. 81, July 1914. 1914c. A third sex-linked lethal factor in _Drosophila_. Jour. Exp. Zool., 17, p. 315, Oct. 1914. 1914d. Sex-limited and sex-linked inheritance. Am. Nat., 48, P. 577, Oct. 1914. 1915a. The infertility of rudimentary-winged females of _Drosophila_. Am. Nat., 49, p. 40, Apr. 1915. 1915b. The rôle of the environment in the realization of a sex-linked Mendelian character in _Drosophila_. Am. Nat., 49, p. 385, July 1915. {86} MORGAN, T. H., and C. B. BRIDGES. 1913. Dilution effects and bicolorism in certain eye-colors of _Drosophila_. Jour. Exp. Zool., 15, p. 429, Nov. 1913. MORGAN, T. H., and ELETH CATTELL. 1912. Data for the study of sex-linked inheritance in _Drosophila_. Jour. Exp. Zool., July, 1912. 1913. Additional data for the study of sex-linked inheritance in _Drosophila_. Jour. Exp. Zool., Jan. 1913. MORGAN, T. H., and H. PLOUGH. 1915. The appearance of known mutations in other mutant stocks. Am. Nat., 49, p. 318, May 1915. MORGAN, STURTEVANT, MULLER, and BRIDGES. The mechanism of Mendelian heredity. Henry Holt & Co., 1915. MORGAN, T. H., and S. C. TICE. 1914. The influence of the environment on the size of the expected classes. Biol. Bull., 26, p. 213, Apr. 1914. RAWLS, ELIZABETH. 1913. Sex-ratios in _Drosophila ampelophila_. Biol. Bull. 24, p. 115, Jan. 1913. SAFIR, S. R. 1913. A new eye-color mutation in _Drosophila_ and its mode of inheritance. Biol. Bull. 25, p. 47, June 1913. STARK, M. B. 1915. The occurrence of lethal factors in inbred and wild stocks of DROSOPHILA. Jour. Exp. Zool., 19, p. 531-538. Nov. 1915. STURTEVANT, A. H. 1913. The linear arrangement of six sex-linked factors in _Drosophila_ as shown by their mode of association. Jour. Exp. Zool., Jan. 1913. 1915. The behavior of the chromosomes as studied through linkage. Z. f. Ind. Abs. u. Vereb. 1915. TICE, S. C. 1914. A new sex-linked character in _Drosophila_. Biol. Bull., Apr., 1914. WHITING, P. W. 1913. Viability and coupling in _Drosophila_. Am. Nat., 47, p. 508, Aug. 1913. * * * * * DESCRIPTIONS OF PLATES. PLATE I. FIG. 1. Normal [female]. FIG. 2. Sable [female]. FIG. 3. Lemon [male]. FIG. 4. Abnormal abdomen [female]. FIG. 5. Abnormal abdomen [female]. FIG. 6. Yellow [female]. PLATE II. FIG. 7. Eosin, miniature, black [male]. FIG. 8. Eosin, miniature, black [female]. FIG. 9. Cherry. FIG. 10. Vermilion. FIG. 11. White. FIG. 12. Bar (from above). FIG. 13. Bar (from side). FIG. 14. Spot [female] (abdomen from above). FIG. 15. Spot [female] (abdomen from side). FIG. 16. Spot [male] (abdomen from above). FIG. 17. Spot [male] (abdomen from side). [Illustration] [Illustration] * * * * * Notes [1] For a fuller discussion see "The Mechanism of Mendelian Heredity" by Morgan, Sturtevant, Muller, and Bridges. Henry Holt & Co., 1915. [2] _B. C._ here and throughout stands for back-cross. [3] The first dark body-color mutation "black" (see plate II, figs. 7, 8) had appeared much earlier (Morgan 1911_b_, 1912_c_). It is an autosomal character, a member of the second group of linked gens. Still another dark mutant, "ebony," had also appeared, which was found to be a member of the third group of gens. [4] Wherever reference numbers are given, these denote the pages in the note-books of Bridges upon which the original entries for each culture are to be found. [5] In addition to these expected F_1 wild-type females there occurred 13 females of an eye-color like that of the mutant pink. So far as was seen none of the F_1 males differed in eye-color from the expected eosin vermilion. Since the eosin vermilion and sable stocks were unrelated and neither was known to contain a "pink" as an impurity, these "pinks" must be due to mutation of an unusual kind. That these "pinks" were really products of the cross is proven by the result of crossing one of them to one of her eosin vermilion brothers, for she showed herself to be heterozygous for eosin, vermilion, and sable. _F_1 "pink" (Ref. 51 C) [female] � F_1 eosin vermilion [male]._ +------+---------------+----------------+---------------+---------------+ | | Wild-type. |Eosin vermilion.| Eosin. | Vermilion. | |Refer-+-------+-------+--------+-------+--------+------+--------+------+ |ence. |[female]|[male]|[female]|[male] |[female]|[male]|[female]|[male]| +------+-------+------+---------+-------+--------+------+--------+------+ |59 C | 59 | 38 | 43 | 40 | 15 | 9 | 16 | 17 | +------+-------+------+---------+-------+--------+------+--------+------+ In addition to the combinations of eosin and vermilion, sable also appeared in its proper distribution though no counts were made. The four smaller classes are cross-overs between eosin and vermilion. Since no "pinks" appeared the color is recessive, and the brother was not heterozygous for it. Two other "pink" females mated to wild males gave similar results in their sons. _F_1 "pink" [female] � wild [male]._ +------------+---------+---------+---------+-------+---------+ | | | | Eosin | | | | |Wild-type|Wild-type|Vermilion| Eosin |Vermilion| | Reference. |[female].| [male]. | [male]. |[male].| [male]. | +------------+---------+---------+---------+-------+---------+ | 61 C | 101 | 33 | 37 | 9 | 11 | +------------+---------+---------+---------+-------+---------+ These F_1 flies should all be heterozygous for "pink." A pair of wild-type flies which were mated gave a 3 : 1 ratio--wild type 51 to "pink" 18. From the "pinks" which appeared in this cross a stock was made which was lost through sterility. Females tested to males of true pink were also sterile, so that no solution can be given of the case. [6] Purple is an eye-color whose gen is in the second chromosome. [7] The curve published by Miss Stark included by mistake 6 cultures from the succeeding generations, and these coming from only one of the lethals (lethal _sb_) increase its mode so that the mode of the other lethal (lethal _sa_) becomes submerged. If these cultures are taken out the curve shows two modes more clearly. [8] The figures to the left in each double column correspond to the symbols above the heavy line, as, in the first example 6,219 white miniature. The similar figure to the right corresponds to the symbol below the heavy line. If no symbols are present below, as in the first example, the column to the right should be read wild-type. * * * * * Changes made against printed original. Page 24. "two contrary classes, eosin vermilion and bar": 'eosin bar and vermilion' in original. Page 59. "The bristles which are most distorted": 'disorted' in original. Pages 69-70. One or more lines are missing before "5,352". Ibid. "The data just given in table 51": 'table 50' in original. Page 75. "lethal 3_a_ lies at about 19.5.": 'lethal 3' in original. Page 77. Table 58, last "Facet": 'Fecet' in original. 
34299	----	Transcriber's Notes: Words in italics in the original are surrounded by _underscores_. Variations in spelling and hyphenation remain as in the original. Ellipses match the original. A complete list of typographical corrections as well as other notes follows the text. [Illustration: THE THEORETICAL BABY AT 18 MONTHS.] HOMO-CULTURE; OR, THE IMPROVEMENT OF OFFSPRING THROUGH WISER GENERATION. BY M. L. HOLBROOK, M. D., EDITOR OF "THE JOURNAL OF HYGIENE," AUTHOR OF "HYGIENE OF THE BRAIN," "HOW TO STRENGTHEN THE MEMORY," "ADVANTAGES OF CHASTITY," ETC., ETC. A New Edition of "Stirpiculture," Enlarged and Revised. NEW YORK: M. L. HOLBROOK & CO. LONDON: L. N. FOWLER & CO. 1899. _Copyright by M. L. Holbrook._ _1897._ _Entered at Stationers' Hall._ PREFACE. During all ages since man came to himself, there have been enlightened ones seeking to improve the race. The methods proposed have been various, and in accordance with the knowledge and development of the time in which they have appeared. Some have believed that education and environment were all-sufficient; others that abstinence from intoxicating drinks would suffice. A very considerable number have held the idea that by prenatal culture alone the mother can mould her unborn child into any desired form. The disciples of Darwin, many of them, have held that natural and sexual selection have been the chief factors employed by nature to bring about race improvement. No doubt all these factors have been more or less effectual, but the time has come for man to take special interest in his own evolution, to study and apply, so far as possible, all the factors that will in any way promote race improvement. In the past this has not been done. We are not yet able to do it perfectly, our knowledge is too deficient, lack of interest is too universal, but we can make a beginning; greater thoughtfulness may be given to suitable marriages; improved environment may be secured; better hygienic conditions taken advantage of; food may be improved; the knowledge we have gained in improving animals and plants, so far as applicable, may aid us; air, exercise, water, employment, social conditions, wealth and poverty, prenatal conditions, all have an influence on offspring, and man should be able, to some extent, to make them all tell to the advantage of future generations. Whatever the conditions of existence, man is able by his intellect to modify and improve them, and make them favorably serve unborn children. Herbert Spencer says: "On observing what energies are expended by father and mother to attain worldly successes and fulfil social ambition, we are reminded how relatively small is the space occupied by their ambition to make their descendants physically, morally and intellectually superior. Yet this is the ambition which will replace those they now so eagerly pursue, and which, instead of perpetual disappointments, will bring permanent satisfactions." If the chapters included in this volume should help to arouse in the minds of readers, and especially the younger portion of them, some healthy feelings relating to the improvement of offspring it will have fulfilled its aim. Two of them have been given as lectures before societies, the main object of which was the discussion of subjects bearing on evolution and human progress, and they are included in this volume because they have a close relation to the main subject, but the others were written especially for this work. While there may appear in a few cases a slight amount of repetition, the author trusts the reader will not consider it as unpardonable. With these few words I send the work on its mission hoping it will bear good fruit. M. L. H. CONTENTS. STIRPICULTURE. _Page._ Plato's Restrictions on Parentage; Lycurgan Laws; Plutarch on the Training of Children; Infanticide Among the Greeks; Group Marriage; Making Children the Property of the State; Grecian Methods Not Suitable to Our Time; Sexual Selection; Difficulties in the Way; An Experiment in Stirpiculture; Intermarriage; Woman's Selective Action; Man's and Woman's Co-operation; The Individual's Rights; Spiritual Sympathy in Marriage; 9 PRENATAL CULTURE. Jacob's Flocks; An Illustrative Case; Beliefs of Primitive Peoples; Birthmarks Rare; Why Children Resemble Parents; Life's Experiences Affecting Child; Germ-plasm; Congenital Deformities; Psychical Diseases; Telegony; Power of Heredity; Sobriety in the Father; Sacredness of Parentage; Self-control; 55 HEREDITY AND EDUCATION. Theories; Continuity of the Germ-plasm; A Rational View of Heredity; Heredity and the Education of Children; Intellectual Acquirements; Instinct; Knowledge or Heredity; Individuality; Spectre of Heredity; 100 EVOLUTION'S HOPEFUL PROMISE FOR A HEALTHIER RACE. Sexual Selection; Human Selection; Natural Selection; Conflict between Evolutionary Theories and our Humane Sentiments; Ideal of Health; Adaptation to Environment; Knowledge; Effects of Living at High Pressure; Girls in Manufacturing Districts; Co-operation: an Example; Hygiene; 130 THE GERM-PLASM; ITS RELATION TO OFFSPRING. What is the Germ-plasm? The Primitive Egg; Fertilization of the Mother-cell Necessary to Produce True Germ-plasm; What Fertilization Does; Its Process; Helps to Explain Heredity; Health of the Germ-plasm Necessary in Stirpiculture; Surplus Vitality Necessary for Producing the Best Children; Duncan's Statistics as to Ages of Parents of Finest Children; Effects of Alcohol on Offspring; Food and the Germ-plasm; Effect of Air and Water on Germ-plasm; Effect of Diseases on Germ-plasm; Every Child Born an Experiment; 162 FEWER AND BETTER CHILDREN. Darwin's Opinions; Race Modifications by Natural Selection; Grant Allen's Views; Spencer's Views on Parental Duties; Limiting Offspring Among the Natives of Uganda; The Fijians; Children of Large Families often Superior to those in Small Families; Some Reasons for this; 179 A THEORETICAL BABY. Our First Baby; We had Theories; What Some of Them Were; My Wife's Love for Me; My Sentiments; The Child's Easy Birth; Mother's Rapid Convalescence; The Child's First Bath; Forming Good Habits Early; No Crying at Night; Never Rocked to Sleep; His Bed; Keeping the Stomach and Bowels Right; Colic, Irritability and the Necessity for Diapers Eliminated; Number of Meals Daily; The Infant's Clothing; At One Year Old; Teething Gives Little Trouble; Requires Considerable Water; Learning to Creep, Stand, Walk and Talk by His Own Efforts; Invents His Own Amusements; Companionship With Parents; Mothering; Learning Self-control; Obedience; Playmates; 184 Notes 199 STIRPICULTURE. Natural selection, which is the central doctrine of Darwinism, has been explained as the "survival of the fittest." On this process has depended the progress observable throughout organic nature to which the term evolution is applied; for, although there has been from time to time degradation, that is, a retrogression, this has had relation only to particular forms, organic life as a whole evidencing progress towards perfection. When man appeared as the culmination of evolution under terrestrial conditions, natural selection would seem almost to have finished its work, which was taken up, however, by man himself, who was able by "artificial" selection to secure results similar to those which Nature had attained. This is true especially in relation to animals, the domestication of which has always been practiced by man, even while in a state of nature. Domestication is primarily a psychical process, but it is attended with physical changes consequent on confinement and variation in food and habits. This alone would hardly account, however, for the great number of varieties among animals that have been long domesticated, and it is probable that actual "stirpiculture" has been practiced from very early times. This term is derived from the Latin _stirpis_, a stock or race, and _cultus_, culture or cultivation, and it means, therefore, the cultivation of a stock or race, although it has come to be used in the sense of the "breeding of offspring," and particularly of human offspring. It is evident, however, that in relation to man this is too restricted a sense, and it must be extended so as to embrace as well the rearing and training as the breeding of children, in fact, _cultivation_ in its widest sense, in which is always implied the idea of improvement. Stirpiculture in this extended sense was not unknown to the ancients, both in theory and in practice. As to the former, the most noted example is that of Plato, who, in his "Republic," proposed certain arrangements as to marriage and the bringing up of children which he thought would improve the race, and hence be beneficial to the State. The State was to Plato all in all, and he considered that it should form one great family. This idea could not be carried into effect, however, so long as independent families existed, and therefore those arrangements had for one of their chief aims the abolition of what we regard as family life. This Plato thought was the best for the State, and the advantage which was supposed to accrue to it by the absence of separate families is expressed in a marginal note, which says: "There will be no private interests among them, and therefore no lawsuits or trials for assault or violence to elders." PLATO'S RESTRICTIONS ON PARENTAGE.--The end would hardly seem to justify the means, in these days, at least, when violence to elders is an uncommon incident; but how was the community of wives and children by which it was sought to be attained to be brought about? It is said, "The best of either sex should be united with the best as often, and the inferior with the inferior as seldom, as possible." Thus the people were to be classified into "best" and "inferior," and while the former were to be brought together as often as possible, the latter were not to be united at all if it could be avoided. There was no question of marriage in either case. In the one, the union was for the purpose of obtaining children, and in the other for the simple gratification of the passions; for only the offspring of the union between the sexes in the "best" class were to be reared. The children of the inferior class were not to be reared, "if the flock is to be maintained in first-class condition." This infanticide would matter little to the parents, as they had no control over their coming together, nor concern with the rearing of their offspring. Lots were to be drawn by the "less worthy" on each occasion of their being brought together. This was that they might accuse their ill-luck and not the rulers, in case their partners were not to their liking. The State was to provide not only what men and women were to be sexually united, but the ages within which this was to be permitted for the purpose of obtaining offspring. For a woman, the beginning of childbearing for the State was fixed at twenty years of age, and it was to continue until forty. For men, the period of procreation is said to be between twenty-five and fifty-five years of age. After the specified ages men and women were to be allowed to "range at will," except within certain prescribed degrees, but on the understanding that no children born to such unions were to be reared. It is evident that under such a system the actual relationship between the members of the State family could be known only to its rulers; but to provide against the union of persons too nearly related by blood, all those who were "begotten at the time their fathers and mothers came together" were regarded as brothers and sisters. But even brothers and sisters might be united "if the lot favors them, and they receive the sanction of the Pythian oracle." Thus far for the breeding of children laid down in Plato's "Republic." As to the rearing of them, we need only say that the children allowed to live were to be placed in the custody of guardians, to be appointed by the State from among the most worthy of either sex, who were to bring them up in accordance with the principles of virtue. The idea which formed the basis of the regulations as to marriage in the "Republic" was carried into practice by Lycurgus in his government of Sparta. We are told by Plutarch in his "Lives," that Lycurgus considered children not so much the property of their parents as of the State, "and therefore he could not have them begotten by ordinary persons, but by the best men in it." But he did not attempt to break up the private family, as was proposed by Plato. He sought rather to enlarge its boundaries by allowing the introduction of a fresh paternal element when this could be done with advantage to the State. Thus, he approved of a man in years introducing to his young wife a "handsome and honest" young man, that she might bear a child by him. Moreover, if a man of character became impassioned of a married woman on account of her honesty and beautiful children, he might treat with her husband for the loan of her, "that so planting in a beauty-bearing soil, he might produce excellent children, the congenial offspring of excellent parents." The principles which influenced Lycurgus were the same as those sought to be applied by Plato, although in a different way. Plutarch says, "He observed the vanity and absurdity of other nations, where people study to have their horses and dogs of the finest breed they can procure, either by interest or money, and yet keep their wives shut up, that they may have children by none but themselves, though they may happen to be doting, decrepid or infirm." Hence Lycurgus sought to drive away the passion of jealousy "by making it quite as reputable to have children in common with persons of merit, as to avoid all offensive freedom in their own behaviour to their wives." LYCURGAN LAWS.--According to Plutarch, the regulations enforced by Lycurgus, so far from encouraging licentiousness of the women, such as afterwards prevailed in Sparta, did just the reverse, as adultery was not known among them. That the system was beneficial to the State by tending to secure healthy offspring is probable; but Lycurgus took other means of bringing about this result. His requiring girls to dance naked in public was intended to teach them modesty. But we are told further: "He ordered the virgins to exercise themselves in running, wrestling and throwing quoits and darts, that their bodies being strong and vigorous, the children produced by them might be the same; and that, thus fortified by exercise, they might the better support the pangs of childbirth, and be delivered with safety." Moreover, he provided against the propagation of disease and deformation by directing that only such children should be reared as passed examination by the most ancient men of the tribe. If a child were strong and well-proportioned, they gave orders for its education and assigned it one of the nine thousand shares of land. Thus infanticide was a recognized part of the Spartan system, as it was in that of Plato. The elders of the tribe were very careful about the nurses to whom the children were assigned. When seven years old, the children were enrolled in companies, where they were all kept under the same order and discipline, and had their exercises and recreations in common. The boy of best conduct and courage was made captain, and their whole education was one of obedience. As for learning, Plutarch says they had just what was absolutely necessary; and certainly it was not such as could be recommended for imitation in these days. Xenophon, in his essay on "The Lacedemonian Republic," adds little to what Plutarch tells us with reference to the marriage regulations of Lycurgus. He remarks, however, that marriage was not allowed until the body was in full strength, as this was conducive "to the procreation of a robust and manly offspring." He affirms, also, that those who were allowed by arrangement to associate with other men's wives were men who had an aversion to living with a wife of their own! PLUTARCH ON THE TRAINING OF CHILDREN.--In his "Morals," Plutarch gives a dissertation on the training of children, the first portion of which deals with stirpiculture in the limited sense of the term, but is very inadequate. Indeed, the only advice he gives is that a man should not keep company with harlots or concubines, because children by them are "blemished in their birth" by their base extraction; and that no man should "keep company with his wife for issue's sake but when he is sober," lest he beget a drunkard. The main portion of Plutarch's treatise is concerned with the education of children, which is the second part of stirpiculture as a system of complete cultivation. Introductory to the subject of education he speaks of nursing, to which he attaches much importance. Plutarch insists on the necessity of mothers nursing their own children; nature, by providing them with two breasts, showing them that they can nurse even twins. But if they cannot, they are to choose the best nurses they can get, and such as are bred after the Greek fashion. For, "as it is needful that the members of children should be shaped aright as soon as they are born, that they may not afterwards prove crooked and distorted, so it is no less expedient that their manners be well fashioned from the very beginning; for childhood is a tender thing, and easily wrought into any shape." After referring to the importance of the choice of good companions for a child, Plutarch proceeds to consider the question of education, which he speaks of as the matter of most concern. As to education in general, he points out that a concurrence of three things is necessary to the "completing of virtue in practice," which is the aim of that process, that is: Nature, reason or learning, and use or exercise; For, "if nature be not improved by instruction, it is blind; if instruction be not assisted by nature, it is maimed; and if exercise fail of the assistance of both, it is imperfect as to the attainment of its end." There cannot be "instruction"--a term which is here used as equivalent to "education," although the latter has a wider signification than the former, and being equivalent to mental cultivation,--without a teacher, and Plutarch says well, "we are to look after such masters for our children as are blameless in their lives, not justly reprovable for their manners, and of the best experience in teaching. For the very spring and root of honesty and virtue lies in the felicity of lighting on good education." He is, indeed, so much impressed with its value that he affirms: "The one chief thing in this matter--which compriseth the beginning, middle and end of all--is good education and regular instruction." These two "afford great help and assistance towards the attainment of virtue and felicity." He adds: "Learning alone, of all things in our possession, is immortal and divine." Plutarch dwells on various other matters connected with education better fitted for his times than ours, but he refers to the importance of example in words that are deserving of careful consideration. He says: "The chiefest thing that fathers are to look to is, that they themselves become effectual examples to their children, by doing all those things which belong to them, and avoiding all vicious practices, that in their lives, as in a glass, their children may see enough to give them an aversion to all ill words and actions. For those that chide children for such faults as they themselves fall into unconsciously accuse themselves, under their children's names. And if they are altogether vicious in their own lives, they lose the right of reprehending their very servants, and much more do they forfeit it to their sons. . . . . Wherefore we are to apply our minds to all such practices as may conduce to the good breeding of our children." It is not improbable that the marriage regulations ascribed to Lycurgus were based on institutions already in existence among the Spartans. From the statement of Polybius, that the brothers of a house often had one wife between them, it has been inferred that in Sparta the Tibetan form of polyandry was practiced. According to Plutarch, another curious marriage custom prevailed, showing that the Spartans, who differed in various respects from other Greeks, had retained primitive habits. Thus, the bridegroom carried off the bride by violence, and for some time after this "marriage by capture" he visited her "with great caution and apprehension" of being discovered by the rest of the family; the bride at the same time exerted all her art to contrive convenient opportunities for their private meetings. And this they did, not for a short time only, but some of them even had children before they had an interview with their wives in the daytime! This custom had much in common with the _sadica_ marriages of the early Arabs, who, as we are told by Professor Robertson Smith, allowed a woman, while she remained with her own tribe, to receive the clandestine visits of a lover. Her offspring were recognized as legitimate and became members of the tribe. The incident of "capture" could not occur, as it was a general custom in ancient Arabia for a husband to live among his wife's kinsfolk. INFANTICIDE AMONG THE GREEKS.--The practice of infanticide, which was the only mode by which Lycurgus, or even Plato in his imaginary republic, could really insure the existence of a healthy and vigorous population, was undoubtedly a survival from primitive times. The sacredness of infant life is the result of the high moral tone which has accompanied the spread of Christianity; and it may be said to be almost unknown outside of the Christian era. Various reasons are assigned by different peoples for the practice of infanticide; but one cause universally operative is the objection to rearing malformed or unhealthy offspring. Savages adopt various modes of improving, according to their ideas, the physical appearance of their children. Giving the proper form to the nose is considered a very important matter by the native Australian mother and by the Polynesian Islanders; as, indeed, it was by the ancient Persians, among whom the molding of the nose to the proper curve was essential, especially in the royal family. The flat head of the American Indian of the northwest coast was at one time considered a beauty, and was restricted to the members of the tribe, slaves not being allowed to undergo the necessary head compression. The small artificial foot of the Chinese lady is another case in point. But however much the physical appearance might be altered, no effect could thus be made in the general physique of the race. The most easy way of keeping this up to a proper standard is to destroy all the infants that possess physical defects; and such a course is adopted by many savages, although it is by no means the most influential cause of infanticide. GROUP MARRIAGE.--A remarkable system of relationships, with which is combined a series of regulations framed with the object of pointing out what persons are entitled to enter into the marital relation, is found to be prevalent in nearly all uncivilized peoples. The members of a tribe are divided into two or more groups, each of which consists of persons who are nearly related by blood, and who are forbidden, therefore, to intermarry. One of the tribes of Central Australia, the Dieyerie, has a legend which explains the marriage system common to them and to all the other tribes, as being intended to prevent the evil effects of intermarriage between persons very near of kin. The story is valuable as showing the opinion entertained by savages as to the effect on the race of breeding in and in--a subject to which we may have occasion to make further reference. Dr. J. F. McLennan and other writers on primitive marriage refer to the practice among certain _civilized_ peoples of antiquity of what we regard as incestuous marriage, in support of the view that in the early history of mankind intercourse between the sexes was promiscuous.[21:A] Such an explanation is entirely uncalled for, however, as the custom was intended to secure purity of blood, that is, blood of a particular line of ancestors. Such marriages were known only to a few peoples, and they were evidently of comparatively late origin. Whether the purity of blood was attended with improvement of the stock may be doubted; as, whatever may have been the actual origin of the marriage regulations of the numerous peoples among whom the classificatory system of relationship is established, they are intended, without question, to prevent the intermarriage of persons who are regarded as near blood relations, the general disapproval of which must have had some sufficient reason, or, at all events, must have originated in ideas supposed to furnish good grounds for it. MAKING CHILDREN THE PROPERTY OF THE STATE.--The principles which were embodied in the scheme proposed by Plato, in his "Republic," to bring about an improvement in the race are mainly two: First, restriction on the formation of procreative unions; second, infanticide. The breaking up of private or separate families necessarily resulted from the operation of his "marriage" regulations, and was intended to emphasize the idea which Plato, like Lycurgus, insisted on, that the children belonged to the State. Lycurgus sought to enforce the same idea by allowing wives to have intercourse with other men than their husbands, thus making children "common" in some sense, while retaining the separate family intact. Thus he introduced, or rather it should be said, established a modified form of polyandrous marriage; Plato's system, on the other hand, being one of mere pairing, as in the breeding of animals. In either case the union of very near relations was not permitted, that is, between brother and sister, or parent and child. Yet Lycurgus allowed marriage between a half-brother and sister by the same mother. Curiously enough, this was forbidden by the Athenian law, which permitted a brother and sister by the same father only to intermarry. The Greek rule, as laid down in Smith's "Dictionary of Greek and Roman Antiquities," was that "proximity of blood or consanguinity was not, with some few exceptions, a bar to marriage," although direct lineal descent was so. Moreover, there was no attempt to enforce consanguineous marriages, so as to ensure purity of blood, such as was customary among the Incas of Peru, the laws of which required that the oldest son and daughter of the sovereign should intermarry because the Incas were descended from the Sun, and the Sun had married his sister the Moon, and had united in marriage his two first children! A more practical reason was found in the rule that the kingdom should be inherited through both parents. Hence it was not permitted to mix the blood of the Sun, or rather of those who claimed solar descent, with that of men. GRECIAN METHODS NOT SUITABLE TO OUR TIME.--It is evident that the principles which governed the ancients in their endeavors to improve the race are not capable of application at the present day, under the conditions of modern civilization. Instead of placing further restrictions on marriage, the tendency now is to loosen those which have hitherto existed, although certain regulations, such as relate to age, consent, etc., are recognized as necessary for the interests of the State. Moreover, greater facilities are given than were formerly allowed for dissolving ill-assorted unions, thus getting rid of the excuse for the formation of irregular connections. Nevertheless, the interests of neither society at large nor of individuals will permit of the introduction of the temporary or occasional pairing system, which is a return to an animal state, and, therefore, not worthy of the dignity implied in the term, marriage, and which is inconsistent with true family life. It would be liable to all kinds of abuse, and would become, in most cases, a legalized system of prostitution, thus dragging society down to a lower level instead of raising it, and tending to the deterioration, instead of the improvement, of the race, if not to its extinction. As to infanticide, this certainly would not be tolerated by public opinion, although it is now largely resorted to under the guise of abortion. To legalize child-killing under any circumstances would be to offer a premium for murder, even if it were permitted only with the express sanction in every case of the officials of the State. There is now no justification for such a course, as the education of those who appear to be on a mental level with the animals has been carried so far that the term "idiot" may soon have to be dropped from our vocabulary. It must be affirmed, however, that the whole subject of the improvement of the race was dealt with by Plato, and, indeed, by the ancients generally, in a very crude and superficial manner. This has been well pointed out by Professor B. Jowett in the Introduction to his translation of Plato's "Republic." Professor Jowett objects generally that the great error in the speculations of Plato and others on the improvement of the race is, "that the difference between men and the animals is forgotten in them." The human being is regarded with the eye of a dog or bird fancier, or at best of a slave owner; the higher or human qualities are left out. The breeder of animals aims chiefly at size or speed or strength; in a few cases, at courage and temper; most often the fitness of the animal for food is the greatest desideratum. But mankind are not bred to be eaten, nor yet for their superiority in fighting or in running or in drawing carts. Nor does the improvement of the human race consist merely in the increase of the bones and flesh, but in the growth and enlightenment of the mind. Hence there must be a marriage of true minds as well as of bodies; of imagination and reason as well as of lusts and instincts. Men and women without feeling or imagination are justly called brutes; yet Plato takes away these qualities and puts nothing in their place, not even the desire of a noble offspring, since parents are not to know their own children. The most important transaction of social life he who is the idealist philosopher converts into the most brutal. For the pair are to have no relation to each other but at the hymeneal festival; their children are not theirs, but the State's; nor is any tie of affection to unite them. Yet the analogy of the animals might have saved Plato from a gigantic error if he had not lost sight of his own illustration! For the "nobler sort of birds and beasts" nourish and protect their offspring and are faithful to one another! It is certainly surprising, as Jowett says, that the greatest of ancient philosophers should, in his marriage regulations, have fallen into the error of separating body and mind. He did so probably through a false notion of the antagonism between the family and the State, and hence, as Lycurgus did not aim at destroying family life he escaped that error. And yet there is nothing to show that the marriage regulations of Lycurgus had any real effect on the children of the State. That the early Spartans were a hardy and courageous people is undoubtedly true; but apart from the practice of infanticide, which would necessarily get rid of the weak, their character and conduct can be explained by reference merely to the system of training, both of youth and maidens, which Lycurgus rigidly enforced. Lacedemon was essentially a military republic, and its rulers aimed to breed soldiers, rather than men in the noble sense in which the term "man" is now used. Indeed, there is nothing to show that any compulsory attempt to improve the race has ever been successful, apart from the effect which the destruction of feeble and deformed offspring may have, and the influence of the severe training of those who are allowed to survive. Nevertheless, the human race has vastly improved since its first appearance on the earth, if the teachings of the doctrine of evolution are true and applicable to man as well as to the inferior animals. The passage from the native Australian to the European is a long one, and yet they are supposed to represent a common primitive stock. The steps by which the European has been gradually developed, with his special characteristics, cannot now be traced; but one of the chief agencies to which the result is due is that to which Darwin applied the term, "sexual selection." As natural selection has relation to _adaptation_, and its aim is "the survival of the fittest," so sexual selection has reference to _beauty_, and its object is the perpetuation of the most beautiful, according to the taste of the peoples practicing it. Darwin was the first to point out the importance of sexual selection for certain purposes which, as stated by Professor G. J. Romanes, in his "Darwin and after Darwin,"[28:A] "have no reference to utility or the preservation of life." The latter writer in treating of the subject affirms it is universally admitted that the higher animals do not pair indiscriminately, the members of either sex preferring "those individuals of the opposite sex which are to them most attractive." Many birds and certain mammals clearly display the esthetic sense, which is shown by the former particularly in the adorning of their nests with colored objects; and it is reflected in the personal appearance of the animals themselves. During the pairing season, birds take on their most brilliant plumage, and the males take great pains to exhibit their charms before the females, actively competing with one another in so doing. There is similar rivalry among song birds, who strive to see which can best please the females by their singing. SEXUAL SELECTION.--Professor Romanes, after referring to those facts, which are considered in detail by his great predecessor, states the theory of sexual selection as follows: "There can be no question that the courtship of birds is a highly elaborate business, in which the males do their best to surpass one another in charming the females. Obviously the inference is that the males do not take all this trouble for nothing; but that the females give their consent to pair with the males whose personal appearance, or whose voice, proves to be the most attractive. But, if so, the young of the male bird who is thus _selected_ will inherit his superior beauty; and thus, in successive generations, a continuous advance will be made in the beauty of plumage or of song, as the case may be,--both the origin and development of beauty in the animal world being thus supposed due to the esthetic taste of the animals themselves." It is not necessary to refer particularly to the evidence in support of the theory of sexual selection. There can be no doubt that it is a most important factor in the perpetuation and increase of certain characters, those which come within the category of "beautiful," the very existence of which proves them to be beneficial to the stock to which the animals exhibiting them belong. The fundamental fact is that they have "the effect of charming the females into a performance of the sexual act;" an opinion which is supported by the more general fact that "both among quadrupeds and birds, individuals of the one sex are capable of feeling a strong antipathy against, or a strong preference for, certain individuals of the opposite sex." These statements are applicable also to man, with whom the principle of sexual selection must have been influential to at least the same degree as among the lower animals. It may be expected, indeed, to be more influential, as the esthetic taste with which it is associated becomes more highly developed with man than with any member of the animal kingdom. Even here it is not a question of mere coloration. The theory of sexual selection as framed by Darwin is concerned, as Romanes points out, not so much with color itself as with the particular disposition of color in the form of ornamental patterns. These have a kind of _structural_ value, and certain birds, moreover, possess actual structural peculiarities, such as ornamental appendages to the beak, the only use of which would appear to be to charm the female during courtship. We may suppose, therefore, that sexual selection has affected not merely what may be termed the superficial characters of man, but to some extent, at least, those which have a structural value. The principle of sexual selection is applicable primarily to the characteristics of the male; but Darwin supposes them to have been transferred to the other sex, and through them transmitted to the race generally. In his "Descent of Man," he remarks of the actual influence over the race of that principle: "The nervous system not only regulates most of the existing functions of the body, but has indirectly influenced the progressive development of various bodily structures and of certain mental qualities. Courage, pugnacity, perseverance, size and strength of body, weapons of all kinds, musical organs, both vocal and instrumental, bright colours and ornamental appendages have all been indirectly gained by the one sex or the other, through the exertion of choice, the influence of love and jealousy, and the appropriation of the beautiful in sound, colour or form; and these powers of the mind manifestly depend on the development of the brain." That sexual selection has actually resulted in modification of human physical structure, Darwin thinks can be shown by reference to the ancient Persians, whose type was greatly improved by intermarriage with the beautiful Georgian and Circassian women. He refers to several similar cases, and particularly to the Jollofs of West Africa, whose handsome appearance is said to be due to their retaining for wives only their most beautiful slaves, the others being sold. Sexual selection may be operative for the improvement of the race through the action of either man or woman, and the conditions of its activity are different in either case. As to the action of man, Darwin says in relation to primitive peoples: "The strongest and most vigorous men--those who could best defend and hunt for their families, who were provided with the best weapons and possessed the most property, such as a large number of dogs or other animals--would succeed in rearing a greater average number of offspring than the weaker and poorer members of the same tribe. There can, also, be no doubt that such men would generally be able to select the more attractive women. At present, the chiefs of nearly every tribe throughout the world succeed in obtaining more than one wife." With reference to selection by the women, Darwin shows that among savages they have much more to say in their marriages than is usually supposed. He remarks: "They can tempt the men they prefer, and can sometimes reject those whom they dislike, either before or after their marriage. Preference on the part of the women, steadily acting in any one direction, would ultimately affect the character of the tribe, for the women would generally choose, not merely the handsomest men, according to their standard of taste, but those who were at the same time best able to defend and support them. Such well-endowed pairs would commonly rear a larger number of offspring than the less favored." Darwin adds: "The same result would obviously follow in a still more marked manner if there were selection on both sides, that is, if the more attractive, and at the same time more powerful men were to prefer, and were preferred by, the more attractive women. And this double form of selection seems actually to have occurred, especially during the earlier periods of our long history." The investigations of Darwin as to the operation of sexual selection had reference chiefly to the modification of physical characters. He did not altogether lose sight, however, of its possible influence in affecting for the better the mental characteristics of the race. He concludes his enquiry by the remark that "Man might by selection do something, not only for the bodily constitution and frame of his offspring, but for their intellectual and moral qualities. Both sexes ought to refrain from marriage if they are in any marked degree inferior in body or mind; but such hopes are Utopian, and will never be even partially realized until the laws of inheritance are thoroughly known. Every one does good service who aids towards this end." It is in the application of the principle of sexual selection to the mental characteristics of man, that any real improvement of the race, viewed as consisting of human beings and not of mere animals, must be brought about. Beauty of physical form and feature is of importance in human relations only so far as it is associated with beauty of mind and character, that is, with high intellectual and moral attainments. That these often go together is true, but it is not always the case. Grant Allen says: "To be sound in wind and limb; to be healthy of body and mind; to be educated; to be emancipated; to be free, to be beautiful--these things are ends towards which all should strive, and by attaining which all are happier in themselves, and more useful to others." But physical and intellectual perfection are not always found together, as was observed by Darwin, when he mentioned among the causes which interfere with the physical action of sexual selection the fact that men are largely attracted by the mental charms of women. Professor Jowett affirms truly that "Many of the noblest specimens of the human race have been among the weakest physically. Tyrtæns or �sop, or our own Newton, would have been destroyed at Sparta, and some of the fairest and strongest men and women have been among the wickedest and worst." Hence, he properly infers that "Not by the Platonic device of uniting the strong and the fair with the strong and the fair, regardless of sentiment and morality, nor yet by his other device of combining dissimilar natures, have mankind gradually passed from the brutality and licentiousness of primitive marriage to marriage Christian and civilized." The truth of this inference cannot be denied, because to leave out of view considerations of sentiment and morality would fatally vitiate any scheme for the improvement of the human race. But Professor Jowett affirms that, "We do not know how by artificial means any improvement in the breed can be effected." The problem is no doubt a complex one. As he points out, a child has usually thirty progenitors only four steps back, and whatever truth there may be in the inheritance of special physical characters, "We have a difficulty in distinguishing what is a true inheritance of genius or other qualities, and what is mere imitation or the result of similar circumstances. _Great men and great women have rarely had great fathers and mothers._" Professor Jowett thinks, indeed, that too much importance may be ascribed to heredity. He says: "The doctrine of heredity may seem to take out of our hands the conduct of our lives, but it is the idea, not the fact, which is really terrible to us. For what we have received from our ancestors is only a fraction of what we are or may become. The knowledge that drunkenness or insanity has been prevalent in a family may be the best safeguard against their recurrence in a future generation. The parent will be most awake to the vices or diseases in his child of which he is most sensible within himself. The whole of life may be directed to their prevention or cure. The traces of corruption may become fainter, or be wholly effaced; the inherited tendency to vice and crime may be eradicated. And so heredity, from being a curse, may become a blessing. We acknowledge that in the matter of our birth, as in our nature generally, there are previous circumstances which affect us. But on this platform of circumstances, or within this wall of necessity, we have still the power of creating a life for availment by the reforming energy of the human will." There is much truth in these remarks of Professor Jowett, but they do not affect the argument in favor of the possibility of bringing about an improvement in the race if the proper means are adopted. It would not be any wiser for the strong and healthy to marry with the sick and weak, because the latter happen to be highly intellectual or moral, than to marry with the strong and healthy if these physical characters are united with mental weakness or immorality. There is a consensus of opinion at the present day, that what should be aimed at is the union of physical perfection with that of intellect and character, in the persuasion that steps towards this end will ultimately lead to the general improvement of the human race. DIFFICULTIES IN THE WAY.--The difficulty is to devise and carry out some scheme for the purpose which shall be both feasible and agreeable to public sentiment. The latter consideration would prevent any attempt at active stirpiculture under State direction, although the State might indirectly affect the result by subsidiary regulations as to marriage and training of children. There is nothing, however, to prevent the systematic efforts of private individuals, and in such cases the causes which Darwin cites as interfering with the physical action of sexual selection would not operate. The most systematic experiment in stirpiculture of modern times was that originated by John Humphrey Noyes at the Oneida Community, in central New York, from 1868 to 1879. A paper on this experiment was read by Anita Newcomb McGee before the American Science Association in August, 1891, which was published in "The American Anthropologist," 1891, and the following facts are taken from that paper. AN EXPERIMENT IN STIRPICULTURE.--Noyes was the founder of a religious sect, the members of which, owing to their desire for freedom from sin, were called Perfectionists. Holiness was the first principle of their creed, and Noyes thought to transmit that condition from one generation to another by a process of stirpiculture. To overcome the "selfishness" of monogamic marriage he devised a "system of regulated promiscuity, beginning at earliest puberty, and by a method of his own invention he separated the amative from the propagative functions." Its first principle was that of a judicious in and in breeding, with occasional mingling of foreign blood, as in stock-raising. The second principle adopted was that of "careful selection of individuals for breeding purposes. Genealogies were studied and medical histories compiled." A committee, headed by Noyes, selected the holiest members who were free from physical defects, intellectual and other considerations being given less weight at first, although in later years they received more consideration. The parents were of all ages, but the father was always older than the mother. Some sympathy between the persons mated was always required; and if a proposition for union came from two individuals it was allowed if no objections were found. Noyes held that uncle and niece are as much related as father and daughter, because brothers have identical blood, and that cousins are in the same relation to each other as half brothers. In the Oneida Community uncles and nieces twice paired, and it is noticeable that a considerable proportion of the children had Noyes' blood on one or both sides. The founder himself had nine children in the Community, to which belonged also his brother, his two sisters and their children. As to the care of the children, this belonged exclusively to the mothers for the first nine months, after which for a further nine months they took charge of their offspring at night only. When eighteen months old, the children were transferred to a separate department which was managed by those who had shown themselves specially fitted for the work. Let us see what was the result of Noyes' experiment. Of the sixty[39:A] children born, five died at or near childbirth from unforeseen causes depending upon the mother. All the others were alive at the date of Mrs. McGee's communication, except a boy who was reared in spite of weakness, and died from a trifling malady when about sixteen years of age. All the children were strong and healthy, the boys being tall--several over six feet--broad-shouldered and finely proportioned; the girls robust and well-built. It is remarkable, that among the children between five and nine years of age, thirteen were boys and six only were girls. With reference to their intellectual ability, it is stated by Mrs. McGee that, of the oldest sixteen boys, ten were in business, chiefly employed as clerks, foremen, etc., in the manufactories of the joint stock company. The eleventh was a musician of repute; another a medical student; one passed through college and studied law; one was a college senior, and one entered college after winning State and local scholarships, and gave great mathematical promise. The sixteenth boy was a mechanic, and the only one employed in manual labor. Of the six girls between eighteen and twenty-two years, three are said by Mrs. McGee to be especially intellectual. The mothers of these children usually belonged to the classes employed in manual labor, while the fathers, with the exception of the Noyes family and half a dozen lawyers, doctors and clergymen, were all farmers and mechanics. It is noteworthy that, as a rule, the fathers were the intellectual superiors of their mates, "and enquiry develops the fact, known in the Community, that in these cases the children are markedly superior to the maternal stock." When this system of complex marriage had been in operation twenty years, the desire to return to the old system of monogamy arose, and it became so strong in the Community that its founder retired from it, and on August 26, 1879, complex marriage was renounced, although nominally "in deference to public sentiment." Twenty-five couples who had been married before entering the Community again became husband and wife, and twenty marriages between other individuals took place within four months after the abandonment of the stirpicultural experiment. There were then in the Community two hundred and sixteen adults and eighty-three children under twenty years of age. So far as the real object which the founder of the Oneida Community had in view in his marriage system, it was undoubtedly a failure, as of the offspring, in spite of their early doctrinal training, only a very few are church members, and but one is a Perfectionist. This is the son of an uncle and a niece, both of Noyes' blood. From a physical and intellectual standpoint the experiment would seem to have given promise of success, but it continued too short a time to be of much scientific value. The result may be stated in the words of Mrs. McGee, who says that the complete failure to perpetuate the church through stirpiculture "would seem to indicate that, while our race would doubtless be greatly benefited by more attention to laws of breeding, yet to attempt promulgation of a belief by this means alone is only to court defeat. In spite of the energy and magnetism of so remarkable a man as Noyes, in spite of his long-continued efforts, and just when success seemed within his grasp, his one misjudgment of human nature bore fruit, the neglected instinct of monogamy arose in its might and crushed to nothing the whole structure, and he, the builder, went last of all. With the close of his life, April 13, 1886, ended a unique and interesting history." INTERMARRIAGE.--We have seen that the founder of the Oneida Community permitted the intermarriage of uncle and niece, although he considered them related as nearly as father and daughter. This question of the intermarriage of near blood relations is an important one in its bearing on the question of stirpiculture, and as already mentioned, it has engaged the attention of nearly all the lower races of mankind. It has, indeed, been provided against by the marriage restrictions of most uncultured peoples, and their systems of relationship clearly point out what persons are within the permitted limits of marriage. It appears to be the general rule that the children of two brothers or of two sisters, whether own or tribal, cannot intermarry, but that the children of a brother and those of a sister may be thus united, although sometimes this is not allowed where own brother and sister are concerned.[42:A] The question of the effect on offspring of consanguineous marriages was some time ago particularly enquired into by Mr. A. H. Huth, who, after a consideration of all the information available, came, in his work, "The Marriage of Near Kin," to the following conclusions: "1--That any deterioration through the marriage of near kin, _per se_, even if there be such a thing in the lower animals, is impossible in man, owing to the slow propagation of the species. "2--That any deterioration through the chance accumulation of an idiosyncrasy, though more likely to occur in families where the marriage of blood relations was habitual, practically does not occur oftener than in other marriages, or it would be more easily demonstrated. "3--That, seeing the doubt, to say the least of it, which exists concerning the effect for harm of marriages between near kin, and on the other hand the certainty that whenever and wherever marriage is impeded a direct and proportionate impulse is given to the practice of immorality, it is advisable not to extend the prohibition against marriage beyond the third collateral degree, and to permit all marriages of affinity excepting those in the direct ascending or descending line." There appears to be no doubt that what are regarded among Christian peoples as incestuous marriages are not desirable. How far marriage unions between first cousins are advisable depends, as appears from Mr. Huth's remarks, on considerations which affect the question generally. If there are any serious physical, intellectual or moral defects on either side, no marriage should take place. WOMAN'S SELECTIVE ACTION.--Apart from the question of consanguinity, the principles which should govern all marriages is that of sexual selection, which should have reference, however, not merely to physical characters, but also to mental and moral characteristics. In applying this principle, it must be remembered that while man, like the male of all animals, does the courting, woman, like all females, makes the selection; at least this is the general rule among the most cultured peoples. Thus it is evident that woman possesses the power of largely influencing the improvement of the human race, and in this fact we may see the possibility of this being effected by the operation of general social causes, without having recourse to individual experiments, such as that undertaken by Noyes, which are necessarily limited in their action, and may, after all, have like practical result. _If all women could be induced to combine for that end they could probably bring about the desired improvement by their own efforts._ On this subject the well-known naturalist, Mr. A. R. Wallace, has some judicious remarks in an article on "Human Progress, Past and Future," in _The Arena_ for January, 1892. Mr. Wallace, who accepts the views of Weismann as to the non-inheritance of acquired characters, thinks that the physical and moral evils and degradation attendant on the conditions of modern city life will have no permanent effects, when a more rational and elevating system of social organization is brought about. The most important agency in this social regeneration will be the selective action of woman, under the influence of her newly acquired freedom and higher education. Says Mr. Wallace: "When such social changes have been effected that no woman will be compelled, either by hunger, isolation or social compulsion, to sell herself, whether in or out of wedlock, and when all women alike shall feel the refining influence of a true harmonizing education, of beautiful and elevating surroundings, and of a public opinion which shall be founded on the highest aspirations of their age and country, the result will be a form of human selection which will bring about a continuous advance in the average status of the race. Under such conditions, all who are deformed either in body or mind, though they may be able to lead happy and contented lives, will, as a rule, leave no children to inherit their deformity. Even now we find many women who do not marry because they have never found the man of their ideal. When no woman will be compelled to marry for a bare living or for a comfortable home, those who remain unmarried from their own free choice will certainly increase in number, while many others, having no inducement to an early marriage, will wait until they meet with a partner who is really congenial to them. In such a reformed society the vicious man, the man of degraded taste or of feeble intellect, will have little chance of finding a wife, and his bad qualities will die out with himself. The most perfect and beautiful in body and mind will, on the other hand, be most sought and therefore be most likely to marry early, the less highly endowed later, and the least gifted in any way the latest of all; and this will be the case with both sexes. From this varying age of marriage, as Mr. Galton has shown, there will result a more rapid increase of the former than of the latter, and this cause continuing at work for successive generations will at length bring the average man to be the equal of those who are now among the more advanced of the race." We have here the application of the principle of sexual selection in its highest sense, although limited in action to women, and it is undoubtedly the phase of stirpiculture which will become operative when the "emancipation of women" is completed. There is one feature of modern society which may retard its operation, and which was referred to by Darwin as interfering with the physical effect of sexual selection in the past. Wealth is now, more than ever before, an important factor in society, and not only man's but woman's choice in matrimony is often governed by money considerations. The possession of wealth may be evidence of mental astuteness, but not necessarily of high morality, and until it ceases to be sought after in marriage it will seriously interfere with the improvement of the race on its higher planes. The sexual selection which Mr. Wallace so ably advocates is to be exercised by woman, and hence its efficiency will depend on the fitness of woman, not only to choose proper partners in marriage, but to communicate the highest physical and mental characters to her offspring. She can transmit only what she herself possesses, and she will choose that which is in sympathy with her own feelings and desires, so that if she is to affect the race beneficially, she must seek first her own perfection. Hence the great importance of the woman's movement of the present day, the basis of which is the better development of her physical, mental and moral faculties, without which she cannot expect to have the increased social privileges to which she may aspire. The greatest social privilege women can have is to be the chief agent in the improvement of the race, and through it the regeneration of society itself. Lady May Jeune, in reply to those who think that the present relations between mothers and daughters threaten family disruption, observes, "That woman was created for the purpose of being the wife and mother of mankind no one can deny, and that none of the discoveries of science or any attempt to solve the mysteries of life have brought her one bit nearer the knowledge of how to unburden herself of these responsibilities, is also a fact." This must be true if the race is to be continued; for without wives there can be no mothers. Being possible mothers, therefore, it is necessary, if the race and society are to be improved, that women shall acquire the highest physical, intellectual and moral education they are capable of, and if they require the same qualities in their husbands, the problem we are considering will be solved. MAN'S AND WOMAN'S CO-OPERATION.--We have here the central idea of the New Hedonism advocated by Mr. Grant Allen, whose views necessitate the active agency of man as well as of woman. This is only reasonable, seeing that offspring depend on the co-operation of two factors, and that if either of them is defective the offspring must share in the defect. "Self-development is an aim of all," says Mr. Grant Allen, "an aim which will make all stronger and braver, and wiser, and better. It will make each in the end more helpful to humanity. To be sound in wind and limb; to be healthy of body and mind; to be educated, to be emancipated, to be free, to be beautiful--these things are ends towards which all should strive, and by attaining which all are happier in themselves, and more useful to others." Hence the New Hedonism teaches that "to prepare ourselves for the duties of paternity and maternity, by making ourselves as vigorous and healthful as we can be is a duty we owe to all our children unborn and to one another." This applies as well to "the body spiritual, intellectual and esthetic" as to the physical body. Mr. Grant Allen thinks the theory he advocates will introduce a new system, which "will not include the selling of self into loveless union for a night or for a lifetime; the bearing of children by a mother to a man she despises or loathes or shrinks from; the production by force, sanctified by law, of hereditary drunkards, hereditary epileptics, hereditary consumptives, hereditary criminals. We shall expect in the future a purer and truer relation between father and mother, parent and child. We shall expect some sanctity to attach to the idea of paternity, some thought and care to be given beforehand to the duties of motherhood. We will not admit that the chance union of two unfit persons, who ought never to have made themselves parents at all, or ought never to have made themselves parents with one another, can be rendered holy and harmless by the hands of a priest extended to bless a bought love, or a bargain of impure marriage. In one word, for the first time in the history of the race, we shall evolve the totally new idea of responsibility in parentage. _And as part of this responsibility we shall include the two antithetical, but correlative, doctrines of a moral abstinence from fatherhood and motherhood on the part of the unfit, and a moral obligation to fatherhood and motherhood on the part of the noblest, the purest, the sanest, the healthiest, the most able among us. We will not doom to forced celibacy half our finest mothers._" THE INDIVIDUAL'S RIGHTS.--From the racial standpoint these views are just and cannot be controverted, but something must be allowed to the individual. The relative position and rights of the race and the individual are in a dispute, which has become intensified since the development of the theory of evolution. _But the individual is the beginning of the race and he should be its end._ Therefore, in seeking to improve the race, violence must not be done to the highest sentiments of the individual. It is a fact that many highly cultured individuals have a repugnance to certain aspects of married life, and this repugnance appears to be justified by the further fact that a high state of refinement is often attended with loss of physical productiveness. One of the most curious results of Galton's enquiries into heredity was that wealthy families have a tendency to die out in heiresses, which is partly, but not wholly, dependent on the fact that childbearing is more often the accompaniment of poverty than of luxurious living. The personal disinclination to marry attendant on intellectual refinement is still more likely to be possessed by those of high spirituality. This is quite natural, notwithstanding the statement of Mr. Grant Allen, which is undoubtedly true, that the origin and basis of all that is best and highest within us is to be found in the sex-instinct. Love may have begotten "all higher arts and all higher customs," and yet love may in the process itself become sexless, as it is when it assumes the noblest form, that of divine charity for our fellowmen. As well might we continue to perpetuate in our highest actions the nature of the ape-man because we are descendants of this creature, as let the idea of sex always rule our thoughts. With the individual the physical influence of sex is weakened and finally ceases, although it ever remains constant in the race, and hence the influence of the idea of sex over the mind of the individual should be similarly affected. "In Heaven," said the founder of Christianity, "there is neither marrying nor giving in marriage," and in that highest mental condition, which is heaven on earth, the sense of sex has ceased to be operative, having given place to the spiritual sense which is the noblest attribute of man because the last to be developed. We have here, however, a question between the individual and the race, and it does not affect the main contention that the improvement of the race, which includes that of the individual, is to be found in the application of the principle of selection. This must necessarily be chiefly in the hands of women, although both men and women must co-operate to bring about the best results, by seeking first of all to improve their own natures by physical, intellectual and moral culture. The statement of the case according to that principle, and the aim to be attained, exhibit the dignity and importance of the subject of stirpiculture. Theoretically this is admitted on all hands, and as soon as the conditions of the subject are clearly understood there will be no practical difficulty in carrying the principle into effect, so that it may have its legitimate consequences. What parents have to realize is the necessity of so training and instructing their children that they may become capable of being the parents of perfect offspring. The good tree only can bear good fruit. But this is not the real starting point of stirpiculture. An essential factor, and one that is seldom thought of, is the spirit in which the inception of offspring is undertaken. Marriage was to the ancients a sacred state, because it was associated with the religion of the domestic altar, and because the perpetuation of the family, which was its aim, was required by the necessity of having a son to perform the sacred rites at that altar after the death of his father. The perpetuation of the family was thus a sacred duty, and the consummation of marriage partook of this character. According to the ancient Persian religion, the union of man and woman is the act most agreeable to God, and the act of consummation is directed to be sanctified, and a prayer directed to God that He would bless it. Marriage must be conducted in this spirit, rather than as a means of gratifying the passions, if the happiest results are to be obtained from the application of the principle of sexual selection. SPIRITUAL SYMPATHY IN MARRIAGE.--That supposes, however, the existence of spiritual sympathy between those who are united in marriage, and this sympathy must form the true basis of all improvements in the race. It was the neglect of this feature, the want of which must render any attempt to carry out Plato's ideas on the subject of marriage futile, that put a stop to the experiments undertaken by his latest imitator, Noyes. His adherents simply made a return to the monogamy which is the heritage of all the Aryan peoples, and which is based on the union of two hearts, and not merely of two persons. This is the first application of the principle of sexual selection above the animal plane, and it must be continued notwithstanding that the range of selection is extended so as to embrace also the intellectual and moral planes. How far the State may ultimately be called on to aid in the improvement of the race, in accordance with the ideas we have been considering, is doubtful. It can aid very materially in placing restraints on too early marriage, and by insisting on the attainment of a proper standard of physical training and of mental culture before marriage is entered on. There is no reason, moreover, why the State should not interfere to prevent the marriage of those who are too near of kin, or who by reason of physical or mental ailment, or by their moral defects are not fit subjects for the propagation of the race. The objection to this interference with personal liberty is so strong, however, that even so rational a procedure as preventing the spread, through marriage alliances, of disease and crime cannot yet obtain the sanction of public opinion. This will be educated with the general improvement of the race that must gradually take place through other agencies, and then the State will have merely to carry into effect the decrees of the people, which will be expressed in no uncertain language when woman has attained to the influence to which her own perfected condition will entitle her. FOOTNOTES: [21:A] Mr. Darwin accepted this view at first; but in a note to the second edition of his "Descent of Man" he says: "C. Staniland Wake argues strongly against the views held by these three writers on the former prevalence of almost promiscuous intercourse." See "Development of Kinship and Marriage." Redway, London. 1888. [28:A] The Open Court Publishing Company, Chicago. 1892. [39:A] It should be sixty-one. [42:A] See Lorimer Fison, in "The Journal of the Anthropological Institute," May, 1895, page 361. The whole subject is exhaustively treated by C. Staniland Wake, in his "Development of Kinship and Marriage." PRENATAL CULTURE. In the last preceding chapter we have considered the subject of the improvement of the race, especially through the action of sexual selection, or, as it may be expressed, selective action in the pairing of individuals, whether brought about compulsorily by the controlling influence of the State or some other external authority, or by the actual choice of one or both of the individuals immediately concerned. We have now to deal with the subject of the influence over offspring of affections of the individual organisms from whose union such offspring is derived. JACOB'S FLOCKS.--The story of Jacob dealing with the flocks of Laban, given in Genesis xxx, is usually alluded to in corroboration of the belief that offspring may be physically affected before birth, by anything which strongly influences the imagination of the mother. Jacob is represented as making an agreement with Laban, his father-in-law, that Jacob should receive as his hire all the ringstreaked and spotted he-goats and all the black she-goats, and also those that were speckled and spotted. When this arrangement had been made, Laban sought to benefit by it by removing from the flock all the goats that answered to that description, and giving them into the care of his sons, leaving the rest of the flock in Jacob's charge. This was undoubtedly an attempt on the part of Laban to cheat his son-in-law out of his wages, but the latter was not to be so cheated, and he adopted a plan which gave him the pick of the flock, leaving the feeble goats to his less wily parent. In describing this operation, the Bible story says: "And Jacob took him rods of fresh poplar [or storax tree] and of the almond and of the plane tree, and peeled white streaks in them, and made the white appear which was in the rods. And he set the rods which he had peeled over against the flocks in the gutters in the watering troughs where the flocks came to drink; and they conceived when they came to drink. And the flocks conceived before the rods, and the flocks brought forth ringstreaked, speckled and spotted. And Jacob separated the lambs, and set the faces of the flocks toward the ringstreaked and all the black in the flock of Laban; and he put his own droves apart, and put them not unto Laban's flock. And it came to pass, whensoever the stronger of the flock did conceive, that Jacob laid the rods before the eyes of the flock in the gutters, that they might conceive among the rods; but when the flock were feeble, he put them not in: so the feebler were Laban's, and the stronger Jacob's." Whether or not this incident actually occurred as stated we do not know. According to the subsequent part of the narrative, the effect of setting up the peeled rods was ascribed to God's interference in his behalf; but it is not improbable that we have in the story a reference to ancient shepherd lore, based on the superstitious notions still so common in the East. In the earlier part of the same chapter is a story relating to mandrakes, which were supposed to have influence on human generation. Jacob is said to have used three kinds of rods, those of the poplar or storax tree, the almond, and the plane tree, which produced ringstreaked, speckled and spotted lambs. The influence exerted by Jacob's rods was of a different character from that which is supposed to give rise to the marking of offspring before birth, which is not uncommon if we are to accept as true all the cases mentioned in books referring to the subject. What occurred took place _before_ conception, and not subsequent to it, as in these cases. Nevertheless, both classes of phenomena are recognized by so competent an authority as M. Th. Ribot, who, in his "Heredity,"[57:A] when criticising Dr. Lucas' explanation of the origin of the numerous exceptions to the law of heredity, as being due to the operation of the law of spontaneity, affirms that there is no law of spontaneity, but that all such exceptions may be explained by reference to certain causes of diversity. M. Ribot gives three causes of diversity, which are: 1--Antagonistic heredities of two parents; 2--Accidental causes in action at the moment of generation; 3--External and internal influences subsequent to conception. He assigns but little importance to causes acting after birth, such as diet, climate, circumstances, education, physical and moral influences, because, though they may produce serious effects, these are not radical. Possibly, however, since the advance made in the education of those who are born with defects of the sensory apparatus, M. Ribot would somewhat modify his opinion on that point. As to the causes which operate at the period of conception, or subsequent thereto and before birth, he says, in relation to the latter class, they "are all the physical and moral disturbances of uterine existence--all those influences which can act through the mother upon the fetus during the period of gestation; impressions, emotions, defective nutrition, effects of imagination." He adds: "These causes are very real, despite the objections of Lucas, who attacks them in order to establish his law of spontaneity. We see from examples that between considerable causes and their effects there exists an amazing disproportion." The causes of diversity which operate at the instant of conception depend, says Ribot, "less upon the physical and moral natures of the parents than on the particular state in which they are at the moment of procreation." This fact is referred to by M. de Quatrefages as fully proving the universality of the law of heredity, and M. Ribot adds, "It enables us to understand that those transitory states which exist at the moment of conception may exert a decisive influence on the nature of the being procreated, so that often, where now we see only spontaneity, a more perfect knowledge of the causes at work would show us heredity." Professor E. D. Cope, the well-known author of "The Origin of the Fittest," would seem to doubt the truth of the stories of birthmarks on the ground that "the effect of temporary impressions on the mother is not strong enough to counterbalance the molecular structure established by impressions oftener repeated throughout much longer periods of time."[59:A] And yet there is no doubt that birthmarks do occasionally occur, although it is very difficult to obtain properly authenticated cases of them. AN ILLUSTRATIVE CASE.--How great is the influence on unborn offspring of the mother's mental condition, as well as the effect over them of pleasant surroundings, is shown by the following case. A young girl attracted attention by her beauty and by the superiority of the type she exhibited over that of either of her parents, and on her mother being spoken to on the subject she remarked: "In my early married life my husband and I learned how to live in holy relations, after God's ordinance. My husband lovingly consented to let me live apart from him during the time I carried this little daughter under my heart, and also while I was nursing her. Those were the happiest days of my life. Every day before my child was born, I could have hugged myself with delight at the prospect of becoming a mother. My husband and I were never so tenderly, so harmoniously, or so happily related to each other, and I never loved him more deeply than during those blessed months. I was surrounded by all beautiful things, and one picture of a lovely face was especially in my thought. My daughter looks more like that picture than she does like either of us. From the time she was born she was like an exquisite rosebud--the flower of pure, sanctified, happy love. She never cried at night, was never fretful or nervous, but was all smiles and winning baby ways, filling our hearts and home with perpetual gladness. To this day, and she is now fourteen years old, I have never had the slightest difficulty in bringing her up. She turns naturally to the right, and I never knew her to be cross or impatient or hard to manage. She has given me only comfort; and I realize from an experience of just the opposite nature that the reason of all this is because my little girl had her birthright." The future experience of this lady was, however, of a very different nature. She added: "A few years later I was again about to become a mother, but with what different feelings! My husband had become contaminated with the popular idea that even more and frequent relations were permissible during pregnancy. I was powerless against this wicked sophistry, and was obliged to yield to his constant desires. But how I suffered and cried; how wretched I was; how nervous and almost despairing! Worst of all, I felt my love and trusting faith turning to dread and repulsion. "My little boy, on whom my husband set high hopes, was born after nine of the most unhappy, distressing months of my life, a sickly, nervous, fretting child--myself in miniature, and after five years of life that was predestined by all the circumstances to be just what it was, after giving us only anxiety and care, he died, leaving us sadder and wiser. "I have demonstrated to my own abundant satisfaction that there is but one right, God-given way to beget and rear children, and I know that I am only one of many who can corroborate this testimony." The following case of prenatal culture appeared in _The Philosophical_ for October 5, 1895, above the signature of "John Allyn," who says: "About forty years ago I was a neighbor of a young couple who had been recently married. They were of fair natural abilities, but not highly educated. The wife could play on the piano well and accompany it with her voice. The husband was a house-building contractor. Before their first child was born the wife was provided with instruments for drawing, and interested herself in their use and mathematical calculations connected with them. The child proved to be a boy, who took to architectural drawing as by instinct. With very little effort he became proficient, and is now employed at a high salary by the Southern Pacific Railroad as their architect. "Some years later, before the second child was born, the mother interested herself with music with reference to the effect it would have on the unborn child. This child proved to be a girl, who is now an expert singer, finding ready employment in opera companies. Though not a star, she has a superior talent for music which enabled her to take advantages of musical training easily." BELIEFS OF PRIMITIVE PEOPLES.--Whenever such cases happen, it is under the influence of some very strong emotion, during the period of gestation, arising from the action on the nervous system of the mother by an external object presented to the sight, the organ of which would seem to have an intimate association with the general muscular system. There is nothing to show that primitive peoples recognized the action of prenatal influence through the senses; but there is a very curious custom, which is so widespread at the present time that we may well suppose it to have been formerly almost universal, dependent upon the imagined effect of the eating of animal flesh. All primitive peoples believe that a man acquires physical or mental characteristics from animals of whose flesh he partakes. Cannibalism is closely connected with this notion, as the man who eats part of the body of a foe is thought to become endowed with the victim's courage, strength or other special quality. Probably the Mosaic regulations as to unclean animals, that is, animals unfit for food, was based on such an idea; and certainly the command to abstain from eating blood was thus connected; as we are told the blood is the life, and if so, then it must be the carrier of vital influences. The custom above referred to, which is known to ethnologists as _la couvade_, or "hatching," supposes injurious action on the organism of the child of food eaten by its parents, as appears from the facts brought together by Dr. E. B. Tylor in his "Researches into the Early History of Mankind." The couvade usually has reference to the period immediately following the birth of a child; but among the native tribes of South America, where it is more extensively prevalent than elsewhere, it is observed while the child is still unborn. Thus, in Brazil, according to Von Martius, "A strict regimen is preserved before the birth; the man and the woman refrain for a time from the flesh of certain animals, and live chiefly on fish and fruits." The peculiarity of the couvade custom, and that which gives it its special interest, is the fact that it usually concerns the father and not the mother, as injury to the child is supposed to be due to the conduct of the former rather than of the latter. Thus, among the Land Dyaks of Borneo, "The husband, before the birth of his child, may do no work with a sharp instrument, except what is necessary for the farm; nor may he fire guns, nor strike animals, nor do any violent work, lest bad influences should affect the child; and after it is born the father is kept in seclusion indoors for several days, and dieted on rice and salt, to prevent not his own but his child's stomach from swelling." Here food abstinence takes place after the birth of the child, but, according to Brett, in Guinea "Some of the Acawois and Caribi nations, when they have reason to expect an increase of their families consider themselves bound to abstain from certain kinds of meat, lest the expected child should, in some mysterious way, be injured by the partaking of it. The acouri (or agouti) is thus tabooed, lest, like that little animal, the child should be meager; the haimara, also, lest it should be blind--the outer coating of the eye of the fish suggesting film or cataract; the labba, lest the infant's mouth should protrude like the labba's, or lest it be spotted like the labba, which spots would ultimately become sores." Another related case, of more recent observation, is that of the Motumotu of New Guinea, who say that after conception the _mother_ must not eat sweet potato or taro, lest the head of the child grow out of proportion, and the _father_ must not eat crocodile or several kinds of fish, lest the child's legs grow out of proportion. At Suan, a husband shuts himself up for some days after the birth of his first child, and will eat nothing.[65:A] Various explanations of the custom of couvade have been offered, and probably C. Staniland Wake is right when he states that it is connected with the idea that the father is the real source of the child's life.[66:A] As he points out, on the authority of M. Girard-Teulon, among the European Basques, even at the present day, a husband enters his wife's abode only "for the purpose of reproduction, and to work for the benefit of his wife." Mr. Wake remarks that, "With some of the Brazilian tribes, when a man becomes a father he goes to bed instead of his wife, and all the women of the village come to console him for the pain and suffering he has had in making this child." This agrees with the idea entertained by so many peoples that the child is derived from the father only, the mother being merely its nourisher. When such an idea is held, it is not surprising if, as among the Abipones, the belief is formed that "the father's carelessness influences the new-born offspring, from a natural bond and sympathy of both," or if the father abstains, either before or after the child's birth, from eating any food, or performing any actions which are thought capable of doing it harm. Still more so, if the child is regarded, as is sometimes the case, as the reincarnation of the father, a notion which is supported by the fact, pointed out by Mr. Gerald Massey, that in the couvade the parent identifies himself with the infant child, into which he has been typically transformed. That conclusion agrees with the opinion expressed by Mr. Tylor, that the couvade "implicitly denies that physical separation of 'individuals' which a civilized man would probably set down as a first principle common by nature to all mankind. . . . It shows us a number of distinct and distant tribes deliberately holding the opinion that the connection between father and child is not only, as we think, a mere relation of parentage, affection, duty, but that their very bodies are joined by a physical bond, so that what is done to the one acts directly upon the other."[67:A] The couvade custom is thus closely connected with the question of the special relationship of a child to one or other of its parents. Curious notions on this subject have been formed from time to time; but the ancients almost universally entertained the idea held by the Greeks that "the father, as endowed with creative power, was clothed with the divine character, but not the mother, who was only the bearer and nourisher of the child." Professor Hearn accepts this view in his work, "The Aryan Household," and suggests as the Aryan thought on the subject: "A male was the first founder of the house. His descendants have 'the nature of the same blood' as he. They, in common, possess the same mysterious principle of life. The life spark, so to speak, has been once kindled, and its identity, in all its transmissions, must be preserved. But the father is the life-giver. He alone transmits the life spark, which from his father he received. The daughter receives, indeed, the principle of life, but she cannot transmit it." M. Ribot, who, as we have seen, endorses the popular belief as to the possibility of the fetus being affected, during uterine existence, through the organism of the mother, reduces all the obscure causes of deviation from heredity to two classes. Of these, the first is the disproportion of effects to causes, already mentioned; and the second is the transformation of heredity. As to the first of these causes, he lays it down as a general truth that "the more complicated the mechanism, the greater the disproportion between accidental causes and their effects." He supports this conclusion by reference to Geoffroy Saint-Hilaire's researches on the production of monsters, and he affirms that the disproportion between cause and effect cannot be foreseen by measuring, but is known only by experience, as "psychological laws are analogous now to mechanical and now to chemical laws," so that it is impossible to proceed by deduction from causes to effects. (Page 207.) BIRTHMARKS RARE.--And yet the very fact that cases of birthmarks are comparatively rare, proves the greatly preponderating influence of heredity over the constitution of the offspring, modified by the disposition of the parents at the time of procreation. Professor Cope has some explanatory remarks on that subject which deserve quotation. He says--after referring to the hypothesis that growth-force may be, through the motive force of the animal, directed to any locality, whether the commencement of an executive organ has begun or not--that "A difficulty in the way of this hypothesis is the frequently unyielding character of the structure of adult animals, and the difficulty of bringing sufficient pressure to bear on them without destroying life. But, in fact, the modifications must, in most instances, take place during the period of growth. It is well known that the mental characteristics of the father are transmitted through the spermatozoid, and that, therefore, the molecular movements which produce the mechanism of such mental characters must exist in the spermatozoid. But the material of the spermatozoid is combined with that of the ovum, and the embryo is compounded of the animal contents of both bodies. In a wonderful way the embryo develops into a being which resembles one or both parents in minute details. This result is evidently determined by the molecular and dynamic character of the original reproductive cells which necessarily communicate their properties to the embryo which is produced by their subdivisions." Professor Cope goes on to say, "Richard Hering has identified this property of the original cells with the faculty of memory. This is a brilliant thought, and, under restriction, probably correct. The sensations of persons who have suffered amputation show that their sensorium maintained a picture or map of the body so far as regards the location of all its sensitive regions. This simulcrum is invested with consciousness whenever the proper stimulus is applied, and the character of the stimulus is fixed by it. This picture probably resides in many of the cells, both sensory and motor, and it probably does so in the few cells of simple and low forms of life. The spermatozoid is such a cell, and, how or why we know not, also contains such an arrangement of its contents, and contains and communicates such a type of force. It is probable that in the brain-cell this is the condition of memory of locality. If, now, an intense and long-continued pressure of stimulus produces an unconscious picture of some organ of the body in the mind, there is reason to suppose that the energies communicated to the embryo by the spermatozoid and ovum will partake of the memory thus created. The only reason why the oft-repeated stories of birthmarks are so often untrue, is because the effect of temporary impressions on the mother is not strong enough to counterbalance the molecular structure established by impressions often repeated throughout much larger periods of time."[71:A] WHY CHILDREN RESEMBLE PARENTS.--That children reproduce the general and physical and mental characteristics of their parents in combination is unquestionable truth, although the particular mode in which they are communicated is yet undetermined, notwithstanding the fact mentioned by Professor Cope that they are somehow conveyed by the microscopic sperm and germ in the union of which the new being has its beginning. Thus every individual must possess the general characteristics of the primitive human family from which through a vast number of ancestors he has descended. And yet at every stage of descent the organism may have obtained fresh characters, or at least have undergone some modification. As remarked by Dr. G. H. Th. Eimer, "Every character which must have been formed through the activity of the organism is an acquired character. All characters, therefore, which have been developed by exertion are acquired, and these characters are inherited from generation to generation. The same holds for all organs atrophied through disease--the degree of atrophy is acquired and inherited. In the first class we see especially the action of direct adaptation; in the second, the results of the cessation of the action. A third class of acquired characters is to be traced simply to the immediate action of the environment on the organism, and, originally, at the commencement of their appearance, all characters must have belonged to this class."[72:A] We have here a general argument in opposition to the theory propounded by Professor Weismann, that acquired characters are not transmissible. Elsewhere (page 382) Dr. Eimer observes: "Phyletic growth, or the evolution of the organic world ever into higher and more complex forms, or at least into forms of different structure, is, as I have said, merely the sum of the processes of growth of the ancestors--together with the result of external influences on the forms during their development and their existence. This additional modification which the individuals as such undergo is--together with the influence of crossing--the very cause of the constantly progressing evolution. All that the members of a series of individuals directly connected by descent acquire constitutes together the material for the formation of a new species." LIFE'S EXPERIENCES AFFECTING CHILD.--Unless characteristics acquired by an individual, that is, the modifications of the organism due to his own life experiences, are capable of being handed down to his offspring, it is difficult to see how any progress could be made in the development of the race. Weismann's declaration that acquired characters are not transmissible was a surprise to the scientific world when first made, but it has been accepted by many Darwinians. His conclusion is dependent on his doctrine of heredity, which differs from that propounded by Darwin, but is by no means new; as its leading ideas, as pointed out by Professor G. J. Romanes,[73:A] are largely a reproduction of those of Mr. Francis Galton, whose work on heredity attracted much attention when first published. The views of Darwin, Galton and Weismann on that subject have been compared by Professor Romanes, who explains the distinction between them. He says (page 133), after referring to the supposed continuity of the germ-plasm, common to the theories of Galton and Weismann, but not required by that of Darwin, "The three theories may be ranked thus--The particulate elements of heredity all proceed centripetally from somatic-cells to germ-cells (gemmules): the inheritance of acquired characters is therefore habitual. "These particulate elements proceed for the most part, though not exclusively, from germ-cells to somatic-cells (stirp): the inheritance of acquired characters is therefore but occasional. "The elements in question proceed exclusively in the centrifugal direction last mentioned (germ-plasm): the inheritance of acquired characters is therefore impossible." The first of these theories is that of Darwin, and the last that of Weismann, whose notion of the continuity of germ-plasm supposes that no part of an organism generates any of the formative material which goes to make up its offspring. This material is regarded in much the same light as the sperm which the male parent confides to the keeping of the female, according to the notion of the ancient world above referred to. For, as Romanes states (page 26): "In each generation a small portion of this substance [germ-plasm] is told off to develop a new body to lodge and nourish the ever-growing and never-dying germ-plasm--this new body, therefore, resembling its so-called parent body simply because it has been developed from one and the same mass of formative material; and, lastly, that this formative material, or germ-plasm, has been continuous through all generations of successively perishing bodies, which therefore stand to it in much the same relation as annual shoots to a perennial stem: the shoots resemble one another simply because they are all grown from one and the same stock." Although Professor Weismann denies that acquired characters, that is, individual peculiarities arising as the result of personal experience, are transmitted, he admits that congenital characters, that is, peculiarities with which an individual is born, are transmitted to offspring. As congenital characters must, originally, have been individual, it is not easy at first sight to perceive Weismann's real meaning. It is necessary, therefore, to enter more particularly into a consideration of his theory, which he regards as in general accord with Darwin's theory of pangenesis. Darwin supposes that all the cells of the body continually give off great numbers of _gemmules_, which are conveyed by the blood and deposited in the germ-cells of the organism. These cells are thus endowed with the power of developing a new organism of the same kind, each gemmule reproducing the cell from which it was derived. These ultimate vital units are called by Weismann _biophors_, but he supposes them not to be the ultimate "bearers of vitality." They are said to be arranged in groups to which the term _determinants_ is applied, and these groups are combined so as to form ancestral _ids_ or germ-plasms. Each determinant, which is made up of perfectly definite numbers and combinations of biophors, is the primary constituent of a particular cell, or of a group of cells, such as a blood corpuscle. The determinants thus "control the cell by breaking up into biophors, which migrate into the cell body through the nuclear membrane, multiply there, arrange themselves according to the forces within them, and determine the histological structure of the cell," impressing upon it its inherited specific character. The structure of the cell, and of every subsequent stage, exists therefore potentially in the inherited structure of the id, and the determination of its character "depends on the biophors which the corresponding determinant contains, and which it transmits to the cell." GERM-PLASM.--While Weismann regarded germ-plasm as absolutely stable, the only mode by which congenital variation could be brought about was that of _amphimixis_, or intermingling of individuals in the process of generation. As modified, however, by his latest work, "The Germ-plasm, a Theory of Heredity," published in 1892, his theory now allows the plasm to be capable of modification, and he ascribes that variation to the direct effects of external influences on the biophors and determinants of the germ-plasm. The instability of this substance is so slight, however, that congenital variations cannot be acted on and perpetuated by natural selection, and the influence of amphimixis is thus required for the purpose. Mr. Herbert Spencer, however, in criticising Weismann's theory, declares that "functionally produced modifications of structure are transmissible," and he refers in support of his contention to the remarkable effect of arrested nutrition on the structure and habits of wasps and bees. It especially affects the reproductive organs, and hence there is no occasion to call in the aid of amphimixis to perpetuate the variations produced, its office being the blending of the elements on which the characteristics of offspring depend. If it be asked how modifications are actually transmitted, we may say that it can be only by an affection of the germ-cell. This probably takes place by deviations in the structure of what Weismann calls determinants, or of groups of determinants, through rearrangement of their primary units. The modification would be preceded, however, by a corresponding change in the nerve centers concerned in the use or disuse of the organs affected. Mr. Spencer shows that under certain conditions changes take place in the conduct of certain insects, and that "the maternal activities and instincts undergo analogous changes,"[77:A] facts which point to a loss of nervous energy and to an intimate connection between the nervous system and the reproductive function. Use or disuse first increases or diminishes the activity of certain nerve centers, and this leads to a modification of the corresponding germ-cells. If so, the determinants, instead of being first affected, as proposed by Weismann, and thus determining the variations, are in reality modified as the result of the functional changes, and are thus capable of transmitting these changes to succeeding generations. In a subsequent article, published in _The Contemporary Review_ for October, 1894, Mr. Spencer recapitulates his argument in favor of the transmission of acquired characters, and refers to observations made by Professor Hertwig and others, which he regards as "showing, firstly, that all the multiplying cells of the developing embryo are alike; and, secondly, that the soma-cells of the adult severally retain, in a latent form, all the powers of the original embryo-cell," facts which he rightly considers disproves Weismann's hypothesis of _panmixia_. If this is surrendered, then, says Mr. Spencer, "all that evidence collected by Mr. Darwin and others, regarded by them as proof of the inheritance of acquired characters, which was cavalierly set aside on the strength of this alleged process of panmixia is reinstated. And this reinstated evidence, joined with much evidence since furnished, suffices to establish the repudiated interpretation." Great stress was laid by Professor Weismann, as evidence in support of his theory, on the supposed fact that the inheritance of injuries sustained during life has not been proved. Particular attention has been paid to this point by Dr. Eimer, in relation to which he remarks: "That injuries incurred during life are but seldom transmitted to the offspring does not appear to me wonderful: the inheritance of the complete form and complete activities of the organism, which took root such enormously long periods of time ago, and has been strengthened at each generation, will, as a rule, counterbalance in the offspring any such injuries incurred only once and not repeated."[79:A] This is the same argument as was used, as quoted above, by Professor Cope, to disprove the occurrence of birthmarks, and Dr. Eimer goes on to state that there are injuries which are not transmitted to offspring, although they are constantly repeated, as an instance of which he refers to the rupture of the hymen. He adds, however: "In such cases we must presume a specially effective power of correlative activity, directed to the part affected and residing in the whole organism--the same compensating power which leads in lower animals, during the life of the individual, to the regeneration of parts which have been lost or artificially removed. But these cases do not prove the general proposition that injuries are not inherited; they do not prove that even injuries which have been repeated during a considerable period are not inherited. Hitherto little importance has been attached to the demonstration of the inheritance of injuries. Yet single cases of the inheritance of injuries only once incurred seem to me to be thoroughly authentic." CONGENITAL DEFORMITIES.--Professor Weismann, in replying to the criticisms of Professor Virchow, admitted the existence of a number of congenital deformities, birthmarks and other individual peculiarities, which are inherited, but he affirms that we do not know from what causes they first appeared, and that a great proportion of them proceed from the germ itself, and are due, therefore, to alteration of the germinal substance. There is no proof of this, however, according to Dr. Eimer,[80:A] who appeals to various facts in support of his contention that injuries and diseases are inherited. He thinks the degeneration of the tail in the higher mammals is a case in point, although it has required great periods of time to complete. Among other instances of inherited injuries mentioned by Dr. Eimer is one in which a scar over the left ear and temple, caused to a girl by being thrown from a carriage, was transmitted to her son and grandson, the son of the latter also showing absence of hair on the injured spot, although the defect gradually disappeared with him, nearly a hundred years after the accident. The case of Dr. Nosseler, who inherited from his mother a crushed finger joint, caused by an accident which happened two years before his birth, would seem to be conclusive proof that injuries are transmissible. Dr. Eimer refers also to the breeding of short-tailed pointers from dogs whose tails had been artificially shortened; and also to Brown-Sequard's experiments with guinea pigs, in which epilepsy was inherited by their offspring, who showed also the loss of certain phalanges, or even whole toes of the hind feet, the parents having suffered a similar loss owing to the division of the sciatic nerve. He adds that numerous other instances of the inheritance of injuries have been recorded, as "inheritance of the artificially shortened tail of the bull, of artificially produced hornlessness in cattle, many cases of inheritance in man of curvature in a finger, caused by injury, inheritance of the absence of one eye which had been lost by the father during life or by disease, etc." The question of the inheritance of deformities and diseases, and the causes of the germ-variations on which it depends, have been considered by Zeigler, whose conclusions, as quoted by Dr. Eimer (page 186), are too important to be omitted. The causes which Zeigler assigns for the origin of such germ-variations are of three kinds. These are: 1--Union of sexual nuclei which are not adapted for copulation; 2--Disturbance of the copulatory process itself; 3--Injurious influences which affect the sexual nuclei or the fertilized ovum at a time when separation of the sexual cells from the body cells has not yet occurred. "If the embryo is injuriously affected at a later period," says Zeigler, "either a malformation or a constitutional anomaly arises, which is not inherited, or only the sexual cells are injured, in which case the body-cells develop normally, and a disturbance shows itself only in the development of the next generation." The union of sexual nuclei not adapted for copulation appears, however, to be "the most frequent and most important cause of hereditary local malformations as well as of hereditary morbid tendencies, or of a defect in any system of the whole organism." If the nuclei are altogether unadapted to each other, sterility occurs, as in the sexual nuclei of distinct species. PSYCHICAL DISEASES.--Zeigler's conclusions are supported by reference to the enquiries of the distinguished psychiatrist, D. Von Krafft-Ebings, who has considered the heredity of psychical diseases, and in connection therewith mentions three "essential facts" which it is necessary to keep in view when dealing with that subject. The first of these facts is Atavism, by which "the bodily and mental organization and character can be transmitted from the first to the third generation, without any necessity that the second and intermediate one should exhibit the peculiarities of the first--thus the condition of the life and health of the grandparents are of interest for us." Secondly, "Only in rare cases is the actual disease transmitted in procreation (congenital insanity, hereditary syphilis), as a rule only the disposition thereto. Actual disease only occurs when accessory injurious influences produce an effect based upon that disposition. . . . We must, therefore, consider also the state of health of the relatives (uncles, cousins, aunts), and since here also the law of atavism holds good, the possible diseases of great-uncles and great-aunts." Thirdly, Dr. Von Krafft-Ebings says, "Only exceptionally does the same disease develop in ascendant as in descendant lines, in consequence of the transmission of morbid dispositions. On the contrary, there exists a remarkable variability in the forms of disease which may almost claim the value of a law (the law of polymorphism or transmutation)." This law is referred to by M. Ribot as one of the causes of deviation from heredity, and he speaks of it as "transformation." As examples of transformation of heredity, Ribot refers to fixed ideas in the progenitor, which may become in the descendants "melancholy, taste for meditation, aptitude for the exact sciences, energy of will, etc.;" the mania of progenitors may be changed in the descendants into "aptitude for the arts, liveliness of imagination, quickness of mind, inconsistency in desires, sudden and variable will." "Just as real insanity," says Moreau of Tours, "may be hereditarily reproduced only under the form of eccentricity, may be transmitted from progenitors to descendants only in modified form, and in more or less mitigated character, so a state of simple eccentricity in the parent--a state which is no more than a peculiarity or a strangeness of character--may in the children be the origin of true insanity. Thus in transformations of heredity we sometimes have the germ attaining its maximum intensity; and again, a maximum of activity may revert to the minimum."[84:A] It should be borne in mind, as mentioned by Von Krafft-Ebings,[84:B] that everything which debilitates the nervous system and the generative powers of the parents, "be it immaturity or too advanced old age, previous debilitating diseases (typhus, syphilis), mercurial treatment, alcoholic and sexual excesses, overwork, etc., may give rise to neuropathic constitutions, and thereby indirectly to every possible nervous disease in the descendants." TELEGONY.--There is one remarkable phenomenon, spoken of by various writers as _telegony_, which has an important bearing on the subject of the transmission of acquired characters, and shows the action of prenatal influence in an unexpected form. It is referred to by Professor Romanes, when he says, "It has not unfrequently been observed, at any rate in mammals, that when a female has borne progeny to a male of one variety, and subsequently bears progeny to a male of another variety, the younger progeny presents a more or less unmistakable resemblance to the father of the older one."[85:A] This curious fact was considered, in relation to plants especially, by Darwin, who affirms, as quoted by Romanes, that it is of the highest theoretical importance, as "The male element not only affects, in accordance with its proper function, the germ, but at the same time various parts of the mother-plant, in the same manner as it affects the same parts in the seminal offspring from the same two parents. We thus learn that an ovule is not indispensable for the reception of the influence of the male element." The curious phenomenon of telegony is not limited, however, to plants. Mr. Herbert Spencer drew attention, in _The Contemporary Review_ for March, 1893, to a case which has long been known to horsebreeders, and which may be said to have become classic. The facts were brought, by the Earl of Morton, to the attention of the Royal Society of Great Britain, as long ago as the year 1820. The Earl, who possessed a male quagga, said, in a letter to the President: "I tried to breed from the male quagga and a young chestnut mare of seven-eighths Arabian blood, and which had never been bred from; the result was the production of a female hybrid, now five years old, and bearing, both in her form and in her colour, very decided indications of her mixed origin. I subsequently parted with the seven-eighths Arabian mare to Sir Gore Ouseley, who has bred from her by a very fine black Arabian horse. I yesterday morning examined the produce, namely, a two-year-old filly and a one-year-old colt. They have the character of the Arabian breed as decidedly as can be expected, where fifteen-sixteenths of the blood are Arabian; and they are fine specimens of that breed; but both in their colour and in the hair of their manes they have a striking resemblance to the quagga. Their colour is bay, marked more or less like the quagga in a darker tint. Both are distinguished by the dark line along the ridge of the back, the dark stripes across the forehead, and the dark bars across the back part of the legs." Mr. Spencer refers to an analogous case of the influence of a wild boar over the subsequent progeny of a domestic sow, and it now appears that such effects are not so uncommon as the scientific world has supposed. Professor Romanes made particular enquiries on this subject of professional and amateur breeders of animals, and he says most of his correspondents "are quite persuaded that it is of frequent occurrence, many of them regard it as a general rule, while some of them go so far as to make a point of always putting a mare, bitch, etc., to a good pedigree male in her first season, so that her subsequent progenies may be benefited by his influence, even though they be engendered by inferior sires."[87:A] His own more modest conclusion is that the evidence he obtained "is enough to prove the fact of a previous sire asserting his influence on a subsequent progeny, although this fact is one of comparatively rare occurrence." The English Darwinian met with only one case in which the offspring of a woman by a second husband, who was a white man, showed the influence of her first husband, who was a negro. Mr. Herbert Spencer would seem to have been more successful. In _The Contemporary Review_ for May, 1893, Mr. Spencer gives the result of his own enquiries as to the effect on a white woman's subsequent progeny of a previous union with a negro, and he quotes the opinion of a "distinguished correspondent," that information given to him many years ago was to the effect that "the children of white women by a white father had been _repeatedly_ observed to show traces of black blood, in cases where the woman had previous connexion with [i. e., a child by] a negro." Mr. Spencer refers also to Professor Marsh as authority for such a case, and to the opinion of several medical professors who assured him, through Dr. W. J. Youmans, that the alleged result "is generally accepted as a fact." He gives as authoritative testimony the following statement by Dr. Austin Flint, taken from his "Text-book of Human Physiology:" "A peculiar and, it seems to me, an inexplicable fact is, that previous pregnancies had an influence upon offspring. This is well known to breeders of animals. If pure blooded mares or bitches have been once covered by an inferior male, in subsequent fecundations the young are likely to partake of the character of the first male, even if they be bred with males of unimpeachable pedigree. What the mechanism of the influence of the first conception is, it is impossible to say; but the fact is incontestable. The same influence is observed in the human subject. A woman may have, by a second husband, children who resemble a former husband, and this is particularly well marked in certain instances by the color of the hair and eyes. A white woman who has had children by a negro may subsequently bear children to a white man, these children presenting some of the unmistakable peculiarities of the negro race." This phenomenon would alone seem to answer the question of the transmission of acquired characters in the affirmative, for its explanation is to be found in the facts brought out by Darwin, as to the action of foreign pollen on the structure of the mother plant; in relation to which Professor Romanes remarks: "When one variety fertilizes the ovules of another not unfrequently the influence extends beyond the ovules to the ovarium, and even to the calyx and flower-stalk, of the mother plant. This influence, which may affect the shape, size, colour, and texture of the somatic tissues of the mother, has been observed in a large number of plants belonging to many different orders."[89:A] May we not have here the explanation of the fact, which has frequently been pointed out, that husband and wife show a tendency to grow like each other, both physically and mentally, the resemblance after a long married life being sometimes very striking? POWER OF HEREDITY.--The most important fact brought out in the discussion of the possibility of the transmission of acquired characters is the power of heredity. If organisms did not reproduce their own special characteristics, there could be no fixity of form and no order in organic nature. Nevertheless, if there were no change by individual modification or divergence, in whatever way this may be rendered permanent in the race, there could be no evolution. Hence we can say, with Dr. Eimer, "Any one who thus completely renders allegiance to the supremacy of the principles of the unity of the organic world, who rejects everything which contradicts that principle, cannot help admitting that in truth, as I assert, the ultimate origin of the various kinships in the animal and vegetable kingdom is to be traced to individual differences, and that the difference between the former, like the latter, must be essentially determined by external conditions, by the modification of organic growth." The causes of diversity which interfere with the action of heredity may operate, as we have seen, at the moment of conception, or subsequent to conception. The former class of causes is of great importance, in accordance with the principle, laid down by M. Ribot, of the disproportion of effects to causes, and it is essential, therefore, if children are to be well-born, that their parents should be careful that at the moment of procreation they are fitted for the performance of so serious an act. Mr. J. F. Nisbet in his "Marriage and Heredity" (page 126), well observes, "Twins usually bear a closer resemblance to each other than to their brothers and sisters born at a different period; and the reason generally assigned is that they are conceived under precisely similar conditions. If so, it follows that the difference existing between ordinary members of a family is due to their being born at considerable intervals of time and therefore under changed conditions on the part of their parents." SOBRIETY IN THE FATHER.--Especially does it concern the father, who is the most active agent in reproduction, to see that he is then in a fit condition. This is quite apart from the question of the diseased condition of the organism treated of by Dr. Von Krafft-Ebings, and refers to temporary rather than to continuing causes. Sobriety is in this connection of great importance, and, as appears from a passage, already quoted, in Xenophon, was insisted on at the time of procreation, by the ancients. Zeigler points out, as quoted by Dr. Eimer, that "substances taken up from without, as, for example, poisons, are brought by the blood to the sexual cells, and others produced in the body are conveyed to the sexual organs."[91:A] It is suggested that alcohol has such an effect, and there can be no doubt that a tendency to the drinking habit may be implanted in a child by a parent intoxicated at the time of procreation, with the possibility of its leading to other evils in succeeding generations, ending in the early extinction of the family. Nisbet refers to several cases of this character, and remarks (page 112) that, "There is a limit to the transmission of abnormal characters, either in an original or in a disguised form. Always striving after perfection, or rather uniformity of type, Nature either purifies a race of its physical and moral defects, or, if the type be too vicious, exterminates it, as in the case of the Cæsars, the Stuarts, and many other historical families." Doutrebente came to the conclusion, however, that insanity--and doubtless it is true of other conditions--may be worked out of a family by the infusion of healthy blood, except where both parents were insane, in which case their offspring will become extinct. The law of Leviticus (chap. x, verse 9) provides, under penalty of death, that the priests should not drink wine or strong drink before going into the tent of meeting. The more stringent regulations provided by this law in relation to intercourse between Jehovah and His people require physical and moral perfection in those who approach the deity, and they may be studied with advantage at the present day by those who wish to aid in the perfecting of the race. The man who had a blemish was not allowed to go near the altar of sacrifice, that the sanctuary might not be profaned; and the sanctuary of the human organism should no less be preserved from profanation. SACREDNESS OF PARENTAGE.--It would be well if the sacred act of procreation were performed more often in the spirit of the ancients, who regarded marriage as a sacred institution, designed not only for the perpetuation of the race, but also for the carrying on of the religion of the domestic hearth. The first-born child especially was considered to have been sent by the gods, and care was taken, therefore, that it should be well-born. Prayer and offerings were made to the spirits before the nuptial bed was approached, and everything was done to ensure the gift they were asked for should be in every respect worthy of them. Among the ancient Hebrews the first-born of "all that openeth the womb" was dedicated to Jehovah (Exodus xxxiv, 19), and hence the rights of the eldest son could not be defeated by his father: "for he is the beginning of his strength" (Deut. xxi, 17). The disturbance of uterine existence between conception and birth is that which has engaged most attention, and the fact that such disturbances can take place requires that the expectant mother should be protected from anything that can so act on her own organism as to prevent the due operation of the law of heredity. The precautions taken by primitive peoples in relation to food may have some foundation in fact, and any food should be avoided by the enceinte woman which will injuriously influence the system, or give rise to organic disturbances that may affect the blood by which the embryo is nourished. Emotional disturbances are to be no less avoided, as through the nervous system they act on the blood itself. How far the action of the emotions can influence the physical organism has become a moot question with psychologists, who now seem inclined to think that "movements are not caused by the emotions, but are aroused reflexly by the object." Thus, if the sight of a disagreeable object affects by reflex action the muscular system of the mother, it will arouse in her a concomitant emotion, which being transmitted to the embryo may act on its muscular system, leaving the impression as a birthmark, which may be regarded as a reflection from the cerebral nerve center of the mother, whether emotion is the cause or effect of muscular movement. If the unborn child can be affected injuriously by disturbances of the mother's environment, it is reasonable to suppose that the child can be influenced in the opposite direction by making that environment as conducive to the normal activity of the material organism as possible. The story of Jacob and Laban, referred to at the beginning of this chapter, affords an important lesson as to the surroundings with which the wife should be provided. The bedchamber itself may become a means of influencing offspring for good or evil, and hence it should contain only what is agreeable to the senses, and capable of giving rise to pleasant imaginings. Especially should this be the case where a woman is of a highly sensitive nature. Impressions received from without depend largely for their force and influence, however, on the condition of the receptive mind, and beautiful surroundings cannot make up for the want of inward harmony. A happy and contented mind is the best guarantee that the due action of the law of heredity will not be disturbed at the time of conception or afterwards. Thus, bickerings between husband and wife must have a disturbing effect, especially if carried into the bedchamber. The sage of old said: "Let not the sun go down upon thy wrath," and parents should make it a point of duty, for the sake of their future offspring, never to let the disputes of the daytime--if unfortunately they occur--be carried into the night. The bedchamber is the place for mental as well as physical repose. The surest guarantee against the occurrence of conditions which may injuriously affect the future offspring, either at the time of procreation, or during the subsequent period of gestation, is to be found in the general life of the parents. This will give the general impress which affects the disposition of the child as a whole, and it will show what are the conditions of the family life under the influence of which it was born. The nature of the "home" is thus an important factor in determining that of the offspring, and it will necessarily be a reflection of the general character of those on whom it depends. A noble life in the parent will bear fruit in the physical, intellectual and moral character of the child, and although this is true in relation to the father as well as to the mother, it is doubly true as to the latter, seeing that the mother alone is the bearer and nourisher of offspring during the period of gestation. During this period the child acquires probably many of the characters which it inherits from its mother, and the maternal influence may thus be extended to the period of lactation. The importance attached to fosterage, where this practice became an established custom, as with the early Irish and Arabs, would seem to prove that the characteristics of the nurse were to some extent transmitted to the child with the milk. The early Arabs regarded the milk-tie as constituting a real unity of flesh and blood between the foster mother and the foster child, and between foster children, so much so as to be a bar to marriage. SELF-CONTROL.--One very serious matter which should be kept in mind by an expectant mother is the duty of exercising self-control. The influence of this principle in relation to the general life and conduct has been repeatedly pointed out, and it is referred to by Jennie Chandler in _The Journal of Hygiene_ for August, 1895, where we are told: "The power of self-mastery is believed by scientists to be the last one acquired by the human race in the process of evolution, and the last powers acquired are not so firmly fixed in our natures as some which have been longer in our possession. The result is, it becomes deranged more readily than more fixed forces. In many cases, self-control has never been acquired at all, and so the person can only partly master himself. As a rule, children have little of this power. They are like animals. Little by little, as they grow older, it grows, and in some it becomes so well developed that it is almost perfect. In others, like music in those who never acquire it, or any other faculty, it never becomes a potent factor in life." Dr. Chandler adds, "Woman as well as man needs to learn self-mastery. With a large amount of feeling in her nature, it is very hard for her to do it, but she should try. Too many of us go through life never making any effort to be our own masters. We give way to caprices, whims, feelings, follies, far more than is good for our health. Hysteria gives us a good example of the loss of self-control. Any uncontrolled passion gives an equally vivid example. Men and women often say they can't govern themselves; that is admitting they have defects of character which are their masters. They ought to make effort and see if they are not mistaken. The worst effect of lack of self-control are on the health. It allows every kind of bad habit in eating, drinking, dressing, sleeping, to gain possession of the person, and the result is a weak instead of a strong character." Considering the effect which the organic disposition of the mother has on the future offspring, it is evident that whether a child shall have the power of self-control depends very largely on the mother herself, and it is all-important, therefore, that she should have and exercise that power herself. As Dr. Chandler remarks, "No matter how much you have been to school, how many college degrees you have, you are not educated till you have a reasonable control of your own nature, and can direct your own lives rather than have them directed for you by your feelings and emotions." This truth obtains fresh significance when we consider that a woman's conduct affects the direction not only of her own life, but the lives of her future children, and possibly of succeeding generations. Although much has yet to be done to prove the actual effects on offspring of the conduct of its parents, enough is known to establish the fact that both the general disposition and the particular conduct of father or mother may interfere with the orderly action of the law of heredity. This law ensures the inheritance of race and individual characters; but when these are good, a noble life will cause the tendencies towards good to be still further strengthened in offspring, and if they are evil, then the disposition will receive an inclination in the opposite direction, or, at least, the further development of evil will be arrested. On the other hand, a degrading life will produce bad effects on offspring, causing deterioration of the organic disposition and strengthening the tendency to evil it may have inherited, or weakening its tendencies towards the good. FOOTNOTES: [57:A] "Heredity." By Th. Ribot (New York: D. Appleton & Co., 1875), p. 201. [59:A] "The Origin of the Fittest." By E. D. Cope (D. Appleton & Co., New York). Page 408. [65:A] "Pioneering in New Guinea." By James Chalmers. 1887. Page 165. [66:A] "Development of Kinship and Marriage." Page 264. [67:A] "Researches into the Early History of Mankind." Page 292. [71:A] Cope's "Origin of the Fittest." (Redway, London. 1889.) Page 407. [72:A] "Organic Evolution." Translated by J. T. Cunningham, M. A. (London, Macmillan & Co., 1890.) Page 86. [73:A] "Examination of Weismannism." The Open Court Publishing Co., Chicago. 1893. [77:A] _The Contemporary Review_, September, 1893. [79:A] "Organic Evolution." Translated by J. T. Cunningham, M. A. Page 13. [80:A] "Organic Evolution," page 176. [84:A] "Organic Evolution," page 211. [84:B] Op. cit., page 201. [85:A] "Examination of Weismannism," page 77. [87:A] "Examination of Weismannism," page 22. [89:A] "Examination of Weismannism," page 79. [91:A] "Organic Evolution," page 187. HEREDITY AND EDUCATION. _A Lecture delivered before the Brooklyn Ethical Association._ In presenting the subject of heredity and its relation to education, it seems to me best to consider first what is meant by the term, and after this the views held on the subject by our leading evolutionists, when its relation to education will be easier and, I hope, more satisfactory. In common parlance, heredity is the transmission of any trait or peculiarity from the parent to the offspring, as the color of the hair, the form of the nose, the tones of the voice; or any disease, or any special character that may exist in either parent. If a horse has a star on its forehead like one of its ancestors, we say it is due to heredity. If an ox has color marks on its body like its parent, it is a case of heredity. If a human being has a disease which his ancestors had, very often he declares he inherited it from them, even if it be only a common catarrh. But this is a narrow view of the subject, and does not include all that a biologist means when he uses this word. By heredity he understands the production from a fertilized ovum of an individual, with all the general characteristics of structure and function of body and brain of the species to which it belongs. It means that the offspring, however much they may vary in general characters, will always be of the same species as the parents. The offspring of dogs will be dogs; of wolves, wolves; of negroes, negroes, and of white men, white men. Anything less is not heredity in its full sense. Darwin, whom we all love and honor, says: "The whole subject of inheritance is wonderful," and in this he but voices the universal sentiment of those who have given any serious consideration to it. Let me try to show you how wonderful it is by an illustration. From very ancient times the horse has been the constant companion of man. This animal, with his splendid muscular system, the most perfect, perhaps, of any creature, has for his food and shelter, and not always the best of these, rendered mankind almost infinite service. Now, every horse that has ever been born into the world began life as a minute ovum, which under the microscope presents no appearance of a horse, or any other animal, and, strange to say, this ovum is, to all appearance, like the ovum of other animals, and no amount of study, without knowing its origin, can decide whether it will develop as a dog, an ox, a horse or a man. After, however, it has gone through the process of gestation, this apparently simple egg becomes an animal of a very complex nature, with heart, lungs, brain, eyes, ears, mouth, stomach, and blood vessels, all where they should be and ready to perform their functions; with mental traits of a peculiar kind which adapt him to the service which man requires. Nay more: In the process of the evolution of the horse, little by little he has changed in various ways, and many, if not all of these changes in his bodily constitution and in his mental characteristics, which have been found useful or made him more serviceable to man, his greater docility, his increased size, his enormous strength and speed, his wonderful beauty, through a wise selection and the weeding out of the unfit on the part of the breeder, have been transmitted through heredity to his offspring, so that today only a paleontologist can tell us if he finds the remains of a primitive horse, that it belongs to the same class of animals as the horse of our time. THEORIES.--Our theories of heredity will depend on the extent of our knowledge, and especially our knowledge of embryology. In the last century knowledge on this subject was very meagre, especially that part of embryology which could only be studied with the microscope; consequently the views of scientists and others of that time were exceedingly crude. The most important was that of Malphigi and Bonnet, who maintained that the miniature animal existed in the egg; that fertilization by the male element simply furnished it with food for growth, and that this was added to and stored up in its interstices. Cuvier, Haller and Leibnitz adopted substantially these views. The latter found them to support his opinion that everything was the result of growth from monads, and that there was no such thing in all nature as generation. Such a theory was very simple, but it explained nothing except the bare production of offspring. It gave no clue to their endless variations, nor to the fact that they often resembled the father more than the mother. According to this theory the offspring should resemble the mother, as the complete individual is formed by her and should be in her image. Leeuwenhock, one of the early microscopists, by the aid of his lenses, opened a new world to mankind, and discovered the sperm cells to be active, living, moving elements, and he gave a death-blow to the belief that the perfect organism exists in the ovum; but he went to the opposite extreme, and maintained that it exists in the male cell and that it is only fed and developed by the female. Even today we find in a vague way both these theories held by educated persons. We are indebted to Harvey in the early part of the eighteenth century for advocating the view held by Aristotle, now known as _Epigenesis_, and combatting the view of growth from a miniature, but already perfectly formed animal, to a visible one. Epigenesis consists in the successive differentiation from the relatively homogeneous elements as found in the egg, to the complicated parts and structure as seen in the offspring. According to Huxley, this work of Harvey alone would have entitled him to recognition as one of the founders of biological science, had he not immortalized himself as the discoverer of the circulation of the blood. Not long after Harvey's publication, Casper Frederick Wolf established the theory of epigenesis upon a firm foundation, where it still remains. The doctrine of _epigenesis_ has very much complicated the whole question of heredity. No wonder even so great a mind as that of Darwin exclaimed, "The whole subject is wonderful." How can an egg, which in structure is comparatively simple, an aggregation of cells, not one of which bears the slightest resemblance to any organ in the body, develop into the perfect individual? How can this egg, formed in special organs, develop other organs than those like the ones in which it was formed? How can sexual cells develop brain cells, with their wonderful modes of action? We cannot explain the philosophy of heredity without being able to answer these questions; but difficult as is the problem, our biologists have made various attempts at an explanation. I cannot go over all the various speculations, but only those most intimately connected with the subject will be mentioned. The first is Darwin's own attempt at an explanation by the theory of _pangenesis_, or genesis from every part. He saw the necessity of having in the sexual cells some power or force to represent the other organs and functions of the body, else how could these organs be formed in the embryo? Pangenesis was supposed to be accomplished as follows: Every organ through its cells gives off _gemmules_. These are inconceivably small, too small for any microscopical vision; also inconceivably great in numbers, and with great power of growth and multiplication. They pass from the various organs in which they are formed to the special sex organs for generating the sexual cells; some of them are stored up as representatives of the various organs from which they have been given off. The consequence is that every egg has in it something from every organ in the body of both parents which is able, during gestation, to develop into that organ. According to this theory, for instance, if no gemmules are given off from the brain, then no brain can be developed from the egg, and so of other organs. As in a representative government, all parts of the country send representatives to the capitol to do the bidding of the people, so every organ of the body sends representatives to the sexual cells to form their respective organs; without them these organs would not be formed. There are many objections to pangenesis, but they need not be named here. It occurred to Galton, whose studies in heredity have been more prolific of good than those of any other man, to test it by practical experiment. If these gemmules are circulating in the blood of animals before being stored up in the sexual cells, by transfusing blood from one variety of any species to another it ought to affect the offspring of this other. For his test cases he chose eighteen silvergrey rabbits which breed true, and into their bodies he transfused the blood of other different varieties, in several cases replacing one-half of this fluid. There were eighty-six offspring bred at once from these silvergrey rabbits, and all true silvergreys. The theory did not work. But if it did not work in practice, it certainly worked on the intellects of biologists everywhere, exactly what Darwin wished; it set them to thinking. It acted as a ferment, so to say, and brought forth a rich harvest in speculation if not in actual knowledge.[106:A] CONTINUITY OF THE GERM-PLASM.--The only other theory which I shall mention is that of Weismann, which has been before the public for more than a decade, and it is safe to say it has produced a more profound impression upon biologists than all others. It has its basis in what he calls _continuity of the germ-plasm_. By the germ-plasm is meant that part of the germ cell containing all the chemical and physical properties, including the molecular structure, which enables it to become, under appropriate conditions, a new individual of the same species as the parents. In it lies hidden all the characteristics both of the species and of the future individual. In it lies all the phenomena of heredity. It is the product of the coalescence of the male and female elements requisite for reproduction. Only, however, in the nuclear substance is to be found the hereditary tendencies. Now, this germ-plasm is _continuous_, that is to say, it contains not only material from both parents, but from grandparents and greatgrandparents, and so on indefinitely. This germ-plasm is exceedingly minute in quantity, but has great power of growth. Not all is used up in the production of any individual, but some is left over and stored up for the next generation. The germ-plasm might be represented as a long creeping root, from which arise at intervals all the individuals of successive generations. The amount of ancestral germ-plasm in each fertilized ovum is calculated in the same way that stock breeders calculate the amount of blood of any ancestor running in any individual. For instance: The germ-plasm contributed by the father and mother is each one-half; each grandparent one fourth, and so on. Ten generations back each ancestor contributes only one part in one thousand and twenty-four parts. This continuity has by some been called the immortality of the germ-plasm. Theoretically, the original Adam and Eve have contributed an infinitesimal part. This probably explains why there is so much of the original Adam in most of us. By it we are able to explain that wonderful fact of _atavism_, or the appearance of characters from a remote ancestor in offspring. Some of the germ-plasm from this ancestor by some means has had an opportunity to grow rapidly and contribute more than its share in the production of the individual in which it appears. It also enables us to explain the fact that no two individuals are quite alike, but that there is constant variation. Each person is the product of a multitude of ancestors, and the germ-plasm which produced them is never mixed, in quite the same proportion, nor do the different parts grow with quite the same vigor. It was on this theory of the continuity of the germ-plasm that Weismann built his doctrine of the non-transmission of acquired characters. On this subject he says: "Hence it follows that the transmission of acquired characters is an impossibility, for if the germ-plasm is not formed anew in each individual, but is derived from that which preceded it, its structure, and above all, its molecular constitution, cannot depend upon the individual in which it happens to occur, but such an individual only forms, as it were, the nutritive soil at the expense of which it grows, while the latter possessed its character from the beginning, that is, before the commencement of growth." Of this, however, I will speak later. A RATIONAL VIEW OF HEREDITY.--I might continue giving other theories of heredity--Hæckel's, for instance--or the metaphysical theory, but it is hardly necessary. I do not accept in full any of them. Their authors, it seems to me, have not worked along the lines of evolution, but have gone further than was necessary into the fields of speculation. Darwin, in his theory of Pangenesis, admitted this frankly, and yet he clung to the idea with great tenacity. If we take the unicellular organisms which multiply by division, we may see that heredity is simple. One unicellular individual growing larger than is convenient, divides into two. Each is like the other. It could hardly be different. Reproduction by spores or buds is practically the same thing. The spores or buds are minute particles of the parent organism. When it comes to the coalescence of the germ and sperm elements from two organisms, the phenomena become more complicated, and it is still more so as the animal rises in the scale of creation; but I believe the processes of organic evolution have gone on so slowly that the sexual cells have acquired the power to transmit the whole organism without the necessity of the germ-plasm being continued from parent to offspring indefinitely, and also without the aid of pangenesis. The egg has acquired a tendency to develop in a certain direction. Just how we cannot tell, further than to say that it was probably the result of variation first and natural selection selecting out those variations most suitable. It is this tendency to vary that gives rise to many of the phenomena of heredity. The subject is, for the present, beyond our power to settle satisfactorily, and so hypotheses must be resorted to. The sexual cells, comparatively simple in anatomical structure, must be highly complex in their molecular structure; and the more highly evolved the organism, the more complex becomes this molecular structure. If it were possible to study this molecular structure we should be able to understand the whole subject far better than is possible now. But this is not possible, and there is little hope that we shall ever be able to accomplish it. HEREDITY AND THE EDUCATION OF CHILDREN.--The next question which comes up for consideration is that of the education of children and its relation to heredity. This brings us at once to the problem as to whether acquired characters are transmitted to offspring or not. If acquired characters are transmitted, the relation of heredity to education must be very close and important. If acquired characters are not inherited, then heredity and education have a very different relation. That acquired characters are transmitted has long been believed. It was the belief of Lamarck. He tried to explain the structure of the organism by this principle. The illustration of the long neck of the giraffe is familiar to every one. It originated by the constant stretching of this part to obtain food from the trees. In times of scarcity, he had to exert himself in this way still more to reach the higher branches. The young of the giraffe had longer necks than their parents because of the efforts of the latter in this way. So the keen sight of birds, it was argued, was acquired in the same manner. The hawk had to exercise his eyes most vigorously to discern his prey at a distance, and his offspring inherited this keenness of sight acquired by the exercise of his ancestors. Darwin believed that the effects of the exercise of any part were transmitted. He says: "We may feel assured that the inherited effects of the use and disuse of parts will have done much in the same direction with natural selection in modifying man's structure of body." We may say that this belief has been held by the common people, uneducated in science. They not unfrequently get at truths in a rude way long before the scientists do. Many parents tell us their children are strongly influenced by some particular occupation of the mother during pregnancy. So strong is this belief, that many mothers are in our times trying to influence the character of their unborn children by special modes of life, by cultivating music or art, or science, in order to give the child a love for these pursuits. It is by Herbert Spencer that this has been most ably presented. Indeed, he holds that there is no explanation of evolution without the transmission of the effects of the use and disuse of parts. His words are: "If there has been no transmission of acquired character there has been no evolution." He also says: "If we go back to the genesis of the human type from some lower type of primates, we see that while the little toe has ceased to be of any use for climbing purposes, it has not come into any considerable use for walking or running. It is manifest that the great toes have been immensely developed since there took place the change from arboreal to terrestrial habits. A study of the mechanism of walking shows why this has happened. Stability requires that the line of direction--the vertical line, let fall from the center of gravity--shall fall within the base, and the walking shall be brought at each step within the area of support, or so near that any tendency to fall may be checked at the next step. A necessary result is that _if_ at each step the chief stress of support is thrown on the outer side of the foot, the body must be swayed so that the line of direction may fall within the outside of the foot, or close to it; and when the next step is taken it must be similarly swayed in an opposite direction, so that the outer side of the foot may bear the weight. That is to say, the body must oscillate from side to side, or waddle. The movement of the duck when walking shows what happens when the points of support are far apart. This kind of movement conflicts with efficient locomotion. There is a waste of muscular energy in making these lateral movements, and they are at variance with the forward movement. We may infer, then, that the developing man profited by throwing the stress as much as possible on the inner side of the feet, and was especially led to do this when going fast, which enabled him to abridge the oscillations, as indeed we see it now in the drunken man. Then there was thrown a continually increasing stress upon the inner digits as they progressively developed from the efforts of use, until now the inner digits, so large compared with the outer, bear the greater part of the weight, and being relatively near one another render needless any swaying of the body from side to side in walking. But what has meanwhile happened to the outer digits? Evidently as fast as the great toes have come more and more into play and the small ones have gone more and more out of play, dwindling for--how long shall we say?--perhaps 100,000 years." In other and simpler words, the great toe of man has wonderfully developed since he began to walk upright. This has been from greater use, and the transmission of the effects of this use to offspring. The small toe has decreased in size proportionately. This we can reasonably infer has been the result of disuse, the effects of which were also transmitted to offspring. A still more remarkable illustration of the effects of use and disuse is seen in the sense of touch in different parts of the body. Prof. Weber, in his laboratory for experimental psychology, has worked out this difference most minutely. He finds that by taking a pair of compasses, the points of which are less than one-twelfth of an inch apart, the end of the forefinger is not able to distinguish more than one point. Going to the middle of the back we have the least discriminating power in the skin, for the points must be separated two and one half inches before the nerves can decide that there are two. Any one may test this on himself. Between these extremes we have many differences. The end of the nose has four times as great power of discrimination as the forehead. When we come to the tip of the tongue, we find it far excels any part of the body in its power of tactual discrimination, it being twice that of the forefinger. In every case we find there is greatest delicacy of touch in those parts where this sense has been most exercised. The tongue is being constantly exercised on our food, on the roof of the mouth, the teeth, etc. It is rarely idle. There is in man no advantage for his survival, Mr. Spencer asserts, by having such a sensitive tongue. He could get on just as well without it. He regards it as a case where the exercise of a function has exalted it remarkably, and this exaltation has been transmitted to offspring. Natural selection, he thinks, is not sufficient to account for it. Natural selection only preserves those characters which will give their possessor some advantage in the struggle for existence. Still another argument is drawn from the whale. This monster once lived, it is believed, partly on land, probably on low land near water, and must have been smaller than now. It had hind legs; but since it has lived continuously in the water its tail has so developed as to make a far better organ of locomotion, and the legs have dwindled from disuse, so that now there is only a remnant left, and this is hidden beneath the skin. The tail has become more efficient from use, and this has been transmitted so that all whales are born with well developed tails. The legs have dwindled for want of use until they have almost disappeared; and this effect of disuse has also been transmitted to offspring. Another illustration is furnished by Havelock Charles, an English surgeon, who has spent much time among the Punjab tribes in India, and studied them anthropologically. His account is given in "The Journal of Anatomy," in a paper on the structure of the skeletons of these people. It appears they have facets on the bones, fitting them for the sitting posture. These do not develop after birth, but are seen in the fetus. It seems hardly possible that these facets could have any other origin except by transmission after being acquired by ages of use of sitting posture. Another argument is drawn from the coadaptation of parts. We know that the male sheep, likewise the goat, the stag, and the males of many other animals, have large horns. They are supposed to be useful in fighting with rivals in order to secure as large a number of females as possible. Now these large horns require at the same time a greater development of the bones of the head to hold them, also larger and stronger vertebræ of the neck and back, and larger muscles of these parts to maintain and use them effectively. In other words, there must be coadaptation of all the parts, otherwise these larger horns would be an incumbrance and useless. Now, if we accept the theory of the inheritance of acquired characters, this is all simple. The use of the head in butting against other males exercises all these parts simultaneously, and they develop equally and at the same time. If, however, inheritance has no part in the matter, then we must fall back on variation in the germ-plasm and natural selection for an explanation; but it is difficult or, as Spencer says, impossible to conceive of variation producing large and heavy horns on these animals and at the same time coadaptation of all the other parts to hold and use them. Sometimes coadaptation does not take place, as in the common brook crab, familiar to every country boy. Its foreclaws or fingers are out of all proportion to the rest of the leg, and its awkwardness is well known. The lobster is another case. Even in human beings we have instances of non-coadaptation, as where the head and brain are out of proportion to the size of the body, or the reverse. I need not multiply instances. Now, if acquired characters are transmitted, any system of training which exists for a considerable time must necessarily appear in the structure of the body and in the character. If the training is not in accord with the laws of evolution, it causes the race to deviate from the true line of progress, and by just so much hinder advancement. If, on the other hand, our systems of education conform to correct principles, progress is advanced by them. Quite recently an entirely new theory has grown up, opposed to Lamarckianism, and the theory of the transmission of acquired characters. It has been before the world little more than a decade and has made remarkable progress, though it is too soon to say it has been established beyond dispute. Prof. Weismann, its author, is well equipped as a biologist to maintain and defend it. I have already stated briefly his theory of heredity, namely, that the germ-plasm is continuous from parent to offspring. This necessitates a remodeling of commonly accepted views, an entire giving up of the Lamarckian belief that use and disuse have their effect on progeny. If the germ-plasm continues from one generation to another, then it must already have been formed, or at least provided for, even before the birth of the parents. They may modify it, through growth and nutrition, but not through exercise of any function. Prof. Weismann went at the demonstration of his views in a thoroughly scientific way by the making of experiments on living animals and the collection of facts. From his experiments it is now pretty well established that wounds and injuries, which he considers to be acquired characters, are not transmitted. No matter for how many generations you cut off the tails of dogs, cats, horses or sheep, the effects of this removal do not appear in the progeny. Most parents have some mark on the body, received in early life, some cut or bruise, some scratch, but their children do not inherit them. The famous experiment of cutting off the tails of mice, for generation after generation, and then breeding from them was one of Weismann's methods of substantiating the theory that acquired character is not inherited. The offspring of these mutilated mice had as long tails as if those of their parents had not been removed. The explanation is, the germ-plasm was not in any way affected by the bodily mutilation. The practice of the Flathead Indian is another case. The children of parents whose heads have been artificially flattened are not affected by it. The small feet of Chinese women, made so by binding them and preventing their growth, may also be mentioned. INTELLECTUAL ACQUIREMENTS.--Not to depend on such evidence, however, he adduces that of a very different character, namely, the non-transmission of intellectual acquirements. Language is an example. Although human beings have been communicating their thoughts to each other from very ancient times by speech, yet every child has to learn how to do this for itself. No matter how many languages the parents master, their children have to go over all the ground the parents did, make all the toil and effort to learn to speak. The children of the most gifted linguists, if brought up without coming in contact with those who can teach them to talk, will never learn a single word. There are, it is claimed, a few cases on record of children who never acquired their natural tongue because they had lived among animals and not among human beings. They learned to make the same vocal sounds the animals did, no more. The environment in this case was everything, the parental acquirements nothing. Music, like language, is also an acquired character, and it is probably not transmitted. Our musical geniuses are not the children of great musicians, but in most cases the reverse. They seem to spring into existence from lowly sources, or at least from parents whose advantages for a musical education have been very limited, though generally they have had good health, and a climatic environment of a favorable kind. Great musical talent usually dies out in any family in a few generations, no matter how much it is cultivated, or, if it does not die out entirely, it becomes mediocre; and yet the opportunities of the children of great musicians, and the ambition of their parents for its culture, are usually very favorable. INSTINCT.--In accepting the theory of the non-transmission of acquired characters, it becomes necessary to give up prevailing views of the origin of instinct. According to the old belief it was a gift of God, and not acquired by any effort on the part of its possessor. In speaking of the instinct of bees, Sidney Smith says: "_Providence has done it._ There are the bees, there is the comb, and the honey, get rid of it or find some other explanation if you can." The early evolutionists changed all this, and made instinct the inheritance of an oft-repeated act. The young kitten, as soon as old enough, hunts for a mouse and catches it without any training. The sight of the mouse acts on its nervous system in such a way as to compel it to creep up softly, jump on it, toy and play with it, and finally kill and eat it. It would have required long practice on the part of its ancestors before so wonderful a character could have become fixed. The same is true of the setter dog. The new view is, that instincts arise from variations in the germ-plasm. The union of the germ elements of two individuals causes it to vary more or less from either parent. These variations will be favorable and unfavorable. The unfavorable ones will produce offspring handicapped in the struggle for life and they will disappear. The favorable variations will produce descendants possessing advantages for survival and leave numerous offspring. It is not easy to accept this view, but I think there are some facts that support it. I will advance a few. The hive of the honey-bee contains three kinds of insects: the queen, the drones or males, and the workers. The queen makes her nuptial flight but once in a life-time, and does it from instinct. How can an instinct like this have been acquired by being performed but once? The drones are derived from unfertilized eggs; yet their instincts are those of the male, not of the female. As they have no male ancestors, it seems probable there was in the germ-plasm of some queen bee, at a time far back, some change which allowed unfertilized eggs to produce males. The workers are all females, not fully developed sexually on account of a diet with too small a proportion of nitrogenous food and containing so large a proportion of the hydrocarbons. They inherit from the mother, or rather from the germ-plasm, the instinct to gather honey, yet neither their male nor female ancestors ever gathered any honey in their lives, nor have they for ages. Far back in antiquity the queen, no doubt, did gather honey, but the disuse of this instinct has not caused it to disappear in the working bee, as it should have done according to the Lamarckian theory of disuse causing decay of function. Is there any way to account for this, except on the theory that the germ-plasm produces working bees as well as the other kinds, irrespective of the habits of the queen? Her character in this respect is fixed and does not change. Is it unreasonable to think that some time in the past, in some queen bee, was formed a germ-plasm capable of producing three varieties, and that there was such an advantage in it for survival, that it has been continued ever since by natural selection? Queens not able to do this have not been selected, left no offspring, and thus the perfection of the stock has been assured. One more case. Some years ago, when interested in agricultural entomology, I made a study of the so-called seventeen-year locust. Noting the wonderful precision with which the female cuts into a soft twig of a tree and lays its eggs in two rows, the thought was suggested to me, how can an instinct, used only a few hours, once in seventeen years, be acquired by exercise and persist in the offspring seventeen years later? Weismann's theory of the origin of instinct from favorable variations in the germ-plasm offers, it seems to me, a rational explanation. I do not need to extend illustrations which abound in the insect world, especially among the ants, which furnish cases of coadaptation that cannot be transmitted, as they do not propagate, so I will not mention them here. Now, if acquired characters _are not_ transmitted to offspring, how should these facts affect our methods of educating children? One advantage will be evident, I think, to all. Erroneous systems of training, which do not injure the health, will not appear through heredity in the offspring of parents thus wrongly trained, except as a result of environment. That is to say, the injury does not become congenital--will not be in the blood--and, consequently, it will be less difficult to eradicate it and to introduce better systems. This may be considered an advantage. But it is not all. If heredity takes place only through the germ-plasm, then it seems to me that whatever promotes a knowledge of how to maintain it in a high degree of health, and how to favor more perfectly natural selection, are subjects with which our educators may busy themselves far more than they do. That is to say, the study of biology, of life--of the laws of human growth and development, and of evolution, will become, more and more, important factors in our school curriculum. We can hardly imagine how much our common every-day life has been aided by even the slight knowledge of mathematics gained by an acquaintance with addition, subtraction, multiplication and division. By it we are able to keep our little accounts correctly, and neither cheat our creditors nor be cheated by them. Could we not by a knowledge of the laws of evolution, and also the laws of growth and development, keep our larger account with nature in a far better condition? Could we not keep ourselves from being cheated out of our health and happiness, and also do something to put an end to physical, intellectual and moral deterioration which threatens so many families and even races? It seems to me that the time is not far distant when these studies will be quite as much attended to as the not unimportant ones of arithmetic and grammar. KNOWLEDGE OF HEREDITY.--Whatever doctrine of heredity prevails, however, one thing is certain, some knowledge of the subject will be very useful to those who have in care the training of children. To them, often more than to the parent, is entrusted the task of developing the character and the individuality of the child. Can he do this well if he knows nothing of what the bent of the child's genius from ancestral influence is? I doubt very much if any of us realize how important it is that this individuality should have its proper share of attention. As the evolution of society goes on, more and more must there be differentiation of our various activities. If every boy and every girl can be educated so that to a considerable extent they can follow the bent of their genius, _whenever that bent is a normal one_, will not the available intellectual and moral energy of society be considerably augmented? If you educate a boy which nature intended for a blacksmith for a preacher, has not the world lost something? Educate another for a blacksmith who should have been a preacher, is there not also a great loss? There are a few children who will come out all right, no matter how much they are schooled, or whether they have any schooling, so well have they been born, but with the majority this is not the case. Now it seems to me that the teacher who knows the natures of his pupils, and something of their ancestors', can direct their energies more satisfactorily than the one who does not. If there are hereditary defects of intellect or morals, he can more easily correct them. If there are ancestral tendencies to disease through imperfections of certain organs, for instance, the lungs or the brain, he can often put the child on such a course of physical culture or mental training as to lift it above danger, so that it may go through life a useful person instead of a feeble one or a lunatic. Even the tendency to crime might be averted. INDIVIDUALITY.--If we could educate the young so as to bring out more fully their normal individualities we should be able to cultivate in them more independence of character. On this subject Prof. Mills says: "With all its imperfections, I am bound to say that the individuality of the pupils in the old log school-house was often more developed than in the city public schools of today, where for a boy to be himself frequently brings with it the ridicule of his fellows--a condition of things that has its effect afterward on the lad at college. I find that this fear of being considered odd,--out of harmony with what others may think,--one of the greatest drawbacks to the development of independent investigating students at college. The case is still worse for girls. When women begin to be really independent in thought, in feeling, in action, I shall be more hopeful of the progress of mankind. Happily, the dawn of this day is already begun." We must not forget that there is also a spectre of heredity. It is seen under different forms. The physician is often reminded by his patients that they have inherited this or that disease from father or mother, or an ancestor farther back. Now, there are few diseases which come to us directly through inheritance. In a majority of cases they are not transmitted. Even consumption is not. If we accept the modern theory of its origin, as we must, this plague is the result of germs floating in the air being introduced into our bodies by respiration, or in food, or through contact with abraided Surfaces. Those with weakened constitutions are more liable to it than the strong, and a weakened constitution may be inherited, for in this case the germ-plasm will not be well nourished and will suffer; but those thus handicapped in the race of life will get on far better by endowing themselves with knowledge and obeying the laws of life than they can by living under the shadow of the great spectre of heredity, and casting anathemas at their ancestors for not having done more for them. No doubt most of them have done the best they could; and if life is worth living, as most of us believe, we owe them many thanks for having brought us into the world. THE SPECTRE OF HEREDITY.--There is a spectre of heredity of a more serious nature. It is the spirit of the dead past, with its mighty hand on society, on institutions, on modes of life. Wendell Phillips used to tell a story, in his anti-slavery addresses, which illustrates the evil effect of this inherited spectre. It ran in this wise. In an Eastern temple, an idol, in the image of a god, stood calmly on its pedestal. It was sacrilege to touch it with human hands; but rats having no such feelings of awe in the presence of a deity, began to gnaw about it in various places, yet no one was bold enough to remove it to a place of safety; and so the rats gnawed on and on, and built their nests within the sacred image. In time they loosened it from its firm foundation, and one morning, when the worshippers came in to pay their devotions, they found their god had fallen prostrate on the floor. So it is sometimes with our inherited beliefs. They hold us back from progress like a heavy weight. We fear to remove them, for they are sacred inheritances, idols, gods, and so our institutions decay, perish. FOOTNOTES: [106:A] Darwin did not regard this experiment as settling this question. He had great affection, so to speak, for this poor, despised theory, and believed it would finally be established as in the main true. EVOLUTION'S HOPEFUL PROMISE FOR A HEALTHIER RACE. _Given before the Greenacre Conference of Evolutionists._ We have most of us in the past looked upon health as a matter of inheritance, or temperance and moderation in working, in eating and drinking; or as depending on climate; or exercise, or plenty of sleep, pure water and a morning bath, or some other secret, one or more of which is pretty sure to be in the possession of most persons who have lived long enough to have had some experience with those things that do them good or harm. All these agencies have great value; but I think few of us realize that nature, through the laws of evolution, has long been working to produce a brave and strong, healthy and hardy race of men and women by other methods than those health habits which most of us value so highly. Nature has been doing this chiefly by two methods, and it seems necessary that I should say something about them in order to present my subject as I wish to present it. The methods to which I refer are those of sexual and natural selection. It is to these two processes that we are largely indebted for race improvements--more perfect bodies, more active brains, and the high degree of health which a considerable portion of the race enjoys. SEXUAL SELECTION.--By sexual selection is meant that preference which the male or the female has for certain characteristics of the other sex. It also includes the advantages which the stronger and more capable male has over the weaker one in obtaining a choice, or, among polygamous animals, a larger number of females, thus allowing offspring to be generated by the most capable, and preventing the most incapable from procuring mates. The first principle of sexual selection, that of preference, would imply a considerable development of the intellect, and some taste, but I do not think it has had great influence on the lower forms of life. It is difficult to study the preferences of insects, for instance; but I have studied the moth of the silkworm, and could never observe that either male or female had a choice for any particular mate. They always appear to take the first one that comes along. I think this is the conclusion come to by those entomologists who have had opportunities for studying other insects. The spider might perhaps be studied in this relation to advantage, as the female is ferocious, often eating her male suitors while they are trying to woo her. Nor do I believe that it is a very important matter in many other animals. Certainly among the domestic ones--the sheep, the horse, the bull and the cow--a superior male and female will mate with inferior ones of the opposite sex, apparently without the slightest objection. I have sometimes thought I had observed in pigeons a preference, having occasionally seen a male leave his mate for a more attractive female; at least one that seemed more attractive to me. When it comes to sexual selection through struggle, no doubt there has been great advantage, and it has produced important effects. This occurs among polygamous and also among non-polygamous animals, and the strong males are certain to secure the largest number of females and, consequently, leave the largest number of offspring. This would, no doubt, through the laws of inheritance, be beneficial in producing animals of greater vigor and more perfect health. But even in this case, the males seem to have little preference for any particular female; and so while the least vigorous ones would leave few, and many no offspring, the least vigorous females would leave nearly as many as the more vigorous ones. Still, through pure-blooded males alone, stockbreeders tell us, herds of cattle can be brought up to a high degree of perfection in three or four generations, even if the females, at the beginning of the experiment, are inferior. The first generation would be half pure blood; the second three-fourths; the third, seven-eighths, and the fourth fifteen-sixteenths, or almost thoroughbred. When it comes to man, however, the case is different. With him sexual selection is more important, and the preference shown by both sexes is very marked. Many women have strong prejudices against marrying men with certain characteristics, and nothing will induce them to such a union. So strong are the desires many of them have for mates with particular qualities, that they prefer to remain single rather than marry one not possessing these qualities. Through this preference, on the whole, the better and those most adapted mate with those most suited to them, and a considerably larger class of physically and mentally inferior ones do not mate at all, or, if they do, leave few offspring. The idiot would stand no chance of securing a mate, although, if left free, he would unite with another idiot, like an animal. Such things have happened, and the offspring were not idiots, as might have been expected; but they were not superior beings. The most deformed in body would, in most cases, unless they had mental traits of a high order to counterbalance them, rarely find mates. Thus, through this agency, some of the poorest specimens of both sexes do not produce offspring, and this raises the standard of the health and ability of the race. There are many characters which have come into existence, it is believed, through sexual selection. One is beauty in women, greater beauty of form, of hair, of eyes, of grace, fidelity, chastity, power of love, etc. These all give pleasure to the opposite sex, and have an element of usefulness in them. Whenever these characters have appeared in women they have given the possessors a better chance to find a partner with superior characters. The same is true of men. Woman being debarred from the hardest labor through maternity has found it useful, even in early times, to choose men who were strong, brave, courageous and capable of defending and caring for her, so far as was possible, and thus by sexual selection she has indirectly promoted health and vigor in man, for these qualities are inseparable from it. But the results of sexual selection are by no means perfect. The sexes are nearly equally divided, and as polygamy is not to any great extent practiced among human beings, with the exception of those already named, most men and women can find mates if they wish, even though they may have many serious imperfections of body and mind, and from them many children will be born physically and mentally incompetent. There is no doubt that sexual selection is coming more and more into play, however. We have abundant evidence of this in the growing sentiment against the marriage of those with a tendency to any serious disease, as insanity, syphilis, etc. Only a little while ago was published an account of a suit for a breach of promise brought by a young woman in an English court against her suitor. He, having in view the value of a healthy wife, and also of children well endowed physically, asked her before the engagement if any of her near relatives had died of consumption, and she replied that none had, which he afterwards found was not true. On learning of it he refused to marry her. I am sorry to say that she won her suit. One of the questions asked in court was: "Is it possible that a lover would ask such questions of his sweetheart as would be asked of a candidate for life insurance?" Courtship is such a delightful occupation for the young, that it seems a pity to mar it by bringing in questions of health. Yet men and women are often such deceivers, and frequently so ignorant, that some way must be devised to prevent deception if sexual selection is ever expected to have its full influence on race improvement. HUMAN SELECTION.--Under the head of human selection Galton and Wallace have made some interesting and valuable suggestions for improving the health and quality of man. Mr. Galton proposed a system of marks for family health, intellect and morals, and those members of families having the highest number were to be encouraged to marry early by state endowments sufficient to enable them to make a good start in life, early marriages being favorable to large families. It was a bold suggestion, savoring too strongly of socialism or state control of marriage to suit many of us. Professor Wallace's plan is that women shall, so far as possible, be made independent, so that they will not feel the necessity of marrying for a home. Her time might be occupied either in public duties or self-culture, or any occupation she might prefer. She should be educated to believe it degrading to marry for a home, without love and adaptation, and equally wrong to marry her inferior. This would compel men to be more manly, to leave off their bad habits and many vices, in order to obtain wives; and the idle, selfish, sickly and deformed would not easily get them. One difficulty in the way of carrying out this plan is the greater number of women in society as it exists today, owing to the larger mortality among boys. But by a better hygiene which is likely to result from the evolution of the race, this greater mortality of the masculine sex is certain in the future to be prevented, and there will then be an excess of men instead of women. This will be a real advantage, for a scarcity of women would give her a greater influence in selection, and the result would be, the worst men would not be able to get wives. Being in a minority, women would be held in higher esteem, be more sought for, and have a real choice in marriage by being able to reject unsatisfactory suitors, which is certainly not the case now to any considerable extent. Mr. Wallace's plan would not require such early marriages as that of Mr. Galton's, and this would be a positive benefit to the physical vigor of the children, for we know that the progeny of too early marriages are more delicate, and reproduction before bodily maturity lowers the standard of health in parents as well as of their offspring. Marriage being delayed, and the culture of the mind being more attended to than is possible when it is early, would reduce the number of children in any family, and this would enable parents to bestow more care upon them. It would also prevent, to a limited extent, over-multiplication of the race, which is a real evil, for if every couple left three or four children the whole world would soon be full, and over-population would result in much disease. Mr. Wallace's scheme has in view the prevention of marriage by the weak and worthless. He believes that if this can be done little more will be required, for the superior would be the only ones to procreate, and this would be quite sufficient in a few generations to produce a strong and healthy race. He calls his plan that of "human selection," but it may be considered practically as a modification of sexual selection. NATURAL SELECTION.--Natural selection is another process which takes place on an enormous scale and constantly among all organisms, whether animal or vegetable. Natural selection is the result of the operation of certain laws in the natural world which brings about the survival of those best fitted for their environment. It is a weeding-out system by the destruction of a certain portion, at least, if not all, of the weak and the bad, and it occurs because there is such a rapid increase of most organisms. We speak of it as the survival of the fittest, but it is also, at the same time, the destruction of the unfit. Mr. Darwin says: "We have seen that man is variable in body and mind, and that the variations are induced either directly or indirectly by the same general causes, and obey the same general laws as with the lower animals. Man has spread widely over the face of the earth, and must have been exposed during his incessant migrations to the most diversified conditions. They must have passed through many climates and changed their habits many times before they reached their present homes. They must have been exposed to a struggle for existence and, consequently, to the rigid law of natural selection. Beneficial variations of all kinds have been preserved and injurious ones eliminated. If, then, the progenitors of man, inhabiting any district, especially one undergoing some changed conditions, were divided into two equal bodies, the one-half including those with the best adapted powers for movement, for gaining a subsistence, for self-defence, would, on the average, have more offspring than the other and the less well endowed half." We may have a good object lesson in the elimination of the unfit going on about us constantly. In New York City, for 1891, the deaths of children under five years of age was 18,112; for 1892 it was 17,577, or slightly less. This is more than one-third, but not quite one-half, of the total deaths at all ages for these years. A very large proportion of these deaths occurred in the tenement house districts, and a very natural question arises in the mind: Are the children of those who live in tenement houses more unfit to survive than those who live in houses in which only one family dwells. No doubt in most cases the children of those are most fit who are most able to provide them with hygienic surroundings, the better food and most suitable care; such are usually the prudent and the capable. The love of children is usually stronger in them. The intelligent affection of parents for their young is one of the incentives to their best training. It certainly is not nearly so strong among the residents of the crowded quarters of a city as among the more prosperous. Any one may observe this by going with a company of mothers on the excursions of some fresh air society, which may be seen in most cities. It is hard to find one of these mothers who shows what we may call intelligent affection or intelligent care of her young. Some pathetic instances illustrating this might be mentioned. When it comes to the question of their physical or mental inferiority, a cursory inspection is all that is required to show they are far below the average. There is a great want of symmetry of body and mind--evidence of degeneration. In order to test the strength of constitution, which is a good way to get at one form of physical fitness for survival, it seems to me, I made a study of the blood of a considerable number of these children and found the amount of protoplasm in the colorless blood corpuscles deficient. This shows that their power to resist disease is slight. It must be borne in mind, however, that a strong constitution alone is not evidence of fitness for survival. A strong person may not have prudence, foresight, keenness of perception, judgment, and many other qualities equally important. The characters just mentioned may constitute fitness when there is only a moderately vigorous body. Mr. Darwin recognized this when he said: "We should bear in mind that an animal possessing great size, strength and ferocity, and which, like the gorilla, could defend itself from all enemies would not, perhaps, have become sufficiently social, and this would effectually have checked the acquirement of the higher mental qualities, such as the sympathy and love of his fellows. Hence, _it might have been of immense advantage to men to have sprung from some comparatively weak but social creature_." Fitness is a complicated condition and not a simple one. It depends upon so many external conditions. Fitness in one place would be unfitness in another. Still, other things being equal, strength of constitution is a very important factor, and must not be left out of consideration. With it there is a surplus of material in the body beyond what is required for digestion, assimilation, circulation and other bodily functions, to enable the parents not only to do hard labor, but also to endow their offspring with vigor equal to their own, often greater vigor. The feeble individuals will have a small amount of stored up material in their bodies which we may designate as physiological capital to give continuous food, warmth and protection to their young; they will not be so well adjusted to their environment, and, consequently, natural selection will cause their non-survival--or their offspring, if not immediately, at no distant period. This doctrine of natural selection has been designated as cruel, harsh, inexorable, and under the influence of the human feeling every effort is in our time being made to prevent this wholesome check upon the processes of nature from having its due influence upon evolution and race progress. Modern hygiene undertakes to put an end to disease, to save all who are born, to surround them with every influence which can favor their health and development. It would stamp out diphtheria, scarlet fever, summer complaint, consumption and a host of other diseases which now decimate the ranks of the unfit, and often, no doubt, of the comparatively fit. This would perpetuate a type of feeble, unhealthy persons. There would not be much hope of more perfect health for the race if our hygienists could carry out this daring scheme along the lines now working. There seems an antagonism between nature's methods of bettering the physical condition of the race and the efforts of man himself, acting under the guidance of his moral feelings, to prevent the action of natural law. Mr. Darwin recognized this, and referred to it in his great work, "The Descent of Man," where he says: "With savages, the weak in body and mind are soon eliminated, and those that survive commonly exhibit a vigorous state of health. We civilized men, on the other hand, do our utmost to check the process of elimination. We build asylums for the imbeciles, the maimed and the sick; we institute poor laws; and our medical men exert their utmost skill to save the life of every one to the last moment." "There is," says he, "reason to believe that vaccination has preserved thousands who from a weak constitution would have succumbed to smallpox. Thus the weak members of civilized communities propagate their kind. No one who has attended to the breeding of domestic animals will doubt but this must be highly injurious to the human race. Excepting in the case of man himself hardly any one is so ignorant as to allow his worst animals to breed." Other evolutionists, in more recent times, have taken a still more somber view of this danger of race deterioration through the prevention of the full action of the law of natural selection. Dr. John Berry Haycraft, in a recent work entitled "Darwinism and Race Progress," has sounded the alarm in no uncertain tones. He says: "Races, therefore, subject to epidemics of a particular fever, suffer selections in the hands of the microbes of that fever, and those living are survivals, cast in the most resisting mould. It may not be flattering to our national vanity to look upon ourselves as the product of the selection of the micro-organism of measles, scarlet fever, smallpox, etc.; but the reasonableness of the conclusion seems to be forced upon us when we consider his immunity from these diseases as compared with the natives of the interior of Africa, or the wilds of America, whose races have never been so selected, and who, when attacked for the first time by these diseases, are ravaged almost to extinction. By exterminating these diseases we shall no doubt preserve countless lives to the community who will, in their turn, become race producers; but in as much as the individuals thus preserved will, in most cases, belong to the feebler and less resisting of the community, _the race will not become more robust_." The same author concludes in these words: "In the meantime we may view, and not without inquietude, the probability that our statistics, as far as they go, indicate that race deterioration has already begun as a consequence of that care for the individual which has characterized the efforts of modern society. The biologist, from quite another group of facts, has independently arrived at conclusions which render this view in the highest degree probable." "Thus, the great English race, once so hardy, so powerful," says this modern writer, "by hygiene and better physical conditions, is becoming weaker and weaker." This view of the case is growing largely in England and, perhaps, other European countries. There is already some evidence of its truthfulness in statistics. The death rate for those in middle life is rather increasing than diminishing. This arises from the fact that the great number of children who formerly died in infancy have lived, but being of more feeble constitutions, they swell the death rate later on. It is felt, also, in many educational institutions in the larger number of youths who cannot stand the strain and stress of student life. They are, high medical authority says, the youth saved from early death by modern hygienic and medical care. Formerly, natural selection would have chosen them as unfit to survive, and there would have remained alive few besides the hardy ones with good constitutions, capable of great strain, with great powers of endurance. It is also shown in the stress of modern competition, in which there are multitudes who cannot stand this strain. It is from these, in some degree, that we hear the cry for governmental aid. "We must make the conditions of life easier for them," say our social reformers, "or they will become 'a submerged class.'" CONFLICT BETWEEN EVOLUTIONARY THEORIES AND OUR HUMANE SENTIMENTS.--And now I wish to consider another phase of my subject. Those who have followed closely what was said concerning natural selection will have seen that there appears to be a conflict between evolutionary theories and the humane sentiment of the age--a want of correspondence between what is being done by natural law and what man is trying to do under the inspiration of his loving heart. Can we reconcile this want of correspondence? To some extent no doubt we can. In the first place, the growth of the moral nature has always been held in high esteem by every nation and every race. Our moral giants stand higher in the scale of being than our great generals or statesmen, even in an age when moral culture is at a low ebb. We draw our moral inspiration from Buddha, Socrates and Christ rather than from Aristotle; their science may be, yes, is, faulty, but their spirit is lofty. And the moral nature is cultivated in laboring for the good of others, in trying to save for a better life the poor, the weak, the distressed. All that is required is that we do this work wisely, not unwisely, under the guidance of reason, not feelings. We want to prevent these calamities rather than cure them. Another satisfaction arises from the fact that in learning how to perfect the lives of the feeble so that they may live longer, we also learn how to perfect, in a still higher degree, the lives of the strong, or those we call the fit, so that they also will not only live longer, but be able to live with much greater satisfaction the complex lives of our times. The knowledge which helps the first may help the second even more than the first, for they have better opportunities and can take advantage of it. We may also comfort ourselves with the fact that a majority of those with feeble constitutions, whose lives have been for a time snatched from the operation of the laws of natural selection, will not, after all, contribute very extensively to the increase of the population. Great powers of generation and numerous offspring rarely go with physical weakness. If there are exceptions they are explainable. It is, I think, pretty certain that a great majority of such leave few, often no offspring. They find their way into places where work is light and the pay small, and they cannot afford to marry and care for families, and do not do it. The law of natural selection will continue to work on them so long as its action is required, with little regard to the efforts of man to abrogate it. Nature works continuously for ages, and she works on every part of man, every organ, every function. We may almost say she is omnipotent; that she watches for every slight improvement; that she knows what to do under every circumstance. Foiled in one direction, she has other means, infinite means, for gaining her ends. Man can no more put a stop to the operation of natural law than he can put a stop to the flow of Niagara. He may turn off a trifle of its water to whirl wheels and spindles, but the mighty river flows on until nature makes some changes in the watersheds, that make its flow impossible. Man, on the other hand, acts on his own body in a finite way. He works mainly for immediate, not remote, ends. He changes his methods as his needs change, or his knowledge increases. Today he works with limited knowledge of hygiene, inspired by old ideas of philanthropy. Tomorrow he may have a vastly extended knowledge of this subject and an entirely new social science which will enable him to do more good and less harm. IDEAL OF HEALTH.--Let me now consider some of the things necessary to give us a greater hope for the future of human health, of ourselves and for our children. The first thing necessary is to get a higher ideal of bodily or physical perfection than we have today. Sir James Paget, in a lecture on National Health, in 1884, put this in the following words: "We want," says he, "more ambition for health. _I should like to see a personal ambition for health as keen as that for bravery, for beauty, or for success in our athletic games or field sports. I wish there was such an ambition for the most perfect national health as there is for national renown in war, in art or in commerce._" Sir James then gives his own ideal. It is for man or woman to be so full of health as to be comparatively indifferent to the external conditions of life, and to make a ready self-adjustment to all its changes. He should not be deemed thoroughly healthy who is made better or worse, more fit or less fit, by every change of weather or food, or who is bound to observe exact rules of living. It is good to observe rules, and to some they are absolutely necessary; but it is better to need none but those of moderation, and, observing these, to be willing to live and work hard in the widest variations of food, air, climate, bathing and all other sustenances of life. ADAPTATION TO ENVIRONMENT.--This sounds very much like saying that to be healthy one must be adjusted to his environment; and this is practically what Herbert Spencer long before said in his "Principles of Biology." Here are his words: "As affording the simplest and most conclusive proof that the degree of life varies as the degree of correspondence, it remains to point out that perfect correspondence would be perfect life. Were there no changes in our environment but such as the organism had adapted changes to meet, and were it never to fail in the efficiency with which it met them, there would be eternal existence and universal knowledge. Death by natural decay occurs because in old age the relations between assimilation, oxidation, and the genesis of force going on in the body gradually fall out of correspondence with the relations between oxygen and the food and absorption of heat by the environment. Death from disease arises either when the organism is congenitally defective in its power to balance ordinary internal actions, or when there has taken place some unusual external action to which there was no answering internal action. Death by accident implies some neighboring mechanical changes of which the causes are either unobserved from inattention, or are so intricate their results cannot be foreseen, and, consequently, certain relations in the organism are not adjusted to the relations in the environment. Manifestly, if, to every outer co-existence and sequence by which it was ever in any degree affected, the organism presented an answering process or act, the simultaneous changes would be indefinitely numerous and complex, and the successive ones endless, the correspondence would be the greatest conceivable and the life the highest conceivable, both in degree and length." KNOWLEDGE.--Another requirement to promote human health is a better knowledge of how the constitution of the body may be strengthened, and more certitude as to whether such improvements as it may receive by hygienic training will be transmitted to offspring. That human health may be improved by right training of the body, a better supply of fresh air, greater moderation in living, there is not a shadow of doubt; but is the constitution itself thus strengthened, or only its original vigor conserved and made effective? I have been working on the problem for some time by a series of studies on the blood, and especially the amount of living matter in the colorless corpuscles, and have satisfied myself, from some observations on individual cases, that the original constitution of feeble persons can be strengthened in early life, but the extent of this strengthening seems somewhat limited. Much original research is still required to get at important facts in this direction. If some of the study now given to micro-organisms could be devoted to this subject it would be most useful. The work might be done in connection with our numerous schools of physical culture, now happily multiplying, and also in our physiological laboratories. That any gain to the vigor of the constitution can be transmitted to the offspring is very probable. While education and training do not seem to affect the germ cells in any marked degree, nutrition does affect them. Whether acquired characters in the form of skill, music, language or other like things are transmitted or not may still be an open question. Strengthening the constitution seems to be best accomplished by increasing the resources of the body beyond its outgo, so that there shall be some gain; and this brings up a very important subject, that of the importance of living within the bodily income. In our fast age we are likely to use up the physiological resources in excessive work or dissipation, and so rob our children of their just inheritance. EFFECTS OF LIVING AT HIGH PRESSURE.--One generation may, by living at high pressure and under specially unfavorable conditions, use up more than its share of the living matter of its bodies and draw a bill on posterity which the next generation cannot pay. Many of us now have the benefit of the calm, unexciting lives of our forefathers. They stored up physiological wealth for us; we are using it. The question is, Can we, working at high pressure, keep this up during our lives (which, in that case, will be on an average rather short), and transmit to the coming generation a large supply of living matter for their needs? How often has it happened in the history of the world that people who for generations have exhibited no special genius, have blazed out in bursts of national greatness for a time, and then almost died out! We ought to take care that this does not happen to us. How often we see a quiet country family, whose members have for generations led calm, temperate lives, suddenly produce one or two great men and then relapse into obscurity. They had by their quiet, inexpensive living stored up energy for this purpose. On the other hand, how often have we seen the reverse--families whose energies have been used up in overwork or sensuality producing offspring below themselves in ability. The true rule, however, is neither to waste the bodily energy nor to keep too much of it lying idle and producing nothing. GIRLS IN MANUFACTURING DISTRICTS.--We need also a new departure in our manufacturing centers. Manufacturing as now conducted is a far less healthy occupation than agriculture and horticulture. The reason for this is that workmen and workwomen and even children in most mills and factories are exposed for hours at a time to an atmosphere which is loaded with dust and the debris of cotton, of wool, and often to that worst of all dust which comes from shoddy and rags. They are also, in many cases, kept away from light, and in cramped positions, and this, continued for years, slowly deteriorates the constitution; and if, in case of a war, we were obliged to enlist a large army, we should find a far less number of able bodied men among the factory workers than among the farmers. Let me give you a picture, perhaps one of the very worst to be seen anywhere, of a visit to a New England paper mill. "We left, with a company of ladies and gentlemen, the light of a mellow afternoon to climb some steep and dusty stairs under the courteous guidance of a superintendent. We had hoped to 'see it all,' 'but that was quite impossible,' said our guide, 'since the room where the rags are sorted is so dusty that the gowns of the ladies would be ruined.' So we contented ourselves with less dangerous rooms. But even about the stairway the dust cloud hung heavily, obscuring the sight and choking the breath. From the narrow landing the room, into which it was impossible to venture, was in full view. It was long and large. From end to end were ranged huge boxes, waist high. Fastened to each were two inverted swords on whose sharp blades the workers cut the piled-up masses of rags, shredding them for the bleaching boiler. All the floor was covered with rags, billows upon billows of soiled white pieces, in which the toilers stood, their feet buried deep beneath the dirty, tattered material. "Not a word was spoken. Even where we stood speech was difficult, so completely did the thick dust fill eyes, mouth and nostrils, choking, blinding and exasperating. The effect of this perfect silence was oppressive. A certain solemnity hung over the place. Through the fog of dust the figures loomed unnaturally large. All the workers were white and hollow-cheeked, with great sunken eyes, emphasized by the circles underneath. Each woman had bound upon her head some rag, larger or finer than the rest, to protect her hair, and the gray-white bands folded straight across the forehead showed weirdly in the dim half-light. "As they stood there in long, silent rows, cutting, _cutting_, CUTTING, they looked like the priestesses of some ancient and frightful ceremonial. We were glad to escape, to exchange the dust, the grime, the wan faces, and the burning eyes for the breath of cool wind, the full glow of the sunlight, and the face of nature herself, so many of whose human children have no time to know or learn her ways. "It gave a tragic significance to the memory of those silent workers to know that they have but a few years to live." The same unfortunate condition of things is complained of in Manchester, England, one of the greatest manufacturing centers in the world. "The heated air of the mills, the dust, lack of light, the employment of children," says the London _Lancet_, "are causing vast deterioration and a most disastrous effect on the morals of the people. Football is popular, but all the players are imported from Scotland. The natives simply look on and shout. If they want men for policemen or constables, they go to Scotland or Ireland for them. The women and girls are equally stunted and feeble." In the manufacturing towns the prospect for a strong, healthy race from such material is poor indeed. CO-OPERATION: AN EXAMPLE.--It is difficult to see the remedy for this state of things. Probably the evolution of a higher standard of ethics, a higher sense of justice, and a more thorough belief that health is a duty, may do something. Meantime it is important that the working man should do all he can for himself; and perhaps I can do no better than to give here a picture of what some of them have done under the inspiration of co-operation, not only for their health but for their pockets. It is a picture of a great manufacturing establishment of the Scottish Co-operative Wholesale Society, at Shieldhall, near Glasgow, on the Clyde. This society is a federation of all the retail societies of Scotland, 238 in number, with a membership of over 150,000 persons. The society began on a moderate scale many years ago, but its development has been marvelous. In 1887 it started out on a career which has since continued, owing to the indomitable energy of one of its members, himself a working man. The buildings stand in a very healthy locality, the health of the working force being considered of the first importance. They seem to have learned that sickness is loss--loss of time, of productive energy--and that it is a costly matter. As Mr. Beecher once said, "it is the one burden that bends, almost breaks, the back of society." These Scotchmen are realizing, just as far as is possible, the condition of a sound mind in a sound body. They recognize the rights of the laborer to health, and place him in a position while working, so that his body may not deteriorate any more than is natural for it to do as age advances. The living machine must not be harmed more than the dead machinery. The land consists of 12 acres, and cost $2,500 an acre; nearly all of it is covered with fine buildings, in which 19 different industries are carried on, many of them on a large scale. Every one of these buildings is constructed after modern methods, with every requirement, not only for convenience but for health. The workrooms are cosy and spacious, well ventilated, warmed in cold weather by steam, and lighted by electricity. The best sanitary arrangements known have been introduced, and the excellent health of the workmen and workwomen, of whom there are over 1,000 of each, tells the story of sanitation. Two large dining-rooms, one for men and one for women, are provided; also two large reading-rooms with all necessary papers, periodicals, books and means of amusement. Its only lack is a gymnasium and a field for athletic sports, but these may in time be added. Food of the best quality is supplied for all who desire it at cost. A dish of oatmeal and milk costs three cents; a large scone with tea or coffee, the same; Scotch broth or soup, two cents; stewed meat and potatoes, eight cents; roast beef or mutton, with potatoes, ten cents; a good and sufficient meal need not cost over twelve cents. Standard wages are paid, and two and one-half hours less time demanded than in private shops. Men work fifty-three hours weekly, women forty-four. Most of the latter work in the shirt factory, but they do not need to sing Hood's _Song of the Shirt_. Sweating is unknown; every worker, from the youngest to the oldest, receives his or her share of the profits, which amount to about $15,000 yearly. Here we have an almost ideal manufacturing establishment, and if all were such we should have higher hopes for human health in the immediate future for our workers in factories. It was the outgrowth, the effort of the Scotch, a highly intellectual race, to adjust itself to its environment. Necessity and competition acting on them forced them to new and better adjustments. Such a result could hardly have been achieved by a less hard-headed and practical people, a race on which evolution has for ages produced some of its best effects. HYGIENE.--But I fancy you ask me, Is there any hope that in the future evolution, and with it adjustment to environment, will carry man so far that an ideal state of health will be the lot of all? This is what hygiene promises. Is it a vain hope? If we look at what older sciences have done for man we find much to encourage us. In astronomy, by the aid of mathematics, we can calculate with certitude the date of future eclipses. In many other sciences we can make accurate predictions and accomplish results of the greatest importance. Indeed, science has become almost our only authority. Imperfect as it yet is, we trust it, perhaps, too implicitly. The science of hygiene is the youngest of all the sciences. Not that the Greeks, the Hebrews, the Hindoos and Chinese did not have some practical knowledge on the subject, but it was rude and empirical. With the discoveries of micro-organisms as the cause of a series of the worst diseases, we have begun to place hygiene alongside mathematics and chemistry. We now know the origin of many diseases which formerly were enveloped in mystery. Can we remove them? That is the next task. Hygiene will in the future busy itself with this great question. It has, it is believed, already made many cities proof, or almost proof, against cholera and yellow fever. It will try to make them proof against other contagious diseases also, and it will without doubt succeed. But its work will not then have been accomplished. We may avoid the causes of disease and still be puny creatures. Our great task will be the building up of bodies equal to the needs of our environment. This we have, in a small way, already begun to do--imitating the ancient Greeks--in our schools of physical culture, where the body can be trained up to its best, and also in our laboratories for psychological research, in which the relation of mind and body are being carefully investigated, where every subject connected with every function is being studied, even weariness, anger, hope, despair, drink, food, sleep, the weather, and their effects on function. The results of such knowledge will prove beyond a doubt that the health of the body, as well as of the mind, is of the highest importance for success in life, for happiness and usefulness, and that we can do much to secure both. My own personal hope for the future of human health lies in the evolution and spread of this gospel of hygiene. Hygiene interests itself in all that relates to human well-being. It may be defined as _the ethics of the body--the science of true living_. It promises health to all who obey its laws. It makes no such promise to those who disregard them. In the future, no doubt, a higher average of health will be the result of our ever-increasing knowledge; and whenever we are able and willing to apply this knowledge to our own bodily and mental conduct we shall be amply rewarded. This much we can safely promise, but no more. On the contrary, the violators of hygienic laws will, with their offspring, suffer in the future as in the past, and that suffering will be in the form of pain, disease, degeneration, premature death. This may seem hard to many who are sensitive to the pains and sorrows of the world, and some have gone so far as to attribute to the author of nature, the unknown cause of all things, a character anything but good. But this is a very erroneous way of looking at the subject. To discuss it fully we should have to consider the question of the mystery of evil, which cannot be done here. Suffice it to say, the creation, the evolution of the race, is by law. Causes produce their legitimate results. If it were not so, our sufferings might be far greater, and no progress would result. Let us be thankful that nature is as it is, and let us do our best to put our lives in harmony with it. By so doing, we may in the end attain all that we strive for. THE GERM PLASM; ITS RELATION TO OFFSPRING. The germ plasm is a most interesting and remarkable substance. It must be interesting, for everything which relates to life and reproduction is interesting. It must be remarkable, for out of it, under proper conditions, remarkable results are produced. Although our knowledge of its nature is very imperfect, yet let us not on this account refuse to try to understand what little is known. In the first place, the germ plasm of animals which reproduce sexually is composed of two germ plasms--that of the male, and that of the female. That of the male is called the _spermatozoon_ (pronounced sper´ma-to-zoön). It is sometimes called spermatozoid; the plural is spermatozoa. It is exceedingly small, the smallest of any cell in the body, and has the power to move from place to place. These cells are produced in enormous numbers, and so far as they have been observed under the microscope they differ considerably in power of movement and in perfection of development. Considering their small size, they must make a very long journey to find the ovum; and if they were only few in number, they would rarely succeed; but existing in large numbers, for there are millions of them produced in each sexual act of the male, some of them are pretty sure to do so, and, probably in most cases, it would be those most vigorous and capable of making the journey most direct and in the least time. That of the female is called the _ovum_, or egg; plural, _ova_. Only a small number are produced, when compared with the number of the male spermatozoa, but there are quite enough for the ends they are to serve. They have not the same power of movement, though they do move somewhat as the amæba does. They are also very much larger than the male cells. The eggs of all mammals look alike as they come from the ovaries, but take on some changes afterward. Hæckel says: "Every primitive egg being an entirely simple, somewhat round, moving, naked cell, possesses no membrane, and consists only of a nucleus and protoplasm. These two parts have long borne distinctive names: the protoplasm being called the _vitellus_, or yelk, and the nucleus the _germinal vesicle_ (_vesicula germinativa_)." The same author also says: "The human egg cannot be distinguished from that of most other mammals, either in its immature or in its more complete condition. Its form, its size, its composition, are approximately the same in all. In its fully developed condition it has an average diameter of one-tenth of a line--about the one hundred and twentieth part of an inch. If the mammalian egg is properly isolated, and held on a plate of glass towards the light, it appears to the eye as a very fine point. The normal eggs of most of the higher mammals are of almost exactly the same size. They have the same spherical form; always the same characteristic covering; always the same clear, round germinal vesicle with its dark germinal spot. Even under the highest power of our best microscopes there _appears_ to be no essential difference between the eggs of a human being and that of the ape, the dog, the cat or other animal." This similarity is one of appearance only. There is a difference, and of this I shall speak later. It may be asked if the egg of a bird is the same as the egg of a mammal. The mature bird's egg, as it is laid in the nest, differs materially from that of any mammal; but in its miniature form, as found in the hen's ovary, it is also the same. The egg of a bird after it leaves the ovary, and as it passes along the oviduct, takes on secretions in its passage which it converts into yelk, and afterwards a shell is added to give it protection in the external world, where it must undergo incubation before it can become a bird; but before it takes on its shell it has been fertilized, and this also causes other changes. Hæckel says: "After the ripe egg of the bird has left the ovary, and has been fertilized in the oviduct, it surrounds itself with various coverings which are secreted from the inner surface of the oviduct. The thick layer of transparent albumen first forms round the yellow yelk; this is followed by the formation of the outer calcareous shell, within which is another envelope, or skin. All these coverings and additions which are gradually formed round the egg are of no importance to the development of the embryo; they are parts which have nothing to do with the simple egg cell. Even in the case of other animals we often find large eggs with thick coverings. For example, the shark's; but even in this case the egg is originally exactly similar to those of mammals when in its primitive condition as it comes from the ovary. In the case of the bird these additions serve only as food for the growing embryo, which, in the case of mammals, is furnished by a stream of the mother's blood, making 'stored-up' nutriment unnecessary." Before, however, we can have _true germ plasm_ the mother cell must be fertilized by the male cell. This is true of all the higher plants and animals. There are some low plants and animals in which fertilization by the male cell is not required. This has been called virginal generation. In no mammal is this possible. How fertilization takes place and what it signifies are both important questions which have not been entirely settled, and it almost seems as if they could not be settled in some of their details, except in the lower forms of life. Nature has so protected the process from observation in the higher animals that it cannot be studied in detail; but in plants and the lowest animals it has been observed with some success, and we may infer that the process is very much the same in the higher animals. Hæckel, in his great work on the Evolution of Man, tells us that "The process of fertilization in sexual generation depends essentially on the fact that two dissimilar cells meet and blend. In former times the strangest views prevailed with regard to this act. Men have always been disposed to regard it as thoroughly mystical, and the most widely different hypotheses have been framed to account for it. It is only within a few years that closer study has shown that the whole process of fertilization is extremely simple, and entirely without special mystery. Essentially, it consists merely in the fact that the male sperm-cell coalesces with the female egg-cell. Owing to its sinuous movements, the very mobile sperm-cell finds its way to the female egg-cell, penetrates the membrane of the latter by a perforating motion, and coalesces with its cell material. "A poet might find in this circumstance a capital opportunity for painting in glowing colors the wonderful mystery of fertilization; he might describe the struggles of the 'seed animalcules' eagerly dancing round the egg-cell shut up in its many coverings, disputing the passage through the minute pore-canals of the chorion, and then of purpose burying themselves in the protoplasm of the yelk mass, where, in a spirit of self-sacrifice, they completely efface themselves in the better 'ego.' But the critical naturalist very prosaically conceives this poetical incident, this 'crown of love,' as the mere coalescence of two cells! The result of this is, that in the first place the egg-cell is rendered capable of further evolution, and, secondly, that the hereditary qualities of _both_ parents can be transmitted to the child." By coalescence is understood, growing together, not mingling as water and milk might when mixed. More recent observations indicate that during coalescence both the male and female cells throw off some portions of their substance. It is also considered that the important part of each cell is its nucleus. In it all hereditary characteristics are stored up. If the nucleus be absent in either cell these cells cannot reproduce. In unicellular, or one-celled, organisms, it has been found in multiplication by division, a part of the nucleus must go with each half, otherwise the half without a part of it does not grow. In experiments in laboratories, artificial division of simple organisms may be made, and each fragment will become a perfect creature if only a very small piece of the nucleus goes with the separated portion; but if a part is cut off without any of the nucleus, then, while it may live on for a short time, it can not grow or propagate. Possibly we have here an explanation of some hereditary phenomena in human beings. If there is an unequal division, and more of the male than of the female nucleus, the child might, as a result, inherit more of the father's than of the mother's characteristics, or the reverse. What has been so far said about the germ plasm has been to enable the reader to possess a degree of intelligence on the nature of fertilization, so far as it is known; but from a practical standpoint the most important knowledge for those prospective parents who wish to practice intelligent stirpiculture is to understand that the health of the germ plasm or fertilized ovum depends on the health of the parents. By health, I mean the possession of a good constitution, to which will be added a strong hold on life, power to do and to endure, and quickly to recover from weariness. Disease will be easily warded off in such persons, so that there will be generally good health. Such a condition of body is usually inherited. It depends on the possession of a large supply in the body of living matter--firm muscles, a good heart, lungs and digestive organs. Those who are feeble cannot endure much; whose heart, lungs and digestive organs are weak; whose hold on life is slight, can rarely endow their offspring with these high qualities. Their children may live if no great strain comes upon them; but if they must take an active part in the struggle and competition going on in the world they cannot endure it. Mr. Spencer puts the case very aptly in his work on Ethics where he says: "It results that where maternal vigor is great, and the surplus vitality consequently large, a long series of children may be borne before any deterioration in their quality becomes marked; while, on the other hand, a mother with but a small surplus may soon cease altogether to reproduce. Further, it results that variations in the state of health of parents which involves variations in the surplus vitality have their effects on the constitutions of offspring to the extent that offspring borne during greatly deranged maternal health are decidedly feebler. And then, lastly and chiefly, it results that after the constitutional vigor has culminated, and there has commenced that gradual decline which in some twenty years or so brings absolute infertility, there goes on a gradual decrease in that surplus vitality on which the production of offspring depends, and a consequent deterioration in the quality of such offspring. This which is _a priori_ conclusion is verified _a posteriori_. "Mr. J. Mathews Duncan, in his work on Fecundity, Fertility, Sterility and allied topics, has given results of statistics which show that mothers of twenty-five bear the finest infants, and that from mothers whose ages at marriage range from twenty to twenty-five years there come infants which have a lower rate of mortality than those resulting from marriages consummated when the mothers' ages are smaller or greater. The apparent slight incongruity between these two statements being due to the fact that whereas marriages commenced before twenty and twenty-five cover the whole of the period of highest vigor, marriages commenced at five and twenty cover a period which lacks the years during which vigor is rising to its climax and includes only the years of decline from the climax." This quotation from Mr. Spencer needs a qualifying remark. Mr. Galton, in his work on Hereditary Genius, found that the average age of mothers of men of the greatest ability was about thirty, and of their fathers thirty-five. In such cases, the physical and intellectual strength must have been above the average, and, consequently, it continued to a more advanced age. Besides, those of great ability mature later. It may also be added that Duncan's statistics, quoted by Spencer, are average statistics gathered from tables of mortality, and include every class of persons. Now, average statistics do not apply to individual cases, and they would not apply to those highly endowed physically and intellectually. Further, those who are well endowed at birth and whose lives are in accordance with hygienic law, that is, those who do not squander their physiological resources by sensuality, by intemperance, or by excesses of any sort retain their health to a greater age than those whose lives are the reverse. Such are of a youthful physiological age, which is not altogether determined by the actual number of years they have lived, but by very high physiological conditions. From all this we conclude that a very important rule in the production of offspring, if we would have those offspring superior, is to maintain a high degree of health--a condition in which there is a surplus of physiological capital to produce children with endowments equal to, if not superior to, their parents. Another subject requires treatment here. It is the effect of alcohol on offspring. We are yet lacking in statistics giving the facts we need to know on this subject; but the general observation of competent persons who have had good opportunities to study it may teach us something. Alcohol, in its circulation in the blood, penetrates every part; not even the germ plasm escapes. Demme studied ten families of drinkers and ten families of temperate persons. The direct posterity of the ten families of drinkers included fifty-seven children. Of these, twenty-five died in the first weeks and months of their lives; six were idiots; in five a striking backwardness of their longitudinal growth was observed; five were affected with epilepsy, and five with inborn diseases. Thus, of the fifty-seven children of drinkers only ten, or 17.5 per cent., had normal constitutions and healthful growth. The ten sober families had sixty-one children, five only dying in the first weeks; four were affected with curable diseases of the nervous system; two only had inborn defects. The remaining fifty, 81.9 per cent., were normal in their constitutions and development. In this statement we have a graphic object lesson of the evil effects of alcohol on the germ plasm. Natural selection had far more to do in removing those unfit to survive in the intemperate than in the temperate families. A knowledge of the evil effects of alcohol on the unborn child was known to the ancients. The mother of Sampson was warned "not to drink any wine or strong drink nor to eat any unclean thing" because she was to conceive and bear a son who was to deliver Israel out of the hands of the Philistines. Manoah was so interested in what the angel of the Lord had said to his wife that he sought an interview with him for further confirmation, and asked: "How shall we order the child, and how shall we do unto him?" evidently meaning, "How shall we train and educate him?" and the same advice was given as before. Whatever view the reader may hold as to the inspiration or non-inspiration of the Bible, certainly this advice was good. Other examples similar to it are to be found, not only in the same book, but in numerous historical works, and also abundant evidence in our own time of the evil effects of alcoholic drinks on unborn children giving them a tendency to insanity, idiocy and other nervous diseases. A whole book might be written on this branch of our subject. To what extent food affects the germ plasm we remain somewhat in ignorance. We know that it is from it that the body is nourished, and from it also the stored up or surplus matter in our systems is obtained. The larger the surplus the more highly will the offspring be endowed with energy is a fact clearly set forth by Mr. Spencer. A surplus of fatty food stored up in the body, however, cannot be of much service and may prove injurious. A deficiency of nitrogenous food would also, it seems to me, be an evil. The germ plasm, or its most important part, is a highly nitrogenous substance, like all protoplasm, or living matter. The highest form of germ plasm, that with a most complex molecular structure, would hardly be formed if there was a deficiency of nitrogenous matter in the blood. Air is also food the same as bread is. The activities, the chemical changes in the body, are mainly, though not entirely, between the oxygen of the air and the carbon and hydrogen of our food. The body is quite as much injured by a deficiency of air inhaled into the lungs by exercise as by a deficiency of food, though the injury may be of a different nature. Physicians and others have long ago observed that the offspring of parents living much in the open air and sunlight are healthier and stronger than those of parents living in confined spaces, where air and light are deficient. Air which is impure, which is loaded with poisonous matter, if inhaled for a long time by the mother, lowers the standard of her health. In malarious regions, the vigor of the offspring is less, and the number who die in infancy greater, than in regions where the air and water are pure. Many years ago I remember reading in one of the journals devoted to sanitary science published in London, an account of a rural town where both air and water were of extraordinary purity, and in this town a very large percentage of the children born lived to grow to maturity. There is also an isolated region in France, bordering on the sea, where both air, water and climate are unusually salubrious, and though intermarriage has been practiced for a long time among the several thousand inhabitants, the people are remarkably well formed and healthy. Similar facts have been observed in other places. They indicate to us that a healthful climate, with good air and water, are important factors in all true stirpiculture. While all diseases which exhaust the physiological resources of the system are detrimental to the offspring, there are certain ones which are peculiarly so. Specific diseases or those resulting from a sensual life are the first to be mentioned. If the bodies of either father or mother become saturated with the poison, which is probably a germ, then the child born of such parents will certainly be infected and either die at birth or live only a short and feeble life. It is one of the penalties of an impure life--a very severe one, no doubt, but perhaps not too severe, that the offspring of the sensualist must suffer the penalties for its parent's physiological sins. Medical men have long been trying to discover a remedy which will make it safe for a man infected with specific disease to marry and become a father, but so far they have not had much success. It is doubtful if they ever will. Epilepsy is another disease which is so often transmitted to children that any one of either sex suffering from it had better abstain from parentage. If one parent is remarkably healthy, the children may escape the severest form of penalty; but even then they may suffer from nervousness and other diseases, and rarely enjoy robust health. The question whether persons who have a consumptive tendency should become parents or not has frequently been discussed by sanitarians, but never settled. Such persons are frequently intellectual, and often of an unusually cheerful and hopeful disposition. They are, in most cases, quite prolific. In the female they generally make excellent wives and mothers; in the case of the male, they are not uncommonly good providers for their families, and also good fathers. Except in the worst cases, does the welfare of the race demand that they shall not marry and become parents. Probably not. But we must advise them to take the very best care of their imperfect bodies; to develop their chests by wise but not excessive physical training; to husband their physiological resources carefully; not to marry young, nor rear too many children. Excessive childbearing is a prolific cause in women of consumption, and excessive sexual indulgence is a frequent cause of it in both sexes. These remarks should not be construed to mean that those who are already in the early stages of this disease, or whose families on both sides have been deeply affected by it, may become parents. They should not. But in the present state of society, we cannot hold men and women up to an ideal standard. Some slight risks may be taken, but not too great ones. As the race progresses in knowledge, however, we may raise our standards, and finally make them so high that no one with a tendency to any serious disease which is likely to affect the offspring unfavorably shall have any right to contribute to the world's population. I have mentioned only a few of the many diseases which affect the germ plasm unfavorably. It is hardly necessary to extend the list. One other subject deserves consideration, when I will bring this chapter to a close. Every child born into the world is, to a certain extent, an experiment. That is to say, the parents cannot predict its sex, nor what its chief characteristics will be. These depend on what potentialities are stored up in the germ plasm. If this be formed by parents in good health, with a surplus of vital force, and a long line of ancestors with normal lives, we may believe that if the environment be favorable, the child will develop so as to show the same characteristics, perhaps in an even higher degree. Whatever variations there are will not be much below or above the average line of its ancestors. The congenital characters will tend to be transmitted. They are in the germ plasm, even in great detail. Whether the acquired ones are transmitted may still be uncertain; but whether they are or not, normal right living will be sure to have good effects. Obey the laws of life and far better results will follow than if they are disobeyed. FEWER AND BETTER CHILDREN. In the present age suggestions on this subject may seem superfluous. The more highly educated and wealthy classes have already sufficiently reduced the number of children which they bring into the world. But are these offspring any better than they would have been had their parents given birth to a larger number? Mr. Darwin did not think much could be done to improve the race by parents limiting the number of their offspring. He would trust to natural selection to weed out the unfit, and to sexual selection as an aid. He thus describes the probable manner of action of sexual selection among primeval men: "The strongest and most vigorous men--those who could best defend and hunt for their families; those who were provided with the best weapons and possessed the most property, such as a large number of dogs or other animals--would succeed in rearing a greater average number of offspring than the weaker and poorer members of the same tribes. Such men would doubtless generally be able to select the more attractive women. . . . If, then, this be admitted, it would be an unexplainable circumstance if the selection of the more attractive women by the more powerful men of the tribes, who would rear on the average a greater number of children, did not, after the lapse of generations, _modify the character of the tribes_." The way in which the tribe would be modified would be by its producing better children. Of course among primitive men the richer and more powerful had several wives, but it is not likely that the number of children by each one was large. Natural selection is, however, a painful process, necessary, no doubt, where ignorance prevails; but if the number of children of each pair could be limited and of a superior character, so far as vigor and adaptation to environment are concerned, would there not be less need for natural selection with all its evils? It seems to us that this would be so. We have already quoted Grant Allen as favoring abstinence from parenthood on the part of the unfit and the duty on the part of the fit to become parents, and, theoretically, Mr. Allen is right; but except as both of these classes are swayed by duty we would make little progress in this way. A majority of mankind think they are the fit. Why should they crucify their desires for the benefit of the race? As mankind becomes more moral Mr. Allen's views may have a larger influence on thought than now; but before that time little can be expected from them. Mr. Spencer says: "We have fallen upon evil times, in which it has come to be an accepted doctrine that part of the responsibilities [of parenthood] are to be discharged, not by parents, but by the public--a part which is gradually becoming a larger part, and threatens to become the whole. Agitators and legislators have united in spreading a theory which, logically followed out, ends in the monstrous conclusion that it is for parents to beget children and for society to take care of them. The political ethics now in fashion makes the unhesitating assumption that while each man, as parent, is not responsible for the mental culture of his offspring he is, as a citizen along with other citizens, responsible for the mental culture of all other men's offspring! And this absurd doctrine has now become so well established that people raise their eyes in astonishment if you deny. But this ignoring of the truth, that only by due discharge of parental responsibilities has all life on the earth arisen, and that only through the better discharge of them have there gradually been made possible better types of life, is, in the long run, fatal. Breach of natural law will, in this case, as in all cases, be followed in due time by nature's revenge--a revenge which will be terrible in proportion as the breach has been great. A system under which parental duties are performed wholesale by those who are not parents, under the plea that many parents cannot or will not perform their duties--a system which fosters the inferior children of inferior parents at the cost of superior parents and consequent injury of superior children--a system which thus helps incapables to multiply and hinders the multiplication of capables or diminishes their capability must bring decay and ultimate extinction. A society which persists in such a system must--other things equal--go to the wall in the competition with a society which does not commit this folly of nourishing its worst at the expense of its best." We have evidence among primitive people that they understand the necessity of limiting offspring, and practice it in a perfectly healthful way. The natives of Uganda, a region in Central Africa, offers an illustration: "The women rarely have more than two or three children; the practice is that when a woman has borne a child she is to live apart from her husband for two years, at which age children are weaned." Seaman, speaking of the Fijians, says: "After childbirth husband and wife keep apart three and even four years, so that no other baby may interfere with the time considered necessary for suckling children." Some fifty years ago there lived in New York a young couple, strong, healthy, ambitious to be rich, and both saving and industrious enough to become so under ordinary conditions. The husband was in a business which required constant attention; and in order to promote it and save the expense of help which he thought he could not afford, he labored nights, often up to the hours of twelve and sometimes one o'clock, and then arose early and went at it again. His wife sympathized with him in all his undertakings, helped him in every way possible, even to the sharing of his midnight toils. In no way did either of them spare themselves. They knew something of the evils of poverty, and were determined that it should not always be their lot. Fortune favored them, and their bank account grew larger and larger until they could count the value of their possessions as amounting to several million dollars. They lived in a fine country seat, and could gratify every wish, so far as food, clothing, books and travel were concerned. During their early married life, when the strain of work was the greatest, two children were born unto them, both boys, and they are alive today; but are they a comfort to their parents, and a help in their declining years? Instead of this they are both deformed and cripples, unable to help themselves or do any labor. Their family physician has told me that the overwork and privation of the parents at the time of their birth and before, was undoubtedly the cause of the children's inferiority. A younger son born after the wife had ceased to toil like a slave, gives some promise of being a man of character. We have here a typical case of strong, healthy parents, with a limited number of offspring, yet they were not superior. On the other hand, it would be easy to collect a large number of instances where the children in large families have had superior endowments. Take Benjamin Franklin as an example. He was the fifteenth child of his father, Josiah Franklin, and the eighth of the ten children of his mother. It seems that superiority is a result of great vigor and perfection of body and mind and of abundant reproductive power. Where this is absent the children will hardly be superior. Yet in both cases a certain degree of limitation ought to be advantageous. In conclusion, let me say what I have indirectly said already. Let the strong, the capable and the good rear as many children as they can without overburdening themselves in any way, and let the weak, the imperfect and the bad rear few or none, but devote their lives to perfecting their own characters. In this way the future race will be modified for good and not for evil. A THEORETICAL BABY. _Reported by request of Dr. Holbrook._ It was our first baby. I was making a living as a doctor by writing articles on the general care of the health; and my wife before her marriage had been a kindergartner, a trainer of kindergartners, and a lecturer to mothers on the scientific and expert methods of rearing children aright. We believed in the theories we had taught, and our baby got nothing else from the start. According to the first applied theory, we made our temporary home before the boy began to be, in the Rocky Mountains of Colorado; and were a large part of the time either in our garden or on horseback, in this perfect outdoor climate. My wife was entirely in love with me, and I made each day count for nothing more certainly than to deserve and return that sentiment of hers. We lived simply but freely, and had next to no anxieties. My wife had practiced general gymnastics for years; but for months prior to the birth of her boy, she every day went through with a series of special maternal gymnastics, by which the muscles that aid in parturition can be made strong and entirely to be relied upon. We were rewarded for this outlay of time in a delivery that was rapid and easy, without more than an ounce of hæmorrhage, and everything so perfectly controlled that--except for the inconvenience of it--the presence and aid of the physician (myself) might have been dispensed with. Recovery was rapid also. My wife made no haste to get up, keeping quiet most of the time for two weeks, to ensure good milk. But she did a family washing without effort after three weeks, and was on horseback again by the sixth week. The baby was not severed from his mother till ten minutes after birth (ensuring a better blood supply). Then he got no bath, no food, no dressing process; but was simply swathed in cotton batting and laid aside for six hours in a padded box-bed, surrounded by bottles of hot water, and covered with plenty of soft blankets, to sleep and get used to his new environment. On the second day we began rubbing him daily from head to foot with vaseline. His first bath, with a flannel cloth dipped in warm milk diluted with soft water and without soap, came when he was a week old, and was followed by the thorough rub with vaseline. This bath he has had nearly every day up to date. He has often cried, or crowed and begged for this bath; but never cried during its performance, except when his clothes were being replaced. On the contrary, he enjoys every moment of it. Feeding began with a meal every hour of the twenty-four, for the first week. Then night feeding was reduced to two meals, and he was fed every two hours, from four or five o'clock in the morning till nine at night, till two months old. About then he began sleeping right through the nights; and until three months old was fed every three hours of the day time; then for a month he went four hours between his meals. At his fourth month began the present regime of four meals _per diem_. Now and then he has cried in the night from thirst, and a few spoonsful of cold water have sufficed to send him off to sleep again. All in all, I think I could count on my fingers the times that he has wakened us out of hours, and not once has anyone walked the floor with him. In fact, no diversions of this sort have ever been practiced on him. He has never been rocked to sleep; whenever cross or fretful in the day, we have known that sleep was all he needed, and into his little bed he has been promptly plumped, and covered with a loosely knit afghan, tented on a light framework, which we call "the extinguisher." Here shut away and entirely unnoticed he soon learned to give himself up to his own reflections, and then presently to sleep. Thus we have kept down the first great nuisance of ordinary infancy, namely, egoism and a habit of howling for attention when no attention is really needed. But social relations, and those of the gayest, he has constantly with both his parents. We take up and make into play with him each idea of his own. We have shown him some finger-plays. In the main we leave him to originate his own amusements. From the keeping of stomach and bowels absolutely healthy, by a regular and reasonable exercise of their all-important functions, not only has the boy been free from irritability, and spontaneously happy and self-amused, sometimes quiet, and sometimes jolly to overflowing. But the second great nuisance of those ordinarily attending baby-raising, namely, sour stomach followed by colic, was eliminated. A secondary result of this entire regularity of functioning at the upper end of the alimentary canal was that a like regularity set in at the other end. That is, at the thirteenth week he began to have but one daily passage of fæcal matter, and that soon after breakfast. Of the approach of this act he notified his mother without fail, and thereafter we had no soiled diapers. Movements were received on pieces of old cloth, and cloth and all tossed into a pan of ashes, or the fire, when we had one. When, at six months, we put him onto cow's milk, mixed with thin graham porridge, to supply the extra nourishment demanded by rapid growth, he went up to two movements per diem--morning and evening. Thus, the third great nuisance of of diaper washing was eliminated, in its more disagreeable feature. Eructation of curds, rashes, colic, diarrhoea--these common ailments of ordinary babyhood, we have never had a sight of. We believe it due solely to strict adherence to the four-meals-a-day plan. These consist of an early breakfast, a later breakfast, a dinner about one o'clock and a supper between six and seven. The bath comes at any convenient time. On pleasant days, even in winter, he is outdoors, well wrapped, in a chair, for hours, and often has a long nap there. He was provided, by my own needle and penknife, with an ample fur sleeping sack, into which he is securely buttoned every evening and laid in his box-bed, on a trunk. He never sleeps with his parents. According to the coolness or coldness of the nights, additional covering, in the shape of soft blankets and shawls, is laid in on the box, their weight supported by the edges of the box. He cannot uncover himself, but he can kick freely, and use his arms. We dressed him, from the first, in the "_Gertrude_" system of baby clothes, introduced by Dr. Grosvenor, of Chicago--all woolen princess garments, with shirring strings at the lower hems, by which they are made closed bags, ending just below the feet; warm, but allowing of kicking _ad libitum_. At five months--it being winter time--he went into short clothes, including solid suits of warm flannel underwear, shirts, drawers and long snug-fitting stockings. He has never had a cold. His muscles, from the first (due to his mother's gymnastics), were firm and active, like those of an adult. At the fourth week he surprised us by suspending his entire weight from his hands and arms one morning. Legs, neck, back and hands particularly have developed steadily in power and quickness. There was never any fat deposited--that _avant courier_ of so much infant mortality--yet he is, and has been all along, a rosy, plump, dimpled baby, or boy, rather, for babyhood very early lost its hold on him. Too often children seem finally to emerge from the miseries and ailments of a tedious infancy and to take on, at last, individuality and distinct character at the second or third year. This child, _per contra_, having never had a sensation of illness, or of pain, save honest hunger, has seemed to be a happy little boy almost from the first, alert or thoughtful, shouting or cooing, laughing and crowing, especially after his meals and movements, studying the world of things about him by the hour, keenly appreciative of colors and of music, and preferring some sorts to others, his face crossed by vivid changes of expression, wonder, merriment, surprise, reverie--all as perfect at six months as ordinarily seen at three years. He has good color from head to foot, is pale when hungry, but the moment a bit of food is down expands to his most genial flow of spirits. Immediately after his day-time naps his cheeks are regularly flushed and rosy. His spirits become more pronounced toward each evening, reaching their high-point of talking, laughing, crowing and squealing at just about bed-time. He keeps it up for some time after being tucked away for the night, till sleep masters him; and begins where he left off early next morning. All this is good physiology. So happy day succeeds happy day, and we trust and hope that many good tendencies are getting a fair start in a harmonious and spontaneous beginning of this great work of growing up that we are fostering but not forcing. AT ONE YEAR OLD.--Everything continues as begun. Teething at times causes slight transient fretfulness, and more cold water is drunk. The bowels remain absolutely regular. The all-night sleep (never "put to sleep,") and two day-time naps are unchanged, in all thirteen or fourteen hours of sleep _per diem_. On warm days he needs _and gets_ plenty of cool water to drink, often two-thirds of a pint at a time. Talking, standing and creeping he has attained by his own unaided initiative (this on principle). As for amusements, he invents his own always, except when engaged in social exchange with his father and mother, and in these, too, we are careful that he makes at least half the advances. On particular occasions he comes in need of mothering--and gets it. On all others he simply lives with two big but highly sympathetic playfellows; and he has developed separate lines of play and talk for each. Often he chooses to alternate as between two poles of attraction, turning his face to his mother's for her sympathy between shouts to his father, or _vice versa_. From week to week we notice that the older plays are mostly dropped one by one, and fresh ones invented. All, however, are real and vivid to him. In early prospect we have but two more points to compass. Perfect health in all respects he has intact. Self-control and self-sufficiency, both in amusing himself and in enduring lesser ills, such as bumps and mild degrees of hunger, he is getting as fast as growth permits. But obedience and responsibility will soon be needed in his repertoire. Negative obedience his mother is obtaining already in response to "No, no," and shakes of the head. Positive obedience will be the far more vital thing to secure--just as soon as he can help in little ways. Here we hope to make him responsible as far as can be for the welfare, safety and amusement of younger playfellows, whether brother or sister it is now too soon to say. AT EIGHTEEN MONTHS.--A cold douche has, for three months past, ended his morning bath, regularly given by his father after his sister arrived, and his weight became considerable. This douche, poured slowly from a dipper until redness set in, has added markedly to his spirits, muscular activity and digestive capacity. It causes screaming at the moment, but an instant later, as three Turkish towels are wrapped closely about him, his exuberance is delightful to see. Coincidently he has taken up a selected diet of solid food, including chocolate and cooked fruits, and will have but one nap, though often that is a long one. As the child is working out of babyhood, every day counting (as no day of half illness in childhood can count), and well into boyhood, the single principle already outlined, of leaving the little individuality to establish its own activities and socialities, seems sufficient, as the illustrations appended, I believe, prove. Doubtless a child that is not, day after day, enjoying, and often thrilled by health and life, as this little boy is, a child not brought up in an unbroken _camaraderie_ with both parents, such as he has had, and particularly a child not having the send-off of trust and amiable impulse which he received before his birth, could not be left to blossom in such wild-flower style. Ugly, sulky or "streaky" conduct, jumping perversely out in place of good cheer, we have never had to deal with. In fact, we have never been able to detect the slightest resentment immediately after punishing him for taking forbidden articles, or for raising an outcry over being denied sundry things he wanted. His crying when punished is that of pure grief, and he is ready at once to nestle down under the hand that had spatted disapproval, to be comforted, resuming good spirits two or three minutes later on. In the main, simply "No, no!" from either parent, has sufficed to stop him in the beginnings of mischief, sometimes resulting in cheerful desisting, and sometimes in a little of what we call the "grieved cry." But this, too, if it becomes loud or insistent, can be hushed by another "No, no," and enable him to regain control of himself. With this regained self-control has always come gratefulness for aid in the matter, as evinced by extra sweetness and brightness immediately after, and eager resumption of some one or other of his plays or calls with one or both of us. This may be what is known as discipline. It always brings a smile to our faces, however. Without a break of more than a day or two at a time, we have been able to be equally near him all the while, and divide up about equally the matters of bathing, feeding, dressing and undressing him. The conventional estimate of those standing nearest to a child of, 1--Mother, 2--Nurse, 3--Teacher, 4--Servants and playmates, 5--Older brother or sister, 6--Father--the man behind the newspaper, certainly does not apply here. When I am absent for from three to six hours his uneasiness sets in, and grows stronger and stronger, ending in repeated expeditions to a short distance along the road, where he stands and calls "Vager," "Vager," (Father, Father,) at first hopefully, then protestingly, and sometimes at last with indignation or tears. When I return--and he listens and catches the first distant sound of hoofs, or wheels, or whinny of the left-at-home colts, or voice, or opening gate--an eager, beaming face welcomes me from gate or doorway, or even several rods down the beaten snow on the road. Once back, things are all right in his little domain again, and he goes on, without special attention to me, in his series of occupations and plays. I say "occupations." They are nothing else to him; serious matters that he goes about accomplishing. He is at his best when he can help his mother at her work--blowing the fire, bringing her kindling, handing her clothespins one by one as she needs them, shutting or opening doors on request, picking up articles from the floor. But there are many hours continuously when he is left to his own devices, which are numerous, though many of them he goes through daily, such as feeding the cat, visiting his little sister, emptying and refilling the wall-pockets, collecting his blocks, and fishing articles off the table with a long stick. He has learned, untaught, to get a cloth to open the stove door with and save burned fingers; to get and bring clean diapers to his mother when he wishes a change; to stoop and lap water out of the pail; to stand by his bed and point up at it when wishing his mid-day nap; to retreat to a dark corner and drape his handkerchief over his head for a brief period towards the close of a day, in lieu of the discarded second nap; to scoop bread or biscuit out of a pail hung above his reach, with an iron spoon; to lasso peaches toward him with a cord, said peaches being in pan on the floor just beyond where he could reach from a little gate separating the kitchen and sitting-room. None of these things has been taught him. Nothing whatever has been taught him, and especially no words and no "tricks." He invents or does without, in all non-essential matters, in regular Spartan style. So, in pursuit of his own undertakings, he rarely asks for what he would have; just tries and tries, day after day, until he succeeds or is beaten. But as he is at some new act or plan much of the time when left to himself, he has, we are satisfied, independently attained to more of childish accomplishment than the most incessant teaching processes could have effected. In doing what he does do, for instance, in certain climbing feats, he has slowly worked up to, he is both cautious and sure; he rarely tumbles and never loses his confidence. Thus for the past two days he has achieved the feat of climbing up and standing erect on a little box fourteen inches high, where he calls and shouts and roars to us his ecstacy over the matter for ten minutes at a time. Today only he has found out how to get down alone. Contrast is taken here with the frequent falls and wailings of children who are first persuaded into attempts of various sorts, but have not worked out a real personal mastery of given acts for themselves. He has quite a vocabulary now of his own invention. The meanings of these terms we have learned mostly, and use them to him. Of our vocabulary he understands the meanings of a large number of the words for things in which he is interested, forty or fifty nouns, and a dozen verbs, perhaps. He sings to his mother, and now and then to me, rude imitations of the songs he has heard us sing, and his mother he roughly accompanies. His inflections of voice have developed to the point of entirely expressing many of his emotions; while his expressions of face are as much beyond these as the inflections are beyond his stock of English--about seven words, and those requiring some exigency to bring out. All this pleases us, because we truly want him to become rich in his own life, to subsist and grow in his own home-made lines of feeling and thought; and not to learn words, parrot-like, before he has the thought formed, and searching, even struggling, for a means by which to convey itself. It is dearth of internal life, emotion and unaided thought that is in need of replenishment in the average young person, not lack of English dictionary terms for things that can be _talked about_, but are evidently not intrinsic and personal. C. W. LYMAN, M. D. _New Castle, Col._ _NOTES._ _War and Parentage._ In the interests of unborn children we should, so far as possible, remove from the world those causes which, acting on the mother, either directly or indirectly, may injure them by lowering the standard of their health, or by altering and debasing their moral and intellectual natures. One of the most potent of the causes for harm is war. War has generally been regarded as one of the ennobling professions. If we look upon it in its most favorable light, all that we can say in its favor is that among primitive and barbarous races it has perhaps resulted in the preservation and spread of the most capable ones, and that it has at the same time welded them together into larger groups, and finally into nations, and habituated them to those restraints which are necessary to social existence; but we no longer require it for this purpose, and the industrial pursuits and the evolution of civilization are so disturbed by them that they should cease, and especially should they cease in the interest of our children, both born and unborn. How can war injure children? We have already shown in the chapter on Prenatal Culture that when the mother is under the influence of any powerful mental emotion, such as fear, depression, anger and similar passions during the months in which the child is being developed in her womb, there is very great danger of permanent injury to it. Only the strongest mothers, those with the most robust health, or who have the most stable nerves, those who are rarely thrown off their balance, are capable of resisting the intense excitements to which they are subject during some of the phases of war. As I mentioned in my early work on Marriage and Parentage, Esquirol, a French historian, gives details of a considerable number of cases of children born soon after some of the sieges of the French Revolution, which were weakly, nervous and idiotic, on account of the terrible strain to which their mothers had been subjected. In every war where a city is besieged, even if its women and children are sent away, they cannot be altogether free from anxieties and mental strains of a most unwholesome nature, and if some of them are soon to become mothers, the offspring not yet born must suffer. No one can estimate the vast number of children injured under such conditions in the ages past. They have been only incidentally referred to in history. The fame and glory of conquerors must not be dimmed by the relation of such occurrences. Joseph A. Allen, in _The Christian Register_, gives the results of some of his observations which bear on this subject. He says: "So much is being said about war and its effects, that I am prompted to send you the result of my observations. "I was in charge of the Massachusetts State Reform School for several years, when every inmate (there were between three and four hundred) was born before the Civil War--during the time of the great anti-slavery agitation, which did so much to educate the moral sense of the people. "I was again in charge of the same institution _when every inmate was born during, or soon after the war, when the mothers were reading, talking and dreaming of battles, and of husbands, fathers or brothers who had gone to the war_. "_I found as great a difference in the character of those inmates born before and after the Civil War as exists between a civilized and a savage nation._ "_Those under my care the second time were much more difficult to control, more quarrelsome and defiant, less willing to work or study. The crimes for which they were sentenced were as different as their characters._ "It was not uncommon for them to be sentenced for breaking and entering with deadly weapons. "This difference was not confined to inmates of reform schools, but it was manifest throughout all classes. "After the war crimes increased rapidly. In Boston garroting was common, and was only checked by Judge Russell sentencing all such subjects to the full extent of the law. "Before the close of the Civil War the State Prison at Charlestown, under Mr. Gideon Haynes, was, according to Dr. D. C. Wines, D. D., the model prison of the United States. Since that time it has been almost impossible to maintain proper discipline, owing, no doubt, to the more desperate character of the inmates. "Let us try to trace these effects back to their causes, and prove, if possible, that whatsoever a man (or nation) soweth, that shall it also reap." But there are other ways in which war militates against the noblest motherhood. Camp life is a school for vice and prostitution. In Camp Chickamauga, which is a sample of them all, during the war with Spain on account of Cuba, the amount and baseness of the prostitution by the soldiers, with both black and white women, exceeded description. In a single day forty-one cases of specific disease applied to the physicians at the hospitals for treatment. These things were not reported in the daily papers; they were too vile. The place was a hot-bed of vice, rather than a school of virtue and patriotism. In all European armies it is the same. In times of peace, soldiers from the highest to the lowest in rank, insist that facility shall be allowed them for the gratification of their passional natures. The officers, not being permitted to marry unless they or their wives have a certain income, keep their mistresses, and not a female servant near a camp is safe. The immoral influences here generated spread throughout society, lower the standard of morals among both men and women in private life, and jeopardize the interests of children born or unborn, morally and intellectually, as well as physically. But there is another view. "Great standing armies," says the Czar of Russia, in his note to the Powers, "_are transforming the armed power of our day into a crushing burden which the people have more and more difficulty in bearing_." That is to say, the tax imposed upon the individuals of any nation to support its army pauperizes or keeps on the verge of poverty a large portion of the race. It is war, far more than any other cause, which has created the burden of taxation. In some European countries almost every man carries a soldier or sailor on his back, that is, he must labor not only to support himself and family, but a soldier or sailor who devotes his life to a murderous profession. Is this not a grievous burden which cripples or paralyzes his life and reacts on his offspring? Now, the poverty caused by this burden is a serious obstacle to the production and training of the young, and especially is this the case in the more populous countries--France, Spain and Italy are examples. These lands were once the most powerful in Europe; they are so no longer. They gloried in war, and spent immense sums of money upon their armies and burdened the people with taxes which should have been reserved for the use of fathers and mothers in educating and providing for the needs of their offspring. War has crushed out the best life of these countries, and other nations which follow in the same path will in the end come to a similar fate. They may hold out a long time, but not forever. "The mills of Gods grind slowly, but they grind exceeding small." It is because war is an enemy to the highest motherhood that women should array themselves against it. It is one of the greatest foes to the development and welfare of the children they love so well. Women should insist that all governments should settle their differences by peaceful rather than by warlike means. The industrial age may have its difficulties, but they are not insurmountable. In it the fathers and mothers may have the time and the means to study and learn how to improve the race through a wiser parentage. I believe that thoughtful women, when they come to see the evils of war in their true light, as they have seen the evils of prostitution and intemperance, will be its greatest foes. _Cases of Prenatal Influences._ Alfred Russell Wallace gives in _Nature_ a few cases of prenatal influences sent him by his correspondents. The first experience is from a mother residing in Australia. She writes: "I can trace in the character of my first child, a girl now twenty-two years of age, a special aptitude for sewing, economical contriving and cutting out, which came to me as a new experience when living in the country among new surroundings, and strict economy being necessary, I began to try to sew for the coming baby and myself. I also trace her great love of history to my study of Froude during that period. Her other tastes for art and literature are distinctly hereditary. "In the case of my second child, also a daughter, I having interested myself prior to her birth in literary pursuits, the result has been a much acuter form of intelligence, which at six years old enabled her to read and enjoy the ballads which Tennyson was then giving to the world, and which at the age of barely twenty years allowed her to take her degree as B. A. of the Sydney University. "Before the third child, a boy, was born, the current of our lives had changed a little. Visits to my own family and a change of residence to a distant colony, which involved a long journey, as well as the work incidental to such changes, together with the care of my two older children, absorbed all my time and thoughts, and left little or no leisure for studious pursuits. My occupations were more mechanical than at any other time previous. This boy does not inherit the studious tastes of his sisters at all. He is intelligent and possesses most of the qualifications which will probably conduce to success in life, but he prefers any kind of out-door work or handicraft to study. Had I been as alive then as I am now to the importance of these theories, I should have endeavored to guard against this possibility; as it is, I always feel that it is, perhaps, my fault that one of the greatest pleasures of life has been debarred to him. "But I must not weary you by so many personal details, and I trust you will not suspect me of vanity in thus bringing my own children under your notice. Suffice it to say that in every instance I can, and do, constantly trace what others might term coincidences, but which appear to me nothing but cause and effect in their several developments." Mr. Wallace then gives extracts from other correspondents as follows: Mrs. B---- says: "I can trace, nay, have traced (in secret amusement often), something in every child of mine. Before the birth of my eldest girl I took to ornithology, for work and amusement, and did a great deal in taxidermy, too. At the age of three years I found this youngster taking such insects and little animals as she could find, and puzzling me with hard questions as to what was inside of them. Later on she used to be seen with a small knife, working and dissecting cleverly and with much care and skill at their _insides_. One day she brought me the tiniest heart of the tiniest lizard you can imagine, so small that I had to examine it through a glass, though she saw it without any artificial aid. By some means she got a young wallaby, and made an apron with a pocket inside which she used to call her 'pouch.' This study of natural history is still of interest to her, though she lacks time and opportunities. Still, she always does a little dissecting if she gets a chance." ANOTHER CASE.--"I never noticed anything about P---- for some years. Three months before he was born a friend, whom I will call Smith, was badly hurt, and was brought to my house to be nursed. I turned out the nursery and he lay there for three months. I nursed him until I could do so no longer, and then took lodgings in town for my confinement. Now after all these years I have discovered how this surgical nursing has left its mark. The boy is in his element when he can be of use in cases of accident, etc. He said to me quite lately: 'How I wish you had made a surgeon of me!' Then all at once it flashed in upon me, but, alas! it was too late to remedy the mistake. "Before the birth of the third child I passed ten of the happiest months of my life. We had a nice house, one side of which was covered with cloth of gold roses and bougainvillea, a garden with plenty of flowers, and a vineyard. Here we lived an idyllic life, and did nothing but fish, catch butterflies and paint them. At least my husband painted them after I had caught them and mixed his colors. At the end of this time L---- was born. This child excels in artistic talent of many kinds; nothing comes amiss to her, and she draws remarkably well. She is of a bright gay disposition, finding much happiness in life, even though not always placed in the most fortunate surroundings. "Before the birth of my next child, N----, a daughter, I had a bad time. My husband fell ill of fever, and I had to nurse him without help or assistance of any kind. We had also losses by floods. I don't know how I got through that year, but I had no time for reading. N---- is the most prudent, economical girl I know. She is a splendid housekeeper and a good cook, and will work till she drops; has no taste for reading, but seems to gain knowledge by suction." Such cases are so numerous that they should be collected and scientifically studied. _Luxury and Parentage._ In all ages of luxury, fine ladies try to avoid maternity. They detest it in theory only, for women are controlled by the instinct of the race. In the circles of which we are speaking, the instincts of the race for children have vanished. Life has lost its serious meaning. Responsibility of any kind is a mere nuisance, and the idea of bringing up a new life, with all its bonds and its charm, is as repellant as the idea of a new bonnet is enticing. For such women the world has no use. Beautiful, in the great sense, they are not. Incapable, in any great way, of either loving or being loved, they are at best the painted bubbles on the stream of life. Such women will always be far inferior as mothers, and less capable of bringing into the world noble offspring than those women in the humble walks of life who live naturally, who love the family ties and are fond of the young. Great mothers must have a certain sort of hardihood which comes from a wise physical culture, not necessarily an artificial one,--a life in the open air, and the avoidance of all social dissipation. _Degeneracy of the Breasts and Motherhood._ A sign of degeneracy is pointed out by Hegar, who appeals to young men on behalf of posterity to choose for wives women with well-developed breasts; he quotes statistics to prove inability to nurse a child a sign of degeneracy which produces degeneracy in the offspring. Among other facts he points out that in a district of his knowledge, which supplies a large number of wet nurses to the city, the percentage of men incapable of military service amounts to 30 per cent., while in the neighboring districts, where the mothers remain at home with their families, it is only 18 per cent. He remarks upon the surprising number of deformed nipples encountered in the hospitals. Fehling mentions "hollow nipples" as occurring in 6.7 of his obstetric cases. He warns mothers not to allow the clothing to constrict the growing breasts of their daughters, and urges general hygiene as the best method to develop them. In this connection the question may be asked, Is it possible for women with defective breasts to become mothers of a virile race of men and strong women. In most cases it is not. A defect in this part of their nature is evidence of a weakened constitution. It may be said, that the breasts do not always develop before marriage and parentage. This is true, and if the health is robust, and the constitution and ancestry good, the mother will, in most cases, be able to nurse her child. If it is known in advance that such cannot be the case, and it may generally be known, then the responsibilities of motherhood should be undertaken with the greater precaution. In modern times we have far better means of bringing up children by hand than formerly. Still, a mother able to nurse her own children should always be preferred. _Location of Birth._ In Manchester, England, in 1892, 37,674 boys out of every 100,000 died before they reached their fifth year. In healthy districts only 17,314 out of 100,000 died. About the same condition prevails in other places. The lesson it teaches us is, that we should choose a healthy region in which to live if we would rear the healthiest offspring. _Evolution._ This word means progress and progress implies improvement, without which there could be no evolution; but improvement of the human race will not be further possible unless the marriage relation is regarded from a higher stand-point than that of sexual indulgence. The practical superiority of man over animals consists in his knowledge of the _aim_ of his conduct. Animals exercise the reproductive function instinctively at particular seasons, but man knowingly always; and thus, unless the latter subordinates his passion to reason he is worse than a brute, as he knows himself to be such. The difference between the chaste marriage of affection and the unchaste marriage of passion, is analogous to that between education and instruction, as explained by Elder Evans of the Shaker Community. Instruction imparts knowledge, such as is associated in Eastern lore with the sexual passion, but education embraces the whole disposition, which is rendered more beautiful and spiritual through a marriage of chastity, and as thus affected is transmitted to the offspring, who exhibit the disposition of their parents at the time of conception. Sexual excess not only tends to produce offspring of a weakly constitution, but it interferes with the organic growth of the parents. It is as wasteful as burning a candle at both ends at the same time. Parents should bear in mind that the mental plan on which their children shall begin life, depends on the desire by which they are governed when they beget their offspring; and as desire depends on disposition, they should aim at requiring harmony of character and conduct. If we think less of ourselves and more of the race to which we belong, we shall have a better chance of improving both ourselves and the race as represented in our offspring. We are all members of a great organism, which is constituted by the whole of human kind, past, present and future, and it is our duty to act in such a manner that the whole shall be benefited by our conduct; which it cannot be if we are careless as to our own disposition or as to the character of our offspring. Our Aryan ancestors were conscious of their duty towards the race, and probably to this fact was largely due the high physical development the white race attained. Only by acting in their spirit can we hope to maintain the race at its high level or prevent its deterioration and decay. The important influence which the gratification of the sexual impulse has had over the development of the aesthetic side of Nature has been often insisted on; and there is no reason why its gratification should not be attended also with the development of the highest mental qualities, if these are made use of in the formation and exercise of the marriage relations between the sexes.--C. STANILAND WAKE. _Too Little Fatherhood._ The modern child is threatened not with too much mother but with too little father, and this danger is heightened by the sudden release of womanhood from the ban of conventionality and of the domineering power of physical force. Let her not too readily accept as complimentary to herself the church's adoration of Mary. Woman is made of no purer stuff than man, her companion, man her father. She cannot transmit from her own veins or her companion's veins any purer life stuff, any finer impulse to her daughter than she does to her son. We need more fathers in the home, more men teachers in our public schools; and if our homes and schools are not organized so as to evoke and direct this masculine investment, then let them be reorganized. It is not true that mothers are peculiarly the divinely appointed teachers of children, that to them is especially entrusted the intellectual or spiritual destinies of the young. That argument is based upon the analogies of the past; it is a reversion to primitive conditions, an illustration of the law of atavism, like the return to six fingers and toes in some people, or the restoration in others of the muscle that can move the ear. The highest reaches of evolution point to a double responsibility and a double potency. In the interest of the child, then, let us lift him out of a mother rule into a father and mother rule. Let the home be girdled with masculine order and justice as well as with feminine love and tenderness. Let there be strength as well as tenderness. Let there be in it mind as well as heart, vigor as well as sympathy. All these are spiritual children which cannot be born except in the bi-sexual realm.--REV. JENKIN LLOYD JONES. _The Flat-Head Indians and Heredity._ Amongst the round-head tribes woman holds a higher position, whereas amongst the flat-heads she is a mere drudge. In by-gone days it was common to see a tired-looking woman walking behind her husband carrying a heavy load, while he walked on before with nothing. Again, the round-heads have a remarkable mythology, while the others have a poor affair. Mr. Dean has informed me that the flat-head, which would be an acquired character, is never transmitted to offspring--another argument against the Lamarchian theory, that acquired characters are transmitted. That whatever injures the physical or intellectual health of parents tends to degrade their offspring has long been evident. I think we have a good race illustration of this in the effects of flattening and deforming the skulls of children among the Flat-Head Indians, who for centuries followed this precedent. Information has been furnished me by special request by Mr. James Dean, of Victoria, B. C., bearing on this point. He writes: "Among the children the mortality seems to be greater with the tribes which flatten the heads of their children than in those who do not. I have long noticed that there is a very marked intellectual difference between them." The Hidery tribes of Northern British Columbia and Southern Alaska, who never flattened their heads, have long been famous for their works of art, such as elaborate carvings in wood and stone. _Suggestion as an Aid in the Training of Children._ Within a few years an old subject, that of hypnotism, formerly called mesmerism, has received new attention under the name of suggestion, or, in medical language, "suggestive therapeutics." It was used in a rude way by Mesmer in the cure of disease. Later it was employed much more effectively by Braid and others for the same purpose, and especially for the prevention of pain in surgical operations. Want of space forbids our going into any extended historical detail as to its application for these purposes, but a few points will be considered, which bear on the subject. It was found that when a person had contracted a bad habit, as, for instance, smoking or drinking, it could often be broken up by placing him in the mesmeric sleep, and telling him he would no longer desire to continue the habit, but would even loathe them. The habit of sucking the thumb, a bad temper, lying, stealing, dullness and lack of ambition, etc., were amenable to this treatment. To illustrate: A boy fifteen years old, always at the foot of his class, was put into the hypnotic sleep, and told that he would be able to study harder and learn his lessons better, so as to go to the head. This was continued daily for several weeks, and, sure enough, he accepted the suggestion, and outstripped every scholar in his class, and kept at the head so long as these means were used; but, unfortunately, when they were discontinued he relapsed into his first state. The suggestions had not been sufficiently thorough to take deep root, and become a part of his nature, as might have been the case with a better knowledge as to how to use them. So long ago as in 1892 Dr. Bérillon, Editor of _The Revue de l' Hypnotism_, read a paper before the Second International Congress of Experimental Psychology, in which he stated that he had observed the beneficial effects of hypnotism in education in some 250 cases, including nervous insomnia, night terror, sleepwalking, kleptomania, stammering, idleness, filthy habits, cowardice and moral delinquency. He also stated that other observers had similar experience. My friend, Dr. B. Osgood Mason, of New York, working on the same lines, has had similar experiences. I will quote a few illustrative cases furnished by him. The first is of a school-girl fifteen years of age, a pupil in one of the grammar-schools of New York--intelligent in many ways; a good reader of such books as interested her--history, biography, and the better class of novels; but for the routine of school studies she had no aptitude, and she was constantly being left behind in her classes. She could not concentrate her mind upon details which did not specially interest her. If she succeeded in learning a lesson she could not remember it, or if she remembered it until she arrived at the classroom, when she arose to recite, it was instantly gone; her mind became a perfect blank; she had not a word to say, and was obliged to sit down in disgrace. She could write a good composition, but could never stand up and read it before the class. Teachers had been engaged to give her special lessons, so as to enable her to pass her preliminary examination, which would allow her to come up for entrance to the Normal College. After months of effort they reported to the mother that it was utterly useless to go on; it was impossible for her to pass her preliminary examination, and they did not think it right to take her money without any such expectation. She was then brought to me to inquire if anything could be done to help her. I proposed hypnotic suggestion. It was then March 30; the first examination was in May. I commenced treatment at once. The patient went into a quiet, subjective condition, with closed eyes, but did not lose consciousness. I suggested that she would be able to concentrate her mind upon her studies; that her memory would be improved; that she would lose her excessive self-consciousness and timidity, and in their place she would have full confidence in herself and be able to stand up before the class and recite. She was kept in the hypnotic condition one-half hour at each treatment, and the same or similar suggestions were quietly but very positively made and repeated at intervals during that time. She at once reported improvement in her ability both to study and recite. She had six treatments, and on May 25 she reported that, greatly to the surprise of her teachers, she had passed her preliminary examination with a percentage of 79, which entitled her to come up for the college examination. In June she passed her examination for entrance to the Normal College with a percentage of 88; entered the College and is at present doing well, though the suggestions have not been repeated since May. Another case from the same author was that of a boy "so bad as to be perfectly unmanageable, and his temper so outrageous, that his mother begged me to come to the house and see if I could do anything with him. "Having secured _carte blanche_ for whatever course I chose to pursue, I went. He was in the back room, his grandmother urging him forward, he kicking and resisting. Without speaking, I went directly to him, seized him firmly by one wrist, and brought him topsy turvy through two intervening rooms, gave him a thorough shaking, and set him down violently in a chair. He smoothed down his bang, whimpered a little, and gruffly remarked that I had rumpled his hair. I told him I had not intended to disturb his hair, but that as he had never obeyed anybody I had come to the house for the express purpose of making him obey me, and I should most certainly do it. After a few moments I said, quietly, 'Now go and lie down on the bed in the next room.' He started, walking toward the bed, but when near it he set off on a full run past it and into the back room. I brought him back and again ordered him to lie down on the bed. He went toward it as if to obey, but suddenly sprang under it, and clung to the slats underneath with hands and feet, and hung there like a monkey. I dislodged him, pulled him out, gave him a spanking, and surprised him by tossing him vigorously upon the bed, with the command to lie there quietly until I gave him permission to move. He obeyed. Presently I ordered him to go into the front room and sit down again in the chair he had before occupied. Again he quietly obeyed, I said: 'All right; now you understand you will obey me. I don't want to hurt you. I want to be a good friend to you, only you must obey me.' "I then in a pleasant way gave him a short lesson, picturing to him very plainly the course of a boy such as he was, and where it would be likely to end; and also showing what he might be if he would change his course. I told him I should be at the house again in a day or two, and I should expect him to meet me pleasantly, shake hands with me, and do whatever I directed him. "Next day there came a telephone message begging me to come up; M. was outrageous again. I went. He was backward in greeting me, but at length came and shook hands. I afterward learned that there had not been the slightest improvement in his behavior; and the cause of his mother's sending for me was his outrageous conduct at the table, when, in a fit of anger, he had thrown a plate at his grandmother. I talked to him pleasantly a moment, and then said very quietly, 'Now go and lie down on the bed.' He did so at once. I sat down beside him, and taking his two thumbs firmly in my hands, I said: 'Now, M., I want you to look steadily at that little stud in my shirt-front; keep your eyes very steadily fixed upon it.' He did so, and I never secured better or more concentrated attention from any patient. "In five or six minutes his eyelids quivered and soon dropped. I closed them, suggesting sleep; and directly he was in the sound hypnotic sleep. I then presented the two pictures again--the bad and the good course--and suggested that they would always be present, distinct in in his mind, that he would dislike the _wrong_ course and desire to avoid it, and choose the _good_ one. I suggested definitely that he would be kind and considerate to his mother, and obey her as well as me. I repeated these suggestions very positively, let him sleep ten minutes, and repeated them again, and then awoke him by counting. "The effect of this treatment was very marked; his whole manner at home was changed, and he became comparatively docile and manageable. "He came to my office for his next treatment, which was perfectly successful. I have given him in all six treatments, and the improvement has been maintained and increased. He is not yet by any means perfect, but his general behavior is changed, and I am suggesting such definite improvements in his conduct, and impressing such pictures upon his mind, as I think will help to develop his better nature and qualities. He is a lover of flowers, and on two occasions has brought some of his own choosing to me. He has lost none of his boyishness; he is full of life; is mischievous, playing tricks even upon his mother; but he is affectionate and generally obedient. His will is not broken, but he has self-control, and he is far more considerate of others than formerly. In short, he is a fair example of one of the educational uses of hypnotism and suggestion." The only other case I will quote is one of night terrors. "A little girl, five years of age, went soundly to sleep when first put to bed, but after two or three hours she awoke screaming and trembling with terror, on account of the hideous black man whom she saw in her dream. The impression of the dream was vivid and persistent, and her screams kept the household aroused and alarmed for hours every night, and this state of things had already continued for months. One day, when she was perfectly bright and happy, I placed her in her high chair in front of me; put my hands gently upon her shoulders, and asked her to look steadily at a trinket easily in her view, and quieted her with passes and soothing touches until her drooping eyelids denoted the subjective condition. I then commenced in a gentle, sing-song manner to suggest that she would go easily to sleep as usual at night, but that she would have no frightful dreams; that she would see the dreadful black man no more, but would sleep quietly on the whole night through. It was repeated over and over in the same gentle manner. "That was a year ago; she has not seen the black man since, and her sleep and health have been perfect. There was no repetition of the treatment." From these few cases, and many not quoted, it appears evident that we have in hypnotism, or suggestion, an agent which, when fully understood, will be of great usefulness to parents in the early training of children. That it should be used wisely no one will deny. The question will naturally arise, How is it that a suggestion to a child while passive or in the hypnotic sleep is more effective than when awake. The answer is not so easy to give; but it is possible that in this state the subliminal self, the higher self, or, perhaps, the spiritual nature is appealed to; and as the active, every-day nature, the conscious self, is now dormant, it receives this appeal more seriously. Perhaps a quotation from Prof. Frederic W. H. Myer, who has given the subject profound attention, will help to make the subject clearer. He says: "In waking consciousness I am like the proprietor of a factory whose machinery I do not understand. My foreman, my subliminal self, weaves for me so many yards of broadcloth per diem (my ordinary vital processes), as a matter of course. If I want any pattern more complex, I have to shout my orders in the din of the factory, where only two or three inferior workmen hear me, and they shift their looms in a small and scattered way. Such are the confined and capricious results of the first, the more familiar stages of hypnotic suggestion. "At certain intervals, indeed, the foreman stops most of the looms, and uses the freed power to stoke the engine and oil the machinery. This, in my metaphor, is sleep; and it will be effective hypnotic trance if I can get the foreman to stop still more of the looms, come out of his private room, and attend to my orders--my-self suggestions--for their repair and re-arrangment." To make this a little plainer. The subliminal self, the foreman, is the one who manages the machinery of the nervous system, and turns out this or that sort of conduct or behavior in the child, or the man or woman, as he is told to turn out by the conscious self. But in the hypnotic trance this subliminal self can take orders, or suggestions, for other kinds of conduct or behavior; alter the action of the brain, so as to make another sort of creature; for he is not so occupied then but that he can receive these orders. As in the kaleidescope, the pictures presented depend entirely on the arrangement of the pieces of glass. So in daily conduct, character depends on the combination and activity of the brain cells. By suggestion in the hypnotic state we are able, to some extent at least, to alter this combination so that new conduct is presented. The question now arises, How can the parent make use of this agent in altering the nature of a child from one that is not desirable to one that is? Probably the best way to proceed would be to take it while sleeping, and make the suggestion then; for ordinary sleep is not different from hypnotic sleep, except in degree. As the child is in the act of going to sleep, let the mother, or whoever is to make the suggestion, sit by its side, take it by the hand and gently soothe it with pleasant words or music, in a firm but agreeable voice. Let her say slowly: Now you are going to sleep, sleep, sleep. You will soon be sleeping sweetly. How nice it is to sleep and rest our bodies so that we can feel well and strong on the coming day. This sleep is going to do you a great deal of good. You will not have bad dreams. You will not see ugly faces or wake up with a fright. Tomorrow you will wake up good-natured, full of life, and will be good boy (or girl, as the case may be), and do your best to make mother happy and proud of you. You will want to play and enjoy the fresh air and sunshine; relish your food; not eat too much, etc., etc., according to the needs of the child. If it is timid and fearful of thunder, or dogs, or horses, or other harmless things, you can say to it, Now, you will not be afraid any more of thunder but like to hear it. This, like all other suggestions, must be repeated several times, so as to make an impression. If afraid of strangers, say, now, you will not fear men, or persons you don't know; repeating it slowly over and over again. If the child uses bad language, say, Now you will not want to use bad words any more, and will be careful how you speak. If it has a cold, put the hand over the chest and say, Now your cold will get well quickly, and not grow worse. If it has the unfortunate habit of wetting the bed at night, even this can be broken up, often by one suggestion, and surely by several repeated so as to take deep root in the mind. This latter is necessary to produce any effect. In case of disease, even serious disease, when a physician is necessary, suggestion may be used by the nurse or parents, or the physician, if he has learned the art, to advantage; but if the parents are anxious or weary, they had better leave it for those who are not weary or anxious; otherwise they may transfer their own condition instead of one of health. The state of mind and body of the operator should be a stable, equable and wholesome one. The age at which suggestion may be of use is hardly yet known. Certainly so soon as the understanding has become developed it may be employed, though the language should be simplified for the childish understanding. Before this it is of doubtful utility; but some experiments which have been made intimate that good health may sometimes be transmitted from a healthy person to a very young sick child by thought transference. Thought transference is the transference from one to another person of some feeling, sensation or idea. The person from whom the thought is transferred is the _active_ agent, and the one who receives it is the _passive_ one. Often this phenomenon takes place spontaneously, as when one is in trouble, or at the point of dying, a knowledge of it may sometimes be transferred to an intimate friend who is in sympathy. In the hypnotic state, thought transference can sometimes be induced artificially; and the point here to be considered is the transference to the child of healthy normal sensations to replace the abnormal ones which may have taken possession of consciousness and caused trouble. The important thing always to have in mind in using psychic forces on children is to instil natural, or normal, conditions, not unnatural or abnormal ones. To this end to produce the best results, the active agent should be a normally healthy person, having good common sense, and living a normal, natural life. Those with sickly, sentimental or fanciful notions, if they try to use suggestion may transfer these states to the child, which would do harm rather than good. INDEX. Acquired characters, inheritance of, 71, 73, 77 _et seq._, 79, 90, 109, 111, _et seq._ Acquired characters not transmitted, 213 Adaptation to environment necessary for health, 149 Aesthetic sense displayed by animals, 28 Aesthetic surroundings during gestation, 95 Air, regarded as food, 174 Alcohol, as a poison, 91 Alcohol, effect of, on offspring, 171 Allen, Joseph A., observations of, as to effects of war on children, 200 _Allen, Grant_, 34, 48, 51, 180 Amphimixis, theory of, 76 Ancestral _ids_, 75 Ancestral tendencies, correction of, 126 Animals, practical superiority of man over, what?, 210 Animal flesh, supposed effect of eating, 63 Atavism in relation to disease, 83 Baby, a theoretical, 185 _et seq._ Bad habits, broken up by suggestion during mesmeric sleep, 214 Bad temper cured by hypnotic suggestion, 217 _et seq._ Beauty, reference of sexual selection to, 28 Bees, instincts of, 122 Bérillon, Dr., on beneficial effect of hypnotism over bad habits, etc., 215 Birthmarks, 59, 68, 94 Blood, healthy, purifying influence of, 92 Blood, study of the, 140, 151 Bones, modification of certain, through sitting, 116 Boys, mortality among larger than with girls, 136 Breasts, best methods of developing, 209 Breasts, defective, women having, incapable of becoming mothers of a virile race, 209 Breasts, development of, after marriage and parentage, 209 Breasts, degeneracy of the, and motherhood, 208 Breeding in and in, Noyes' first principle for race improvement, 38 Camp life, evils of, 202 Cases of prenatal influences, 204 _et seq._ Cells, sexual, 110, 162 _Chandler, Jennie_, 97 Character, dependence of, on arrangement of nerve cells, 222 Character, improvement by suggestion, method to be employed by parents for, 223 Character of children affected by war, 201 Characteristics, origin of, through sexual selection, 134 _Charles, Havelock_, 116 Chickamauga Camp, prostitution at, 202 Children acquire special aptitudes from mothers, 205 Child bearing, best age for, 170 Children, breeding of, in Plato's Republic, 11, 12 Children considered as belonging to the State, 10 _et seq._, 22 Children, deaths of, in New York city, 139 Children, healthy, essentials for having, 168 Children, interests of unborn, 199 Children, characteristics of, in the Oneida Community, 39 Children in the Oneida Community, care of, 38 Children, mortality among, 136 Children, obstacle of war to production and training of, 203 Child training aided by suggestion, 214 _et seq._ Children, training of, 16 _et seq._, 52 Civil War and how it affected the character of children, 201 Co-adaptation of parts as evidence of transmission of acquired characters, 116 Coalescence of sperm and germ cells, 166 Concentrative power, want of, cured by hypnotic suggestion, 216 Conduct, knowledge of its object, not possessed by animals, 210 Congenital characters, transmission of, 177 Congenital deformities, 80 Consanguineous marriages among the Greeks, 23 Consanguineous marriages, regulations as to, among uncultured peoples, 21, 42 Consanguineous marriages, effect on offspring, 42 Constitution, bodily, improvement of the, 150 Consumption, causes of, 176 Consumption, tendency to, whether a bar to marriage, 176 Contentment, value of, 95 Continuity of germ-plasm, 107, 118 Co-operation, hygienic value of, 156 _et seq._ _Cope, Prof. E. D._, 59, 69 Cousins, marriage between, 43 Couvade, custom of the, 63 _et seq._ Crimes, increase of, caused by war, 201 _Darwin, Charles_, 28, 30 _et seq._, 73, 75, 85, 100, 105, 106, 109, 141, 179, 184 Death, causes of, 150 Deformities, congenital, 80 Degeneracy of the breasts and motherhood, 208 Degeneracy in offspring due to maternal degeneracy evidenced by inability to nurse a child, 208 Degeneration, evidence of, 140 Development of breasts after marriage and parentage, 209 Diseases, influence of hygiene over, 159 Diseases, inheritance of, 80 Diseases which affect offspring, 175 Disposition spiritualized through marriage of chastity, 210 Disproportion between accidental causes and effects, 68, 90 Diversity between offspring and parents, causes of, 58 Domestication of animals, 9 _Doutrebente, Prof._, 92 Drink, influence of, over offspring, 16 _Duncan, J. C. Mathews_, 170 Education, beneficial effects of hypnotism in, 215 Education and heredity, 111 _et seq._ Education and non-transmission of acquired characters, 124 Education of Spartan children, 15 Education, Plutarch on, 17 Education, study of laws of evolution, as part of, 125 Educational uses of hypnotism and suggestion, 220 Egg. See _Ovum_. _Eimer, Dr. G. H._, 71, 79 _et seq._, 90 Embryo, how parental properties communicated to, 69 Embryology, importance of, 103 Energy, bodily, use and abuse of, 153 Environment, adaptation to, necessary for health, 149 Epigenesis, theory of, 104 Esquirol on the effects of the French Revolution over children, 200 Ethics of the body, hygiene as the, 160 Evolution, a superior race produced by, 130 _et seq._ Evolution, meaning of the term, 210 Evolution of the horse, 102 Evolution, study of laws of, as part of education, 125 Evolutionary theories, conflict of, with humane sentiments, 145 _et seq._ Example, influence of, over children, 18 Exercise, transmission of effects of, 111 Experiment in race improvement by Noyes, 37 _et seq._ Explanation of the action of hypnotic suggestion, 221 Family life, abolition of, in Plato's Republic, 10 Father rule should be combined with mother rule, 213 Fatherhood, too little importance assigned to, 212 Feeble constitutions prevent numerous offspring, 147 Fertilization essential to true germ plasm, 165 Fertilization, nature of, 166 _Fison, Lorimer_, 42 Fitness for survival, characteristics of, 140 Flat head Indians and heredity, 213 Flat head and round head tribes, comparison between, 213 Flat head not transmitted to offspring, 213 Flattening the skull, injurious effect of on health, 214 _Flint, Dr. Austin_, 88 Food, how it affects germ plasm, 173 Food (certain) injurious influence of, 94 Foot, compression of, by Chinese ladies, 20 Fosterage, 96 French Revolution, evil effects of over children, 200 _Galton, Francis_, 46, 50, 73, 106, 135, 170 Gemmules, essential to pangenesis, 105, 106 Generation, influences over, at time of conception, 57, 58 Generation, influences over, subsequent to conception, 58 Generative powers, debilitation of the, 84 Germ plasm and heredity, 107, 162 Germ plasm, continuity of the, 73, 74 _et seq._, 107, 118 Germ plasm, how affected by food, 173 Germ plasm, modification of the, 76, 80 Germ variations, causes of, 81 Gestation (period of) importance of pleasant surroundings during, 93 Gestation, maternal influence during, 96 Gestation, strong emotion during, effect of, 63, 94 Gestation, uterine disturbances during, 93 Girls, physical training of, among Spartans, 14 Girls, mortality among, smaller than with boys, 136 Great mothers, how constituted, 208 Group marriage of Australian natives, 21 _Hæckel, Ernst_, 109 _Harvey_, 103 _Haycraft, John Berry_, 143 Head flattening, 20 Health, action of nature in relation to, 130 Health, transmission of, by thought transference, to young sick child, 224 Healthy localities enable the healthiest offspring to be reared, 210 Health, adaptation to environment necessary for, 149 Health, ideal of, 148 Health, importance of, in relation to marriage, 135, 168, 171 _Hearn, Professor_, 67 Hedonism, New, 48 Hereditary tastes of children, 204 _et seq._ Heredities, antagonistic, of two parents, 58 Heredity among Flat-head Indians, 213 Heredity, definition of, 100 Heredity and education, 111 _et seq._ Heredity, evils arising from, may be cured, 35 Heredity, exceptions to law of, 58 Heredity and germ plasm, 107 Heredity, importance of knowledge of, by teachers, 125 Heredity, modification of law of, 99 Heredity, preponderating influence of, 69, 89 Heredity, rational view of, 109 Heredity, spectre of, 127 _et seq._ Heredity, theories of, 73 _et seq._ Heredity, transformation of, 83 _Hering, Richard_, 70 Hidery tribes of British Columbia, 214 High-pressure, effects of living at, 152 Hypnotic sleep, differs from ordinary sleep only in degree, 223 Hypnotic suggestion, value of, as aid to education, 216 Hypnotism as suggestive therapeutics, 214 Horse, evolution of the, 102 Human selection, plans for, 135 _et seq._ Human kind, regarded as a whole, should be benefited by our conduct, 211 Human race, further improvement of impossible, if marriage relation be regarded only from standpoint of sexual indulgence, 210 Humane sentiments, conflict of, with theories of evolution, 145 _et seq._ Husband and wife, tendency to resemble each other, 89 _Huth, A. H._, 42 Hygiene, modern, as opposed to natural selection, 142 _et seq._ Hygiene, as the ethics of the body, 160 Hygiene, promises of, 158 _et seq._ Hygienic laws, punishment for infraction of, 161 Hygienic surroundings, importance of, 139 Hygienic training, value of, 151 Ideal of Health, 148 Idiots, education of, 25 Illustrative cases of prenatal influence, 60 _et seq._ Imagination, effect of, on unborn offspring, 55 _et seq._ Improvement of race. See _race improvement_. Incas of Peru, consanguineous marriages among the, 23 Income, bodily, importance of living within, 152 Individual, the, as the beginning and end of the race, 50 Individuality, development of the, 126 Infanticide among Spartans, 15 Infanticide, former general prevalence of, 19 Infanticide in Plato's Republic, 11 Infanticide not morally permissible, 24 Inheritance of acquired characters, question as to the, 71, 73, 77, 79, 90, 109, 111 _et seq._ Inheritance, organic, wonders of, 101 Injuries during life, transmission of, 79 _et seq._ Injury to health through flattening the skull, 214 Instinct, explanations of origin of, 121 Instincts of the race for children, loss of, 208 Instruction and education, difference between, 210 Intelligence affected by head flattening, 214 Jacob, rods of, 56 _Jeune, Lady Mary_, 47 _Jowett, Professor B._, 25 _et seq._, 34 _Krafft, D. Von Ebing_, 82, 84, 91 _Lamarck_, 111 Lamarchian theory of transmission, 213 Language, not transmitted to offspring, 119 _Leeuwenhock_, 103 Limitation of offspring, 179 _et seq._ Locust, egg-laying instinct of, 123 Luxury and parentage, 208 _Lycurgus_, marriage regulations of, 13 _et seq._, 22, 27 _Lyman, Dr. C. W._, on treatment of a baby, 185 _et seq._ Man, variations undergone by, 138 Man, practical superiority of, over animals, what, 210 Manufacturing life, unhealthiness of, 152 Manufacturing mills, deterioration caused by, 158 Marriage, consanguineous, ideas as to, 21, 42 Marriage customs among Spartans, 18, 19 Marriage, early, disadvantages of, 137 Marriage, importance of health in relation to, 135 Marriage, regulations as to, in Plato's Republic, 22, 25 Marriage of weak and worthless, 137 Marriage, a sacred state, 52 Marriage of chastity, disposition spiritualized by, 210 Marriages of affection and passion, difference between, analogous to that between education and instruction, 210 _Mason, Dr. R. Osgood_, on beneficial effect of hypnotism in education, 215 Maternity, avoidance of, 208 _McGee, Dr. Anita Newcomb_, 37 Memory, endowment of reproductive cells with, 70 Memory, improvement of, by hypnotic suggestion, 210 Mental dullness, curable by suggestion during hypnotic sleep, 215 Mental emotion of mother, injury to unborn child through, 200 Mesmeric sleep, effect of suggestion during, 214 Mesmerism, now known as hypnotism, 214 Method to be employed by parents for using suggestion in child training, 223 Microbes, selective action of, 143 Mind of operator, state of, necessary to successful suggestion, 224-5 Modification of certain bones through sitting, 116 Modification of the organism during descent from first ancestors, 71 Modification of sense of touch, 114 Modification of toes, 112 Modification of the whale, 115 Molecular structure of sexual cells, 110 Monogamy, return to, by the Oneida Community, 40, 41, 53 Moral nature, growth of the, 146 Mosaic regulations as to unclean animals, 63 Motherhood, highest, war an enemy to, 204 Motherhood and degeneracy of the breasts, 208 Mothers, not peculiarily the divinely appointed teachers of children, 212 Musical talent, not transmitted to offspring, 120 Mutilations, not transmissible, 119 _Meyer, Prof. Frederic W. H._, on hypnotic suggestion, 221 Natural selection, 9, 115, 138, 142 Natural selection, always operative, 147 Nature, action of, in relation to health, 130 Nerve cells, constitution of, alterable by hypnotic suggestion, 222 Nervous system, debilitation of the, 84 Night terrors cured by hypnotic suggestion, 220 Nipples, deformed, common occurrence of, 209 _Nisbet, J. F._, 90, 92 Non-nursing of children a sign of degeneracy, 208 Normal conditions only should be transferred by hypnotic suggestion, 225 Nose molding, 20 Notes, 199 _et seq._ _Noyes, John Humphrey_, 37 _et seq._ Nucleus of cell, essential to reproduction, 167 Nutrition, action of, on germ cells, 151 Nutrition (arrested) organic effect of, 77 Obedience the basis of education among the Spartans, 15 Offspring, effect of alcohol on, 171 Offspring, effect of consanguineous marriage on, 42 Offspring, influence of locality on health of, 210 Offspring, injuriously affected by sexual excess of parents, 211 Offspring, inception of, the starting point of stirpiculture, 52 Offspring, limitation of, 179 _et seq._ Oneida Community, 37 _et seq._ Ovum, 163 _et seq._ Ovum, the beginning of animal life, 101, 163 Ovum, developmental tendency of the, 110 Ovum, effect of gestation on the, 102 Ovum of different animals, apparent similarity of the, 163 _Paget, Sir James_, 148 Pain, prevention of, in surgical operations, 214 Pangenesis, experiments in, 106 Pangenesis, theory of, 75, 105, 109 Panmixia, theory of, 78 Paper mill (New England), 154 Parentage and luxury, 208 Parentage and war, 199 Parentage, responsibility in, 49, 181 Parentage, Plato's restrictions on, 11 Parentage, sacredness of, 93 Parents, how to make use of suggestion in the training of children, 222 Parents, organic growth of, injuriously affected by sexual excess, 211 Parental life, influence of, over offspring, 95 Perfectionists of the Oneida Community, 37 _et seq._ _Phillips, Wendell_, 128 Physical culture, 160 Physical training of girls among Spartans, 14 Physical weakness may be associated with mental greatness, 34 Plato, Republic of, 10 _et seq._, 25 Plutarch, 13, 16 _et seq._ Poisons, actions of, on the sexual cells, 91 Poverty, obstacle of, to production and training of the young, 203 Preference, as exhibited among animals, 131 Preference, as exhibited among men, 133 Preference, first principle of sexual selection, 131 Prenatal culture, 55 _et seq._ Prenatal culture, illustrative cases of, 60 _et seq._ Prenatal influence, 112 Prenatal influence in telegony, 85 Prenatal influences, cases of, 204 _et seq._ Principles on which sexual selection is based, 38, 131 Progress in organic life, 9 Promiscuity regulated in Oneida Community, 37 Promiscuity regulated in Plato's Republic, 11 Prostitution, camp life a school for, 202 Psychical diseases, heredity of, 82 _et seq._ Psychological laws, uncertain effect of, 68 Psychological research, laboratories for, 160 _Quatrefages, M. de_, 59 Race (human) deterioration of the, through hygienic action, 143 _et seq._ Race, improvement of the, aim of, 36 Race, improvement of the, based on spiritual sympathy, 58 Race improvement, experiment in, of the Oneida Community, 37 _et seq._ Race improvement, failure of compulsory attempts at, 27 Race improvement, Grecian methods for, 10 _et seq._ Race improvement, Grecian methods not suited for modern times, 24 Race improvement, natural factors in, 1 Race improvement, State aid to, 37, 53 Race should be thought of before ourselves, 211 Reproductive function, difference in exercise of, by animals and man, 210 Responsibility in parentage, 49, 181 _Ribot, Th._, 57, 68, 83 _Romanes, G. J._, 28, 73, 85, 87 Ruin of countries by the burdens of war, 203 Sacredness of parentage, 93 _Saint-Hilaire, Geoffroy_, 68 Sampson, mother of, 172 Science of true living, hygiene as the, 160 Scottish Co-operative Wholesale Society's manufacturing mill, 156 _et seq._ Selection, artificial, by man, 9 Selection, individual, by Noyes, 38 Selection, natural, _see_ "Natural selection." Selection, sexual, _see_ "Sexual selection." Selective action of female animals, 28 _et seq._ Selective action of woman in marriage, 43 _et seq._ Self-control, importance of, 96 Self-consciousness, excessive, cured by hypnotic suggestion, 216 Self-development, 48 Sense of touch, modification of, through use, 114 Sex-instinct, 51 Sexual cells, 162 Sexual cells, acquired powers of, 110 Sexual excess injuriously affects both parents and offspring, 211 Sexual impulse, gratification of the, consistent with the development of the highest mental qualities, 212 Sexual selection, 27 _et seq._, 131 _et seq._ Sexual selection, action of, among primeval men, 179 Sexual selection applicable primarily to male characteristics, 30 Sexual selection by women, effect of, 44 _et seq._ Sexual selection, influence of, 31, 33 Sick child, transmission of health to, by thought transference, 224 Sire, previous, influence of, on subsequent progeny, 86 _et seq._ Sleep, ordinary, differs from hypnotic sleep only in degree, 223 _Smith, Sidney_, 121 Sobriety, importance of, in relation to offspring, 91 _See_ "Alcohol." Soldiers demand gratification of their passional natures, 202 Spartans, marriage relations among, 13 _et seq._ Special aptitudes of child determined by prenatal influences, 204 Spectre of heredity, 127 _et seq._ _Spencer, Herbert_, 4, 77, 78, 85, 87, 112, 115, 149, 169, 181 Spermatozoon, 162 Spiritual nature, appeal to, in hypnotic suggestion, 221 Spontaneous thought transference, 224 Standing armies, crushing burden of, 203 State, aid of the, to race improvement, 53 State, children regarded as belonging to the, 10 _et seq._, 22 Stirpiculture. _See_ "Race, improvement of the." Stirpiculture, meaning of, 10 Stirpiculture, good air and water as factors in, 175 Stirpiculture, Noyes' experiment in, 37 _et seq._ Stirpiculture, starting point of, 52 Strength as necessary as tenderness to bringing up of children, 213 Struggle, sexual selection through, 132 Studious habits transmitted to children, 205 Subliminal self, orders conveyed to, by hypnotic suggestion, 222 Suggestion as an aid to child training, 214, 221 Suggestion by parents to children for educational purposes, 223 Suggestion during mesmeric sleep, bad habits cured by, 214 Suggestion during mesmeric sleep, beneficial effect of, over mental dullness, 215 Suggestion, hypnotic, influence of, in developing self-control, 219 Suggestion, hypnotic, method of, employed by Dr. R. Osgood Mason for educational purposes, 215 _et seq._ Suggestive therapeutics, 214 Superiority of offspring, where limited, 184 Surgical operations, prevention of pain in, by mesmerism, 214 Survival of the fittest, 9 Survival, what constitutes fitness for, 141 Sympathy, spiritual, as the basis of race improvement, 53 Taxation, burden of, created by war, 203 Telegony, 85 _et seq._ Temper, bad, cured by hypnotic suggestion, 217 Tenderness to be combined with strength in bringing up children, 213 Theoretical baby, 185 _et seq._ Thought transference induced artificially in hypnotic state, 224 Thought transference, nature of, 224 Thought transference, transmission of health by, to a young sick child, 224 Timidity cured by hypnotic suggestion, 216 Toes, modification of the, in man, 112 Touch, modification of the sense of, 114 Training of children aided by hypnotic suggestion, 221 Training of children, Plutarch on the, 16 _et seq._ Transformation of heredity, 83 Transitory states of parents, effect of on offspring, 59 Transmission by mother to child of aptitude for hard work, 207 Transmission by mother to child of artistic and literary tastes, 204 _et seq._, 207 Transmission by mother to child of taste for study of natural history, 206 Transmission by mother to child of taste for surgical nursing, 207 Transmission of acquired characters. _See_ "Acquired characters." Transmission of effects of exercise, 111 _Tylor, E. B._, 64, 67 Twins, resemblance of, 90 Unborn children injured by war, 199 Unborn children, interests of, 199 Unfit, elimination of the, 139 Unicellular organisms, 109 Uterine existence, disturbances of, 58, 68 Vaccination as a preserver of weak constitutions, 143 Vitality, surplus, production of offspring depends on, 169 _Wake, C. Staniland_, 21, 42, 66 _Wallace, A. R._, 44, 136 Wallace, Alfred Russell, on prenatal influences, 204 War and parentage, 199 War, effects of, on civilization, 199 War, effects of, on unborn children, 199 _et seq._ War, enemy to the highest motherhood, 204 _Weber, Professor_, 114 _Weismann, Professor_, 72, 74 _et seq._, 78, 107, 118 Wet nurses, use of, accompanied by physical weakness, 208 Whale, modification of structure of the, 115 White race, superiority of the, due to consciousness of duty towards the race, 211 _Wolf, Caspar Frederick_, 104 Woman, condition of, among Flat head Indians, 213 Woman, first duty of, 47 Woman not superior to man, 212 Woman, selective action of, in marriage, 32, 43 _et seq._ Women incapable of love inferior as mothers, 208 Women more numerous than men, 136 Women, preference for certain characteristics in men, 133 _Xenophon_, 15 _Zeigler, Professor_, 81, 91 TRANSCRIBER'S NOTES: The word "diarrhoea" uses an oe ligature in the original. The following corrections have been made to the text: Page 19: visited her "with great caution and apprehension"[quotation mark missing in original] Page 25: "that the difference between men and the animals is forgotten in them."[quotation mark missing in original] Page 62: _The Philosophical[original has Philosphical] Journal_ for October 5, 1895 Page 66: come to console him [original has extraneous quotation mark]for the pain Page 82: distinguished psychiatrist, D. Von Krafft-Ebings[original has Kraft-Ebings] Page 84: inconsistency in desires, sudden and variable will."[quotation mark missing in original] Page 104: develop[original has devolop] other organs than those like the ones in which it was formed Page 109: theories of heredity--Hæckel's[original has Heckel's], for instance Page 112: without the transmission[original has transmision] of the effects of the use Page 141: to give continuous[original has continous] food, warmth and protection Page 164: the ape, the dog, the cat or other animal."[quotation mark missing in original] Page 164: clear, round germinal vesicle[original has vescicle] Page 167: they completely[original has competely] efface themselves Page 176: often of an unusually[original has unsually] cheerful and hopeful disposition Page 180: quoted Grant Allen as favoring abstinence[original has abstainence] Page 182: must bring decay and ultimate extinction.[original has comma] Page 199: children, both born and unborn.[period missing in original] Page 200: capable of resisting the intense excitements[original has excitments] Page 200: dimmed by the relation of such occurrences[original has occurrencies] Page 203: Is this not a grievous[original has grevious] burden Page 206: [original has extraneous quotation mark]Mrs. B---- says: "I can trace Page 207: cloth of gold roses and bougainvillea[original has bougianvillea] Page 210: only 17,314 out of 100,000 died.[original has comma] Page 213: mind as well as heart,[comma missing in original] vigor as well as sympathy Page 217: gruffly[original has grufly] remarked that I had rumpled his hair Page 217: suggestions have not been repeated since May."[original has extraneous quotation mark] Page 226: number "200" is below the entry for "Air" in the original, but it belongs to the entry for "Allen, Joseph A.", and has been moved accordingly Page 228: page numbers for the entry on Darwin have been put in numerical order Page 228: Eimer,[original has period] Dr. G. H., 71, 79 _et seq._, 90 Page 230: Hæckel[original has Haeckel], Ernst, 109 Page 232: Inheritance of acquired characters, question as to the, 71, 73, 77,[comma missing in original] 79 Page 232: Krafft[original has Kraft], D. Von Ebing, 82, 84, 91 Page 232: Leeuwenhock[original has Leeukwenhock], 103 Page 233: Jowett[original has Jewett], Professor B., 25 _et seq._,[comma missing in original] 34 Page 233: Mason, Dr. R. Osgood, on beneficial effect of hypnotism[original has hynotism] Page 235: Quatrefages[original has Quartrefages], M. de, 59 Page 235: Saint-Hilaire, Geoffroy[original has Geoffory], 68 Page 238: Transmission[original has Tranmission] of acquired characters 
8517	----	HORMONES AND HEREDITY A Discussion Of The Evolution Of Adaptations And The Evolution Of Species By J. T. CUNNINGHAM, M.A. (OXON), F.Z.S. Sometime Fellow of University College, Oxford Lecturer in zoology at East London College, University of London LONDON CONSTABLE AND CO. LTD. 1921 PREFACE My chief object in writing this volume was to discuss the relations of modern discoveries concerning hormones or internal secretions to the question of the evolution of adaptations, and on the other hand to the results of recent investigations of Mendelian heredity and mutations. I have frequently found, from verbal or written references to my opinions, that the evidence on these questions and my own conclusions from that evidence were either imperfectly known or misunderstood. This is not surprising in view of the fact that hitherto my only publications on the hormone theory have been a paper in a German periodical and a chapter in an elementary text-book. The present publication is by no means a thorough or complete exposition of the subject, it is merely an attempt to state the fundamental facts and conclusions, the importance of which it seems to me are not generally appreciated by biologists. I have reviewed some of the chief of the recent discoveries concerning mutations, Mendelism, chromosomes, etc., but have not thought it necessary to repeat the illustrations which are contained in many of the volumes to which I have referred. I have made some Mendelian experiments myself, not always with results in agreement with the strict Mendelian doctrine, so that I am not venturing to criticise without experience. I have not hesitated to reprint the figure, published many years ago, of a Flounder showing the production of pigment under the influence of light, because I thought it was desirable that the reader should have before him this figure and those of an example of mutation in the Turbot for comparison when following the argument concerning mutation and recapitulation. I take this opportunity of expressing my thanks to the Councils of the Royal Society and the Zoological Society for permission to reproduce the figures in the Plates. I also desire to thank Professor Dendy, F.R.S., of King's College for his sympathetic interest in the publication of the book, and Messrs. Constable and Co. for the care they have taken in its production. J. T. CUNNINGHAM. London, _June_ 1921. CONTENTS INTRODUCTION - Historical Survey Of Theories Or Suggestions Of Chemical Influence In Heredity CHAPTER I - Classification And Adaptation CHAPTER II - Mendelism And The Heredity Of Sex CHAPTER III - Influence Of Hormones On Development Of Somatic Sex-Characters CHAPTER IV - Origin Of Somatic Sex-Characters In Evolution CHAPTER V - Mammalian Sexual Characters, Evidence Opposed To The Hormone Theory CHAPTER VI - Origin Of Non-Sexual Characters: The Phenomena Of Mutation CHAPTER VII - Metamorphosis and Recapitulation INDEX LIST OF PLATES PLATE I. Recessive Pile Fowls PLATE II. Abnormal Specimen Of Turbot PLATE III. Flounder, Showing Pigmentation Of Lower Side After Exposure To Light INTRODUCTION Historical Survey Of Theories Or Suggestions Of Chemical Influence In Heredity Weismann, strongly as he denied the possibility of the transmission of somatic modifications, admitted the possibility or even the fact of the simultaneous modification of soma and germ by external conditions such as temperature. Yves Delage [Footnote: Yves Delage, _L'Hérédité_ (Paris, 1895), pp. 806-812.] in 1895, in discussing this question, pointed out how changes affecting the soma would produce an effect on the ovum (and presumably in a similar way on the sperm). He writes:-- 'Ce qui empêche l'oeuf de recevoir la modification reversible c'est qu'étant constitué autrement que les cellules différenciées de l'organisme il est influencé autrement qu'elles par les mêmes causes perturbatrices. Mais est-il impossible que malgré la différence de constitution physico-chimiques il soit influencé de la même façon?' The author's meaning would probably have been better expressed if he had written 'ce qui paraît empêcher.' By 'modification reversible' he means a change in the ovum which will produce in the next generation a somatic modification similar to that by which it was produced. It seems natural to think of the influence of the ovum on the body and of the body on the ovum as of similar kind but in opposite directions, but it must be remembered always that the development of the body from the ovum Is not an influence at all but a direct conversion by cell-division and differentiation of the ovum into the body. Delage argues that if the egg contains the substances characteristic of certain categories of cells of the organism it ought to be affected at the same time as those cells and by the same agents. He thinks that the egg only contains the substances or the arrangements characteristic of certain general functions (nervous, muscular, perhaps glandular of divers kinds) but without attribution to localised organs. In his view there is no representation of parts or of functions in the ovum, but a simple qualitative conformity of constitution between the egg and the categories of cells which in the body are charged with the accomplishment of the principal functions. Thus mutilations of organs formed of tissues occurring also elsewhere in the body cannot be hereditary, but if the organ affected contains the whole of a certain kind of tissue such as liver, spleen, kidney, then the blood undergoes a qualitative modification which reacts on the constitution of the egg. Suppose the internal secretion of a gland (_e.g._ glucose for the liver, glycolytic for the ferment for the pancreas) is the physiological excitant for the gland. If the gland is removed in whole or in part the proportion of its internal secretion in the blood will be diminished. Then the gland, if the suppression is partial, will undergo a new diminution of activity But in, the egg the specific substance of the gland will also be less stimulated, and in the next generation a diminution of the gland may result. Thus Delage states Massin found that partial removal of the liver in rabbits had an inherited effect. In the case of excretory glands the contrary will be the case, for their removal causes increase in the blood of the exciting urea and uric acid. The effects of disuse are similar to those of mutilations and of use vice versa. Delage, as seen above, does not consider that increase or decrease of particular muscles can be inherited, but only the muscular system in general. If, however, in consequence of the disuse of a group of muscles there was a general diminution of the inherited muscular system, the special group would remain diminished while the rest were developed by use in the individual: there would thus be a heredity produced indirectly. With regard to general conditions of life, Delage states that there are only two of which we know anything--namely, climate and alimentation--and he merely suggests that temperature and food act at the same time on the cells of the body and on the similar substances in the egg. H. M. Vernon (_Variation in Animals and Plants_, 1903, pp. 351 _seq._) cites instances of the cumulative effects of changed conditions of life, and points out that they are not really instances of the inheritance of acquired characters, but merely of the germ-plasm and the body tissues being simultaneously affected. He then asks, Through what agency is the environment enabled to act on the germ-plasm? And answers that the only conceivable one is a chemical influence through products of metabolism and specific internal secretions. He cites several cases of specific internal secretions, making one statement in particular which seems unintelligible, viz. that extirpation of the total kidney substance of a dog leads not to a diminished secretion of urine but to a largely increased secretion accompanied by a rapid wasting away which soon ends fatally. Whenever a changed environment acts upon the organism, therefore, it to some extent affects the normal excretions and secretions of some or all of the various tissues, and these react not only on the tissues themselves, but also to a less degree upon the determinants representing them in the germ-plasm. Thus the relative size of the brain has decreased in the tame rabbit. This may be due to disuse; the excretions and secretions of the nervous tissues would be diminished, and the corresponding determinants less stimulated. Another instance is afforded by pigmentation of the skin in man; which varies with the amount of light and heat from the sun to which the skin is exposed. Specific excretory products of pigment in the skin may stimulate the pigment determinants in the germ-plasm to vigour. But only those characters of which the corresponding tissues possess a specific secretion or excretion could become hereditary in this way. For instance, the brawny arm of the blacksmith could not be transmitted, as it is scarcely possible that the arm muscles can have a secretion different from that of the other muscles. In 1904, P. Schiefferdecker [Footnote: P. Schiefferdecker, _Ueber Symbiose_. S.B. d. Niederrhein. Gesellsch. zu Bonn. Sitzung der Medicinischen Sektion, 13 Juni 1904.] made the definite suggestion that the presence of specific internal secretions could be very well used for the explanation of the inheritance of acquired characters. When particular parts of the body were changed, these modifications must change the mixture of materials in the blood by the substances secreted by the changed parts. Thereby would be found a connexion between the modified parts of the body and the germ-cells, the only connexion in existence. It is to be assumed, according to this author, that only a qualitative change in the nutritive fluid of the germ-cells could produce an effect: a quantitative change would only cause increased or decreased nourishment of the entire germ cells. In my own volume on _Sexual Dimorphism in the Animal Kingdom_, published in 1900, I attempted to explain the limitation of secondary sexual characters not only to one sex, but usually to one period of the individual life, namely, that of sexual maturity; and in some cases, as in male Cervidae, to one season of the year in which alone the sexual organs are active. It had been known for centuries that the normal development of male sexual characters did not take place in castrated animals, but the exact nature of the influence of the male generative organs on that development was not known till a year or two later than 1900, when it was shown to be due to an internal secretion. My argument was that all selection theories failed to account for the limitation of secondary sexual characters in heredity, whereas the Lamarckian theory would explain them if the assumption were made that the effects of stimulation having been originally produced when the body and tissues were under the influence of the sexual organs in functional activity, these effects were only developed in heredity when the body was in the same condition. About the year 1906, when preparing two special lectures in London University on the same subject, I became acquainted with the work of Starling and others on internal secretions or hormones, and saw at once that the hormone from the testes was the actual agent which constituted the 'influence' assumed by me in 1900. In these lectures I elaborated a definite Lamarckian theory of the origin of Secondary Sexual Characters in relation to Hormones, extending the theory also to ordinary adaptive structures and characters which are not related to sex. Having met with many obstacles in endeavouring to get a paper founded on the original lectures published in England, I finally sent it to Professor Wilhelm Roux, the editor of the _Archiv für Entwicklungsmechanik der Organismen_, in which it was published in 1908. In his volume on the Embryology of the Invertebrata, 1914 (_Text-Book of Embryology_, edited by Walter Heape, vol. i.), Professor E. W. MacBride in his general summary (chapter xviii.) puts forward suggestions concerning hormones without any reference to those who have discussed the subject previously. He considers the matter from the point of view of development, and after indicating the probability that hormones are given off by all the tissues of the body, gives instances of organs being formed in regeneration (eye of shrimp) or larvae (common sea-urchin) as the result of the presence of neighbouring organs, an influence which he thinks can only be due to a hormone given off by the organ already present. He then states that Professor Langley had pointed out to him in correspondence that if an animal changes its structure in response to a changed environment, the hormones produced by the altered organs will be changed. The altered hormones will circulate in the blood and bathe the growing and maturing genital cells. Sooner or later, he assumes, some of these hormones may become incorporated in the nuclear matter of the genital cells, and when these cells develop into embryos the hormones will be set free at the corresponding period of development at which they were originally formed, and reinforce the action of the environment. In this way MacBride attempts to explain recapitulation in development and the tendency to precocity in the development of ancestral structures. His idea that the hormones act by 'incorporation' in the genital cells is different from that of stimulation of determinants put forward by myself and others, but it is surprising that he should refer to unpublished suggestions of Professor Langley, and not to the publications of authors who had previously discussed the possible action of hormones in connexion with the heredity of somatic modifications. Dr. J. G. Adami in 1918 published the Croonian Lectures, delivered by him in 1917 under the title 'Adaptation and Disease,' together with reprints of previous papers, in a volume entitled _Medical Contributions to the Study of Evolution_. In this work (footnote, p. 71) the author claims that he preceded Professor Yves Delage by some two years in offering a physico-chemical hypothesis in place of determinants, and also asserts that 'the conclusions reached by him in 1901 regarding metabolites and, as we subsequently became accustomed to term them, hormones, and their influence on the germ-cells, have since been enunciated by Heape, Bourne, Cunningham, MacBride, and Dendy, although in each case without note of his (Adami's) earlier contribution.' These somewhat extensive claims deserve careful and impartial examination. The paper to which Dr. Adami refers was an Annual Address to the Brooklyn Medical Club, published in the _New York Medical Journal_ and the _British Medical Journal_ in 1901, and entitled 'On Theories of Inheritance, with special reference to Inheritance of Acquired Conditions in Man.' The belief that this paper had two years' priority over the volume of Delage entitled _L'Hérédité_ appears to have arisen from the fact that Adami consulted the bibliographical list in Thomson's compilation, _Heredity_ 1908, where the date of Delage's work is as 1903. But this was the second edition, the first having been published, as quoted above, in 1895, six years before the paper by Adami. Next, with regard to the claim that Adami's views as stated in the paper to which he refers were essentially the same as those brought forward by myself and others many years later, we find on reading the paper that its author discussed merely the effect of toxins in disease upon the body-cells and the germ-cells, causing in the offspring either various forms of arrested and imperfect development or some degree of immunity. In the latter case he argues that the action of the toxin of the disease has been to set up certain molecular changes, certain alterations in the composition of the cell-substance so that the latter responds in a different manner when again brought into contact with the toxin. Once this modification in the cell-substance is produced the descendants of this cell retain the same properties, although not permanently. Inheritance of the acquired condition has to be granted, he says, in the case of the body-cells in such cases. But this is not the question: inheritance in the proper sense of the word means the transmission to individuals of the next generation. On this point Adami says we must logically admit the action of the toxins on the germ-cells, and the individuals developed from these must, subject to the law of loss already noted, have the same properties. He admits that inherited immunity is rare, but says that it has occasionally been noted. Here we have again merely the same influence, chemical in this case, acting simultaneously on somatic cells and germ-cells, which is not the inheritance of acquired characters at all. Adami remarks that Weismann would make the somewhat subtle distinction that the toxins produce these results not by acting on the body-cells but by direct action on the germ-cells, that the inheritance is blastogenic not somatogenic, and calls this 'a sorry and almost Jesuitic play upon words.' On the contrary, it is the essential point, which Adami fails to appreciate. However, he goes further and refers to endogenous intoxication, to disturbed states of the constitution, due to disturbances in glandular activity or to excess of certain internal secretions. Such disturbances he says, acting on the germ-cells, would be truly somatogenic. In the case of gout he considers that defect in body metabolism has led to intoxication of the germ-cells, and the offspring show a peculiar liability to be the subjects of intoxications of the same order. Now, however important these views and conclusions may be from the medical point of view, in relation to the heredity of general physiological or pathological conditions, they throw no light on the problems considered by myself and other biologists--namely, the origin of species and of structural adaptations. There is no mention anywhere in Adami's short paper of the evolution or heredity of structural characters or adaptations such as wing of Bird or Bat, lung of Frog, asymmetry of Flat-fish or of specific characters, still less of secondary sexual characters, which formed the basis of the hormone theory in my 1908 paper. He does not even consider the evolution of the structural adaptations which enable man to maintain the erect position on the two hind-limbs. He does not consider the action of external stimulation, whether the direct action on epidermal or other external structures or the indirect action through stimulation of functional activity. All his examples of external agents are toxins produced by bacteria invading the body, except in the case of gout, for which he suggests no external cause at all. Only once in the last of the part of the paper considered does Adami mention internal secretions. His actual words are: 'We recognise yearly more and more the existence of auto-intoxications, of disturbed states of the constitution due to disturbances in glandular activity or to excess of certain internal secretions or of the substances ordinarily neutralised by the same.' The only example he gives is that of gout. How remote this is from the discoveries concerning the specific action of hormones on the growth of the body or of special parts of the body, or on the function of glands, and from a definite hormone theory of heredity as proposed by myself, is sufficiently obvious. CHAPTER I Classification And Adaptation The study of the animals and plants now living on the earth naturally divides itself into two branches, the one being concerned with their structure and classification, the other with their living activities, their habits, life histories, and reproduction. Both branches are usually included under the terms Natural History, or Zoology, or Botany, and a work on any group of animals usually attempts to describe their structure, their classification, and their habits. But these two branches of biological science are obviously distinct in their methods and aims, and each has its own specialists. The pursuit, whose ultimate object is to distinguish the various kinds of organisms and show their true and not merely apparent relations to one another in structure and descent, requires large collections of specimens for comparison and reference: it can be carried on more successfully in the museum than among the animals or plants in their natural surroundings. This study, which may be called Taxonomics, deals, in fact, with organisms as dead specimens, and it emphasises especially the distinguishing characters of the ultimate subdivisions of the various tribes of animals and plants--namely, species and varieties. The investigation, on the other hand, of the different modes of life of animals or plants is based on a different mental conception of them: it regards them primarily as living active organisms, not as dead and preserved specimens, and it can only be carried on successfully by observing them in their natural conditions, in the wide spaces of nature, under the open sky. The object of this kind of inquiry is to ascertain what are the uses of organs or structures, what they are for, as we say in colloquial language, to discover what are their functions and how these functions are useful or necessary to the life of the animals or plants to which they belong. For example, some Cuttle-fishes or Cephalopoda have eight arms or tentacles and others ten. The taxonomist notices the fact and distinguishes the two groups of Octopoda and Decapoda. But it is also of interest to ascertain what is the use of the two additional arms in the Decapoda. They differ from the other arms in being much longer, and provided with sockets into which they can be retracted, and suckers on them are limited to the terminal region. In the majority of zoological books in which Cephalopoda are described, nothing is said of the use or function of these two special arms. Observation of the living animal in aquaria has shown that their functions is to capture active prey such as prawns. They act as a kind of double lasso. Sepia, for instance, approaches gently and cautiously till it is within striking distance of a prawn, then the two long tentacles are suddenly and swiftly shot out from their sockets and the prawn is caught between the suckers at the ends of them. Another example is afforded by the masked crab (_Corystes cassivelaunus_). This species has unusually long and hairy antennae. These are usually tactile organs, but it has been found that the habit of _Corystes_ is to bury itself deep in the sand with only the tips of the antennae at the surface, and the two are placed close together so as to form a tube, down which a current of water, produced by movements of certain appendages, passes to the gill chamber and provides for the respiration of the crab while it is buried, to a depth of two or three inches. The results of the investigation of habits and functions may be called Bionomics. It may be aided by scientific institutions specially designed to supplement mere observation in the field, such as menageries, aquaria, vivaria, marine laboratories, the objects of which are to bring the living organism under closer and more accurate observation. The differences between the methods and results of these two branches of Biology may be illustrated by comparing a British Museum Catalogue with one of Darwin's studies, such as the 'Fertilisation of Orchids' or 'Earthworms.' Other speculations in Biology are related to Taxonomics or Bionomics according as they deal with the structure of the dead organism or the action of the living. Anatomy and its more theoretical interpretation, morphology, are related to Taxonomics, physiology and its branches to Bionomics. In fact, the fundamental principles of physiology must be understood before the study of Bionomics can begin. We must know the essential nature of the process of respiration before we can appreciate the different modes of respiration in a whale and a fish, an aquatic insect and a crustacean. The more we know of the physiology of reproduction, the better we can understand the sexual and parental habits of different kinds of animals. The two branches of biological study which we are contrasting cannot, however, be completely separated even by those whose studies are most specialised. In Bionomics it is necessary to distinguish the types which are observed, and often even the species, as may be illustrated by the fact that controversies occasionally arise among amateur and even professional fishermen on the question whether dog-fishes are viviparous or oviparous, the fact being that some species are the one and others the other, or the fact that the harmless slow-worm and ring-snake are dreaded and killed in the belief that they are venomous snakes. Taxonomics, on the other hand, must take account of the sex of its specimens, and the changes of structure that an individual undergoes in the course of its life, and of the different types that may be normally produced from the same parents, otherwise absurd errors are perpetrated. The young, the male, and the female of the same species have frequently been described under different names as distinct species or even genera. For example, the larva of marine crabs was formerly described as a distinct genus under the name of _Zoaea_, and in the earlier part of the nineteenth century a lively controversy on the question was carried on between a retired naval surgeon who hatched _Zoaea_ from the eggs of crabs, and an eminent authority who was Professor at Oxford and a Fellow of the Royal Society, and who maintained that _Zoaea_ was a mature and independent form. In the end taxonomy had to be altered so as to conform with the fact of development, and the name _Zoaea_ disappeared altogether as that of an independent genus, persisting only as a convenient term for an important larval stage in the development of crabs. These two kinds of study give us a knowledge of the animals now living. But we find it a universal rule that the individual animal is transitory, that the duration of life, though varying from a few weeks to more than a century, is limited, and that new individuals arise by reproduction, and we have no evidence that the series of successive generations has ever been interrupted; that is to say, the series in any given individual or species may come to an end; species may be exterminated, but we know of no instance of individuals coming into existence except by the process of reproduction or generation from pre-existing individuals. Further, we know from the evidence of fossil remains that the animals existing in former periods were very different from those existing now, and that many of the existing forms, such as man, mammals, birds, bony fishes, can only be traced back in the succession of stratified rocks to the later strata or to those about the middle of the series, evidence of their existence in the periods represented by the most ancient strata being entirely absent. Existing types then must have arisen by evolution, by changes occurring in the succession of generations. These three facts--namely, the limited duration of individual life, the uninterrupted succession of generations, and the differences of the existing animals and plants from those of former geological periods whose remains are preserved in stratified rocks--are sufficient by themselves to prove that evolution has taken place, that the history of organisms has been a process of descent with modification. If the animals and plants whose remains are preserved as fossils, or at any rate forms closely related to these, were not the ancestors of existing forms, there are only two other possibilities: either the existing forms came into existence by new creations after the older forms became extinct, or the ancestors of existing forms, although they coexisted with the older forms, never left any fossil remains. Each of these suppositions is incredible. In view of these plain facts and their logical conclusion it is curious to notice how Darwin in his _Origin of Species_ constantly mingles together arguments to prove the proposition that evolution has occurred, that the structure and relations of existing animals can only be explained by descent with modification, with arguments and evidence in favour of natural selection as the explanation and cause of evolution. In the great controversy about evolution which his work aroused, the majority of the educated public were ultimately convinced of the truth of evolution by the belief that a sufficient cause of the process of change had been discovered, rather than by the logical conclusion that the organisms of a later period were the descendants of those of earlier periods. Even at the present day the theory of natural selection is constantly confused with the doctrine of evolution. The fact is that the investigation of the causes of evolution has been going on and has been making progress from the time of Darwin, and from times much earlier than his, down to the present day. Bionomics show that every type must be adapted in structure to maintain its life under the conditions in which it lives, the primary requirements being food and oxygen. Every animal must be able to procure food either of various kinds or some special kind--either plants or other animals; it may be adapted to feed on plants or to catch insects or fish or animals similar to itself; its digestive organs must be adapted to the kind of food it takes; it must have respiratory organs adapted to breathe in air or water; it must produce eggs able to survive in particular conditions, and so on. One of the most interesting results of the study of the facts of evolution is that each type of animal tends to multiply to such an extent as to occupy the whole earth and adapt itself to all possible conditions. In the Secondary period reptiles so adapted themselves: there were oceanic reptiles, flying reptiles, herbivorous reptiles, carnivorous reptiles. At the present day the Chelonia alone include oceanic, fresh-water, and terrestrial forms. Birds again have adapted themselves to oceanic conditions, to forests, plains, deserts, fresh waters. Mammals have repeated the process. The organs of locomotion in such cases show profound modifications, adapting them to their special functions. One thing to be explained is the origin of adaptations. It is, however, necessary to distinguish between the adapted condition or structure of an organ and the process by which it became adapted in evolution; two ideas which are often confused. The eye would he equally adapted for seeing whether it had been created in its actual condition or gradually evolved. We have to distinguish here, as in other matters, between being and becoming, and, further, to distinguish between two kinds of becoming--namely, the development of the organ in the individual and its evolution in the course of descent. The word 'adaptation' is itself the cause of much fallacious reasoning and confusion of ideas, inasmuch as it suggests a process rather than a condition, and by biological writers is often used at one time to mean the former and at others the latter. We may take the mammary glands of mammals or organs adapted for the secretion of milk, whose only function is obviously the nourishment of the offspring. Here the function is certain whatever view we take of the origin of the organs, whether we believe they were created or evolved. But if we consider the flipper or paddle of a whale, we see that it is homologous with the fore-leg of a terrestrial mammal, and we are in the habit of saying that in the whale the fore-limb is modified into a paddle and has become adapted for aquatic locomotion. This, of course, assumes that it has become so adapted in the course of descent. But the pectoral fin of a fish is equally 'adapted' for aquatic locomotion, but it is certainly not the fore-leg of a terrestrial mammal adapted for that purpose. The original meaning of adaptation in animals and plants, of organic adaptation to use another term, is the relation of a mechanism to its action or of a tool to its work. A hammer is an adaptation for knocking in nails, and the woodpecker uses its head and beak in a similar way for making a hole in the bark of trees. The wings and the whole structure of a bird's body form a mechanism for producing one of the most difficult of mechanical results, namely, flight. Then, again, there are stationary conditions, such as colour and patterns, or scales and armour, which may he useful in the life of an animal or flower, but are not mechanisms of moving parts like a bird's wing, or secreting organs like mammary glands. Unless we choose or invent some new term, we must define adaptations apart from all questions of evolution as any structures or characters in an organism which can be shown either by their mere presence, or by their active function, to be either useful or necessary to the animal's existence. We must be on our guard against assuming that the word 'adaptation' implies any particular theory or conclusion concerning the method and process by which adaptations have arisen in the course of evolution. It is that method and process which we have to investigate. On the other hand, when we look primarily at differences of structure we find that not only are there wide and distinct gaps between the larger categories, such as mammals and birds, with few or no intermediate forms, but the actual individuals most closely similar to one another naturally and inevitably fall into distinct groups which we call kinds or species. The conception of a species is difficult to define, and authorities are not agreed about it. Some, like Professor Huxley, state that a species is purely a mental conception, a generalised idea of a type to which actual individuals more or less closely conform. According to Huxley, you cannot lock the species 'horse' in a stable. Others regard the matter more objectively, and regard the species merely as the total number of individuals which possess a certain degree of resemblance, including, as mentioned above, all the forms which may be produced by the same parents, or which are merely stages in the life of the individual. There are cases in which the limits of species or the boundaries between them are indistinct, where there is a graduated series of differences through a wide range of structure, but these cases are the exception; usually there are a vast majority of individuals which belong distinctly to one species or another, while intermediate forms are rare or absent. The problem then is, How did these distinct species arise? How are we to explain their relations to one another in groups of species or genera; why are the genera grouped into families, families into orders, orders into classes, and so on? There are thus two main problems of evolution: first, how have animals become adapted to their conditions of life, how have their organs become adapted to the functions and actions they have to perform, or, at least, which they do perform? The power of flight, for example, has been evolved by somewhat different modifications in several different types of animals not closely related to one another: in reptiles, in birds, and in mammals. We have no reason to believe that this faculty was ever universal, or that it existed in the original ancestors. How then was it evolved? The second great problem is, How is it that existing animals, and, as the evidence of the remains of extinct animals shows, these that existed at former periods of time also, are divided into the groups or types we call species, naturally classified into larger groups which are subdivisions of others still larger, and so on, in what we call the natural system of classification? The two problems which naturalists have to solve, and which for many recent generations they have been trying to solve, are the Origin of Species and the Origin of Adaptations. Former generations of zoologists have assumed that these problems were the same. Lamarck maintained that the peculiarities of different animals were due to the fact that they had become adapted to modes of life different to those of their ancestors, and to those in which allied forms lived, the change of structure being due to the effect of the conditions of life and of the actions of the organs. He did not specially consider the differences of closely allied species, but the peculiarities of marked types such as the long neck of the giraffe, the antlers of stags, the trunk of the elephant, and so on; but he considered that the action of external conditions was the true cause of evolution, and assumed that in course of time the effects became hereditary. Lamarck's views are expounded chiefly in his _Philosophie Zoologique_, first published in 1809, and an excellent edition of this work with biographical and critical introduction was published by Charles Martins in 1873. Although his conception of the mode in which structural changes were produced is of little importance to those now engaged in the investigation of the process of evolution, since it was naturally based on the physiological ideas of his time, many of which are now obsolete, for the sake of accuracy it is worth while to cite his principal propositions in his own words:-- 'Il sera en effet évident que l'état où nous voyons tous les animaux, est d'une part, le produit de la composition croissante de l'organisation, qui tend à former une gradation régulière, et de l'autre part qu'il est celui des influences d'une multitude de circonstances très différentes qui tendent continuellement à détruire la régularité dans la gradation de la composition croissante de l'organisation. 'Ici il devient nécessaire de m'expliquer sur le sens que j'attache à ces expressions: Les circonstances influent sur la forme et l'organisation des animaux, c'est-à-dire qu'en devenant très différentes elles changent avec le temps et cette forme et l'organisation elle-même par des modifications proportionnées. 'Assurément si l'on prenait ces expressions à la lettre, on m'attribuerait une erreur; car quelles que puissent être les circonstances elles n'opèrent directement sur la forme et sur l'organisation des animaux aucune modification quelconque. Mais de grands changements dans les circonstances amènent pour les animaux de grands changements dans leurs besoins et de pareils changements dans les besoins en amènent nécessairement dans les actions. Or, si les nouveaux besoins deviennent constants ou très durables, les animaux prennent alors de nouvelles habitudes qui sont aussi durables que les besoins qui les ont fait naître. Il en sera résulté l'emploi de telle partie par préférence à celui de telle autre, et dans certains cas le défaut total d'emploi de telle partie qui est devenue inutile.' The supposed effect of these changes of habit is definitely stated in the form of two 'laws':-- PREMIÈRE LOI 'Dans tout animal qui n'a point dépassé le terme de ses développements l'emploi plus fréquent et soutenu d'un organe quelconque, fortifie peu à peu cet organe, le développe, l'agrandit et lui donne une puissance proportionée à la durée de cet emploi; tandis que le défaut constant d'usage de tel organe Paffaiblit insensiblement, le détériore, diminue progressivement ses facultés, et finit par le faire disparaître. DEUXIÈME LOI 'Tout ce que la nature a fait acquérir ou perdre aux individus par l'influence des circonstances ou leur race se trouve depuis longtemps exposée, et par conséquent, par l'influence de l'emploi prédominant de tel organe, ou par celle d'un défaut constant d'usage de telle partie, elle le conserve par la génération aux nouveaux individus qui en proviennent, pourvu que les changements acquis soient communs aux deux sexes, ou à ceux qui ont produits ces nouveaux individus.' It will be seen that this last condition excludes the question of the origin of organs or characters confined to one sex, or secondary sexual characters. With regard to the expression 'emploi de telle partie,' the explanation which Lamarck gives of the evolution of horns and antlers is curious. He does not attempt to show how the use or employment of the head leads to the development of these outgrowths of bone and epidermic horn, but attributes their development in stags and bulls to an 'interior sentiment in their fits of anger, which directs the fluids more strongly towards that part of their head.' Lamarck's actual words (_Phil. Zool.,_ edit. 1873, p. 254) are: 'Dans leurs accès de colière qui sont fréquents surtout entre les mâles, leur sentiment intérieurs par ses efforts dirige plus fortement les fluides vers cette partie de leur tete, et il s'y fait une secrétion de matière cornée dans les uns (_Bovidae_) et de matière osseuse mélangée de matière cornée dans les autres (_Cervidae_), qui donne lieu à des protubérances solides: de là l'origine des cornes, et des bois, dont la plupart de ces animaux ont la tête armée.' Darwin, on the other hand, definitely set before himself the problem of the origin of species, which the majority of naturalists, in spite of Lamarck and his predecessor Buffon, regarded as permanent and essentially immutable types established by the Creator at the beginning of the world. This principle of the persistence and fundamentally unchangeable nature of species was regarded as an article of religion, following necessarily from the divine inspiration of the Bible. This theological aspect of the subject is sufficiently curious when we consider it in relation to the history of biological knowledge, for Linnaeus at the beginning of the eighteenth century was the first naturalist who made a systematic attempt to define and classify the species of the whole organic world, and there are few species of which the limits and definition have not been altered since his time. In fact, at the present time there are very numerous groups, both in animals and plants, on the species of which scarcely any two experts are agreed. In many cases a Linnaean species has been split up till it became, first, a genus, then a family, and, in some cases, an order. What one naturalist considers a species is considered by another a genus containing several species, and, vice versa, the species of one authority is described as merely a variety by another. The older naturalists might have said with truth: we do not know what the species are, but we are quite certain that whatever they are they have never undergone any change in their distinguishing characters. At the same time we know that whether we call related forms varieties or species or genera in different cases, we find, whatever organisms we study, whether plants or animals, definite types distinguished by special characters of form, colour, and structure, and that individuals of one species or type never give rise by generation to individuals of any other known species or type. We do not find wolves producing foxes, or bulldogs giving birth to greyhounds. As a general rule the distinguishing characters are inherited, and it is by no means easy even in domesticated animals and plants to obtain an exact and complete record of the descent of a new variety from the original form. Among species in a state of nature it is the exception to find two recognised species which can be crossed or hybridised. In the case of the horse and the ass, although mules are the hybrid offspring of the two, the mules themselves are sterile, and there are many similar cases, so that some naturalists have maintained that mutual infertility should be recognised as the test of separation in species. Darwin founded his theory on the assumption that differences of species were differences of adaptation. His theory of natural selection is a theory of the origin of adaptations, and only a theory of the origin of species on the assumption that their distinguishing characters are adaptations to different modes and conditions of life, to different requirements. He pointed out that there is always a considerable range of variation in the specific characters, that, as a rule, no two individuals are exactly alike, even when produced by the same two parents. The central principle of his theory was the survival of individuals possessing those variations which were most useful in the competition of species with species and of individual with individual. He thus explained adaptation to new conditions and divergence of several species from a common ancestor. Characters which were not obviously adaptive were explained either by correlation or by the supposition that they had a utility of which we were ignorant. Darwin also admitted the direct action of conditions as a subordinate factor. Weismannism not only retained the principle of utility and selection, but made it the only principle, rejecting entirely the action of external conditions as a cause of congenital modifications, _i.e._ of characters whose development is predetermined in the fertilised ovum. It is to Weismann that we owe precise and definite conceptions, if not of the nature of heredity, at least of the details of the process. From him we learned to think of the ova or sperms, of the reproductive cells or 'gametes' of an individual, as cells which were from an early stage of development distinguished from the cells forming the organs and tissues; to regard the organism as consisting of soma on the one hand and gametes on the other, both derived from the original zygote cell, not the gametes from the soma. Weismann saw no possibility of changes induced by any sort of stimulation in the soma affecting the gametes in such a way as to be redeveloped in the soma of the next generation. He attributed variation partly to the union of gametes containing various determinants, which he termed amphimixis: this, however, would introduce nothing new. Then he proposed his theory of germinal selection, determinants growing and multiplying in competition, some perhaps disappearing altogether, though this does not satisfactorily account for entirely new characters. With Weismann, however, every species was a different adaptation, and natural selection was the _deus ex machina_; to quote his own words, _Alles ist angepasst_. Romanes and other writers, on the other hand, had always maintained that in many cases the constant peculiarities of closely allied species had no known utility whatever, so that the problem presented by these characters was not explained by any theory of the origin of adaptations. Mendelism, since 1900, has studied experimentally the transmission of definite characters, and maintains that the characters of species are of the same nature as the characters which segregate in Mendelian experiments. Such characters are not in any way related to external conditions, and cannot, therefore, be adaptive except by accident. Professor Bateson goes so far as to admit that such large variations or mutations offer more definite material to selection than minute variations too small to make any important difference in survival, but as regards species the important factor is the occurrence of mutations which are inherited and at once form a distinct definite difference between allied species which is not due to selection and has nothing to do with adaptation. In a book entitled _Problems of Genetics_, 1913, Bateson describes several particular cases which show how impossible it is to find any relation at all between the diagnostic characters of certain species or local forms and their mode of life. One of these cases is that of the species of _Colaptes_, a genus of Woodpeckers in North America, of which a detailed study was published in the _Bull. Am. Mus. Nat. Hist._, 1892. The two forms specially considered are named _C. auratus_ and _C. cafer_, and they differ in the following seven characters:-- _C. auratus._ _C. cafer._ 1. Quills yellow. 1. Quills red. 2. Male with black cheek stripe. 2. Male with red cheek stripe. 3. Adult female with no 3. Adult female with usually cheek stripe. brown cheek stripe. 4. A scarlet nuchal crescent 4. No nuchal crescent in in both sexes. either sex. 5. Throat and fore-neck brown. 5. Throat and fore-neck grey. 6. Top of head and hind-neck grey. 6. Top of head and hind-neck brown. 7. General tone of plumage 7. General tone of plumage olivaceous. rufescent. _C. auratus_ occurs all over Canada, and the United States, from the north to Galveston; westwards it extends to Alaska and the Pacific coast to the northern border of British Columbia. _C. cafer_ in comparatively pure form occupies Mexico, Arizona, California, part of Nevada, Utah, Oregon, and is bounded on the east by a line drawn from the Pacific south of Washington State, south and eastward through Colorado to the mouth of the Rio Grande on the Gulf of Mexico. Between the two areas thus roughly defined is a tract of country about 300 to 400 miles wide, which contains some normal birds of each type, but chiefly birds exhibiting irregular mixtures of the characters of both. Bateson remarks that some naturalists may be disposed once more to appeal to our ignorance, and suggest that if we only knew more we should find that the yellow quills, the black 'moustache,' and the red nuchal crescent specially adapt _auratus_ to the conditions of the northern and eastern region, while the red quills, red moustache, and absence of crescent fit _cafer_ to the conditions of the more southern and western territory. But, as the author we are quoting points out, when we think of the wide range of conditions in the country occupied by _auratus_, extending from Florida to the Arctic, it is impossible to believe that there is any common element in the conditions which demands a scarlet nuchal patch in _auratus_, while the equally varied conditions in the _cafer_ area do not require that character. It may be added that the same objection is equally valid whether we apply it to the utility of such a character or to the supposition that the character has been caused by external conditions; in other words, whether we attempt to explain the facts by selection or by the Lamarckian principle. Another case quoted by Bateson is that of the two common British Wasps, _Vespa vulgaris_ and _Vespa germanica_. Both usually make subterranean nests, but of somewhat different materials. That of _V. vulgaris_ is of a characteristic yellow colour, because made of rotten wood, while that of _V. germanica_ is grey, from the weathered surface wood of palings or other exposed timber which is used in its construction. In characters the differences of the two forms are so slight as to be distinguishable only by the expert. _V. vulgaris_ often has black spots on the tibiae, which are wanting in _germanica_. A horizontal yellow stripe on the thorax is enlarged downwards in the middle in _germanica_, not in _vulgaris_. There are distinct though slight differences in the genital appendages of the males in the two species. Here there are differences of habit, and slight but constant differences of structure; but it is impossible to find any relation between the former and the latter. Mendelism in itself affords no evidence of the origin of new characters, since it deals only with the heredity of the characters which it finds usually in the varieties of cultivated animals and plants. But indirectly it draws the inference that new characters arose in the form in which they are found to be inherited, as complete units, and not by gradual, continuous increase, that specific characters are due to mutations, and that all evolution has been the result of similar hereditary factors, arising by some internal process in the divisions of reproductive cells, and not determined by external conditions. Some Mendelians maintain that if the mutations are not compatible with the existing conditions of life, the organism must either die or find new conditions in which it can live. Bateson remarks (_Mendel's Principles of Heredity_, 1909, p. 288): 'Mendelism provides no fresh clue to the problem of adaptation except in so far as it is easier to believe that a definite integral change in attributes can make a perceptible difference to the prospect of success, than that an indefinite and impalpable change should entail such consequences.' Here the distinction between adaptive and non-adaptive characters is recognised, but both are emphatically attributed to the same origin. The American evolutionist, T. H. Morgan, also a specialist in Mendelism, goes further, and maintains, not merely that mutations which happened to make a 'difference to the prospect of success' survived, or were selected, but that if a mutation arising from a change in the gametes was not compatible with the conditions of the animal's life at the time, it either died, or found other conditions, or adopted new habits which were adapted to the new character or structure. He takes Flat-fishes as an example, and suggests that having by mutation become asymmetrical, and having both eyes on one side, etc., the fish adopted the habit of lying on the ground on one side of its body. This is, of course, the exact opposite of the older conception: the structure of the animal has not been changed by new habits or conditions, but new habits and conditions have been sought and found in order to meet the requirements of the change of structure. The present writer, on the other hand, believes that not only are adaptive characters distinct from non-adaptive specific characters, and from non-adaptive diagnostic characters in general, but that their origin and evolution are entirely distinct and different. There are two separate problems, the origin of adaptations and the origin of species, and the investigation of these two problems leads not to one explanation common to both, but to two entirely different explanations, to two different processes going on throughout the organic world and affecting every individual and every group in classification. The Flat-fishes, now regarded not as merely a family but a sub-order of Teleosteans, afford a good example of the contrast between adaptive and non-adaptive diagnostic characters. For the whole group the adaptive characters are diagnostic, distinguishing it from other sub-orders. It is conceivable that different phyletic groups of fishes, that is fishes of different descent, might have been modified in the same way, as, for instance, grasshoppers and fleas have been adapted for leaping without being closely related to each other. It is generally held, however, that the Flat-fishes are of common descent. In this group the adaptive characters are diagnostic; that is to say, they distinguish the group from other sub-orders, though there are other non-adaptive characters which indicate the relationship to other groups and which are not adapted to the horizontal position of the original median plane of symmetry. The principal adaptive characters are: both eyes and the pigmentation on the side which is uppermost in the natural position, lower side without eyes and colourless; dorsal and ventral fins continuous and extending nearly the whole length of the dorsal and ventral edges; dorsal fin extending forwards on the head, not along the morphological median line, which is between the eyes, but between the more dorsal eye and the lower side of the body, in the same horizontal plane as the posterior part of the same fin. The 'adaptive' quality in these characters, as in other cases, does not necessarily consist in their utility to the animal, but in the definite relation between them and the external conditions. When the relation is one of function, the organ may be said to be useful: for example, the position of the two eyes is adaptive because they are on the upper side where alone light can reach them, the other side resting on the ground; and the adaptation is one of function, and therefore useful, because if the eyes were in their normal position, one of them would be useless, being generally in contact with the ground or buried in it. Similarly with the extension of the dorsal and ventral fins, the undulations of which serve to move the fish gently along in a plane parallel to the ground. If the dorsal fin was not extended forward, the head would not be so well supported. But when we consider the pigmentation of the upper side and the normally white lower side, although the adaptation is equally obvious, the utility is by no means certain. To any naturalist who has observed these fishes in the living state the protective resemblance of the pigmentation of the upper side is very evident, especially because, as in many other fishes and amphibians, the intensity of the colour varies in harmony with the colour of the ground on which the fish rests. But the utility of the white lower side is not so easy to prove. Would the fish be any worse off if the lower side were coloured like the upper? Probably it would not, although it has been maintained that the white lower side serves to render the fish less visible when seen against the sky by an enemy below it. Ambicolorate specimens occur, and there is no evidence that their lives are less secure than those of normal specimens. The essential and universal quality of adaptation, then, is not utility, but relation to surroundings or to function or to habit. In this case colour is related to incidence of light, absence of colour to absence of light. Position of eyes is also related to light; they are situated where they can see, absent from the side which is shut off from light. The marginal fins are extended where their movements best support and move the body. It is to be noted also that these adaptations of different organs of the body, eyes, fins, colour, are entirely independent of each other physiologically. It may appear on first consideration that eyes and colour, being both on the upper side, may have been somehow connected in the constitution of the body, whereas the only connexion is external in their common relation to light. This independence is well shown in the modification of the dorsal fin: if this were physiologically affected by the change in the eyes, which is brought about by the twisting of the interorbital region of the skull, the anterior end of the fin would be between the two eyes, since the morphological median line of the body is in that position. In fact, on the contrary, the attachment of the dorsal fin is continued forward where it is required for its mechanical function, regardless entirely of the morphology of the head. This is even more clearly evident in the structure of the jaws and teeth. These are entirely unaffected by the torsion of the interorbital part of the skull. In cases where the mouth is large and teeth are required on both sides, the prey being active fish of other species, as in Turbot, Brill, and Halibut, the jaws and teeth are equally developed on the upper and lower sides, and there is almost complete symmetry in these parts of the skull. In Soles and Plaice, on the other hand, whose food consists of worms, molluscs, etc., living on or in the ground, the jaws of the lower side are well developed and strong, those of the upper side diminished, and teeth are confined to the lower side. Here it is not a question of the jaws twisted, but simply unequally developed. There is no general and constitutional asymmetry of head or body, but a modification of different organs independently of each other in relation to external conditions-- light, food, movement. On the other hand, let us consider some of the diagnostic characters by which species and genera are distinguished in the Flat-fishes or Pleuronectidae. The genus _Pleuronectes_ is distinguished by the following characters: eyes on the right side, mouth terminal and rather small, teeth most developed on the blind (left) side. Of this genus there are five British species, namely:-- _P. platessa_, the Plaice: scales small, mostly without spinules, reduced and not imbricated, imbedded in the skin; bony knobs on the head behind the eyes, red spots on the upper side. _P. flesus_, the Flounder: no ordinary scales; rough tuberoles along the bases of the marginal fins and along the lateral line; these are modified and enlarged scales; elsewhere scales of any kind are absent. In these two species the lateral line is nearly straight, having only a slignt curve above the pectoral fin. _P. limanda_, the Dab: scales uniform all over the body, with spinules on the projecting edges, making the skin rough; lateral line with a semicircular curve above the pectoral fin. _P. microcephalus,_ the Lemon-dab: scales small, smooth, and imbedded; skin slimy, head and mouth very small, colour yellowish brown with large round darker marks. _P. cynoglossus,_ the Witch or Pole-dab: head and mouth smaller than in the Plaice, eyes rather larger; scales all alike and uniformly distributed, slightly spinulate on upper side, smooth on the lower; blister-like cavities beneath the skin of the head on the lower side. With regard to the generic characters, it is difficult to give any reason why the mouth should be at the end of the head instead of behind the apex of the snout as in the genus _Solea,_ but, as we have seen already, the small size of the mouth and the greater development of teeth on the lower side are adapted to the food and mode of feeding. It is impossible to say why one genus of Flat-fishes should have the right side uppermost and others, _e.g._ Sole and Turbot, the left; it would almost seem to have been a matter of chance at the commencement of the evolution: reversed specimens occur as variations in most of the species. When we consider the specific differences, we find very definite characters in the structure and distribution of the scales, and no evidence has yet been discovered that these differences are related to external conditions. There are, of course, slight differences in habits and habitat, but no constant relation between these and the structural differences of the scales. Plaice and Dab are taken together on the same ground, and nothing has been discovered to indicate that the spinulate scales of the Dab are adapted to one peculiarity in habits or conditions, the spineless scales of the Plaice to another. In comparing certain geographical races of Plaice and Flounder the facts seem to suggest that differences of habitat may have something to do with the development of the scales. In the Baltic the Flounders are as large as those on our own coasts, but the thorny tubercles are much more developed, nearly the whole of the upper surface being covered with them. The Plaice, on the other hand, are smaller than those of the North Sea, and the _males_ have the scales spinulate over a considerable portion of the upper side. The chief difference between the Baltic and the North Sea is the reduced salinity of the former, so that it might be supposed that fresher water caused the greater development of the dermal skeleton. On the other hand, a species or geographical variety of the Plaice, whose proper is _P. glacialis_, is found on the Arctic coasts of Asia and America, on both sides of the extreme North Pacific, and on the east coast of North America. In this form the bony tubercles on the head in the Plaice are replaced by a continuous rough osseous ridge, and the scales are as much spinulated as in the Plaice of the Baltic. On the east coast of North America the males in this form are more spinulated than the females; on the Alaskan coast, and apparently the Arctic coast, the females are spinulated, and the sexual difference in this respect is slight or absent. Lower salinity cannot be the cause of greater spinulation in this case, and thus it might be suggested that the condition was due to lower temperature. But we do not find that northern or Arctic species of fish in general have the scales more developed than southern species. The Dab, which occurs in the same waters as the Plaice, has the spines more spinulated than any of the forms of plaice above mentioned, therefore the absence or slight development of spinules in the typical Plaice is not explained by physical conditions alone. Freshness of water again will not explain the difference of the structure and distribution of scales in Flounder and Plaice, considering the variety of squamation in fishes confined to fresh water. Still less can we attribute any of the peculiarities of scales to utility. We can discover no possible benefit of the condition in one species which would be absent in the case of other species. We can go much further than this, and maintain that there is no reason to believe that scales in general in Teleosteans, or any of their various modifications, are of special utility: they are not adaptive structures at all, although of great importance as diagnostic characters. It may be urged that in some cases, such as the little _Agonus cataphractus_ or the Seahorse among the Syngnathidae, the body is protected by a complete suit of bony armour; but accompanying these in the littoral region are numerous other species such as the Gobies, and even other species of Syngnathidae which have soft unprotected skins. Similarly with colour characters: the power of changing the colour so as to harmonize with the ground is obviously beneficial and adaptive, but in each species there is a specific pattern or marking which remains constant throughout life and has nothing to do with protective resemblance, variable or permanent. The red spots of the Plaice are specific and diagnostic, but they confer no advantage over the Dab or the Lemon-dab, in which they are absent, nor can any relation be discovered between these spots and mode of life or habits. The function of the lateral line organs is still somewhat obscure. The theory that they are sensitive to differences of hydrostatic pressure as the fish moves from one depth to another rests on no foundation, since it has yet to be shown how a change of pressure within the limits of the incompressibility of water can produce a sensation in an organ permeated throughout with water. It is more probable that the organs are affected by vibrations in the water, but we are unable to understand how a difference in the anterior curvature of the lateral line would make a difference in the function in any way related to the difference in conditions of life between Plaice and Dab. There is, however, reason to conclude that the organs, especially on the head, are more important and larger in deeper water, and thus the enlargement of the sensory canals in the head of the Witch, which lives in deeper water than other species, may be an adaptive character. Another genus of whose characters I once made a special study is that named _Zeugopterus._ The name was originally given by Gottsche to the largest species _Z. punctatus,_ from the fact that the pelvic fins are united to the ventral, but this character does not occur in other species now included in the genus. There are three species, occurring only in European waters, which form this genus and agree in the following characters. The outline of the body is more nearly rectangular than in other Flat-fishes from the obtuseness of the snout and caudal end, and the somewhat uniform breadth of the body. The surface is rough from the presence of long slender spines on the scales. There is a large perforation in the septum between the gill cavities, but this occurs also in _Arnoglossus megastoma,_ which is placed in another genus. But the generic character of _Zeugopterus,_ which is most important for the present discussion, is the prolongation of the dorsal and ventral fins on to the lower of the body at the base of the tail, the attachments of these accessory portions being transverse to the axis of the body. These fishes have the peculiar habit of adhering to the vertical surfaces of sides of aquaria, even the smooth surfaces of slate or glass. In nature they are taken occasionally on gravelly or sandy ground, but probably live also among rocks and adhere to them in the same way as to vertical surfaces in captivity. Many years ago (_Journ. Mar. Biol. Assn._, vol. iii 1893-95) I made a careful investigation of the means by which these fishes were able to adhere to a smooth surface, at least in the case of the largest and commonest species _Z. punctatus._ It was observed that so long as the fish was clinging to a vertical surface the posterior parts of the fins were in rhythmical motion, undulations passing along them in succession from before backwards, the edge of the body to which they were attached moving with them. The effect of these movements was to pump out water backwards from the space between the body and the surface it was clinging to, and to cause water to flow into this space at the anterior edges of the head. The subcaudal flaps were perfectly motionless and tightly pressed between the base of the tail and the surface of support, so that any movement of them was impossible. The question arose, however, whether the tail and these flaps acted as a sucker which aided in the adhesion. The flaps were therefore cut off with scissors--an operation which caused practically no pain or injury to the fish--and it adhered afterwards quite as well as when the fin-flaps were intact. The subcaudal prolongations of the fins are therefore not necessary to the adhesion, nor to the pumping action, of the muscles and fins, which went on as before. It seemed probable, therefore, that the pumping action was itself the cause of the adhesion. But the difficulty in accepting this conclusion was that there was a distinct though gentle respiratory movement of the jaws and opercula; and if the pumping of the water from beneath the body caused a negative pressure there, and a positive pressure on the outer side of the body, it seemed equally certain that the respiratory movement must force water into the space beneath the body and so cause a positive pressure there which would tend to force the fish away from the surface with which it was in contact. Examination of the currents of water around the edges of the fish, by means of suspended carmine, showed that water passed in at the mouth and out at the lower respiratory orifice, but also into the space below the body at the upper and lower edges of the head, without passing through the respiratory channel. It was thus proved that the rate at which water was pumped out at the sides of the tail was greater than that at which it passed in by the respiratory movements, and consequently there a resultant negative pressure beneath the body. By means of a model made of a thin flexible sheet of rubber, at each end of which on one side was fastened a short piece of glass tube, I was able to imitate the physical action observed in the fish. A long piece of rubber tube was attached to one of the pieces of glass tube, and brought over the edge of the glass front of an aquarium. The long rubber tube was set in action as a siphon and the sheet of rubber placed against the glass. As long as water was running through the siphon the sheet of rubber remained pressed against the glass and supported. As soon as the current of water was stopped the apparatus fell to the bottom of the tank. In this model water passed out from beneath the rubber through the glass tube attached to the siphon and passed in by the opposite glass tube, and at the sides of it. The latter tube represented the respiratory channel of the fish, and the space between tube and rubber represented the spaces between the head of the fish and the vertical surface to which it clung. In the fish the marginal fins not only extend to the base of the tail, but are broader at the posterior end than elsewhere, whereas in other Flat-fishes the posterior part of the marginal fins are the narrowest parts. The shape of the fins and the breadth of the body posteriorly, then, are adaptations which have a definite function, that of enabling the fish to adhere to vertical surfaces. But, on the other hand, the extension of the marginal fins in a transverse direction beneath the tail has no use in the process of adhesion, nor has any other use been found for it. It is a generic character, so far as we know, without utility. On the other hand, it is very probable that this subcaudal extension of the fins is merely a result of the posterior extension and enlargement of these fins which has taken place in the evolution of the adaptation. If the Lamarckian explanation of adaptation were true, it would be possible to understand that the constant movements of the fins and muscles by which the adhesion was effected caused a longitudinal growth of the fins in excess of the length actually required, and that this extra growth extended on to the body beneath the tail, although the small flaps on the lower side were not necessary to the new function which the fins performed. When we consider such cases as this we are led to the conclusion that the usual conception of adaptation is not adequate. We require something more than function or utility to express the difference between the two kinds of characters to be distinguished. For example, the absence of pigmentation from the lower sides of Flat-fishes may have no utility whatever, but we see that it differs from the specific markings of the upper side in the fact that it shows a relation to or correspondence with a difference of external conditions--namely, the incidence of light, while in such a case as the red spots of the Plaice we can discover no such correspondence. We know that the American artist and naturalist Thayer has shown that the lighter colour of the ventral side of birds and other animals aids greatly in reducing their visibility in their natural surroundings, the diminution in coloration compensating for the diminution in the amount of light falling on the lower side, so that the upper and lower sides reflect approximately the same amount of light, and contrast, which would be otherwise conspicuous, is avoided. But the white lower sides of Flat-fishes are either not visible at all, or, if visible, are very conspicuous, so that the utility of the character is very doubtful. We may distinguish then between characters which correspond to external conditions, functions, or habits, and those which do not. The word 'adaptation,' which we have hitherto used, does not express satisfactorily the peculiarities of all the characters in the former of these two divisions. If we consider three examples--enlarged hind-legs for jumping as in kangaroo or frog, absence of colour from the lower sides of Flat-fishes, and, thirdly, the finlets on the lower side of _Zeugopterus_--we see that they represent three different kinds of characters, all related to habits or external conditions. We may say that the third kind are correlated with some other character that has a relation to function or external conditions, as the extension of the fins on the under side of _Zeugopterus_ is correlated with the enlargement of the fins, whose function is to cause the adhesion of the fish to a vertical surface. With regard to the specific characters of the species of _Zeugopterus_ nothing is known of peculiarities in mode of life which would give an importance in the struggle for existence to the concrescence of the pelvic fins with the ventral in _punctatus_, to the absence of this character and the elongation of the first dorsal ray in _unimaculatus_, or to the absence of both characters in _norvegicus_. No use is known for any of the other specific characters, which tend in each case to form a series. Thus in size _norvegicus_ is the smallest, _unimaculatus_ larger, and _punctatus_ largest, the last reaching a of 8-1/2 inches. The subcaudal fin-flaps are developed in _norvegicus_, most in _punctatus_; each has four rays in _norvegicus_ and _unimaculatus_, six in _punctatus_. The shortening and spinulation of the scales are greatest in _punctatus_, least in _norvegicus_. In _punctatus_ there are teeth on the vomer, in _unimaculatus_ none, in _norvegicus_ they are very small. If we consider fishes in general, we see that there is no evidence of any relation between many of the most important taxonomic characters and function or external conditions. In the seas Elasmobranchs and Teleosteans exist in swarming numbers side by side, but it is impossible to say that one type is more adapted to marine life than the other. There is good reason to believe that bony fishes were evolved from Elasmobranchs in fresh water which was shallow and foul, so that lungs were evolved for breathing air, and that marine bony fishes are descended from fishes with lungs; but no reason has been given for the evolution of bone in place of cartilage or for the various kinds of scales. Professor Houssaye, on the other hand, believes that the number and position of fins is adapted to the shape and velocity of movement of each kind of fish. If we turn to other groups of animals we find everywhere similar evidence of the distinction between adaptive and non-adaptive characters. Birds are adapted in their whole organization for flight, the structure of the wing, of the sternum, breast muscles, legs, etc., are all co-ordinated for this end. But how do we know that feathers in their origin were connected with flight? It seems equally probable that feathers arose as a mutation in place of scales in a reptile, and the feathers were then adapted for flight. Nothing shows the distinction better than convergent adaptation. Owls resemble birds of prey in bill and claw and mode of life, yet they are related to insect-eating swifts and goat-suckers and not to eagles and hawks. Swifts and swallows are similar in adaptive characters, but not in those which show relationship. It may be said that the characters believed to show true affinities were originally adaptive, but we do not know this. Similarly, in reptiles the Chelonia are distinguished by the most extraordinary union of skin-bones and internal skeleton enclosing the body in rigid armour: it may be said that the function of this is protection, that it is adaptation, and can be explained by natural selection, but the adaptation in this case is so indefinite that it is difficult to be convinced of it. Systematists have always distinguished between adaptive characters and those of taxonomic value--those which show the true affinities--and they are perfectly right: also they have always distrusted and held aloof from theories of evolution which profess to explain all characters by one universal formula. In my opinion, those who, like Weismann, consider all taxonomic characters adaptive, are equally mistaken with Bateson and his followers, who regard all characters as mutational. No system of evolution can be satisfactory unless it recognises that these two kinds of characters are distinct and quite different in their nature. But it may be asked, What objection is there to the theory of natural selection as an explanation of adaptations? The objection is that all the evidence goes to show that the necessary variations only arose under the given conditions, and, further, that the actions of the conditions and the corresponding actions of the organism give rise to stimuli which would produce somatic modifications in the same direction as the permanent modifications which have occurred. My view is, then, that specific characters are usually not adaptations, that other characters of taxonomic value are some adaptive and some unrelated to conditions of life, and that while non-adaptive characters are due to spontaneous blastogenic variations or mutations, adaptive characters are due to the direct influence of stimuli, causing somatic modifications which become hereditary, in other words, to the inheritance of acquired characters. It has become a familiar statement that every individual is the result of its heredity and its environment. The thesis that I desire to establish is that the heredity of each individual and each type is compounded of variations or changes of two distinct origins, one external and one internal; that is to say, of variations resulting from changes originating in the germ-cells or gametes, and of modifications produced originally in the soma by the action of external stimuli, and subsequently affecting the gametes. When we study the characters of animals in relation to sex we find that in many cases there are conspicuous organs or characters present in one sex, usually the male, which are absent or rudimentary in the other. The conception of adaptation applies to these also, since we find that characters consist often of weapons such as horns, antlers, and spurs, used in sexual combat, of copulatory or clasping organs such as the pads on a frog's forefeet, of ornamental plumage like the peacock's tail serving to charm the female, or of special pouches as in species of pipe-fish and frog for holding the eggs or young. Darwin attempted to explain sexual adaptation by sexual selection. The selective process in this case was supposed to be, not the survival of individuals best adapted to secure food or shelter or to escape from enemies, but the success of those males which were victorious in combat, or which were most attractive to the females, and therefore left the greater number of offspring which inherited their variations. But, as Darwin himself admitted, this theory of selection does not in any way explain the differences between the sexes--in other words, the limitation of the characters or organs to one sex--since there is no reason in the process of selection itself why the peculiarity of a successful male should not be inherited by his female offspring as well as by his male offspring. The real problem, then, is the sex-limited heredity, and we shall consider later whether in this kind of heredity also there are characters of internal as well as external origin, blastogenic as well as somatogenic. CHAPTER II Mendelism And The Heredity Of Sex We know that now individuals are developed from single cells which have either been formed by the union of two cells or which develop without such union, and that these reproductive cells are separated from pre-existing organisms: the gametes or gonocytes are separated from the parents and develop into the offspring. The zygote has the power of developing particular structures and characters in the complicated organisation of the adult, and we recognise that the characters are determined by the properties and constitution of the zygote; that is to say, of one or both of the gametes which unite to form the zygote. The distinction between peculiarities or 'characters,' determined in the ovum before development, and modifications due to influences acting on the individual during its development or life, is often obvious enough. A child's health, size, mode of speech, and behaviour may be greatly influenced by feeding, training, and education, but the colour of his or her eyes and hair were determined before birth. A human individual has, we know, a number of congenital or innate characters, by which we mean characters which arise from the constitution of the individual at the time of birth, and not from influences acting on him or her after birth. We have to remember, however, that modifications may be caused during development in the uterus, as, for example, birth-marks on the skin, and these would not be due to peculiarities in the constitution of the ovum. Karl Pearson and other devotees of the cult of Eugenics have been lately impressing on the public by pamphlets, lectures, and addresses the great importance of nature as compared with nurture, maintaining that the latter is powerless to counteract either the good or bad qualities of the former, and that the effects of nurture are not transmitted to the next generation. We recognise that the characters of varieties of flowers, fruits, and domesticated animals are not to be produced by any particular mode of treatment. We see the various kinds of orchids or carnations in the same greenhouse, of sweet peas and roses in the same garden. We go to a show and see the extraordinary variety of breeds of pigeons, rabbits, or fowls, and we know that these cannot be produced by treating the progeny of individuals of one kind in special ways, but are the progeny of parents of the same various races. If we want fowls of a particular breed we obtain eggs of that breed and hatch them with the certainty born of experience that we shall obtain chickens of that breed which will develop the colour, comb, size, and qualities proper to it. Similarly, in nature we recognise that the 'characters' of species or varieties are not due to circumstances acting on the individual during its development, but to the properties of the ova or seeds from which the individuals were developed. Formerly we regarded these congenital or innate characters as derived from the parents or inherited, and heredity was the transmission of constitutional characters from parent to offspring. Now that we fix our attention on the fertilised ovum or the gametes by which it is formed we see that the characters are determined by some properties in the constitution of the gametes. What, then, is heredity? Clearly, it is merely the development in the offspring of the same characters which were present in the ova from which the parents developed. When the characters persist unchanged from generation to generation, we call the process by which they are continued heredity. When new characters appear, _i.e._ new characters determined in the ovum not due to changes in the environment, we call them variations. When a fertilised ovum develops into a new individual, it divides repeatedly to form a very large number of cells united into a single mass. Gradually the parts of this mass are differentiated to form the tissues and organs of the body or soma, but some of the cells remain in their original condition and become the reproductive cells which will give rise to the next generation. The reproductive cells also undergo division and increase in number, and when they separate from the new individual and unite in fertilisation they still possess all the determinants of the fertilised ovum from which they are descended. Heredity thus continues from gamete to gamete, not from zygote to soma, and then from soma to gamete. Modern researches have shown that the nucleus, when the cell divides, assumes the form of a spindle of fibres, associated with which are distinct bodies called chromosomes, that the number of these chromosomes where it can be counted is constant for all individuals of the same species, and that before the gametes are ready for fertilisation two cell-divisions take place, which result in the reduction of the number of chromosomes to half the original number. When two gametes unite, the specific number is restored. Since the male gamete is very small and seems to contribute to the zygote almost nothing except the chromosomes, which carry with them all the characters of the male parent, it seems a necessary conclusion that the chromosomes alone determine the character of the adult. There are, however, facts which point to an opposite conclusion. Hegner, [Footnote: R. W. Hegner, 'Experiments with Chrysomelid Beetles,' III., _Biological Bulletin_, vol. xx. 1910-11.] for example, found that in the egg of the beetle _Leptinotarsa_, which is an elongated oval in shape, there is at the posterior end in the superficial cytoplasm a disc-shaped mass of darkly staining granules, while the fertilised nucleus is in the middle of the egg. When the protoplasm containing these granules was killed with a hot needle, development in some cases took place and an embryo was formed, but the embryo contained no germ cells. Here no injury had been done to the zygote nucleus, but these particular granules and the portion of protoplasm containing them were necessary for the formation of germ cells. In other experiments a large amount of protoplasm at the posterior end of the ovum was killed before the nucleus had begun to segment, and the result was the development of an embryo consisting of the head and part of the thorax, while the rest was wanting. The nucleus segmented and migrated into that part of the superficial cytoplasm which remained alive, and this proceeded to develop that particular part of the embryo to which it would have given rise if the rest of the egg had not been killed. There was no regeneration of the part killed, no formation of a complete embryo. It may be pointed out that segmentation in the insect egg is peculiar. The nuclei multiplied by segmentation migrate into the superficial cytoplasm surrounding the yolk, and then this cytoplasm segments, and each part of the cytoplasm develops into a particular region of the embryo. This, of course, does not prove that the nuclei or their chromosomes do not determine the _characters_ of the parts of the embryo developed, but they show that the parts of the non-nucleated cytoplasm correspond to particular parts of the embryo. The most important object of investigation at the present time is to find the origin of these properties of the chromosomes. We may say, using the word 'determinant' as a convenient term for that which determines the adult characters, that in order to explain the origin of species or the origin of adaptations we must discover the origin of determinants. Mendelism does not throw any direct light on this question, but it certainly has shown how characters may be inherited as separate and independent units. When one difference between two breeds is considered, _e.g._ rose comb and single in fowls, and individuals are crossed, we have the determinant for rose and the determinant for single in the same zygote. The result is that rose develops and single is not apparent. In the next generation rose and single appear, as at the beginning, in separate individuals. When two or three or more differences are studied we find that they are usually inherited separately without connexion with each other, although in some cases they are connected or coupled. The facts of Mendelism are of great interest and importance, but we have to consider the general theory based on them. This theory is that characters are generally separate units which can exist side by side, but do not mingle, and cannot be divided into parts. When an apparently single character shows itself double or treble, it is concluded that it has not been really divided, but consists of two or three units (Castle). Further, although Mendelism in itself shows no evidence of the origin of the characters, it assumes that they arose as complete units, and one suggestion is that a dominant factor might at some of the divisions in gametegenesis pass entirely into one daughter cell, and therefore be absent from the other, and thus individuals might be developed in which a dominant character was absent. Bateson in his well-known books, _Mendel's _Principles of Heredity_, 1909, and _Problems of Genetics_, 1913, discusses this question of the origin of the factors which are inherited independently. The difficulty that troubles him is the origin of a dominant character. Naturally, if he persists in regarding the determinant factor as a unit which does not grow nor itself evolve in any way, it is difficult to conceive where it came from. The dominant, according to Bateson, must be due to the presence of something which is absent in the recessive. He gives as an instance the black pigment in the Silky fowl, which is present in the skin and connective tissues. In his own experiments he found this was recessive to the white-skin character of the Brown Leghorn, and he assumes that the genetic properties of _Gallus bankiva_ with regard to skin pigment are similar to those of the Brown Leghorn. Therefore in order that this character could have arisen in the Silky, the pigment-producing factor _P_ must be added and the inhibiting factor _D_ must drop out or be lost. He says we have no conception of the process by which these events took place. [Footnote: _Problems of Genetics_, p. 85.] Now my experiment in crossing Silky with _bankiva_ shows that no inhibiting factor is present in the latter, so that only one change, not two, was necessary to produce the Silky. Mendelians find it so difficult to conceive of the origin of a new dominant that they even suggest that no such thing ever occurs: what appears as a new character was present from the beginning, but its development was prevented by an inhibiting factor: when this goes into one cell of a division and leaves the other free, the suppressed character appears. This is the principle proposed to get over the difficulty of the origin of a new dominant. All characters are due to factors, and all factors were present in the original ancestor--say Amoeba. Evolution has been merely 'the rejection of various factors from an original complex, and a reshuffling of those that were left.' Professor Lotsy goes so far as to say that difference in species arose solely from crossing, that all domestic animals are of mixed stocks, and that it is easier to believe that a given race was derived from some ancestor of which all trace has been lost than that all races of fowls, for example, arose by variation from a single species, but the evidence that our varieties of pigeons have been derived from _C. livia_, and of fowls from _G. bankiva_, is too strong to be disregarded because it does not agree with theoretical conceptions. My own experiments in crossing Silky fowls with _Gallus bankiva_ (_P.Z.S._, 1919) show that the recessive is not always pure, that segregation is not in all cases complete. The colour of the _bankiva_ is what is called black-red, these being probably the actual pigments present, mixed in some parts of the plumage, in separate areas in other parts: the Silky is white. There are seven pairs of characters altogether in which the Silky differs from the _bankiva_. Both the pigmented skin of the Silky and the colour in the plumage of the _bankiva_ are dominant, so that all the offspring in _F1_ or the first generation are coloured fowls with pigmented skins. But in later generations I found that with regard to skin pigment there were no pure recessives. Since the heterozygote in _F1_ was deeply pigmented, it is certain that a bird with only a small amount of pigment in its skin was a recessive resulting from incomplete segregation of the pigmented character. The pigment occurred chiefly in the skin of the abdomen and round the eyes, and also in the peritoneum and in the connective tissue of the abdominal wall. It varied in different individuals, but in some, at any rate, was greater in later generations than in the earlier. The condition bred true, as pure recessives do; and when such an impure recessive was mated with a heterozygote with black skin, the offspring were half pigmented and half recessive, with some pigment on the abdomen of the latter. Still more striking was the incomplete segregation in the plumage colour. The white of the Silky was recessive, all the birds of the _F1_ generation being fully coloured. In the _F2_ generation there were two recessive white cocks which when mature showed slight yellow colour across the loins. These two were mated with coloured hens, and in later generations all the recessives instead of being pure white, like the Silky, had reddish-brown pigment distributed as in pile fowls. [Illustration: PLATE I. Recessive Pile Fowls] In the hens (Plate I., fig. 1) it was chiefly confined to the breast and abdomen, and was well developed, not a mere tinge or trace, but a deep coloration, extending on to the dorsal coverts at the lower edge of the folded wings. The back and tail were white. In the cocks the colour was much paler, and extended over the dorsal surface of the wings, where it was darker than on the back and loins (Plate I., fig. 2). These pile-coloured fowls when mated together bred true, with individual differences in the offspring. The pile fowl as recognised and described by fanciers is dominant in colour, not recessive as in the case above described. In fact, a recessive pile does not appear ever to have been mentioned before the publication of the results of my experiment. From the statements of John Douglas in _Wright's Book of Poultry_ (London, 1885), it appears that fanciers knew long ago that the pile could be produced from a female of the black-red Game mated with a white Game-cock. It would seem, therefore, that the pile is the heterozygote of black-red and 'dominant' white. Bateson, however (_Principles of Heredity_, 1909, p. 120), writes that the whole problem of the pile is very obscure, and treats it as a case of peculiarity in the genetics of yellow pigments. On p. 102 of the same volume he describes the results of crossing White Leghorn with Indian Game or Brown Leghorn, the _F1_ being substantially white birds with specks of black and brown, though cocks have sometimes enough red in the wings to bring them into the category known an pile. To test the matter I have crossed White Leghorns with a pure-bred black-red Game-cock, and in the offspring out of eight six were fairly good piles, but with not quite so much red on the back as in typical birds: one was a pile with yellow on the back instead of red, and one was white with irregular specks. Of the hens, four were of pile coloration with breast and abdomen of uniform reddish-brown colour, back, neck, and saddle hackles laced with pale brown, tail white. The other four were white with black and brown specks. Whether these pile heterozygotes will breed true I do not yet know. These results tend to show that factors are not indivisible units, and segregation is rather the difficulty of chromatin or germ plasm from different race uniting together. It must be remembered that the fertilised ovum which forms one individual gives rise also to dozens or hundreds or thousands or millions of gametes. If a given character is represented by a portion of the chromatin in the original ovum, this has to be divided so many times, and each time to grow to the same condition as before. How can we suppose that the divisions shall be exactly equal or the growth always the same? It is inevitable that irregularities will occur, and if the original chromatin produced a certain character, who shall say what more or less of that chromatin will produce? In the case of my recessive pile, my interpretation is that when the chromosomes corresponding to two distinct characters such as colour and absence of colour are formed they do not separate from each other completely. Whether the mixture of the chromosomes occurs in every resting stage of the nucleus in the successive generations of the gametocytes, or whether it occurs only in the synapsis stage preceding reduction division, it is not surprising that the colloid substance of the chromosomes should form a more or less complete intermixture, and that the two original chromosomes should not be again separated in the pure condition in which they came into contact. A part, greater or less, of each may be left mixed with the other. This is the probable explanation of the fact that the recessive white plumage has some of the pigment from the dominant form. Segregation, the repulsion between chromosomes, or chromatin, from gametes of different races may occur in different degrees from complete segregation to complete mixture. When the latter occurs there would be no segregation and the heterozygote would breed true. The most interesting fact is that a given factor in the cases I have described, namely, colour of plumage and pigmentation, of skin in the Jungle fowl and the Silky, is not a permanent and indivisible unit, but is capable of subdivision in any proportion. Bateson has already (in his Address to the Australian meeting of the British Association) expressed the same conclusion. He states that although some Mendelians have spoken of genetic factors as permanent and indestructible, he is satisfied that they may occasionally undergo a quantitative disintegration, the results of which he calls subtraction or reduction stages. For example, the Picotee Sweet Pea with its purple edges can be nothing but a condition produced by the factor which ordinarily makes the fully purple flower, quantitatively diminished. He remarks also that these fractional degradations are, it may be inferred, the consequences of irregularities in segregation. Bateson, however, proceeds to urge that the history of the Sweet Pea belies those ideas of a continuous evolution with which we had formerly to contend. The big varieties came first, the little ones arose later by fractionation, although now the devotees of continuity could arrange them in a graduated series from white to deep purple. Now this may be historically true of the Sweet Pea, but I would point out that once the dogma of the permanent indivisible unit or factor is abandoned, there is nothing in Mendelism inconsistent with the possibility of the gradual increase or decrease of a character in evolution. I do not suggest that the colour and markings of a species or variety were, in all cases, due to external conditions, but if the effect of external stimuli can be inherited, can affect the chromosomes, then the evidence concerning unit factors no longer contradicts the possibility of a character gradually increasing, under the influence of external stimuli acting on the soma from zero to any degree whatever. SEX AND SECONDARY SEXUAL CHARACTERS The mystery of sex is hidden ultimately in the phenomenon of conjugation, that union of two cells which in general seems necessary to the maintenance of life, to be a process of rejuvenation. We know nothing of the nature of this process, or why in general it should produce a reinvigoration of the cell resulting from it. We know little if anything of the relation between the two conjugating cells or gametes, of the real nature of the attraction that causes them to approach each other and ultimately unite together. We have, it is true, some evidence that one cell affects the other by some chemical action, as for instance in the fact that the mobile male gametes of a fern are attracted to a tube containing malic acid, but this may be merely an influence on the direction of movement of the male gamete, while there are cases in which neither cell is actively mobile. What we know in higher animals and plants is that each gamete contains in its nucleus half the number of chromosomes found in the other cells of the parent, and that in the fertilised ovum the chromosomes of both gametes form the new nucleus, in which therefore the original number of chromosomes is restored. The remarkable fact is that from this fertilised ovum or zygote is developed usually an individual of one sex or the other, male or female, other cases being comparatively exceptional, although each act of fertilisation is the union of the two sexes together. Various attempts have been made to prove that the sex of the organism is determined by conditions affecting it during development subsequent to fertilisation, but now there is good reason to believe that generally the sex of the individual is determined at fertilisation, though as we shall see there is evidence that it may in certain cases be changed at a later stage. In Mendelian experiments, a heterozygote individual is one arising from gametes containing opposite members of a pair of characters, in other words, from the union of a gamete carrying a dominant with another carrying a recessive. A pure recessive individual is one arising from the union of two gametes both carrying recessives. If a heterozygote is bred with a pure recessive the offspring are half heterozygote and half recessive. The heterozygote individual in typical cases shows the dominant character. In the formation of its gametes when the reduction division of the chromosomes takes place, half of them receive the dominant character, half the recessive. When the division in the gametes of the recessive individual takes place its gametes all contain the recessive character. Thus, if we indicate the dominant character by _D_ and the recessive by _d_, the constitution of the two individuals is _Dd_ and _dd_. The gametes they produce are _D+d_ and _d+d_, and the fertilisations are therefore _Dd_, _Dd_, _dd_, _dd_, or heterozygote dominants and pure recessives in equal numbers. It is evident that the reproduction of the sexes is very similar to this. One of the remarkable facts about sex is that, although the uniting gametes are male and female yet they give rise to males and females in equal numbers. If one sex were a dominant this would be in accordance with Mendelian theory. In accordance with the view that the dominant is something present which is absent in the recessive, the Mendelian theory of sex assumes that femaleness is dominant, and that maleness is the absence of femaleness, the absence of something which makes the individual female. If we represent the character of femaleness by _F_ and maleness or the recessive by _f_, we have the ordinary sexual union represented by _Ff_x_ff_; the gametes will then be _F_+_f_ and _f_+_f_ and the fertilisations _Ff_ and _ff_, or males and females in equal numbers, as they are, at least approximately, in fact. The close agreement of this theory with what actually happens is certainly important and suggests that it contains some truth. But it cannot be said to be a satisfactory explanation. It ignores the question of the nature of sex. According to the theory the female character is entirely wanting in the male. But what is sex but the difference between ovum and spermatozoon, between megagamete and microgamete? The theory then asserts that an individual developed from a cell formed by the union of male and female gametes is entirely incapable of producing female gametes again. Every zygote after conjugation or fertilisation may be said to be bisexual or hermaphrodite. How comes it then that the female quality entirely disappears? Whether the gametocytes are distinguishable at an early stage in the segmentation of the ovum, or only at a later stage of development, we know that the gametes ultimately formed have descended by a series of cell-divisions from the fertilised ovum or zygote cell from which development commenced. If segregation takes place at the reduction divisions we might suppose that half the gametes formed are sperms and half are ova, and that in the male the latter do not survive but perish and disappear. But in this case it would be the whole of the chromosomes coming from the original female gamete which would disappear, and the spermatozoon would be incapable of transmitting characters derived from the female parent of the individual in which the spermatozoa were formed. An individual could never inherit character from its paternal grandmother. This, of course, is contrary to the results of ordinary Mendelian experiments, for characters are inherited equally from individuals of either sex, except secondary sexual characters and sex-linked characters which we shall consider later. Similarly, if we suppose that segregation of ovum and sperm occurs in the female, the sperms must disappear and the ovum would contain no factors derived from the male parent. But the theory supposes that the segregation of male and female does occur in the female, that half the ova are female and half are male. What meaning are we to attach to the words 'male ovum' or even 'male producing ovum'? It is a fundamental principle of Mendelism that the soma does not influence the gametocytes or gametes; we have therefore only to consider the sex of the gametes themselves, derived from a zygote which is formed by the union of two sexes. The quality of maleness consists only in the size, form, and mobility of the sperm in the higher animals and of the microgamete in other cases. In what sense then, can an ovum be male? It may perhaps be said that though it is itself female, it has some property or factor which when united with a sperm causes the zygote to be capable of producing only sperms, and conversely the female ovum has a quality which causes the zygote to produce only ova. But since these qualities segregate in the reduction divisions, how is it that the male quality in the _f_ ovum does not make it a sperm? We are asked to conceive a quality, or the absence of a factor, in an ovum which is incapable of causing that ovum to be a sperm, but which, when segregated in the gametes descended from that ovum, causes them all to be sperms. It is impossible to conceive a single quality or factor which at different times produces directly opposite effects. The Mendelian theory is merely a theory in words, which have an apparent relation to the facts, but which when examined do not correspond to any real conceptions. However, we have to consider a number of remarkable facts concerning the relation of chromosomes to sex. In the ants, bees, and wasps the unfertilised ovum always develops into a male, the fertilised into a female. The chromosomes of the ovum undergo reduction in the usual way, and are only half the number of those present in the nucleus before reduction. We may call this reduced number _N_ and the full number _2N_. The ova developing by parthenogenesis and giving rise to males segment in the usual way, and all the cells both of soma and gametocytes contain only _N_ chromosomes. In the maturation divisions reduction does not occur, _N_ chromosomes passing to one gamete, none to the other, and the latter perishes so that the sperms all contain _N_ chromosomes. When fertilisation occurs the zygote therefore contains _2N_ chromosomes and becomes female. Here then we have no segregation of _Fxf_ in the ova. The difference of sex merely corresponds to duplex and simplex conditions of nucleus, but it is curious that the simplex condition in the gametes occurs in both ova and sperms. In Daphnia and Rotifers the facts are different. Parthenogenesis occurs when food supply is plentiful and temperature high. In this case reduction of the chromosomes does not occur at all, the eggs develop with _2N_ chromosomes and all develop into females. Under unfavourable conditions reduction or meiosis occurs, and two kinds of eggs larger and smaller are formed, both with _N_ chromosomes. The larger only develops when fertilised and give rise to females with _2N_ chromosomes. The smaller eggs develop without fertilisation, by parthenogenesis, and become males. Here then we have three kinds of gametes, large eggs, small eggs, and sperms, each with the same number of chromosomes. It is not the mere number then which makes the difference, but we find a segregation in the ova into what may for convenience be called female ova and male ova. In Aphidae or plant lice a third condition is found. Here again parthenogenesis continues for generation after generation so long as conditions are favourable, _i.e._ in summer, and the eggs are in the same condition as in Daphnia, etc., that is to say, reduction does not occur, and the number of chromosomes is 2_N_. Under unfavourable conditions males are developed as well as females by parthenogenesis, but the males arise from eggs which undergo partial reduction of chromosomes, only one or two being separated instead of half the whole number. The number then in an egg which develops into a male is 2_N_-1, while other eggs undergo complete reduction and then have _N_ chromosomes. The latter, however, do not develop until they have been fertilised. In the males, when mature, reduction takes place in the gametes, so that two kinds of sperms are formed, those with _N_ chromosomes and those with _N_-l chromosomes. The latter degenerate and die, the former fertilise the ova, and the fertilised ova develop only into females. The chief difference in this case then is that the reduction in the male to the _N_ or simplex condition takes place in two stages, one in the parthenogenetic ovum, one in the gametes of the mature male. In Hymenoptera and in Daphnia, etc., the whole reduction takes place in the parthenogenetic ovum, and in the mature male, though reduction divisions occur, no separation of chromosomes takes place: at the first division one cell is formed with _N_ chromosomes and one with none, and the latter perishes. In many insects and other Arthropods which are not parthenogenetic the male has been found to possess fewer chromosomes than the female. The female forms, as in the above cases of parthenogenesis, only gametes of one kind each with _N_ chromosomes, but the male forms gametes of two sorts, one with N chromosomes, the other with _N_-l or _N_-2 chromosomes. On fertilisation two kinds of zygotes are formed, female-producing eggs with 2_N_ chromosomes, and male-producing eggs with 2_N_-1 or 2_N_-2 chromosomes. There is also evidence that in some cases, _e.g._ the sea-urchin, the female is heterozygous, forming gametes, some with _N_ and some with _N_+ chromosomes, while the male gametes are all _N_. Fertilisation then produces male-producing eggs with 2_N_ chromosomes, female-producing with 2_N_+. Such is the summary given by Castle in 1912. [Footnote: _Heredity and Eugenics_, by Castle and Others. University of Chicago Press, 1912.] It will be seen that he treats the differences as purely quantitative, mere differences in the number of the chromosomes. Professor E. B. Wilson, however, who had contributed largely by his own researches to our knowledge of sex from the cytological point of view, had already published, in 1910, [Footnote: '_The Determination of Sex_,' _Science Progress_, April 1910.] a very instructive _résumé_ of the facts observed up to that time. The important fact which is generally true for insects, according to Wilson, is that there is a special chromosome or chromosomes which can be distinguished from the others, and which is or are related to sex differentiation. This chromosome, to speak of it for convenience in the singular, has been variously named by different investigators. Wilson called it the 'X chromosome,' McCluny the 'accessory chromosome,' Montgomery the 'hetero-chromosome,' while the names 'heterotropic chromosome' and idiochromosome have also been used. For the purpose of the present discussion we may conveniently name it the sex-chromosome. It is often distinguished by its larger size and different shape. Wilson describes the following different cases:-- (1) The sex-chromosome in the male gametocytes is single and fails to divide with the others, but passes undivided to one pole. This may occur in the first reduction division (Orthoptera, Coleoptera, Diptera) or in the second (many Hemiptera). But it is difficult to understand what is meant by 'fails to divide.' In one of the reduction divisions all the chromosomes divide as in ordinary or homotypic nucleus division, but in the other the chromosomes simply separate into two equal groups without division. If there are an odd number of chromosomes, 2_N_-1, in all the gametocytes of the male, as stated in most accounts of the subject, then if one chromosome fails to divide in the homotypic division, we shall have 2_N_-2 in one spermatocyte and 2_N_-1 in the other. Then when the heterotypic division takes place and the number of chromosomes is halved, we shall have two spermatocytes with _N_-1 chromosomes from one of the first spermatocytes and one with _N_ and one with _N_-1 from the other. Thus there will be three spermatozoa with _N_-1 chromosomes and one with _N_ chromosomes, whereas we are supposed to find equal numbers with _N_ and _N_-1 chromosomes. It is evident that what Dr. Wilson means is that the sex-chromosome is unpaired, and that although it divides like the others in the homotypic division, in the heterotypic division it has no mate and so passes with half the number of chromosomes to one pole of the division spindle, while the other group of chromosomes has no sex-chromosome. Examples of this are the genera _Pyrrhocoris_ and _Protenor_ (Hemiptera) _Brachystola_ and many other Acrididae, _Anasa, Euthoetha, Narnia, Anax_. In a second class of cases the sex-chromosome is double, consisting of two components which pass together to one pole. Examples of this are _Syromaster, Phylloxera, Agalena_. In a third class the sex-chromosome is accompanied by a fellow which is usually smaller, and the two separate at the differential division. The sizes of the two differ in different degrees, from cases as in many Coleoptera and Diptera in which the smaller chromosome is very minute, to those (_Benacus, Mineus_) in which it is almost as large as its fellow, and others (_Nezara, Oncopeltus_) in which the two are equal in size. Again, there are cases in which one sex-chromosome, say _X_, is double, triple, or even quadruple, while the other, say _Y_, is single. In all these cases there are two _X_ chromosomes in the oocytes (and somatic cells) of the female, and after reduction the female gametes or unfertilised ova are all alike, having a single _X_ chromosome or group. On fertilisation half the zygotes have _XX_ and half _XY_, whether _Y_ is absence of a sex-chromosome, or one of the other _Y_ forms above mentioned. The sex is thus determined by the male gamete, the _X_ chromosome united with that of the female gamete producing female individuals, while the _Y_ united with _X_ produces male individuals. Professor T. H. Morgan has made numerous observations and experiments on a single culture of the fruit-fly, _Drosophila ampelophila_, bred in bottles in the laboratory for five or six years. He has not only studied the chromosomes in the gametes of this fly, and made Mendelian crosses with it, but has obtained numerous mutations, so that his work is a very important contribution to the mutation doctrine. Drosophila in the hands of Professor Morgan and his students and colleagues has thus become as classical a type as Oenothera in those of the botanical mutationists. Different branches of Morgan's work are discussed elsewhere in this volume, but here we are concerned only with its bearing on the question of the determination of sex. He describes [Footnote: _A Critique of the Theory of Evolution_. Princeton University Press and Oxford University Press, 1916.] the chromosomes of Drosophila as consisting in the diploid condition of four pairs, that is to say, pairs which separate in the reduction division so that the gamete contains four single chromosomes, one of each pair. In two of these pairs the chromosomes are elongated and shaped like boomerangs, in the third they are small, round granules, and the fourth pair are the sex-chromosomes: in the female these last are straight rods, in the male one is straight as in the female, the other is bent. The straight ones are called the X chromosomes, the bent one the Y chromosome. The fertilisations are thus XX which develops into a female fly, and XY which develops into a male. Drosophila therefore is an example of one of the cases described by Wilson. Dr. Wilson (_loc. cit._) discusses the question of how we are to interpret these facts, in particular, the fact that the X chromosome in fertilisation gives rise to females. He remarks that the X chromosome must be a male-determining factor since in many cases it is the only sex-chromosome in the males, yet its introduction into the egg establishes the _female_ condition. This is the same difficulty which I pointed out above in connection with the Mendelian theory that the female was heterozygous and the male homozygous for sex. Dr. Wilson points out that in the bee, where fertilised eggs develop into females and unfertilised into males, we should have to assume that the _X_ chromosome in the female gamete is a female determiner which meets a recessive male determiner in the _X_ chromosomes of the sperm. When reduction occurs, the _X_[female] must be eliminated since the reduced egg develops always into a male. But on fertilisation, since the fertilised egg develops into a female, a dominant _X_[female] must come from the sperm, so that our first assumption contradicts itself. Dr. Wilson, T. H. Morgan, and Richard Hartwig have therefore suggested that the sex-difference as regards gametes is not a qualitative but a quantitative one. In certain cases there is no evident quantitative difference of chromatin as a whole, but there may in all cases be a difference in the quantity of special sex-chromatin contained in the _X_ element. The theory put forward by Wilson then is that a single _X_ element means _per se_ the male condition, while the addition of a second element of the same kind produces the female condition. Such a theory might apply even to cases where no sex-chromosomes can be distinguished by the eye: the ova, in such cases (probably the majority), might also have a double dose of sex-chromatin, the males a single dose. This theory, however, is still open to the objection that the female gametes before fertilisation, and half the male gametes, have the half quantity of sex-chromatin which by hypothesis determines the male condition, so that here again we have the male condition as something which is distinct from the characteristics of the spermatozoon. But if this is the case, what is the male condition? The parthenogenetic ovum of the bee is male, and yet it is an ovum capable only of producing spermatozoa. If the single X chromosomes is the cause of the development of spermatozoa in the male bee, why does it not produce spermatozoa in the gametes of the female bee, since when reduction takes place all these gametes have a single X chromosome? In biology, as in every other science, we must admit facts even when we cannot explain them. The facts of what we call gravitation are obvious, and any attempt to disregard them would result in disaster, yet no satisfactory explanation of gravitation has yet been discovered: many theories have been suggested, but no theory has yet been proved to be true. In the same way it may be necessary to admit that two X chromosomes result in the development of a female, and one X, or XY chromosomes result in the development of a male. But Mendelians have omitted to consider what is meant by male and female. The soma with its male and female somatic characters has nothing to do with the question, since somatic sex-differences may be altogether wanting, and moreover, the essential male character, the formation of spermatozoa, is by the Mendelian hypothesis due to descent of the male gametes from the original fertilised or unfertilised _ovum_. The Mendelian theory therefore is that when an ovum has two X sex-chromosomes it can only after a number of cell-divisions, at the following reduction division, give rise to ova, while an ovum containing one X sex-chromosome, or two different, XY, chromosomes, at the next reduction division gives rise to spermatozoa. The X sex-chromosome is not in itself either female or male, since, as we have seen, either ovum or spermatozoon may contain a single X chromosome. The ovum then with one X chromosome or one X and one Y changes its sex at the next reduction division and becomes male. In parthenogenetic ova this happens without conjugation with a spermatozoon at all: in other cases, since the zygote is compounded of spermatozoon and ovum, we can only say that in the XX zygote, the ovum developing only ova, the female is dominant, in the X or XY zygote developing only spermatozoa the male is dominant. Hermaphrodite animals, as has been pointed out by Correns and Wilson, cannot be brought under this scheme at all. In the earthworms, for instance, we have, in every individual developed from a zygote, ova and spermatozoa developing in different gonads in different parts of the body. The differentiation here, therefore, must occur in some cell-division preceding the reduction divisions. Every zygote must have the same composition, and yet give rise to two sexes in the same individual. Further light on the sex problem, as in many other problems in biology, can only be obtained by more knowledge of the physical and chemical processes which take place in the chromosomes and in the relations of these structures to the rest of the cell. The recent advances in cytology, remarkable as they are, consist almost entirely of observations of microscopic structure. They may be said to reveal the statics of the cell rather than its dynamics. Cytology is in fact a branch of anatomy, and in the anatomy of the cell we have made some progress, but our knowledge of the physiology of the cell is still infinitesimal. The nucleus, and especially the chromosomes, are supposed in some unknown way to influence or govern the metabolism of the cytoplasm. From this point of view the hypothesis mentioned above that the sex-difference in the gametes is not qualitative but quantitative is probably nearer to the truth. Geddes and Thomson and others have maintained that the sex-difference is one of metabolism, the ovum being more anabolic, the sperm more katabolic. A double quantity of special chromatin may be the cause of the greater anabolism of the ovum. In that case the difficulty indicated in a previous part of this chapter, that the ovum after reduction resembles the sperm in having only one X chromosome, may be explained by the fact that the growth of the ovum and its accumulation of yolk substances has been already accomplished under the influence of the two chromosomes before reduction. Other difficulties previously discussed also appear to be diminished if we adopt this point of view. We need not regard maleness and femaleness as unit characters in heredity of the same kind as Mendelian characters of the soma. Instead of saying that the zygote composed of ovum and spermatozoon is incapable of giving rise in the male to ova, or in the female to sperms, we should hold that the gametocytes ultimately give rise to ova or to sperms according to the metabolic processes set up and maintained in them through their successive cell-divisions under the influence of the double or single X chromosome. There still remains the difficulty of explaining why the male gametocytes after reduction develop into similar sperms, with their heads and long flagella, although half of them possess one X chromosome each and the other half none. We can only suppose that the final development of the sperms is the result of the presence of the single X chromosome in the successive generations of male gametocytes before the reduction divisions. The Mendelian theory of sex-heredity assumed that in the reduction divisions the two sex-characters, maleness and femaleness, were segregated in the same way as a pair of somatic allelomorphs, but the words maleness and femaleness expressed no real conceptions. The view above suggested merely attempts to bring our real knowledge of the difference between ovum and sperm into relation with our real knowledge of the sex-chromosomes and their behaviour in reduction and fertilisation. CHAPTER III Influence Of Hormones On Development Of Somatic Sex-Characters We have next to consider what are commonly called secondary sexual characters. These are characters or organs more or less completely limited to one sex. When we distinguish in the higher animals the generative organs or gonads on the one hand from the body or soma on the other, we see that all differences between the sexes, except the gonads, are somatic, and we may call them somatic sexual characters. The question at once arises whether the soma itself is sexual, that is to say, whether on the assumption that the sex of the zygote is already determined before it begins to develop, the somatic cells as well as the gametocytes are individually and collectively either male or female. In previous discussions of the subject I have urged that the only meaning of sex was the difference between the megagamete or ovum, and the microgamete or sperm. But if the zygote, although compounded of ovum and sperm, is predestined to give rise in the gametes descended from it, either to sperms only or to ova only, it may be suggested that all the somatic cells descended from the zygote are likewise either male or female, although they do not give rise to gametes. It is evident, however, that the somatic cells, organs, and characters do not differ necessarily or universally in the two sexes. On the one hand, we have extraordinary and very conspicuous peculiarities in the male, entirely absent in the female, such as the antlers of stags, and the vivid plumage of the gold pheasant; on the other we have the sexes externally alike and only distinguished by their sexual organs, as in mouse, rabbit, hare, and many other Rodents, most Equidae, kingfisher, crows and rooks, many parrots, many Reptiles, Amphibia, Fishes, and invertebrate animals. In the majority of fishes, in which fertilisation is external and no care is taken of the eggs or young, there are no somatic sexual differences. Moreover, somatic sexual characters where they do occur have no common characteristics either in structure or position in the body. It may be said that any part of the soma may in different cases present a sex-limited development. In the stag the male peculiarity is an enormous development of bone on the head, in the peacock it is the enlargement of the feathers of the tail. In some birds there are spurs on the legs, in others spurs on the wings. It is no explanation, therefore, to say that these various organs and characters are the expression of sex in the somatic cells. As I pointed out in my _Sexual Dimorphism_ (1900), the common characteristic of somatic sexual characters is their adaptive relation to some function in the sexual habits of the species in which they occur. There is no universal characteristic of sex except the difference between the gametes and the reproductive organs (gonads) in which they are produced. All other differences, therefore, including genital ducts and copulatory or intromittent organs, are somatic. When we examine these somatic differences we find that they can be classified according to their relation to fertilisation and reproduction, including the care or protection of the offspring. The precise classification is of no great importance, but we may distinguish the following kinds to show the chief functions to which the characters or organs are adapted. 1. GENITAL DUCTS AND INTROMITTENT ORGANS.--According to the theory of the coelom which we owe to Goodrich, in all the coelomata the coelom is primarily the generative cavity, on the walls of which the gametocytes are situated, and the coelomic ducts are the original genital ducts. In Vertebrates we find two such ducts in both sexes in the embryo, originally formed apparently by the splitting of a single duct. In the male one of these ducts becomes connected with the testis while the other degenerates: the one which degenerates in the male forms the oviduct in the female, while the one which is functional in the male degenerates in the female. Intromittent organs are formed in all sorts of different ways in different animals. In Elasmobranchs (sharks and skates) they are enlarged portions of the pelvic fins, and therefore paired. In Lizards they are pouches of the skin at the sides of the cloacal opening. In Mammals the single penis is developed from the ventral wall of the cloaca. In Crustacea certain appendages are used for this function. There are a great many animals, from jelly-fishes to fishes and frogs, in which fertilisation is external, and there are no intromittent organs at all. 2. ORGANS FOR, CAPTURING OR HOLDING THE FEMALE: for example, the thumb-pads of the frog, and a modification of the foot in a water-beetle. Certain organs on the head and pelvic fins of the Chimaeroid fishes are believed to be used for this purpose. 3. WEAPONS.--Organs which are employed in combats between males for the exclusive possession of the females. For example, antlers of stags, horns of other Ruminants, tusks of elephants, spurs of cocks and Phasiamidae generally, horns and outgrowths in males of Reptiles and many Beetles, probably used for this purpose. 4. ALLUREMENTS.--Organs or characters used to attract or excite the female. These might be called the organs of courtship, such as the peacock's tail, the plumes of the birds-of-paradise, and the brilliant plumage of humming birds and many others. The song of birds is another example, and sound is produced in many Fishes for a similar purpose. 5. ORGANS FOR THE BENEFIT OF THE OFFSPRING: for example, the extraordinary pouches in which the eggs are developed in certain Frogs. In the South American species, _Rhinoderma darwinii_, the enlarged vocal sacs are used for this purpose. Pouches with the same function are developed in many animals, for instance in Pipe-fishes and Marsupials. Abdominal appendages are enlarged in female Crustacea for the attachment of the eggs, the abdomen also being larger and broader. The argument in favour of the Lamarckian explanation of the evolution of these adaptive characters is the same as in the case of adaptations common to both sexes, namely that in every case the function of the organs and characters involves special irritations or stimulations by external physical agents. Mechanical irritation, especially of the interrupted kind, repeated blows or friction causes hypertrophy of the epidermis and of superficial bone. I have stated this argument and the evidence for it in some detail in my volume on _Sexual Dimorphism_. It is one of the most striking facts in support of this argument that the hypertrophied plumage which constitutes the somatic sexual character of the male in so many birds is habitually erected by muscular action for the purpose of display in the sexual excitement of courtship. I doubt if there is a single instance in which the male bird takes up a position to present his ornamental plumage to the sight of the female without a special erection and movement of the feathers themselves. Such a stimulation must affect the living epidermic cells of the feather papilla. Even supposing that the feather is not growing at the time, it is probable, if not certain, that the stimulation will affect the papilla at the base of the feather follicle, so as to cause increased growth of the succeeding feather. But we have no reason to believe that erection in display occurs only when the growth of the feathers is completed, still less that it did so always at the beginning of the evolution. The antlers of stags are the best case in favour of the Lamarckian view of the evolution of somatic sexual characters. The shedding of the skin ('velvet') followed by the death of the bone, and its ultimate separation from the skull, are so closely similar to the pathological processes occurring in the injury of superficial bones, that it is impossible to believe that the resemblance is only apparent and deceptive. In an individual man or mammal, if the periosteum of a bone is destroyed or removed the bone dies, and is then either absorbed, or separated from the living bone adjoining, by absorption of the connecting part. In the stag both skin and periosteum are removed from the antler: probably they would die and shrivel of their own accord by hereditary development, but as a matter of fact the stag voluntarily removes them by rubbing the antler against tree trunks, etc. When the bone is dead the living cells at its base dissolve and absorb it, and when the base is dissolved the antler must fall off. The adaptive relation is not the only common characteristic of these somatic sexual characters. Another most important fact is not only that they are fully developed in one sex, absent or rudimentary in the other, but that their development is connected with the functional maturity and activity of the gonads. There is usually an early immature period of life in which the male and female are similar, and then at the time of puberty the somatic sexual characters of either sex, generally most marked in the male, develop. In some cases, where the activity of the gonads is limited to a particular season of the year, the sexual characters or organs are developed at this season, and then disappear again, so that there is a periodic development corresponding to the periodic activity of the testes or ovaries. Stags have a limited breeding or 'rutting' season in autumn (in north temperate regions), and the antlers also are shed and developed annually. In this case we cannot assert that the development of the antler takes place during the active state of the testes. The antlers are fully developed and the velvet is shed at the commencement of the rutting season, and development of the antlers takes place between the beginning of the year and the month of August or September. In ducks and other birds there is a brilliant male-breeding plumage in the breeding season which disappears when breeding is over, so that the male becomes very similar to the female. In the North American fresh-water crayfishes of the genus Cambarus there are two forms of males, one of which has testes in functional activity, while in the other these organs are small and quiescent: the one form changes into the other when the testes pass from the one condition to the other. It has long been known that the development of male sex-characters is profoundly affected by the operation of castration. The removal of the testes is most easily carried out in Mammals, in consequence of the external position of the organs in these animals, and the operation has been practised on domesticated animals as well as on man himself from very ancient times. The effect is the more or less complete suppression of the male insignia, in man, for example, the beard fails to develop, the voice does not undergo the usual change to lower pitch which takes place at puberty, and the eunuch therefore has much resemblance to the boy or woman. Many careful experimental researches have been made on the subject in recent years. The consideration of the subject involves two questions: (1) What are the exact effects of the removal of the gonads in male and female? (2) By what means are these effects brought about, what is the physiological explanation of the influence of the gonads on the soma? I have quoted the evidence concerning the effects of castration on stags in my _Sexual Dimorphism_ and in my paper on the 'Heredity of Secondary Sexual Characters.' [Footnote: _Archiv für Entwicklungesmechanik_, 1908.] When castration is performed soon after birth a minute, simple spike antler is developed, only two to four inches in length: it remains covered with skin, is never shed, and develops no branches. When the operation is performed on a mature stag with antlers, the latter are shed soon after the operation, whether they have lost their velvet or not. In the following season new antlers develop, but these never lose their velvet or skin and are never shed. CASTRATION IN FOWLS The removal of the testes from young cocks has been commonly practised in many countries, _e.g._ France, capons, as such birds are called, being fatter and more tender for the table than entire birds. The actual effect, however, on the secondary sexual characters has not in former times been very definitely described. The usual descriptions represent the castrated birds as having rather fuller plumage than the entire birds; but the comb and wattles are much smaller than in the latter, more similar to those of a hen. It is stated that the capon will rear chickens, though he does not incubate, and that they are used in this way in France. The most precise of the statements on the subject by the earlier naturalists is that of William Yarrell [Footnote: _Proc. Linn. Soc., 1857.] (1857), who writes as follows:-- 'The capon ceases to crow, the comb and gills do not attain the size of those parts in the perfect male, the spurs appear but remain short and blunt, and the hackle feathers of the neck and saddle instead of being long and narrow are short and broadly webbed. The capon will take to a clutch of chickens, attend them in their search for food, and brood them under his wings when they are tired.' It would naturally be expected, on the analogy of the case of stags, that when a young cock was completely castrated all the male secondary characters would be suppressed, namely, the greater size of the comb and wattles in comparison with the hen, the long neck hackles, and saddle hackles, long tail feathers, especially the sickle-feathers, and the spurs. As a matter of fact, the castrated specimen usually shows only the first of these effects to any conspicuous degree. The comb and wattles of the capon are similar to those of the hen, but he still has the plumage and the spurs of the entire cock. Many investigators have made experiments in relation to this subject, and most of them have found that complete castration is difficult, and that portions of the testes left in the bird during the operation become grafted in some other position either on the parietal peritoneum, or on that covering the intestines, and produce spermatozoa, which, of course hare no outlet. In such cases the secondary male characters may fee more or less completely developed. Thus Shattock and Seligmann (1904) state that ligature of the vas deferens made no difference to the male characters, and that after castration detached fragments were often left in different positions as grafts, when the secondary characters developed. In one particular case only a minute nodule of testicular tissue showing normal spermatogenesis was found on post mortem examination attached to the intestine. In this bird there was no male development of comb or wattles, a full development of neck hackles, a certain development of saddle hackles, a few straggling badly curved feathers in the tail and short blunt spurs on the legs. Lode [Footnote: _Wiener klin. Wochenschr._, 1895.] (1895) found that testes could easily be transplanted into subcutaneous tissue and elsewhere, and that the male characters then developed normally. Hanau [Footnote: _Arch. f. ges. Physiologie_, 1896.] (1896) obtained the same result. The question, however, to what degree the male characters of the cock are suppressed after complete castration is not so definitely answered in the literature of the subject. Shattock and Seligmann in their 1904 paper make no definite statement on the subject. Rieger (1900), Selheim (1901), and Foges [Footnote: _Pfügers Archiv_, 1902.] (1902) state that the true capon is characterised by shrivelling of the comb, wattles, _and spurs_; poor development of the neck and tail feathers; hoarse voice and excessive deposit of fat. Shattock and Seligmann, on the other hand, have placed in the College of Surgeons Museum the head of a Plymouth Rock which was castrated in 1901. It was hatched in the spring of that year. In December 1901 the comb and wattles were very small, the spurs fairly well developed, and the tail had a somewhat masculine appearance. In September 1902, when the bird was killed, the comb and wattles were still poorly developed, the neck hackles fairly well so; saddle hackles rather well developed; the tail contained rather loosely-grouped long sickle feathers; the spurs stout. The description states that dissection showed no trace of either testicle, and I am informed by Mr. Shattock that there were no grafts. The description ends with the conclusion that the growth of the spurs, and to a certain extent that of the long, curved sickle feathers, is not prevented by castration. With regard to the spurs this result does not agree with that of the German investigators, but it must be remembered that the latter speak only of the reduction of the spurs, not entire absence. It is important in discussing the effects of castration in cocks to bear in mind the actual course of development of the secondary sexual characters. When the chicks are first hatched they are in the down: rudimentary combs are present, wattles can scarcely be distinguished, and there is no external difference between the sexes. The ordinary plumage begins to develop immediately after hatching, the primaries of the wings being the first to appear. The feathers are completely developed in about five weeks, and still there is no difference between the sexes. The first sexual difference is the greater size of the combs in the males, and this is quite distinct at the age of six weeks. At nine to ten weeks in black-red fowls, in which the cocks have black breasts and red backs with yellow hackles, the black feathers on the breast and red on the back are gradually developing, both sexes previously having been a dull speckled brown, closely similar to the adult hens. The spurs are the last of the male characters to develop, these at the age of four months being still mere nodules, scarcely, if at all, larger than the rudiments visible in adult hens. This is the age at which castration is usually performed, as at an earlier age the birds are too small to operate on successfully. It follows, therefore, that the spurs develop after castration, and it would seem that their development does not depend upon the presence of the sexual organs. It is a question, however, whether castration in the cock is ever quite complete. In the original wild species and in the majority of domesticated breeds the spurs are confined to the male sex, and are typical secondary sex-characters, as much so as the antlers of stags or the beard of man, yet the above discussion shows that there is some doubt whether their development is prevented as much as in other cases by the absence of the sexual organs. Even if it should be proved that in supposed cases of complete castration, such as that of Shattock and Seligmann, some testicular tissue remained at the site of the testes, it would still be true that the development of the comb and wattles is more affected by the removal of the sexual organs than that of the spurs or tail feathers. My own experiments in castrating cocks were as follows: On August 20, 1910, I operated on a White Leghorn cock about five months old. One testis was removed, with a small part of the end broken off, but the other, after it was detached, was lost among the intestines. On the same day I operated on another about thirteen weeks old, a speckled mongrel. In this case both testes were extracted but one was slightly broken at one end, although I was not sure that any of it was left in the body. An entire White Leghorn of the same age as the first was kept as a control. On August 27 the two castrated birds had recovered and were active. Their combs had diminished in size and lost colour considerably, that of the White Leghorn was scarcely more than half as large as that of the control. Such a rapid diminution can scarcely he due to absorption of tissue, but shows that the size of the normal cock's comb is largely due to distension with blood, which ceases when the sexual organs are removed. In the following January, the second cock, supposed to be completely castrated, was seen to make a sexual gesture like a cock, though not a complete action like an entire animal: this showed that the sexual instinct was not completely suppressed. In February this same bird was seen to attempt to tread a hen, while the white one, supposed to be less perfectly emasculated, had never shown such male instinct. The White Leghorn cock was killed and dissected on May 13, 1911, nine months after castration. I found an oval body of dark, dull brown colour loose among the intestines: this was evidently the left testis which was separated from its natural attachment and lost in the abdomen at the time of the operation. I examined the natural sites of the testes: on the right side there was a small testis of considerable size, about half an inch in diameter. When a portion of this was teased up and examined under the microscope moving spermatozoa were seen, but they were not in swarms as in a normal testis, but scattered among numerous cells. On the left side was a much smaller testis, in the tissue of which I with difficulty detected a few slowly moving spermatozoa. The vasa deferentia were seen as white convoluted threads on the peritoneum, but contained no spermatozoa. On July 29, 1911, a little more than eleven months after the operation, I examined and killed the second of these castrated cocks, the speckled mongrel-bred bird. I measured the comb and wattles while it was alive, in case there might be reduction in the size of these appendages when the bird was killed. The comb was 1-1/3 inches high by 2-3/8 inches in length. The spurs were 1 inch long, curved and pointed. Saddle hackles short, hanging only a little below the end of the wing. Neck hackles well developed, similar to those of an entire cock. Longest tail feather 15-5/8 inches, blue-black in colour. I had no entire cock of same breed, but measured the entire White Leghorn for comparison. Comb 1-3/4 inches high by 3-3/4 inches in length. (It is to be remembered that the comb and wattles are especially large in Leghorns.) Wattle 1-1/4 inches in vertical length. Spur 1 inch long, stouter and less pointed than in the capon. Longest tail feather 12 inches long. When killed the capon was found to be very fat: there were masses of fat around the intestines and under the peritoneum, which made it impossible to make out details such as ureter and vas deferens properly. I found a white nodule about half an inch in diameter attached to mesentery. The liquid pressed from this was swarming with spermatozoa in active motion. Two other masses about the same size or a little larger were found on the sites of the original testes. These also were full of mobile spermatozoa, and must have grown from portions of the testes left behind at castration. In ducks the sexual characters of the male differ from those in the fowl, especially in the fact that they almost completely disappear after the breeding season and reappear in the following season. In the interval the drake passes into a condition of plumage in which he resembles the female; and this condition is known as 'eclipse.' The male plumage, therefore, in the drake has a history somewhat similar to that of the antlers in deer. Two investigations of the effects of castration on ducks and drakes have been recorded. H. D. Goodale [Footnote: 'Castration of Drakes.' _Biol. Bulletin_, Wood's Hole, Mass., vol. xx., 1910] removed the generative organs from both drakes and ducks of the Rouen breed, which is strongly dimorphic in plumage. One drake was castrated in the early spring of 1909 when a little less than a year old. This bird did not assume the summer plumage in 1909, that is, did not pass into eclipse. It was in the nuptial plumage when castrated. This breeding or nuptial plumage is well known: it includes a white neck-ring, brilliant green feathers on the head, much claret on the breast, brilliant metallic blue on the wing, and two or more upward curled feathers on the tail. The drake mentioned above was accidentally killed in the spring of 1910. Another drake was castrated on August 8, 1909: only the left testis was removed, the other being ligatured. At this time the bird would be in eclipse plumage. It appears from the description that it assumed the nuptial plumage in the winter of 1909, and did not pass into eclipse again in the summer of 1910. Thus in drakes the effect of castration is that the secondary sexual character remains permanently instead of being lost and renewed annually. Goodale, however, does not describe the moults in detail. In the natural condition the drake must moult twice in the year, once when he sheds the nuptial plumage, and again when he drops the summer dress. Goodale insists, from some idea about secondary sexual characters which is not very obvious, that the eclipse or summer plumage is not the same as that of the female. He states that the male in summer plumage merely mimics the female but does not become entirely like her. In certain parts of the body there are no modifications toward the female type. In others, i.e. head, breast, and keel region, the feathers of the male become quite like those of the female. 'It can hardly be maintained that this is an example of assumption by the male of the female's plumage, especially as the presence of the testis is necessary for its appearance.' The idea here seems to be that since the eclipse plumage is only assumed when the testis is present, therefore it must be a male character. Out of five females on which the operation was performed only two lived more than a few days afterwards. One of these (a) was castrated in the spring of 1909 when a little less than a year old, the other (b) on August 13 when twelve weeks old. In October 1909 they showed no marked modifications. In July 1910 it was noticed that they had the male curled feathers in the tail, and (a) had breast feathers similar to those of the male in summer plumage, (b) was rather more strongly modified: she had a very narrow white neck-ring, and breast feathers distinctly of male type. The next moult began in September, and in November was well advanced. On the whole (a) had made little advance towards the male type, but (b) closely resembled the male in nuptial plumage. It had brilliant green feathers on the head, a white neck-ring, much claret colour on the breast, and some feathers indistinguishable from those of the male, and also the male sex feathers on the tail. Goodale concludes that the female owes her normal colour to the ovaries or something associated with them which suppresses the male characters and ensures the development of her own type. He considers it is quite as conceivable that selection should operate to pick out inconspicuously coloured females as that selection of brilliantly coloured males should bring about an addition to the female type. But as pointed out above, selection cannot explain the dimorphism in either case. It may be mentioned here that owing to the fact that the single (left) ovary in birds is very closely attached to the peritoneum immediately covering the great post-caval vein, it is generally impossible to remove the whole of the ovary without cutting or tearing the wall of the vein and so causing fatal hemorrhage. The above results observed by Goodale are therefore all the more remarkable, and it may be assumed that he removed at any rate nearly all the ovary. The research of Seligmann and Shattock [Footnote: Relation between Seasonal Assumption of the Eclipse Plumage in the Mallard _(Anas boscas_) and the Functions of the Testicle.' _Proc. Zool. Soc._ 1914.] begins with a comparison between the stages of the development of the nuptial plumage and the stages of spermatogenesis. In the young pheasant the male plumage is fully developed in the autumn of its first year, but no pairing occurs and no sexual instinct is exhibited till the following spring. The wild duck pairs in autumn or early winter, after the assumption of the nuptial plumage, but copulation does not occur till spring is advanced. The investigation here considered was made upon specimens of semi-domesticated _Anas boscas_, such as are kept in London parks and supplied from game farms. The testes attain their maximum size during the breeding season-- end of March or beginning of April. At this time each organ is almost as large as a pigeon's egg, is very soft, and the liquid exuding from it when cut is swarming with spermatozoa. The bird is of course in full nuptial plumage. By the end of May, although the plumage is unchanged, the testes have diminished to the size of a haricot bean, and spermatogenesis has ceased. They diminish still further during June, July, and August, and acquire a yellow or brownish colour, while microscopically there is no sign of activity in the spermatic cells. The change from nuptial plumage to eclipse takes place between the beginning of June and the middle of July. The reappearance of the nuptial plumage takes place in the month of September, and while this process takes place there is no sign of change or renewed activity in the testes. During October and November, when the brilliant plumage is fully developed, the testes increase slowly in size but remain yellow and firm and exude no liquid on incision. Spermatogenesis does not commence until the end of November or beginning of December. The testes increase greatly in size in January and February, and again reach their maximum size by the end of March. It is shown, therefore, that the loss of the nuptial plumage takes place in June when spermatogenesis has ceased and the testes are diminishing in size, but the redevelopment of this plumage takes place in September without any renewed activity of the testis and long before the beginning of spermatogenesis. The case of the antlers in the stag is probably very similar. The important statement is made with regard to castration (under anaesthetics, of course) that it was found impossible to extirpate the testes completely. When the bird was killed some months after the operation, a greater or lesser amount of regenerated testicular tissue was found either on the original site of the organs or engrafted upon neighbouring organs. This experience, it will be noted, agrees with my own in the case of fowls. There were, however, reasons for believing that the results observed within the first six or eight months after the operation are not much different from those which would follow complete castration. Castration carried out when the drake was in nuptial plumage produced the same effect which was observed by Goodale, namely, delay, and imperfection in the assumption of the eclipse condition, but the observations of Seligmann and Shattock are more precise and detailed. One example described was castrated in full winter plumage in December 1906. On July 11, when normally it would have been in eclipse, the nuptial plumage was unmodified except for a diffuse light-brown coloration on the abdomen, which is stated to be due not to any growth of new feathers but to pigmentary modification in the old. By September 1 this bird was almost in eclipse but not quite; curl feathers in the tail had disappeared, the breast was almost in full eclipse, the white ring was slightly indicated at the sides of the neck, the top of the head and the nape had still a good deal of gloss. After this the nuptial plumage developed again, and on November 12 the bird was in full nuptial plumage, with good curl feathers in the tail. The only trace of the eclipse was the presence of a few brown feathers on the flanks. This bird was killed July 30, 1908, when the bird was in eclipse, but not perfectly so, as there were vermiculated feathers mixed with eclipse feathers on the breast, abdomen, and flanks. Dissection showed on the right side a series of loosely attached nodular grafts of testicular tissue, in total volume about the size of a haricot bean: on the left side two small nodules, together about the size of a pea, and two other grafts at the root of the liver and on the mesentery. Several other cases are described, and the general result was that the eclipse was delayed and never quite complete, while although the nuptial plumage was almost fully developed in the following winter, it retained some eclipse feathers, and was also delayed and developed slowly. Several drakes were castrated in July when in the eclipse condition, and although the authors state, in their general conclusions, that this does not produce any constant appreciable effect upon the next passage of the bird into winter plumage, they describe one bird so treated which on November 18 retained many eclipse feathers: the general appearance of the chestnut area of the breast was eclipse. It must be remembered that not only was the castration in these cases incomplete, but also that it was performed on mature birds. Birds differ from Mammals, firstly, in the difficulty of carrying out complete castration, and secondly, in the fact that the occurrence of puberty is not so definite, and that immature birds are so small and delicate that it is almost impossible to operate upon them successfully. ASSUMPTION OF MALE CHARACTERS BY THE FEMALE That male somatic sexual characters are latent in the female is shown by the frequent appearance of such characters in old age, or in individual cases. The development of hair on the face of women in old age, or after the child-bearing period, is a well-known fact. Rorig, [Footnote: 'Ueber Geweihbildung und Geweihentwicklung.' _Arch. Ent.-Mech._ x. and xi.] who carefully studied the antlers of stags, states that old sterile females, and those with diseased ovaries, develop antlers to some degree. Cases of crowing hens, and female birds assuming male plumage have long been known, but the exact relation of the somatic changes to the condition of the ovaries in these cases is worthy of consideration in view of the results obtained by Goodale after removal of the ovaries from ducks. Shattock and Seligmann [Footnote: 'True Hermaphroditism in Domestic Fowl, etc.' _Trans. Path. Soc._, Lond., 57. 1, 1906.] record the case of a gold pheasant hen which assumed the full male plumage after the first moult: it had never laid eggs or shown any sexual instincts. The only male character which was wanting was that of the spurs. The ovary was represented by a smooth, slightly elevated deep black eminence 1 cm. in length and 1-5 mm. in breadth at its upper end. These authors also mention three ducks in male plumage in which the ovary was similarly atrophied but not pigmented. They regard the condition of the ovary as insufficient to explain the development of the male characters, and suggest that such birds are really hermaphrodite, a male element being possibly concealed in a neighbouring organ such as the adrenal or kidney. This hypothesis is not supported by observation of testicular tissue in any such case, but by the condition found in a hermaphrodite specimen of the common fowl described in the paper. This bird presented the fully developed comb and wattles and the spurs of the cock, but the tail was quite devoid of curved or sickle feathers, and resembled that of the hen. Internally there were two oviducts, that of the left side normally developed, that of the right diminutive and less than half the full length. The gonad of the left side had the tubular structure of a testis, but showed no signs of active spermatogenesis, but in its lower part contained two ova. The organ of the right side was somewhat smaller, it had the same tubular structure, and in one small part the tubules were larger, showed division of nuclei (mitotic figures), and one of them showed active spermatogenesis. In discussing Heredity and Sex in 1909, [Footnote: _Mendel's Principles of Heredity_. Camb. Univ. Press, 1909.] Bateson referred to the effects of castration as evidence that in different types sex may be differently constituted. Castration, he urged, in the male vertebrate on the whole leads merely to the non-appearance of male features, not to the assumption of female characters, while injury or disease of the ovaries may lead to the assumption of male characters by the female. This was supposed to support the view that the male is homozygous in sex, the female heterozygous in Vertebrates: that is to say, the female sex-character and the female secondary sex-characters are entirely wanting in the male. This argument assumes that the secondary characters are essentially of sexual nature without inquiring how they came to be connected with sex, and it ignores the fact that the influence of castration on such characters is a phenomenon entirely beyond the scope of Mendelian principles altogether. The fact that castration does affect, in many cases very profoundly, somatic characters confined to one sex, proves that Mendelian conceptions, however true up to a certain point, are by no means the whole truth about heredity and development. For it is the essence of Mendelism as of Weismannism that not only sex but all other congenital characters are determined in the fertilised ovum or zygote. The meaning of a recessive character in Mendelian terminology is one that is hidden by a dominant character, and both of them are due to factors in the gametes, particularly in the chromosomes of the gametes which come together in fertilisation. For example, in fowls rose comb is dominant over single. A dominant is something present which is absent in the recessive: the rose comb is due to a factor which is absent from the single. The two segregate in the gametes of the hybrid or heterozygote, and if a recessive gamete is fertilised by another recessive gamete the single comb reappears. But castration shows that the antlers of stags and other such characters are not determined in the zygote when the sex is determined, but owe their development, partly at least, to the influence of another part of the body, namely, the testes during the subsequent life of the individual. According to Mendelism the structure and development of each part of the soma is due to the constitution of the chromosomes of the nuclei in that part. The effects of castration show that the development of certain characters is greatly influenced in some way by the presence of the testes in a distant part of the body. The Mendelians used to say it was impossible to believe in the heredity of somatic modifications due to external conditions, because it was impossible to conceive of any means by which such modifications could affect the constitution of the chromosomes in the gametes within the modified body. It would have been just as logical to deny the proved effects of castration, because it was impossible to conceive of any means by which the testes could affect the development of a distant part of the body. But this is not all. The supposed fact that female secondary characters in Vertebrates are absent in the male is completely disproved for Mammals by the presence of rudimentary mammary glands in the male. It is true that secondary sex-characters are usually positive in the male, while those of the female are apparently negative, but in the case of the mammary glands the opposite is the case. There is no room for doubt that the mammary glands are an essentially female somatic sex-character, not only in their function but in the relation between the periodicity of that function and those of the ovaries and uterus, and it is equally certain from their presence in rudimentary condition in the male that they are not absent from the male constitution. INFLUENCE OF GONADS DUE TO HORMONES The existence and the influence of hormones or internal secretions may be said to have been first proved in the case of the testes, for Professor A. A. Berthold [Footnote: 'Transplantation der Hoden,' _Archiv. f Anat. u. Phys._, 1849.] of Göttingen in 1849 was the first to make the experiment of removing the testicles from cocks and grafting them in another part of the body, and finding that the animals remained male in regard to voice, reproductive instinct, fighting spirit, and growth of comb and wattles. He also drew the conclusion that the results were due to the effect of the testicle upon the blood, and through the blood upon the organism. Little attention was paid to Berthold's experiment at the time. The credit of having been the first to formulate the doctrine of internal secretion is generally given to Claude Bernard. He discovered the glycogenic function of the liver, and proved that in addition to secreting bile, that organ stores up glycogen from the sugar absorbed in the stomach and intestines, and gives it out again as sugar to the blood. In 1855 he maintained that every organ of the body by a process of internal secretion gives up products to the blood. He did not, however, discover the action of such products on other parts or functions of the body. Brown-Séquard, in his address before the Medical Faculty of Paris in 1869, was the first to suggest that glands, with or without ducts, supplied special substances to the blood which were useful or necessary to the normal health, and in 1889 at a meeting of the Société de Biologie he described the experiment he had made upon himself by the injection of testicular extract. This was the commencement of organotherapy. Since that time investigation of the more important organs of internal secretion--namely, the gonads, thyroid, thymus, suprarenals, pituitary, and pineal bodies--has been carried on both by clinical observation and experiment by a great number of physiologists with very striking results, and new hormones have been discovered in the walls of the intestine and other organs. Here, however, we are more especially concerned with the gonads and other reproductive organs. A great deal of evidence has now been obtained that the influence of the testes and ovaries on secondary sexual characters is due to a hormone formed in the gonads and passing in the blood in the course of the circulation to the organs and tissues which constitute those characters. The fact that transplanted portions of testes in birds (cocks and drakes) are sufficient to maintain the secondary characters in the same condition as in normal individuals shows that the nexus between the primary and somatic organs is of a liquid chemical nature and not anatomical, through the nervous system for example. Many physiologists in recent years have maintained that the testicular hormone is not derived from the male germ-cells or spermatocytes, but from certain cells between the spermatic tubuli which are known as interstitial cells, or collectively as the interstitial gland. The views of Ancel and Bouin, [Footnote: _C. R. Soc. Biol., iv._] published in 1903, may be described in large part as theory. They state that the interstitial cells appear in the male embryo before the gametocytes present distinctive sex-characters. They conclude that the interstitial cells supply a nutritive material (hormone?), which has an effect on the sexual orientation of the primitive generative cells. In addition to this function, the interstitial cells by their hormone also give the sexual character to the soma. When castration is carried out at birth the male somatic characters do not entirely disappear, because the hormone of the interstitial cells has acted during intrauterine life. The functional independence between the interstitial cells and the seminal tubules is shown by the fact that if the vasa deferentia are closed the seminal gland (_i.e._ tubules) degenerates while the interstitial cells do not. In the embryo the interstitial gland is large, in the adult proportionately small. There is complete disagreement between the results of Ancel and Bouin on the one hand, and those of Shattock and Seligmann on the other, with regard to the effects of ligature of the vasa deferentia. The latter authors, as mentioned above, found that after ligature not only the somatic characters but the testis itself developed normally. The experiments were performed on Herdwick sheep and domestic fowls. They state that on examination the testes were found to be normally developed, and spermatogenesis was in progress. The experiments of Ancel and Bouin were carried out on rabbits seven to eight weeks old, and consisted in removing one testis, and ligaturing the vas deferens of the other. About six months after the operation the testis left _in situ_ was smaller, the seminal tubules contained few spermatogonia, though Sertoli's cells (cells on the walls of the tubules to which the true spermatic cells are attached) were unchanged; while the interstitial cells were enormously developed, by compensatory hypertrophy in consequence of the removal of the other testis. At the same time the male instincts and the other generative organs were unchanged. In a few cases, however, Ancel and Bouin observed atrophy of the interstitial cells as well as the spermatic cells. They believe this is due to the nerves supplying the testis being included in the ligature. This is rather a surprising conclusion in view of the fact that testicular grafts show active spermatogenesis. It is difficult to understand why nerve connection should be necessary for the interstitial cells and not for the spermatic, and, moreover, if the interstitial cells are really the source of the hormone on which the somatic characters depend, they must be acting in the grafts in which the nerve connections have been all severed. The facts concerning cryptorchidism, that is to say, failure of the descent of the testes in Mammals, seem to show that the hormone of the testis is not derived from semen or spermatogenesis, for in the testes which have remained in the abdomen there is no spermatogenesis, while the interstitial cells are present, and the animals in some cases exhibit normal or even excessive sexual instinct, and all the male characteristics are well marked. It may be remarked, however, in criticism of this conclusion that the descent of the testes being itself a somatic sexual character of the male, its failure when the interstitial cells are normal and the spermatic cells defective, would rather tend to prove that the defect of the latter is itself the cause of cryptorchidism. Many investigators have found that the Röntgen rays destroy the spermatic cells of the testis in Mammals, leaving the cells of Sertoli, the interstitial tissue, nerves, and vessels uninjured. Tandler and Gross [Footnote: _Wiener klinische Wochenschrift_, 1907.] found that the antlers of roebuck were not affected after the testes had been submitted to the action of the rays, showing that the interstitial cells were sufficient to maintain the normal condition of the antlers. Simmonds, [Footnote: _Fortschr. a. d. G. d. Röntgenstr._, xiv., 1909-10.] however, found that isolated seminal tubules remained, and regeneration took place, and concludes that both spermatic cells and interstitial cells take part in producing the testis hormone. The conclusions of two other investigators have an important bearing on this question--namely, that of Miss Boring [Footnote: _Biol. Bull._, xxiii. 1912.] that there is no interstitial tissue in the bird's testis, and that of Miss Lane-Claypon, [Footnote: _Proc. Roy. Soc._, 1905] that the interstitial cells of the ovary arise from the germinal epithelium, and are perfectly equipotential with those which form the ova and Graafian follicles. It seems possible, although no such suggestion has been made, that the interstitial cells might either normally or exceptionally give rise to ova and spermatocytes. The observations of Seligmann and Shattock on the relation of spermatogenesis to the development of nuptial plumage in drakes probably receive their explanation from the above facts. Spermatogenesis is not the only source of the testicular hormone: changes in the secretory activity of the interstitial cells or spermatocytes are sufficient to account for periodic development of somatic sex-characters, and the same reasoning applies to the antlers of stags. THE MAMMARY OR MILK GLANDS The milk glands in Mammals constitute one of the most remarkable of secondary sexual characters. Except in their functional relations to the primary organs, the ovaries, and to the uterus, there is nothing sexual about them. They are parts of the skin, being nothing more or less than enormous enlargements of dermal glands, either sebaceous or sudoriparous. Uterine and mammary functions are generally regarded as essentially female characteristics, and are included in the popular idea of the sex of woman. Scientifically, of course, they are not at all necessary or universal features of the female sex, but are peculiar to the mammalian class of Vertebrates in which they have been evolved. Milk glands, then, are somatic sex-characters common to a whole class, instead of being restricted to a family like the antlers in Cervidae. There is not the slightest trace or rudiment of them in other classes of Vertebrates, such as Birds or Reptiles. They are not actually sexual in their nature, since their function is to supply food for the young, not to play a part in the relations of the sexes. What is sexual about them is--firstly, that they are normally fully developed only in the female, rudimentary in the male; secondly, that their periodical development and functional activity depends on the changes which take place in the ovary and uterus. Many investigators have endeavoured to discover the nature of the nexus between the latter organs and the milk glands. That this nexus is of the nature of a hormone is generally agreed, and may be regarded as having been proved in 1874 when Goltz and Ewald [Footnote: _Pflügers Archiv,_ ix., 1874.] removed the whole of the lumbo-sacral portion of the spinal cord of a bitch and found that the mammae in the animal developed and enlarged in the usual way during pregnancy and secreted milk normally after parturition. Ribbert [Footnote: _Fortschritte der Medicin,_ Bd. 7.] in 1898 transplanted a milk gland of a guinea-pig to the neighbourhood of the ear, and found that its development and function during pregnancy and at parturition were unaffected. The effective stimulus, therefore, is not conveyed through the nervous system, but must be a chemical stimulus passing through the vascular system. Physiologists, however, are not equally in agreement concerning the source of the hormone which regulates lactation. Starling and Miss Lane-Claypon concluded from their experiments on rabbits that the hormone originated in the foetuses themselves within the pregnant uterus. In virgin rabbits it is difficult to find the milk glands at all. When found the nipple is minute and sections through it show the gland to consist of only a few ducts a few millimetres in length. Five days after impregnation the gland is about 2 cm. in diameter. Nine days after impregnation the glands have grown so much that the whole inner surface of the skin of the abdomen is covered with a thin layer of gland tissue. In six cases by injecting subcutaneously extracts of foetus tissue Starling and Lane-Claypon obtained a certain amount of growth of the milk glands. The hormone in the case of the pregnant rabbit is of course acting continuously for the whole period of pregnancy, while the artificial injection took place only once in twenty-four hours, and the amount of hormone it contained may have been absorbed in a very short time. The amount of growth obtained experimentally in five weeks was less than that occurring in pregnancy in nine days. Extracts of uterus, placenta, or ovary produced no growth, although the ovaries used were taken from rabbits in the middle of pregnancy. In one experiment ovaries from a pregnant rabbit were implanted into the peritoneum of a non-pregnant rabbit, but on post-mortem examination of the latter eleven days later the implanted ovaries were found to be necrosed and no proliferation of milk gland had taken place. The conclusions of Starling and Lane-Claypon were confirmed by Foa, [Footnote: _Archivo d. Fisiologia_, v., 1909.] and by Biedl and Königstein, [Footnote: _Zeitschrift f. exp. Path. und Therap_., 1910.] Foa states that extracts of foetuses of cows produced swelling of the mammae in a virgin rabbit. O'Donoghue, however, concludes from a study of the Marsupial _Dasyurus_ that the stimulus which upon the milk glands proceeds from the corpora lutea in the ovary. In this animal changes in the pouch occur in pregnancy, which are doubtless also due to hormone stimulation, but which we will not consider here. The most important evidence in O'Donoghue's paper [Footnote: _Quart. Journ. Mic. Sci_., lvii., 1911-12.] is that development of the milk glands takes place after ovulation not succeeded by pregnancy; that is to say, when corpora lutea are formed but no fertilised ova or foetus are present in the uterus. In one case eighteen days after heat, the milk gland was in a condition resembling that found in the stages twenty-four and thirty-six hours after parturition. In another specimen, twenty-one days after heat, the milk glands were still more advanced, with distended alveoli and enlarged ducts. The alveoli contained a secretion which was almost certainly milk, O'Donoghue states that the entire series of growth changes in these animals up to twenty-one days after heat in identical with that which occurs in normally pregnant animals. O'Donoghue's conclusion is in agreement with that of Basch,[Footnote: _Monatesschr. f. Kinderh. V._, No. ix., Dec. 1909.] who states that implantation of the, ovaries from a pregnant bitch under the skin of the back of a one-year-old bitch that was not pregnant was followed by proliferation of the mammary glands of the latter. After six weeks the glands were considerably enlarged, and after eight weeks they were caused to secrete milk by the injection of extract of the placenta. It has to be remembered, however, that the milk glands undergo considerable growth, especially in the human species, at puberty and at every menstruation, or at oestrus in animals, which correspond to menstruation. In these cases there is no question of any influence of the foetus, and experiment has shown that if the ovaries are removed before puberty, the milk glands nor the uterus undergo the normal development and menstruation does not occur. According to Marshall to Jolly [Footnote: _Quart. Journ. Exp. Phys._, i. and ii., 1906.] the symptoms of oestrus in castrated bitches were found to result from the implantation of ovaries from other individuals in the condition of oestrus. Before considering further the question of the corpora lutea as organs of internal secretion, we may briefly refer to the origin and structure of these bodies and of other parts of the mammalian ovary. The mature follicle containing the ovum differs from that of other Vertebrates in the fact that it is not completely filled by the ovum and the follicular cells surrounding it, but there is a cell-free space of large size into which the ovum covered by follicular cells projects. In the wall of the follicle two layers are distinguished, the theca externa, which is more fibrous, and the theca interna, which is more cellular. In the connective tissue stroma of the ovary between the follicles are scattered, or in some cases aggregated, epithelioid cells known as the interstitial cells, and it is stated that the cells of the theca interna are exactly similar to the interstitial cells. According to Limon [Footnote: _Arch. d'Anat. micr._, v., 1902.] and Wallart [Footnote: _Arch. f. Gynock_, vi. 271.] the interstitial cells are actually derived from those of the theca interna of the follicles. Numbers of ova die without reaching maturity, the follicular cells degenerate, and the follicle becomes filled with the cells of the theca interna, which have a resemblance to those of the true corpus luteum. These degenerate follicles have been termed spurious corpora lutea, or atretic vesicles. The interstitial cells are the remains of these atretic vesicles. The true corpora lutea arise from follicles in which the ova have become mature and from which they have escaped through the surface of the ovary. As a result of the escape of the ovum and the contents of the cell-free space, the follicle contracts and the follicular (so-called granulosa) cells secrete a yellow substance, lutein, and enlarge. Buds from the theca interna invade the follicle and form the connective tissue of the corpus luteum. Somewhat similar processes take place in the ovaries of Teleostean fishes, as I know from my own observations, but no corpora lutea are formed in these, although the degenerating follicles in course of absorption correspond to corpora lutea. The spawning of Fishes, usually annual, corresponds to ovulation in Mammals, and in the ovary after spawning the numerous collapsed follicles containing the follicular cells may be seen in all stages of absorption. [Footnote: Cunningham, 'Ovaries of Teleosteans.' _Quart. Journ. Mic. Sci._, vol. xl. pt. 1., 1897.] At other times of the year sections of the ovary show here and there ova which after developing to a certain stage die and undergo absorption with their follicles. In the higher Mammals (Eutheria) the corpora lutea show a special relation in their development to the occurrence of pregnancy, that is to say, they have a different history when ovulation is followed by pregnancy to that which they have when the ova, from the escape of which they arise, are not fertilised. When fertilisation occurs the corpus luteum increases in size during the first part of the period of gestation (four months, or nearly a half of the whole period in the human species). It then remains without much change till parturition, after which it shrinks and is absorbed. When pregnancy does not occur the corpus luteum is formed, but begins to diminish within ten or twelve days in the human species and is then gradually absorbed. According to O'Donoghue, in the Marsupial _Dasyurus_ there seems to be no difference either in the development of the milk glands or of the corpora lutea between the pregnant and the non-pregnant animal. Sandes [Footnote: _Proc. Lin. Soc._, New South Wales, 1903.] showed that in the same species the corpora lutea persisted not only during the whole of pregnancy, which Professor J. P. Hill [Footnote: _Anat. Anz._, xviii., 1900.] estimates at a little over eight days, but during the greater part of the period of lactation, which according to the same authority is about four months. In the specimens of _Dasyurus_ described by O'Donoghue, in which the milk glands developed after ovulation without ensuing pregnancy, normally developed corpora lutea were present in the ovary. Of the five females which he mentions, the first three, one with unfertilised ova in the uteri, two five and six days after heat, could not have been pregnant, but the other two killed eighteen and twenty-one days after heat might, since pregnancy lasts only eight days, have been pregnant, the young having died at parturition or before. To make certain on this point it would have been necessary to examine the ovaries and milk glands of females which had been kept separate from a male the whole time. There is no doubt, however, about the development of the milk glands in the first three specimens, which were certainly not pregnant. It is difficult to reconcile entirely the evidence described by O'Donoghue from _Dasyurus_, with that obtained from higher Mammals, although on the whole there is reason to conclude that the corpora lutea have an important influence on the development of the milk glands. According to Lane-Claypon and Starling, if the ovaries and uteri are removed from a pregnant rabbit before the fourteenth day the development of the mammary gland ceases, retrogression takes place, and no milk appears in the gland. If, on the other hand, the operation be performed after the fourteenth day, milk appears within two days after the operation. It is to be concluded from this that the cause of _secretion_ of milk is the withdrawal of a stimulus proceeding from ovary or uterus. But O'Donoghue believes that milk is secreted in _Dasyurus_ when no pregnancy has occurred. Ancel and Bouin [Footnote: _C. R. Soc. de Biol._, t. lxvii., 1909.] have shown that the growth of the mammary glands was produced in rabbits by the artificial rupture of egg follicles and consequent production of corpora lutea: the growth of the glands continued up to the fourteenth day, after which regression set in. This shows that the development of the milk glands in rabbits is due to the corpora lutea. On the other hand, Lane-Claypon and Starling state that in rabbits the corpora lutea diminish after the first half of pregnancy, while the growth of the milk glands is many times greater during the second half than during the first half of the period, and during the second half the ovaries may be removed entirely without interfering with the course of pregnancy or the normal development of the milk glands. It is evident, therefore, that in rabbits, whatever influence the corpora lutea may have in the first half of pregnancy, they have none in the second half, and that at this period the essential hormone proceeds from the developing foetus or foetal placenta. Again, if it is the withdrawal of a hormone stimulus which changes the milk gland from growth to secretion, it cannot be the corpora lutea which are exclusively concerned even in _Dasyurus_, for they persist during lactation, while secretion begins shortly after parturition. Gustav Born suggested, and Fränkel tested the suggestion experimentally, that the corpus luteum of pregnancy is a gland of internal secretion whose function is to cause the attachment of the ovum in the uterus and the normal development of uterus and placenta. Fränkel found that removal of both ovaries in rabbits between the first and sixth days after fertilisation prevented pregnancy, and that the same result followed if the corpora lutea were merely destroyed _in situ_ by galvano-cautery. Either process carried out between the eighth and twentieth days of pregnancy causes abortion. Lane-Claypon and Starling also found that removal of both ovaries in the rabbit before the fifteenth day was apt to cause abortion, but at a later stage the same operation could be performed without interfering with the course of pregnancy. According to these authors numberless instances prove that in women double ovariotomy does not necessarily interfere with the course of pregnancy or the development of the milk glands. Parturition may take place and be followed by normal lactation. This shows that a hormone from the corpora lutea is not necessary either to the uterus or the milk glands, at any rate in the last third of pregnancy, though of course this does not prove that such a hormone is not necessary for the earlier stages both of pregnancy and growth of the milk glands. The results of Steinach, if confirmed, would prove conclusively that the ovaries and testes produce hormones which determine the development of all the sexual characters, not merely physical but psychical. He adopts the view that the interstitial cells or gland are the source of the active hormone. He claims by transplantation of the gonads in young rats and guinea-pigs to have feminised males and masculised females. The females are smaller, and hare finer, softer hair than the males. The testes were removed and ovaries implanted in young males. The animals so treated grew less than the merely castrated specimens, and therefore when full-grown resembled females in size. In the young state both sexes have fine, soft hair, the feminised males had the same character, like the normal females. They also developed teats and milk glands like the females, and were sought and treated as females by the normal males. When the implanted ovaries are able to resist the influence of their new surroundings, the female interstitial gland, which Steinach calls the puberty gland, develops so much that an intensification of the female character takes place: the animals are smaller than normal females, the milk glands develop and secrete milk, which can be easily pressed out, and if young are given to them they suckle them and show all the maternal instincts. Why the ovary in normal circumstances only when in the gravid condition calls forth this perfection of femaleness is to be shown in a later publication. By acting with Röntgen rays on the region where the ovaries lie, Steinach and his colleague Holzknecht brought about all the symptoms of pregnancy, development of teats and milk glands, secretion of milk, and great growth of the uterus in all its layers. Masculising of females was much more difficult than feminising of males because the testicular tissue was less resistent, and could not be grafted so easily. When it succeeded, however, degeneration of the seminal tubules took place, with increase of the interstitial or Leydig's cells. The vaginal opening in rats disappeared, partly or completely. The sexual instincts became male, the animals recognised a female in heat from one that was not, and attempted to copulate. Steinach considers that he has proved from results that sex is not fixed or predetermined but dependent on the puberty gland. By sex here he obviously means the instincts and somatic characters, for sex in the first instance, as we have already pointed out, means the difference between ovary and testis, between ova and spermatozoa. It is difficult to accept all Steinach's results without confirmation, especially those which show that the feminised male is more female than the normal female. Such a conclusion inevitably suggests that the investigator is proving too much. The subject of the influence of hormones from the gonads is mentioned, but not fully discussed, in a volume by Dr. Jacques Loeb, entitles _The Organism as a Whole_. [Footnote: Putnam's Sons, 1916.] Loeb entirely omits the problem of the _origin_ of somatic sex-characters, and fails to perceive that the fact that such characters are dependent to a marked degree on hormones derived from the gonads, together with their relation to definite habits and functions connected with the behaviour of the sexes to each other, is proof are these characters are not gametogenic, but were originally due to external stimulation of particular parts of the soma. CHAPTER IV Origin Of Somatic Sex-Characters In Evolution In his _Mendel's Principles of Heredity_, 1909, Bateson does not discuss the nature of somatic sex-characters in general, but appears to regard them as essential sex-features, as male or female respectively. As mentioned above, he argues from the fact that injury or disease of the ovaries may lead to the development of male characters in the female, that the female is heterozygous for sex, and from the supposed fact that castration of the male leads merely to the non-appearance of male somatic characters, that the female sex-factor is wanting in the male. He does not distinguish somatic sex-characters from primary sex-factors, and discusses certain cases of heredity limited by sex as though they were examples of the same kind of phenomenon as somatic sex-characters in general. One of these cases is the crossing by Professor T. B. Wood of a breed of sheep horned in both sexes with another hornless in both sexes. In the _F1_ generation the males were horned, the females hornless. Here, with regard to the horned character, both sexes were of the same genetic composition, _i.e._ heterozygous, or if we represent the possession of horns by _H_, and their absence by _h_, both sexes were _Hh_. Thus _Hh[male]_ was horned and _Hh[female]_ was hornless, or, as Bateson expresses it, the horned character was dominant in males, recessive in females. Bateson offers no explanation of this, but it obviously suggests that some trace of the original dimorphism of the sheep in this character was retained in both horned and hornless breeds. We may suppose that the factor for horns had disappeared entirely from the hornless sheep by a mutation, but in the horned breed another mutation had been a weakening of the influence of the sexual hormones on the development of the character, which, as in all such cases, is really inherited in both sexes. In the _F1_, when the horned character in the female is only inherited from one side, the hereditary tendency is not enough to overcome the influence of the absence of the testis hormone and presence of the ovarian hormone, and so the horns do not develop. The Mendelian merely sees a relation of the character to sex, but overlooks entirely the question of the dimorphism in the original species from which the domesticated breeds are descended. Similarly, with regard to cattle where it has been found that hornlessness is dominant or nearly so in both sexes, no reference is made to the opposite fact that wild cattle have horns in both sexes and are not dimorphic in this character. Bateson proceeds to consider colour-blindness as though its heredity were of similar kind. He refers to it as a male character latent in the female, remarks that we should expect that disease or removal of the ovaries might lead to the occasional appearance of colour-blindness in females. He also discusses the case of _Abraxas grossulariata_ and its variety _lacticolor_, and other cases of sex-linked heredity, apparently with the idea that all such cases are similar to those of sexual dimorphism. _A. lacticolor_ occurs in nature only in the female sex, and when bred with _grossulariata_ [male] produces [male]'s and [female]'s all _grossulariata_, these of course being heterozygous. When the _F1 grossulariata_ [male] was bred with the wild _lacticolor_ [female] it produced both forms in both sexes, and thus _lacticolor_ [male] was obtained for the first time. When this _lacticolor_ [male] was bred with _F1 grossulariata_[female] it produced all the [male]'s _grossulariata_ and all the [female]'s _lacticolor_. Bateson's explanation is that the female, according to the Mendelian theory of sex, is heterozygous in sex, the male homozygous and recessive, and that _lacticolor_ is linked with the female sex-character, _grossulariata_ being repelled by that character. Thus we have, the _lacticolor_ character being recessive, lact. male, LL male male x F, gross. female, GL female male Gametes L male + L male x G male + L female _____________________|______________________ | | GL male male LL male female gross. male lact. female It will be seen that although in the progeny of this mating all the _grossulariata_ were males and all the _lacticolor_ females, yet this case is by no means similar to that of sexual dimorphism in which the characters are normally always confined to the same sex. For the _lacticolor_ character in the parent was in the male, while in the offspring it was in the female. We cannot say here that in the theoretical factors which are supposed to represent what happens, the _lacticolor_ character is coupled with the female sex-factor, for we find it with the male sex-character in the _lacticolor_ [male]. It is so coupled only in the heterozygous _grossulariata_ [female], and at the same time the _grossulariata_ character is repelled. According to Doncaster [Footnote: _Determination of Sex_, Camb. Univ. Press, 1914.] sex-limited, or as it is now proposed to call it sex-linked, transmission in this case means that the female _grossulariata_ transmits the character to all her male offspring and to none of the female, while a heterozygous male _grossulariata_ mated with _lacticolor_ female transmits the character equally to both sexes: that is to say, the heredity is completely sex-limited in the female but not at all in the male. This is evidence that the female produces two kinds of eggs, one male producing and the other female producing. With regard to the ordinary form of colour-blindness, Bateson's first explanation was that it was like the horns in the cross-bred sheep, dominant in males, recessive in females. About 4 per cent. of males in European countries are colour-blind, but less than 1/2 per cent. of females. Affected males may transmit the defect to their sons but not to their daughters: but daughters of affected persons transmit the defect frequently to their sons. Bateson gives [Footnote: _Mendel's Principles of Heredity_, 1909.] a scheme of the transmission, but corrects this in a note stating that colour-blindness does not descend from father to son, unless the defect was introduced by the normal sighted mother also, _i.e._ was carried by her as a recessive. The fact that unaffected males do not transmit the defect shows, according to Bateson, that it is due to the addition of a factor to the normal, not to omission of a factor. According to later researches as quoted by Doncaster, colour-blindness is due to the loss of some factor which is present in the normal individual. The normal male is heterozygous for this normal factor. If we denote the presence of the normal factor by _N_ and its absence or recessive by _n_, then the male is _Nn_, while the female is homozygous or _NN_. But in addition to this it is the male in this case which is heterozygous for sex, and _n_ goes to the male-producing sperms, _N_ to the female-producing. Thus in the mating of normal man with normal woman the transmission is as follows:-- Nn (male) x NN (female) Gametes n (male) + N (female) x N + N n (male) + N N (female) + N | | Nn (male) NN (female) That is all offspring normal, but the males again heterozygous. An affected male has the constitution _nn_, and if he marries a normal woman the descent is as follows:-- nn (male) x NN (female) Gametes n (male) + n (female) x N + N n (male) + N N (female) + N | | nN (male) nN (female) When a normal male is mated with a heterozygous _nN_ female we get nN (male) x nN (female) Gametes n (male) + N (female) x n + N ______________________|______________________ | | | | nn (male) nN (male) nN (female) NN (female) that is, half the sons are normal and half colour-blind, while half the females are homozygous and normal, and the other half heterozygous and normal. T. H. Morgan [Footnote: _A Critique of the Theory of Evolution._] has observed a number of cases of sex-linked inheritance in the mutations which occurred in his cultures of _Drosophila_. The eye of the wild original fly is red, one of the mutants has a white eye, _i.e._ the red colour and its factor are absent. When a white-eyed male is mated to a red-eyed female all the offspring have red eyes. If these are bred _inter se_, there are, as in ordinary Mendelian cases, three red-eyed to one white-eyed in the _F2_ generation, but white eyes occur only in the males, in other wards half the males are white-eyed. On the other hand, when a white-eyed _female_ is mated to a red-eyed male all the daughters have red eyes, and all the sons white eyes. This has been termed crisscross inheritance. If these are bred together the result in _F2_ is equal numbers of red-eyed and white-eyed females, and equal numbers of red-eyed and white-eyed males. The ration of dominant to recessive is 2 to 2 instead of the usual Mendelian ration of 3 to 1. According to Morgan the interpretation is as follows: In the nucleus of the female gametocytes there are two _X_ chromosomes related to sex, in those of the male there is one _X_ chromosome and one _Y_ chromosome of slightly different shape. The factor for red eye occurs in the sex-chromosomes, that is to say, according to this theory, the sex-chromosome does not merely determine sex but carries other factors as well, and this fact is the explanation of sex-linked inheritance. The factor for red eye then is present in both _X_ chromosomes of the wild female, absent from both _X_ and _Y_ chromosomes of the white-eyed male. The gametes of the female each carry one _X_ red chromosome, of those of the male half carry an _X_ white chromosome, and half the _Y_ white chromosome. The fertilised female ova therefore carry an _X_ red chromosome + an _X_ white chromosome, the male producing ova one _X_ red chromosome and one _Y_ white chromosome. They are all therefore red-eyed, but heterozygous--that is, the red eye is due to one red-eye factor, not two. When the _F1_ are bred together, half the female gametes carry one _X_ red chromosome, the other half one _X_ white chromosome; half the male gametes carry one _X_ red chromosome, the other half one _Y_ white chromosome. The fertilisations are therefore one _X_ red _X_ red, one _X_ red _X_ white, one _X_ red _Y_ white, and one _X_ white _Y_ white. These last are the white-eyed males. The two different crosses are represented diagrammatically below, the dark rod representing the _X_ red chromosome, the clear rod the _X_ white chromosome, and the bent clear rod the _Y_ white chromosome. According to Morgan, the heredity of colour-blindness in man is to be explained exactly in the same way as that of white eye in _Drosophila_. A colour-blind man married to a normal (homozygous) woman transmits the peculiarity to half his grandsons and to none of his grand-daughters. Colour-blind women are rare, but in the few cases known where such women have married normal husbands the defect has appeared only in the sons, as in the second of the diagrams below. Parents Red-eyed male White-eyed female XR XR x XW YW F1 Red-eyed male Red-eyed female XR XW XR YW F2 Red-eyed male Red-eyed male Red-eyed female White-eyed female XR XR XW XR XR YW XW YW Homozygous. Heterozygous. Heterozygous. Homozygous. White-eyed male Red-eyed female XW XW x XR YW F1 Red-eyed male White-eyed female XW XR XW YW F2 White-eyed male Red-eyed male White-eyed female Red-eyed female XW XW XR XW XW YW XR YW Homozygous. Heterozygous. Homozygous. Heterozygous. It must be explained that according to this theory the normal male is always heterozygous, because the _Y_ chromosome never carries any other factor except that for sex; it is thus of no more importance than the absence of an _X_ chromosome which occurs in those cases where the male has one sex-chromosome and the female two. According to the researches of von Winiwarter [Footnote: 'Spermatogénèse humaine,' _Arch. de Biol._, xxvii., 1912.] on spermatogenesis in man, the latter is actually the case in the human species. This investigator found that there were 48 chromosomes in the female cell, 47 in the male; after the reduction divisions the unfertilised ova had 24 chromosomes, half the spermatids 24 and half 23, so that sex is determined in man by the spermatozoon. Morgan believes that the heredity of haemophilia (the constitutional defect which prevents the spontaneous cessation of bleeding) follows the same scheme, and also at least some forms of stationary night-blindness-- that is, the inability to see in twilight. We may mention a few other in animals, referring the reader for a fuller account to the works cited. One example in the barred character of the feathers in the breed of fowls called Plymouth Rock. In this the female is heterozygous for sex as in _Abraxas grossulariata_, and the barred character is sex-linked. When a barred hen is crossed with an unbarred cock all the male offspring are barred, all the females plain. On the other hand, if a barred cock is crossed with an unbarred hen, the barred character appears in all the offspring, both and females. The female thus transmits the character only to her sons. If we represent the barred character by _B_, and its absence by _b_, we can represent the heredity as follows:-- BARRED FEMALE WITH UNBARRED MALE B female b male X b male b male Bb male bb female Barred male. Unbarred female. Heterozygous. Homozygous. B male B male X b female b male B male b female b male b male Barred female. Barred male. Heterozygous. Heterozygous.] This case is thus exactly similar to that of _Abraxas grossulariata_ and _A. lacticolor_. The barred character like _grossulariata_ is dominant, the unbarred recessive, and to explain the results it is necessary to assume that the female is not only heterozygous for the barred character, but also for sex, with the female sex-factor dominant. The recessive character in this case is linked to the female sex chromosome, or, as Bateson described it, the dominant character is repelled by the sex-factor. We may make a diagram of the kind given by Morgan if we use a rod of different shape for the female-producing sex-chromosome, and use the black rod for the dominant character:-- BARRED female x unbarred male BX uY uX uX | \/ | | /\ | BX uX uY uX BARRED male unbarred female Heterozygous Homozygous BARRED male x unbarred female BX BX uX uY | \/ | | /\ | BX uX BX uY BARRED male BARRED female Heterozygous Heterozygous Another case is that of tortoise-shell, _i.e._ black and yellow cats. The tortoise-shell with very rare exceptions is female, the corresponding male being yellow, without any black colour. Doncaster found that a yellow male mated to a black female produced black male offspring and tortoise-shell females. When a black male is mated to a yellow female, the female kittens are tortoise-shell as before, but the males yellow. The Mendelian hypothesis which explains these results is that the male is always heterozygous, or has only one colour factor whether yellow or black, and transmits these colours only to his daughters, while the female has two colour factors, either _BB_, _YY_, or _BY_. Thus the crosses are:-- YELLOW male x BLACK female YO male BB female | \/ | | /\ | YB female BO male Tortoise-shell female BLACK male BLACK male x YELLOW female BO male YY female | \/ | | /\ | BY female YO male Tortoise-shell female YELLOW male The sex must be determined therefore by the spermatozoa, as in the case of colour-blindness, etc., in man, and the colour factor must always be in the female-producing sperm. SEXUAL DIMORPHISM It is obvious from the above facts that however interesting and important sex-linked heredity may be, it is not the same thing as the heredity of secondary sexual characters, and does not in the least explain sexual dimorphism. In the first place, the term sex-linked does not mean occurring always exclusively in one sex, but the direct contrary-- transmitted by one sex to the opposite sex--and in the second place there is no suggestion that the development of the character is dependent in any way on the presence or function of the gonad. The problem I am proposing to consider is what light the facts throw on the origin of the secondary sexual characters in evolution. In endeavouring to answer this question there are only two alternatives: either the characters are blastogenic-- that is, they arise from some change in the gametocytes occurring somewhere in the succession of cell-divisions of these cells--or they arise in the soma and are impressed on the gametocytes by the influence of the soma within which these gametocytes are contained--that is to say, they are somatogenic. That characters do originate by the first of these processes may be considered to be proved by recent researches, and such characters are called mutations. There can be little doubt that the so- called sex-linked characters, of which examples have been given above, have originated in this way, and that their relation to sex is part of the mutation. According to T. H. Morgan, it is simply due to the fact that the determinants for such characters are situated in the sex-chromosome. Morgan, however, also states that a case of true sexual dimorphism arose as a mutation in his cultures of _Drosphilia_. The character was eosin colour in the eye instead of the red colour of the eye in the original fly. In the female this was dark eosin colour, in the male yellowish eosin. But this case differs from the characters particularly under consideration here in two points: (1) there is no suggestion that it was adaptive, (2) or that it was influenced by hormones from the gonads. No character whose development is dependent in greater or less degree on the stimulation of some substance derived from the gonads can have originated as a mutation, because the term mutation means a new character which develops in the soma as a result of the loss or gain of some factor or determinant in the chromosomes. To say that certain mutations consist of new factors which only the development of characters in the soma when the part of the soma concerned is stimulated by a hormone, is a mere assertion unsupported at present by any evidence. As an example of the way in which Mendelians misunderstand the problem to be considered, I may refer to Doncaster's book, _The Determination of Sex_ [Footnote: Camb. Univ. 1914, p. 99.] in which he remarks: 'It follows that the secondary sexual characters cannot arise simply from the action of hormones; they must be due to differences in the tissues of the body, and the activity of the ovary or testis must be regarded rather as a stimulus to their development than as their source of origin.' This seems to imply a serious misunderstanding of the idea of the action of the hormones from the gonads and of hormones in general. No one would suggest that the hormones from the testis should be regarded as in any sense the origin of the antlers of a stag. If so, why should not antlers equally develop in the stallion or in the buck rabbit, or indeed in man? How far Doncaster is right in holding that the soma is different in the two sexes is a question already mentioned, but it is obvious that in each individual the somatic sexual characters proper to its species are present potentially in its constitution by heredity--in other words, as factors or determinants in the chromosomes of the zygote from which it was developed; but the normal development of such characters in the individual soma is either entirely dependent on the stimulus of the hormone of the gonad or is profoundly influenced by the presence or absence of that stimulus. The evidence, as we have seen, proves that, at any rate in the large number of cases where this relation between somatic sex-characters and hormones produced by the reproductive organs exists, the characters are inherited by both sexes. In one sex they are fully developed, in the other rudimentary or wanting. But the sex, usually the female, in which they are rudimentary or wanting is capable of transmitting them to offspring, and also is capable of developing them more or less completely when the ovaries are removed, atrophied or diseased. If we state these facts in the terms of our present conceptions of chromosomes and determinants or factors, we must say that the factors for these characters are present in the chromosomes of both male and female gametes. The question then is, how did these factors arise? If they were mutations not caused by any influence from the exterior, what is the reason why these particular characters which alone have an adaptive relation to the sexual or reproductive habits of the animal are also the only characters which are influenced by the hormones of the reproductive organs? The idea of mutations implies neither an external relation nor an internal relation in the organ or character; but these characters have both, the external relation in the function they perform in the sexual life of the individual, the internal relation in the fact that their development is affected by the sexual hormones. There is no more striking example of the inadequacy of the current conceptions of Mendelism and mutation to cover the of bionomics and evolution. The truth is that facts and experiments within a somewhat narrow field have assumed too much importance in recent biological research. No increase in the number of facts or experimental results of a particular class will compensate for the want of sound reasoning and a comprehensive grasp of the phenomena to be explained. The coexistence of the external and the internal relation in the characters we are considering suggests that one is the cause of the other, and as it is obvious that the relation for instance of a stag's antlers to a testicular hormone could not very well be the cause of the use of the antlers in fighting, the reasonable suggestion is that the latter is the cause of the former. We have already seen that the development and shedding of the antler are processes of essentially the same kind physiologically, or pathologically, as these which can be and are occasionally produced in the individual soma by mechanical stimulus and injury to the periosteum. The fact that a hormone from the testis affects the development of the antler, as well as our knowledge of hormones in general, suggests a special theory of the heredity of somatic modifications due to external stimuli. Physiologists are apt to look for a particular gland to produce every internal secretion. But the fact that the wall of the intestine produces secretion, which carried by the blood causes the pancreas to secrete, shows that a particular gland is not necessary. There is nothing improbable in supposing that a tissue stimulated to excessive growth by external irritation would give off special substances to the blood. We know that living tissues give off products, and that these are not merely pure CO2 and H2O, but complicated compounds. The theory proposed by me in 1908 was that we have within the gonads numerous gametocytes whose chromosomes contain factors corresponding to the different parts of the soma, and that factors or determinants might be stimulated by products circulating in the blood and derived from the parts of the soma corresponding to them. There is no reason to suppose that an exostosis formed on the frontal bone as a result of repeated mechanical stimulation due to the butting of stags would give off a special hormone which was never formed in the body before, but it would probably in its increased growth give off an increased quantity of intermediate waste products of the same kind as the tissues from which it arose gave off before. These products would act as a hormone on the gametocytes, stimulating the factors which in the next generation would control the development of the frontal bone and adjacent tissues. The difficulty of this theory is one which has occurred to biologists who have previously made suggestions of a connexion between hormones and heredity--namely, how hormones or waste products from one part of the body could differ from these from the same tissue in another part of the body. If there were no special relation, hypertrophy of bone on one part of the body such as the head, would merely stimulate the factor for the whole skeleton in the gametocytes, and the result would merely be an increased development of the whole skeleton. On the other hand, we have the evident fact that a number of chromosomes formed apparently of the same substance, by a series of equal chromosome divisions determine all the various special parts of the complicated body. This is not more difficult to understand than that every part of the body should give off special substances which would have a special effect on the corresponding parts of the chromosomes. We know that skin glands in different parts of the body produce special odours, although all formed of the same tissue and all derived from the epidermis. It seems not impossible that bones of different parts of the body give off different hormones. If the factors in the gametes were thus stimulated they would, when they developed in a new individual, product a slightly increased development of the part which was hypertrophied in the parent soma. No matter how slight the degree of hereditary effect, if the stimulation was repeated in every generation, as in the case of such characters as we are considering it undoubtedly was, the hereditary effect would constantly increase until it was far greater than the direct effect of the stimulation. We may express the process mathematically in this way. Suppose the amount of hypertrophy in such a case as the antlers to be _x,_ and that some fraction of this is inherited. Then in the second generation the same amount of stimulation together with the inherited effect would produce a result equal to _x+x/n_. The latter fraction being already hereditary, a new fraction _x/n_ would be added to the heredity in each generation, so that after _m_ generations the amount of hereditary development would be _x+mx/n_. If _n_ were 1000, then after 1000 generations the inherited effect would be equal to _x_. This, it is true, would not be a very rapid increase. But it is possible that the fraction _x/n_ would increase, for the heredity might very well consist not only in a growth independent of stimulation, but in an increasing response to stimulation, so that _x_ itself might be increasing, and the fraction _x/n_ would become larger in each generation. The death and loss of the skin over the antler, originally duo to the laceration of the skin in fighting, has also become hereditary, and it is certainly difficult to conceive the action of hormones in this part of the process. All we can suggest is that the hormone from the rapidly growing antler, including the covering skin, is acting on the corresponding factor in the gametocytes for a certain part of every year, and then, when the skin is stripped off, the hormone disappears. The factor then may be said to be stimulated for a time and then the stimulus suddenly ceases. The bone also begins to die when the skin and periosteum is stripped off, and the hormone from this also ceases to be produced. The annual shedding and recrescence of the antler, however, is only to be understood in connexion with the effect of the testicular hormone. According to my theory there are two hormone actions, the centripetal from the hypertrophied tissue to the corresponding factor in the gametocytes, and the centrifugal from the testis to the tissue of the antler or other organ concerned. The reason why the somatic sexual character does not develop until the time of puberty, and develops again each breeding season in such cases as antlers, is that the original hypertrophy due to external stimulation occurred only when the testicular hormone was circulating in the blood. The factor in the gametocytes then in each generation acted upon by both hormones, and we must suppose that in some way the result was produced that the hereditary development of the antler in the soma only took place when the testicular hormone was present. It is to be remembered that we are unable at present to form a clear conception of the process of development, to understand how the simple fertilised ovum is able by cell-division and differentiation to develop into a complicated organism with organs and characters predetermined in the single cell which constitutes the ovum. If we accept the idea that characters are represented by particular parts of the chromosomes, according to Morgan's scheme, our theory of development is the modern form of the theory of preformation. When in the course of development the cells of the head from which the antlers arise are formed, each of these cells must be supposed to contain the same chromosomes as the original ovum from which the cells have descended by repeated cell-division. The factors in these chromosomes corresponding to the forehead have been stimulated while in the parent animal by hormones from the outgrowth of tissue produced by external mechanical stimulation, while at the same time they were permeated by the testicular hormone produced either by the gametocytes themselves or by interstitial cells of the testis. When the head begins to form in the process of individual development, the factors, according to my theory, have a tendency to form the special growth of tissue of which the incipient antler consists, but part of the stimulus is wanting, and is not completed until the testicular hormone is produced and diffused into the circulation--that is to say, when the testes are becoming mature and functional. I do not claim that this theory in complete--it is impossible to understand the process completely in the present state of knowledge--but I maintain that it is the only theory which affords any explanation of the remarkable facts concerning the influence of the hormones from the reproductive organs on the development of secondary sexual characters, while at the same time explaining the adaptive relation of these characters or organs to the sexual habits of the various species. On the mutation hypothesis, adaptation is purely accidental. T. H. Morgan considers that the appearance of two slightly different shades of eye colour in male and female in a culture of a fruit-fly in a bottle is sufficient to settle the whole problem of sexual dimorphism, and to supersede Darwin's complicated theory of sexual selection. The possibility of a Lamarckian explanation he does not even mention. He would doubtless assume that the antlers of stags arose as a mutation, without explaining how they came to be affected by the testicular hormone, and that when they arose the stags found them convenient as fighting weapons. But the complicated adaptive relations are not to be disposed of by the simple word mutation. The males have sexual instincts, themselves dependent on the testicular hormone, which develop sexual jealousy and rivalry, and the Ruminants fight by butting with their heads because they have no incisor teeth in the upper jaw, or tusks, which are used in fighting in other species. Doubtless, mutations have occurred in antlers as in other characters; in fact all hereditary characters are subject to mutation. This in the most probable explanation, not only of the occasional occurrence of hornless individual stags, but of the differences between the antlers of different species, for there is no reason to believe that the special character of the antler in each species is adapted to a special mode of fighting in each species. The different structure of the horns of the Bovine and Ovine Ruminants is, in my view, the result of a different mode of fighting. If we suppose that the fighting was slower and less fierce in the Bovidae, so that the skin over the exostosis was subject to friction but not lacerated, the result would be a thickening of the horny layer of the epidermis as we find it, and the fact that the skin and periosteum are not destroyed explains why the horns are not shed but permanent. There is a tendency among Mendelians and mutationists to overestimate the importance of experiments in comparison with reasoning, either inductive or deductive. Bateson, however, has admitted that Mendelian experiments and observations on mutation have not solved the problem of adaptation. It seems to be demanded, nevertheless, that characters must be produced experimentally and then inherited before the hereditary influence of external stimuli can be accepted. Kammerer's experiments in this direction have been sceptically criticised, and it must be granted that the evidence he has published is not sufficient to produce complete conviction. But experiments of this kind are from the nature of the case difficult if not impossible. There is, however, another method--namely, to take a character which is certainly to some extent hereditary, and then to ascertain by experiment if it is 'acquired.' If it be proved that a hereditary character was originally somatogenic, it follows that somatogenic characters in time become hereditary. This is the reasoning I have used in reference to my experiments on the production of pigment on the lower sides of Flat-fishes, and I obtained similar evidence with regard to the excessive growth of the tail feathers in the Japanese Tosa-fowls, [Footnote: 'Observations and Experiments on Japanese Long-tailed Fowls,' _Proc. Zool. Soc._, 1903.] which is a modification of a secondary sexual character. In these fowls the feathers of the tail in the hens are only slightly lengthened. I learned from Mr. John Sparks, who himself brought specimens of the breed from Japan, that the Japanese not only keep the birds separately on high perches in special cages, but pull the tail feathers gently every morning in order to cause them to grow longer. One question which I had to investigate on my specimens, hatched from eggs obtained from Mr. Sparks, was the relation of the growth of the feathers to the moult which occurs in ordinary birds. My experiment consisted in keeping two cocks, A and B, the first of which was left to itself, while in the second the feathers were gently pulled by stroking between the finger and thumb from the base outwards. The feathers in the tail were seven pairs of rectrices, two rows of tail coverts, anterior and posterior, four or five pairs in each row, a number of transition feathers: all these were steel-blue, almost black; in front of them on the saddle were a number of reddish yellow, very slender saddle hackles. In September 1901, when the birds ware just over three months old, the adult feathers of the tail were all growing. The growing condition can be distinguished by the presence of a horny tubular sheath extending up the base of the feather for about one inch. When growth ceases this sheath is shed. In cock A growth continued till the end of the following March, when the longest feathers, the central rectrices, 2 feet 4-1/2 inches long. One of the feathers--namely, one of the anterior tail coverts--was accidentally pulled out on 11th February 1902, when it was 15-1/4 inches long and had nearly ceased to grow and formed its quill, and it immediately began to grow again and continued to grow till the following September, when it was accidentally broken off at the base: it was then 18 inches (44.5 cm.) long. The effect of stroking in cock B was to pull out from time to time one of the growing feathers. Of the original feathers, one, the left central posterior covert, continued to grow till 13th July 1902, when it was 2 feet 9-1/2 inches long without the part contained in the follicle. All the feathers pulled out immediately commenced to grow again, except the last two pulled out 27th May and 13th July, which did not grow again till the following moulting season, in September. The first right central rectrix in cock B was accidentally pulled out on 13th April 1902, when it was 2 feet 9-7/8 inches long. Its successor began to grow immediately, and in course of time pieces of it were broken off accidentally without injury to the base in the socket, which continued to grow until 16th June 1905, when it torn out of its socket. The total length of the feather with the pieces previously broken off, which were measured and preserved, was 11 feet 5-1/2 inches. It therefore continued to grow without interruption for three years and two months at an average rate of 3.6 inches per month. In cock A only four of the short outer rectrices were moulted in the beginning of September 1902: the longer feathers--namely, central rectrices and tail coverts--which ceased to grow naturally in the spring of 1902, were not moulted till the beginning of October. This shows the great importance of pulling out the feathers as soon as they show signs of ceasing to grow, in order to obtain the abnormally long feathers. The central rectrices continued to grow till the beginning of September 1903, when that of the left side was 3 feet 6 inches long, that of the right about an inch shorter. The coverts had ceased to grow of their own accord some time before this, and the central ones of the posterior row were about 3 feet long. As it seemed possible that there was some natural congenital difference in growth of feathers between cocks A and B, I commenced early in March 1903 to pull and stroke the feathers of the left side only in cock A, leaving those of the right side untouched. On 30th July on the left side the central rectrix and the first and second posterior coverts were still growing, on the right side the central rectrix was also growing, but the first and second posterior coverts had ceased growth and formed their quills. The first posterior covert on the left or pulled side was 3 inches longer than that of the right. The second posterior covert on the left side was still longer. The first and second posterior coverts of left side did not cease growth till 26th August. On 2nd September the left central rectrix was almost at the end of its growth, the right had ceased to grow a little before. The left was about an inch longer than the right. Thus both in length in duration of growth the feathers of the pulled side were longer than those of the right, and this was the result of treatment continued only six months, and commenced some months after the feathers had begun to grow. I have no doubt, however, that the pulling out of the feather as soon as it shows signs of forming quill, so that its successor at once grows again, is even more important in producing the great length of feather than the stroking of the feather itself. In this case, then there is no doubt (_a_) that the long-tailed birds are artificially treated with the utmost care and ingenuity by the Japanese, who produced them; (_b_) that the mechanical stimulus in my experiments did cause the feathers to grow for a longer period and attain greater length; (_c_) that the tendency to longer growth is, even when no treatment is applied, distinctly inherited. It is a legitimate and logical conclusion that the inherited tendency is the result of the artificial treatment. No other breed of fowls shows such excessive growth of tail feathers. It may be admitted that individuals differ considerably in their congenital tendency to greater growth, _i.e._ greater length of the tail feathers, but according to my views this is not contradictory to the main conclusion, for every hereditary character shows individual variation. It may be pointed out here that on the Lamarckian theory the conception of adaptations is not teleological: they do not exist for a certain purpose, but are the result of external stimulations arising from the actions and habits of the organism. The latter conception is the more general, for cases of somatic sexual characters exist which cannot be said to have a use or function. For example, the comb and wattles of _Gallus_ are sexually dimorphic, being in the original species larger in the cock than in the hen. There is no convincing evidence that these appendages are either for use or ornament. They are, in fact, a disadvantage to the bird, being used by his adversary to take hold of when he strikes. The first thing that happens when cocks fight is the bleeding and laceration of the comb, as they peck at each other's heads. This laceration of the skin is, in my view, the primary cause of the evolution of these structures, leading to hypertrophy. But in this, as in other cases, the hereditary result is regular, constant, and symmetrical, while the immediate effect on the individual is doubtless irregular. CHAPTER V Mammalian Sexual Characters Evidence Opposed To The Hormone Theory Perhaps the most remarkable of all somatic sexual characters are those which are almost universal in the whole class of Mammalia, the mammary glands in the female, the scrotum in the male. We have considered the evidence concerning the relation of the development and functional action of the milk glands to hormones arising in the ovary or uterus, now we have to consider the origin of the glands and of their peculiar physiology in evolution. The obvious explanation from the Lamarckian point of view, and in my opinion the true one, is that they owed their origin at the beginning to the same stimulation which is applied to them now in every female mammal that bears young. There is, as we have seen, a difficulty in explaining how the occurrence of parturition causes the secretion of milk to begin, but it is certain that the secretion soon stops if the milk is not drawn from the glands by the sucking action of the offspring, or the artificial imitation of that action. A cow that is not milked or milked incompletely ceases to give milk. When the stimulus ceases, lactation ceases. The pressure of the secretion in the alveoli causes the cells to cease to secrete, much in the same way that pressure in the ureters injures the secretory action of the renal epithelium. In the earliest Mammals we may suppose that the young were born in a well-developed condition, for at first the supply of milk would not have been enough to sustain them for a long time as their only food. We must also suppose that the mother began to cherish the young, keeping them in contact with her abdomen. Then being hungry they began to suck at her hair or fur. The actual development of the milk glands in Marsupials has been described by Bresslau [Footnote: Stuttgart, 1901.] and by O'Donoghue. [Footnote: _Q.J.M.S._, lvii., 1911-12.] The rudiment of the teat is a depression or invagination of the epidermis from the bottom of which six stout hairs arise. The follicles of these hairs extend down into the derma, and from the upper end of the follicle, _i.e._ near the aperture of the invagination, a long cellular outgrowth extends down into the derma, branches at its end, and becomes hollow. These branches are the tubules of the future milk gland. Another outgrowth from the follicle forms a sebaceous gland. Later on the hairs and the sebaceous glands entirely disappear, and the milk gland alone is left with its tubules and ducts opening into the cavity of the teat. This is clear evidence that the milk gland was evolved in connexion with hairs, and was an enlargement of glands opening into the hair follicle, but it is difficult to understand why a sebaceous gland is developed and afterwards disappears. This would seem to indicate that the milk gland was not a hypertrophied sebaceous gland, but a distinct outgrowth, which however had nothing to do with sweat glands. That the intra-uterine gestation, or its cessation, were not originally necessary to determine the functional periodicity of the milk glands is proved by their presence in the Monotremes, which are oviparous. It is evident from the conditions in these mammals that both hair and milk glands were evolved before the placenta. It may also be pointed out here that, according to the evidence of Steinach, in the milk glands at least among somatic sexual characters there is no difference between the male and female in the heredity of the organs. The zygote therefore, whether the sex of it is determined as male or female, has the same factor for the development of milk glands. On the chromosome theory as formulated by Morgan this factor must be in the somatic chromosomes and not in the sex-chromosomes, and must be present in every zygote. All the cells of the body, assuming that somatic segregation does not occur, must possess the same chromosomes as the zygote from which it developed, and whether the sex chromosomes are _XX_ or _XY_ or _X_, there must be at any rate one chromosome bearing the factor for milk glands. The functional development of these depends normally, according to the evidence hitherto discovered, on the presence or absence of hormones from the ovary or from the uterus. If we attribute, as in my opinion we must, the primary origin of the milk glands in evolution to the mechanical stimulus of sucking, we may attempt to reconstruct the stages of the evolution of the present relation of the glands to the other organs and processes of reproduction. In the earliest stage represented by the Monotremata or Prototheria, there was no intra-uterine development. We must suppose that in the beginning the sucking stimulus caused both growth and secretion, for at first there was nothing but sebaceous or sweat glands, and although a mutation might be supposed to have produced larger glands, no mutation could explain the influence of hormones on the growth and function of such glands. Then heredity of the effect of stimulus took place to some slight degree, and this would occur, according to my theory, only in the presence of the hormone from the ovary in the same condition as that in which the modification was first caused. This would be of course after ovulation, and after hatching of the eggs. In the next stage, if we adopt the modern view that Marsupials are descended from Placental Mammals, the eggs would be retained for increasing periods in the uteri, and would be born in a well-developed condition, since lactation would demand active sucking effort on the part of the young. The early Placentalia would inherit from the Monotreme-like ancestors the development of the milk glands after ovulation, although no sucking was taking place while the young were inside the uterus. It seems probable that the relation between parturition and actual milk secretion originated with the sucking stimulus of the young after birth. There is good evidence that the secretion of milk may continue almost indefinitely under the stimulus of sucking or milking. Neither menstruation nor gestation put an end to it. Cows may continue to give milk until the next parturition, and if castrated during lactation will continue to yield milk for years. Women also may continue to produce milk as long as the child is allowed to suck, and this has been in some cases two or three years or even more. Moreover, lactation may be induced by the repeated act of sucking without any gestation. This has happened in mares, virgin bitches, mules, virgin women, and in one woman lactation continued uninterruptedly for forty-seven years, to her eighty-first year, long after the ovary had ceased to be functional. Lactation has also been induced in male animals, _e.g._ in a bull, a male goat, male sheep, and in men. [Footnote: Knott, 'Abnormal Lactation,' _American Medicine_, vol. ii (new series), 1907.] We may conclude, therefore, that the secretion of milk normally begins by heredity after parturition, and this, in accordance with what we have learned about hormones in connexion with the reproductive system, is probably the consequence of the withdrawal of the hormone absorbed from the foetus. I do not think it is necessary to suppose, as do Lane-Claypon and Starling, that the hormone physiologically inhibits the dissimilative process and augments the assimilative, and that the withdrawal of the hormone at parturition therefore causes the dissimilative process, _i.e._ secretion of milk. My conclusion is that the process of secretion set up by the mechanical stimulus of sucking is inherited as it was acquired, so that it only begins to take place in the individual in the absence of the hormone from the foetus, which was absent when the process was acquired. The growth of the gland during gestation would then be due to the postponement of the process of secretion in consequence of the presence of the foetal hormone, and in this way this hormone has become in the course of evolution at once the stimulus to growth and the cause of the inhibition of secretion. This interpretation does not, however, agree with the case of _Dasyurus_. If the foetal hormone is absorbed from the pouch, as I have suggested, in order to explain the persistence of the corpora lutea during lactation, then the secretion of milk after parturition ought not to take place. But in this case the sucking stimulus has been applied to the glands after a very short gestation, while the hormone from the foetus is being absorbed in the pouch, and therefore the hereditary correlation between secretion and absence of foetal hormone may be assumed to have been lost in the course of evolution. We have next to consider the question of the evolution of the corpora lutea. If these bodies are formed only in Mammals which have uterine gestation, and not in Prototheria, they cannot be the only essential source of the hormone which stimulates the development of the milk glands, since the latter develop in Prototheria. Again it is difficult, it might be said impossible, to believe that an accidental mutation gave rise to corpora lutea the secretion of which caused uterine gestation and ultimately the formation of the placenta. It seems more probable that the retention of the originally yolked ova within the oviduct, however this retention arose, was the essential cause of the formation of the placenta and all the changes which the uterus undergoes in gestation. The absorption of nutriment from the walls of the uterus, and the chemical and mechanical stimulation of those walls, might well be the cause of the diversion of nutrition from the ovary, leading gradually to the decline of the process of secretion of yolk in the ova. The conceptions and the mode of reasoning of the physiologist are very different from those of the evolutionist. The former concludes from certain experiments that a given organ of internal secretion has a certain function. The corpora lutea, for example, according to one theory are ductless glands, the function of whose secretion is to establish ova in the uterus and promote their development. Another function suggested for the secretion of the corpora lutea is to prevent further ovulation during pregnancy. The evolutionist, on the other hand, asks what was the origin of this corpora lutea, why should the ruptured ovarian follicles after the escape of the ova in Mammals undergo a progressive development and persist during the greater part of the whole of pregnancy? It seems obvious that the corpora lutea in evolution were a consequence of intra-uterine gestation, for they occur only in association with this condition, and it is impossible to suppose that a mutation could arise accidentally by which the ruptured follicles should produce a secretion which would cause the fertilised ova to develop within the oviducts. The developing ovum within the uterus may, however, reasonably be supposed to give off something which is absorbed into the maternal blood, and this something would be of the same nature as that which was given off by the ovum while still within the ovarian follicle. The presence of this hormone might cause the follicular cells to behave as though the ovum was still present in the follicle, so that they would persist and not die and be absorbed. But this leaves the question, what is lutein and why is it secreted? Lutein is a colouring matter sometimes found in blood-clots, and probably derived from haemoglobin. In the corpus luteum the lutein is contained in the cells, not in a blood-clot. Chemical investigation shows that the lutein of the corpus luteum is almost if not quite identical with the colouring matter of the yolk in birds and reptiles. Escher [Footnote: _Ztschr. f. Physiol. Chem._, 83 (1912).] found that the lutein of the corpus luteum had the formula C{40}H{56} and was apparently identical with the carotin of the carrot, while the lutein of egg-yolk was C{40}H{56}O{2} and more soluble in alcohol, less soluble in petroleum ether, than that of the corpus luteum. The difference, if it exists, is very slight, and it is evident that one compound could easily be converted into the other. Moreover, the hypertrophied follicular cells which constitute the corpus luteum secrete fat which is seen in them in globules. The similarity of their contents therefore to yolk is very remarkable, and it may be suggested that the hormones absorbed from the ovum or embryo in the uterus acts upon the follicular cells in such a way as to cause them to secrete substances which in the ancestor were passed on to the ovum and formed the yolk. It may be urged that this idea is contradictory to the previous suggestion that the absorption of nourishment by the intra-uterine embryo was the cause of the gradual decline of the process of yolk-secretion by the ova in the ovary, but it is not really so. Originally in the reptilian ancestor, or in the Monotreme, the ovum in the follicle secreted yellow-coloured yolk. The materials for this, at any rate, passed through the follicle cells, and it is probable that these cells were not entirely passive, but actively secretory in the process. Substances diffusing from the ovum would be present in the follicle cells during this process, and probably act as a stimulus. The same substances diffusing from the ovum during its development in the uterus would continue to stimulate the follicle cells, and thus explain not merely their persistence, but their secretory activity. The ovum being no longer present in the ovary, the secretions would remain in the follicular cells, and the corpus luteum would be explained. If this theory is sound, it would follow that corpora lutea are not formed in cases where the ova are not retained in the oviduct during their development. The essential process in the development of these structures is the hypertrophy and, in some cases at least, multiplication of the follicular cells in the ruptured follicle. I have already mentioned that this process does not occur in Teleosteans whose ovaries were studied by me. These were species of Teleosteans in which fertilisation is external. Marshall, in his _Physiology of Reproduction_, [Footnote: London, 1910, p. 151.] quotes a number of authors who have published observations on the changes occurring in the ruptured follicle in the lower Vertebrata, and also in the Monotremes. According to Sandes, [Footnote: 'The Corpus Luteum of Dasyurus,' _Proc. Lin. Soc._, New South Wales, 1903.] in the latter there is a pronounced hypertrophy of the follicular epithelium after ovulation, but no ingrowth of connective tissue or blood-vessels from the follicular wall. Marshall himself examined sections of the corpus luteum of _Ornithorhynchus_ and saw much hypertrophied and apparently fully developed luteal cells, but no trace of any ingrowth from the wall of the follicle. This fact would appear to be quite inconsistent with the theory above proposed, but it must be remembered that the ovum of Monotremes is known to remain for a short period in the oviduct, or in other words to pass through it very slowly, and to absorb fluid from its walls, as shown by the considerable increase in size which the ovarian ovum undergoes before it is laid. It would be interesting to know how long the rudimentary corpus luteum persists in _Ornithorhynchus_: the period, according to my views, should be very short. It is remarkable that in the results quoted by Marshall a well-developed corpus luteum was found and exclusively found in the lower Vertebrates which are viviparous. For example, among fishes in the Elasmobranchs _Myliobatis_ and _Spinax_; in Teleosteans, in _Zoarces_; in Reptiles, in _Anguis_ and _Seps_. Bühler on the other hand, confirmed my own negative result with regard to oviparous Teleosteans, and also found no hypertrophy of the follicle in Cyclostomes which are also oviparous. In the viviparous forms mentioned there is yolk in the ovum which is retained in oviduct or ovary, but additional nutriment is also absorbed from the uterine or ovarian walls. In these cases there is no placenta and generally no adhesion of ovum or embryo to walls of oviduct or ovary. These facts alone would be sufficient to disprove the theory that the corpora lutea are organs producing a secretion whose function is to cause the attachment of the embryo to the uterine mucosa. It is also, in my opinion, unreasonable to suppose that the rudimentary corpora lutea of lower viviparous Vertebrates arose as a mutation the result of which was to cause internal development of the ovum. Habits might easily bring about retention of the fertilised ova for gradually increasing periods, [Footnote: According to Geddes and Thomson (_Evolution of Sex_, 1889), the common grass-snake has been induced under artificial conditions to bring forth its young alive.] and the correlation between the retained developing ova and the hypertrophy of the ruptured follicles is comprehensible on my theory of the influence of substances absorbed by the walls of oviduct or ovary from the developing ovum. The case of _Dasyurus_, however, seems inconsistent with this argument, for, as previously mentioned, Sandes found that in this Marsupial the corpora lutea persisted during the greater part of the period of lactation, which continues for four months after parturition. During the whole of this time there are no embryos in the uteri, and therefore it might be urged absorption of hormones from the embryos cannot be the cause of the persistence of corpora lutea in pregnancy. But it seems to me that a complete answer to this objection is supplied by the peculiar relations of the embryos to the pouch in _Dasyurus_ and other Marsupials. The skin of the pouch while the embryos are in it is very soft, congested, and glandular; at the same time the embryos when transferred to the pouch at parturition are very small, immature, and have a soft delicate skin. The relation of embryos to pouch in _Dasyurus_, therefore, is closely similar to that of embryos to uterus after the first few days of pregnancy in the Eutheria. It is true there is no placenta, but the mouths of the embryos are in very close contact with the teats, and both the skin of the embryos and that of the pouch are soft and moist. If any special substances are given off by the embryos in the uterus in ordinary gestation, the same substances would continue to be given off by the embryos in the marsupial pouch, and these must be absorbed by the skin of the pouch. In this way it seems to me we have a logical explanation of the fact that the corpora lutea in the Marsupial are not absorbed at parturition as in Eutheria. As Sandes says the 'greater part of the period of lactation,' it would appear that absorption of the corpora lutea takes place when the young _Dasyurus_ have grown to some size, become covered with hair, and are able to leave the teats or even the pouch at will. Under these conditions it is obvious that diffusion of chemical substances from the young through the walls of the pouch would come to an end. It would be interesting in this connexion to know more of the relation of egg and embryo to the pouch and to the corpora lutea in _Echidna_. In _Ornithorhynchus_ the eggs are hatched in a nest and there is no pouch. On this view that the corpora lutea are the result, not the cause, of intra-uterine gestation, it would no longer be possible to maintain the theory that the corpus luteum in the human species is the cause by its internal secretion of the phenomenon of menstruation. This was the theory of Born and Fränkel. [Footnote: See Biedl, _Internal Secretory Organs_ (Eng. trans.), 1912, p. 404.] Biedl's conclusion is that the periodic development and disintegration of the uterine mucous membrane in the menstrual cycle is due to the hormone of the interstitial cells of the ovary. Leopold and Ravana found that ovulation as a rule coincides with menstruation, but may take place at any time. Here, again, the problem must be considered from the point of view of evolution. It can scarcely be doubted that the thickening and growth of the mucous membrane in the menstrual cycle is of the same nature as that which takes place in pregnancy. When the ovum or ova are not fertilised the development comes to an end after a certain time, differing in different species of Mammals, and the membrane sloughs, returns to its original, state, and then begins the same process of development again. Menstruation, then, must be interpreted as an abortive parturition, both in woman and lower Mammals, though in the latter it is not usually accompanied by hemorrhage, and is called pro-oestrus. The question then to be considered is, what determines parturition and menstruation? The presence of the fertilised ovum must have been the original cause of the hypertrophy of the uterine mucous membrane, and in its congenital or hereditary development the chemical substances diffusing from the ova in the uterus or even in the Fallopian tube may well be the stimulus starting the hypertrophy. But what determines the end of the pregnancy? Is it merely the increasing distension of the uterus by the developing foetus? This could scarcely be the case in the Marsupials in which the foetus when born is quite minute. Nor can we attribute parturition to renewed ovulation, for this occurs in _Dasyurus_ only once a year. All we can suggest at present is that a certain periodic development takes place by heredity in presence of the hormones exuded by the fertilised ovum and the embryo developed from it. When the ovum or ova, not being fertilised, die the period of development is (usually) shortened and pro-oestrus or menstruation occurs. In the dog, however, the period of the oestrus cycle is about the as that of gestation--namely, six months. The so-called descent of the testicles occurs exclusively in Mammals, in which with a few important exceptions it is universal. This is a very remarkable case of the change of position of an organ in the course of development. The original position of the testis on either side is quite similar to that of the same organ in birds or reptiles. The genital ridge runs along the inner edge of the mesonephros, with which the testicular tubules become connected. The testis, with the mesonephros, forming the epididymis, closely attached to it, projects into the coelom, and without losing its connexion with the peritoneum changes its position gradually during development, passing backwards and downwards until it comes to lie over the wall of the abdomen just in front of the pubic symphysis of the pelvic girdle. There the abdominal wall on either side of the middle line becomes thin and distended to form a pouch, the scrotal sac, into which the testis passes, still remaining attached to the peritoneum which lines the pouch, while the distal end of the vas deferens retains its original connexion with the urethra. The movement of the testis can thus be accurately described as a transposition or dislocation. Various causes have been suggested for the formation of the scrotum, but no one has ever been able to suggest a use for it. It has always been quite impossible to bring it within the scope of the theory of natural selection. The evolution of it can only be explained either on the theory of mutation or some Lamarckian hypothesis. The process of dislocation of the testis does not conform to the conception of mutation, nor agree with other cases of that phenomenon. A mutation is a change of structure affecting more or less the whole soma, but showing itself especially in some particular organ or structure. But I know of no mutation occurring under observation which consisted, not in a change of structure or function, but merely in a change of position of an organ from one part of the body to another, and moreover a change which takes place by a continuous process in the course of development. If the testes were developed from the beginning in a different part of the abdomen, there might be some reason in calling the change a mutation. Moreover, if it is a mutation, why has it never occurred in any other class of Vertebrates except Mammals? In 1903 Dr. W. Woodland published [Footnote: _Proc. Zool. Soc._, 1903, Part 1.] a Lamarckian theory of this mammalian feature, the probability of which it seems to me has been increased rather than decreased by the progress of research concerning heredity and evolution since that date. Dr. Woodland correlated the dislocation of the testes with the special mechanical features of the mode of locomotion in Mammalia. His words are: 'The theory here advocated is to the effect that the descent of the testes in the Mammalia has been produced by the action of mechanical strains causing rupture of the mesorchial attachments, such strains being due to the inertia of the organs reacting to the impulsiveness involved in the activity of the animals composing the group.' The 'impulsiveness' is the galloping or leaping movement which is characteristic of most Mammals when moving at their utmost speed, as seen, for example, in horses, deer, antelopes, dogs, wolves, and other Ungulata and Carnivora. It is obvious that when the body is descending to the ground after being hurled upwards and forwards, the abdominal organs have acquired a rapid movement downwards and forwards; when the body reaches the ground its movement is stopped suddenly, while the abdominal organs continue to move. The testes therefore are violently jerked downwards away from their attachments and at the same time forward. The check to the forward movement, however, is momentary, while the body is immediately thrown again upwards and forwards, which by the law of inertia means that the testes are thrown still more downwards and backwards. There is no reason to suppose, as Dr. Woodland suggests, that any rupture of the mesorchium was the usual result of these strains, but a constant pull or tension was caused in the direction in which the testes actually move during development. On this theory we have to consider (1) how such strains could cause a shifting of the peritoneal attachment, (2) why the testes should be supposed to be particularly affected more than other abdominal organs. The answer to the first question is that the strains would cause a growth of the connecting membrane (mesorchium) at the posterior end, accompanied by an absorption of it at the anterior end. The answer to the second question is that the testes are at once the most compact and heaviest organs in the abdomen, and at the same time the most loosely attached. The latter statement does not apply to the mesonephros or epididymis which has moved with the testis, but the latter cannot function without the former, and it may be supposed that the close attachment of the epididymis to the testis had come about in the early Mammalia before the change of position was evolved. It is evident that the violent shocks of the galloping or leaping movement do not occur in Birds, Reptiles, or Amphibia. Ostriches run very fast and do not fly, but their progression is a stride with each foot alternately, not a gallop. The Anura among the Amphibia are saltatory, but their leaps are usually single, or repeated only a few times, not sustained gallops. The exceptions among the Mammalia still more tend to prove the close correspondence between the 'impulsive' mode of progression and the dislocation of the male gonads. In the Monotremata there is no scrotum, the testes are in a position similar to that which obtains in Reptiles, and they are the only Mammals in which these organs are anterior to the kidneys. In locomotion they are sluggish, there is no running or galloping among them. _Ornithorhynchus_ is aquatic in its habits, and _Echidna_ is nocturnal and moves very slowly. In Marsupials the scrotum is in front of the penis, but really in the same position as in other Mammals--that is, in front of the ventral part of the pelvic girdle. It is the penis which is different, as the skin around the organ has not united in a ventral suture below it, while the organ itself has not grown forward adnate to the abdominal skin as in most other Mammals. The scrotum is always anterior to the origin of the penis, although in the Eutheria apparently behind that organ. The larger Marsupials like the kangaroos are eminently saltatory, and the others are active in locomotion. The aquatic Mammals Sirenia and Cetacea have no scrotum, the testes being abdominal. It is unnecessary to inquire whether this is the original position, or whether they are descended from ancestors which had a scrotum: in either case the position of the testes corresponds to the absence of what Dr. Woodland calls impulsiveness in progression. The Fissipedia offer an instructive example, for while the Otariidae have the hind feet turned forward and can move on land somewhat like ordinary Mammals, the Phocidae cannot move their hind legs independently or turn them forward, and can only drag themselves about on land for short distances. In the former the testes are situated in a well-defined scrotum, in the latter these organs are abdominal. The Phocidae are probably descended from Mammals of the terrestrial type with a scrotum, which has disappeared in the course of evolution. Perhaps the most curious exception is that of the elephants, in which the testes are abdominal. Here, in consequence of their structure and massive shape, locomotion in usually a walk, and though they run occasionally the gait is a trot, not a sustained gallop, and leaping is out of the question. Sloths which hang from branches upside down have abdominal testes, but even here they are in a posterior position, between, the rectum and the bladder, so there has apparently been a degree of dislocation, probably inherited from ancestors with more terrestrial habits. The fact that the ovaries do not occupy normally a position similar to that of the testes is in accordance with the theory, for they are very much smaller than the testes; and yet they have undergone some change of position, for they are posterior to the kidneys. The facts agree with the hormone theory, for it is to be noted that although the development of the scrotum is confined to the males, the 'descent' or dislocation takes place in the foetus, and not at the period of puberty. This is in accordance with the fact that the mechanical conditions to which the change is attributed are not related to sexual habits, but to the general habits of life which begin soon after birth. The development, therefore, may be considered to be related to the presence of a hormone derived from the normal testis, but not to a special quantity or quality of hormone associated with maturity or the functional activity of the organ. In Rodents, however, there is a difference in the organs, not only at maturity, but in every rutting season, at any rate in Muridae such as rats and others. In the rutting season the testes become much larger and descend into the scrotal sacs, at other times of the year being apparently more or less abdominal. In rabbits and hares, which have a much more impulsive progression, the organs seem to be always in the scrotal sacs. It might be thought that in this case, although the hormone theory of heredity might be applied, there was no reason to suppose that a hormone derived from the testis in the individual development was necessary in order that the hereditary change should take place. If the individual was male and therefore had a testis, this organ would by heredity go through the process of dislocation. But there is the curious fact that when the descent is not normal and complete, in what is called cryptorchidism, the organs are always sterile. The retention of the testes within the abdomen may be regarded as a case of arrested development, like many other abnormalities, but this does not explain why the retained testes should always be sterile, without spermatogenesis. If the inherited or congenital process of dislocation requires the presence of hormones produced by a normal testis, then we can understand why a defective testis does not descend completely, because it does not produce the hormone which is necessary to stimulate the hereditary mechanism to complete dislocation. It is often stated that in cryptorchidic individuals the sexual instincts and somatic sexual characters are well developed, which would appear contradictory to the above explanation, but according to Ancel and Bouin such individuals in the case of the pig show considerable differences in the secondary signs of sex and in the external genital organs, presenting variations which lie between the normal and the castrated animal. We have here, then, in the position of the testes in Mammalia a condition which is not in the slightest degree 'adaptive' in the ordinary sense-- that is, fulfilling any special function or utility. The condition must be regarded as distinctly disadvantageous, since the organs are more exposed to injury, and the abdominal wall is weakened, as we know from the risk of scrotal hernia in man. But from the Lamarckian point of view the facts support the conclusion that the condition is the effect of certain mechanical strains, and is of somatic origin, while the correlations here reviewed are entirely unexplained by any theory of mutation or blastogenic origin. OPPOSING EVIDENCE We have now to review certain cases which seem to support conclusions contrary to those which we have maintained in the preceding pages, and to consider the evidence which has been published in support of other theories. It must be admitted that the occurrence of male secondary characteristics on one side of the body, and female on the other, is in consistent with the view that the development of such characters is due to the stimulus of a hormone, since the idea of a hormone means something which diffuses by way of the blood-vessels, lymph-vessels, and interstices of the tissues, throughout the body, and the hormone theory of secondary sexual characters assumes that these characters are potentially present by heredity in both sexes. The occurrence of male somatic characters on one side or in some part of the body and female on the other, usually associated with the corresponding gonads, has been termed gynandromorphism, and has long been known in insects. Cases of this condition have been observed, though much more rarely, in Vertebrates. I am not aware of any authentic instances in Mammals, and the supposition that in stags reduction or abnormality of one antler may be the result of removal or injury to the testis of one side, or the opposite, have been completely disproved by experiments in which unilateral castration has been carried out without any effect on the antlers at all. In birds, however, a few cases have been recorded by competent observers with a definiteness of detail which leaves no possibility of doubt. One of the more recent of these is that of a pheasant of the white-ringed Formosan variety, _P. torquatus_, of the Chinese pheasant. [Footnote: C. J. Bond, 'Unilateral Development of Secondary Male Characters in a Pheasant,' _Journ. of Genetics_, vol. iii., 1914.] On the left side this bird shows the plumage, colour, and the spur of the male; on the right leg there is no spur except the small rudiment normally occurring in the hen. The difference in plumage between the two sides, however, is not complete. The white collar is strictly limited to the left side, but the iridescent blue green of head and neck is present on both sides, though more marked on the left. Only a few male feathers appear in the wing coverts of the left side. The breast feathers are rufous, especially on the left side. The tail coverts show marked male characters, more especially on the left side. In the tail, however, the barred character of the male is not present on one side, absent on the other, but in most of the feathers is confined to one, the _outer_ side of each feather. With regard to the gonads, in this bird a single organ was found on the left side, _i.e._ in the position of the ovary in normal females, and there was no trace of a gonad on the right side. The organ present was small, 3/4 inch long by 1/2 inch broad, and microscopic sections showed in one part actively growing areas of tubular gland structure in some of which bodies like spermatozoa could be detected, while in another were fibrous tissue with degenerating cysts. The latter appear to have been degenerating egg follicles. The author concludes that the organ was originally a functional ovary, and that the ovarian portion had atrophied while a male portion had become functionally active. Another case in birds was described by Poll [Footnote: _B.B. Ges. Naturf. Freunde_, Berlin, 1909.] and is mentioned by Doncaster. [Footnote: _Determination of Sex_, Cambridge, 1914.] It is that of a Bullfinch which had the male and female plumage sharply separated on the two sides of the body. The right side of the ventral surface was red like a normal male, the left side grey like a normal female. In this case there was a testis on the right side, on the left an ovary as in normal females. A third case in birds, somewhat different from the two first mentioned, is that of a domestic fowl described by Shattock and Seligmann. [Footnote: _Trans. Pathol. Soc._ (London), vol. 57, Part i., 1906.] It was a bird of the Leghorn breed, two years old, and had the fully developed comb and wattles of the cock. Each leg bore a thick blunt spur, nearly an inch in length, but in the Leghorn breed spurs are by no means uncommon in hens of mature age, before they have ceased to lay eggs. In plumage the characters were mainly female. The colour being white could not show sexual differences, the neck hackles were but moderately developed, saddle hackles practically absent, the tail resembled that of the hen. There was a fully developed oviduct on the left side, on the right another less than half the full length. There was also a vas deferens on each side. There was a gonad on each side, that of the right about one-fourth the size of that on the left. In microscopic structure the right gonad resembled a testis consisting entirely of tubuli lined by an epithelium consisting of a single layer of cells. In one part of this organ the tubules were larger than elsewhere, and one of them exhibited spermatogenesis in progress. The left and larger gonad had a quite similar structure, but at its lower end were found two ova enclosed within a follicular epithelium. With regard to the last case it is to be remarked that though the gonad on the right side was entirely male, there was no unilateral development of male characters. With regard to the other two cases it must be pointed out (1) that the difference between the two somatic sex-characters on the two sides is chiefly a difference of colour, except the difference in the spurs in Bond's pheasant; (2) that the evidence already cited shows that in fowls castration does not prevent the development of the colour and form of the male plumage, nor of the spurs: that in drakes, although castration does not seem to have been carried out on young specimens before the male plumage was developed, when performed on the mature bird it prevents the eclipse, and does not cause the male to resemble the hen. Castration, then, tends to prove that in Birds the development of the male characters is not so closely dependent on the stimulation of testicular hormone as in Mammals. The characters must therefore be developed by heredity in the soma, which implies that the soma must itself be differentiated in the two sexes. The development must therefore be more in the nature of gametic coupling. It does not follow that the primary sex-character or the somatic characters are exclusive in either sex. We may suppose that the zygote contains both sexes, one or other of which is dominant, and that dominance of one primary sex involves dominance of the corresponding sexual characters. This does not, however, agree with the result of removal of the ovaries in ducks, for this causes the characters of the male to appear, so that the dominance of the female is not a permanent condition of the soma but is dependent on the ovarian hormone. In the hermaphrodite individuals mentioned above the difference of dominance is on two sides of the body instead of two different individuals. It may also be remarked here that while it is very difficult to believe that spurs were not due in evolution to the mechanical stimulation of striking with the legs in combat, and while specially enlarged feathers are erected in display, we cannot at present attribute the varied and brilliant _colour_ of male birds to the direct influence of external stimuli. In Lepidoptera among insects the evidence concerning castration tends to prove that hormones from the gonads play no part at all in the development of somatic sexual characters. Kellog, an American zoologist, in 1905 [Footnote: _Journ. Exper. Zool._ (Baltimore), vol. i., 1905.] described experiments in which he destroyed by means of a hot needle the gonads in silkworm caterpillars (_Bombyx mori_), and found no difference in the sexual characters of the moths reared from such caterpillars. Oudemans had previously obtained the same result in the Gipsy Moth, _Limantria dispar_. Meisenheimer [Footnote: _Experimentelle Studien zur Soma- und Geschlechtedifferenzierung_. Jena, 1909.] made more extensive experiments on castration of caterpillars in the last-mentioned species, in which the male is dark in colour and has much-feathered antennae, while the female is very pale and has antennae only slightly feathered. In the moths developed from the castrated larvae there was no alteration in the male characters, and in the females the only difference was that some of them were slightly darker than the normal. Meisenheimer and Kopee after him claim to have grafted ovaries into males and testes into females, with the result that the transplanted organs remained alive and grew, and in some cases at least became connected with the genital ducts. Even in these cases the moth when developed showed the original characters of the sex to which belonged the caterpillar from which it came, although it was carrying a gonad of the opposite sex. It will be seen that these results are the direct opposite of those obtained by Steinach on Mammals. We have no evidence that the darker colour of the normal male in this case is adaptive, or due to external stimuli, but the feathering of the antennae is generally believed to constitute a greater development of the olfactory sense organs, and is therefore adaptive, enabling the male to find the female. This is therefore the kind of organ which would be expected to be affected by hormones from the generative organs. It is stated that the sexual instincts were also unaltered, a male containing ovaries instead of testes readily copulating with a normal female. These results, almost incredible as they appear, are in harmony with the relatively frequent occurrence of gynandromorphism in insects.[Footnote: See Doncaster, _Determination of Sex_ (Camb. Univ. Press, 1914), chap. ix.] One of the most remarkable cases of this is that of an ant (_Myrmica scabrinodis_) the left half of which is male, the right half not merely female, but worker--that is, sterile female, without wing. Cases in Lepidoptera, _e.g. Amphidasys betularia_, have frequently been recorded. Presumably not only the antennae and markings, but also the genital appendages and the gonads themselves, are male and female on the two sides. On the view that both sexes and the somatic sex-characters of both sexes are present in each zygote, and that the actual sex is due to dominance, we must conclude that the male primary and secondary characters are dominant on one side, and the female on the other, and it is evident that hormones diffusing throughout the body cannot determine the development of somatic sexual characters here. Various attempts have been made to explain gynandromorphism in insects in accordance with the chromosome theory of sex-determination. These are discussed by Doncaster in the volume already cited, but from the point of view of the present work the important question is that concerning the somatic sex-characters. According to Doncaster it has been found that in some Lepidoptera the different sex-chromosomes occur in the female, not in the male as in other insects. Half the eggs, therefore, contain an X chromosome, and half a Y, while all the sperms contain an X chromosome. Doncaster has seen in _Abraxas grossulariata_ ova with two nuclei both undergoing maturation. If one of these in reduction expelled a Y chromosome, the other an X, then one would retain an X and the other a Y. Each was fertilised by a sperm, one becoming therefore XX or male and the other XY or female. It may be supposed that as there was only the cytoplasm of one ovum, each nucleus would determine the characters of half the individual developed. The question remains, therefore, where are the factors of the somatic sex-characters? One suggestion which might be made is that the female characters are present in the _Y_, in this case female producing chromosome, or, if the female characters are merely negative, that the male characters are in the _X_ chromosome, but only show themselves in the homozygous condition, thus:-- FEMALE x MALE XY XX | \/ | | /\ | XX YX MALE FEMALE The male characters in the male, _XX_, would appear because present in two chromosomes, but would be recessive in the female because present only in one chromosome. The validity of this scheme, however, is disproved by the fact that males can transmit the female characters of their race, as in the case mentioned by Doncaster where a male _Nyssia zonaria_ when crossed transmits the wingless character of its own female. Another, perhaps better, suggestion is that the somatic characters of both sexes are present in each. Then as each somatic cell is descended without segregation from the fertilised ovum, we may suppose that the presence of the sex-chromosomes in the somatic cells themselves in some way determines whether male or female characters shall develop, without the aid of any hormones from the gonads. This theory would be quite compatible with the belief that adaptive somatic sex-characters may be due to external stimulation, for supposing that the hypertrophy or modification is conveyed to the determinants in the gametocytes, and was confined to one sex, _e.g._ the male, then these determinants would be modified in association with the sex-chromosomes of that sex, and thus though after reduction and fertilisation they would be present in the female zygote also, they would not develop in that sex. Thus supposing _M_ to represent a modification acquired in the male and _m_ the absence of the modification, such as the feathered antenna of a moth, and the sex-chromosomes to be _X_ and _Y_, then we should have in the gametocytes-- Male Female _MM mm_ _XX XY_ Gametes _MX, MX: mXmY_ Zygotes _MmXX male, MmXY female_, and the character _M_ would only appear in the male because it only develops in association with _XX_ in the somatic cells descended from the male zygote. This would be the result in the first generation in which a somatic modification affected the factors in the chromosomes. In the next generation _m_ in the male would be affected, and the male for the sake of simplicity might be supposed to become _MMXX_. When the female gametes segregated, some would always be _mY_, and some zygotes therefore _MXmY_. Others might be _MMXY_. On this theory, therefore, there would always be some females heterozygous for the male character. Geoffrey Smith, one of the many promising young scientific investigators whose careers were cut short in the War, maintained views concerning somatic sex-characters different from that which explains their development as due to a hormone from the testis or ovary. Nussbaum in 1905 [Footnote: 'Ergebuisse der Anat. und Entwicklungsgesch.,' Bd. xv.; _Pflügers Archiv_, Bd. cxxvi, 1909.] had recorded experiments on _Rana fusca_ (which is identical with the British species commonly called _R. temporaria_) which appeared to prove that in the male frog after castration the annual development of the thumb-pad and the muscles of the fore-leg does not take place, and if these organs have begun to enlarge before castration they atrophy again. When pieces of testis were introduced into the dorsal lymph-sac of a castrated frog the thumb-pads and muscles developed as in a normal frog. Geoffrey Smith and Edgar Schuster [Footnote: _Quart Journ. Mic. Sci_., lvii, 1911-12.] investigated the subject again with results contrary to those of Nussbaum. Smith and Schuster begin by describing the normal cycle of changes in the testes on the one hand and the thumb-pad on the other. After the discharge of the spermatozoa in March or April the testes are at their smallest size. From this time onwards till August they steadily increase in size, attaining their maximum at the beginning of September. From then till the breeding season no increase in size or alteration of cellular structure occurs, the testes apparently remaining in a state of complete inactivity during this period. With regard to internal development, after the discharge of spermatozoa in the breeding season the spermatogonia divide and proliferate, forming groups of cells known as spermatocysts. In June and July spermatogenesis is active, and from August to October the formation of ripe spermatozoa is completed. The corresponding changes in the thumb-pads are as follows. Immediately after the breeding season the horny epidermis of the pad with its deeply pigmented papillae is cast off, and the thumb remains comparatively smooth from April or May until August or September. When the large papillae are shed, smaller papillae remain beneath, and are gradually obliterated by the epidermis growing up between them. The epidermis is therefore growing while the spermatogenesis is taking place. In August and September the epidermic papillae begin to be obvious, and from this time till February a continuous increase in the papillae and their pigmentation occur. Geoffrey Smith argues that the development of this somatic character occurs while the testes are inactive and unchanged. Considering that the testes throughout the winter months are crammed with spermatozoa, which must require some nourishment, and which may be giving off a hormone all the time, the argument has very little weight. Smith and Schuster found that ovariotomy, with or without subsequent implantation of testes or injection of testis extract, had no effect in causing the thumb of the female to assume any male characters. Castration during the breeding season causes the external pigmented layer with its papillae to be cast off very soon--that is to say, it has the same effect as the normal discharge of the spermatozoa. Smith and Schuster found that castration at other seasons caused the pad to remain in the condition in which it was at the time, that there was no reduction or absorption as Nussbaum and Meisenheimer found, and that allo-transplantation of testes--that is, the introduction of testes from other frogs either into the dorsal lymph-sacs or into the abdominal cavity--or the injection of testis extract, had no effect in causing growth or development of the thumb-pad. There seems to be one defect in the papers of both Nussbaum and Smith and Schuster--namely, that neither of them mentions or apparently appreciates the fact that the thumb-pads, apart from the dermal glands, consist of horny epidermis developed from the living epidermis beneath. The horny layer is not shown clearly in the figures of Smith and Schuster. It seems impossible that the horny layer or its papillae could atrophy in consequence of castration, or be absorbed. The horny part of the frog's thumb-pad is comparable with the horny sheath of the horns in the mammalian Prong-buck (_Antilocapra_) which are shed after the breeding season and annually redeveloped. Meisenheimer claims that he produced development of papillae on the thumb-pad, not only by implantation of pieces of testis, but also by implantation of pieces of ovary. This seems so very improbable that it suggests a doubt whether the same investigator was not mistaken with regard to the results of his experiments in transplanting gonads in Moths. Smith and Schuster conclude that the normal development of the thumb-pad depends on the presence of normal testes, but that there is no sufficient evidence that the effect is due to a hormone derived from the testis. It is equally probable, according to Smith, that the testicular cells take up some substance or substances from the blood, thus altering the composition of the latter and perhaps stimulating the production of these substances in some other organ of the body. These substances may be provisionally called sexual formative substances. Smith's theory therefore is that the action of the testes in metabolism is rather to take something from the blood than to add something to it, and that it is this subtractive effect which influences the development of somatic sexual organs. Geoffrey Smith in fact, in the paper above considered, attempts to apply to the frog the views he put forward [Footnote: _Fauna und Flora des Golfes van Neapel_, 29 Monographie Rhizocephala.] in relation to the effect of the parasite _Sacculina_ on the sexual organs of crabs. The species in which he made the most complete investigation of the influence of the parasite was _Inachus scorpio_ (or _dorsettensis_). Figures showing the changes in the abdomen produced by the presence of _Sacculina_ are given in Doncaster's _Determination of Sex_, Pl. xv. _Sacculina_ is one of the Cirripedia, and therefore allied to the Barnacles. It penetrates into the crab in its larval stage, and passes entirely into the crab's body, where it develops a system of branching root-like processes. When mature the body of the _Sacculina_ containing its generative organs forms a projection at the base of the abdomen of the crab on its ventral surface, and after this is formed the crab does not moult. Crabs so affected do not show the usual somatic sexual characters, and at one time it was supposed that only females were attacked. It is now known that both sexes of the host may be infected by the parasite, but the presence of the latter causes suppression of the somatic sex-differences. The entry of the parasite is effected when the crab is young and small, before the somatic sex-characters are fully developed. The gonads are not actually penetrated, at least in some cases, by the fibrous processes of the parasite, but nevertheless they are atrophied and almost disappear. In _Inachus_ the abdomen of the normal male is very narrow and has no appendages except two pairs of copulatory styles. The abdomen of the female is very broad, and has four pairs of biramous appendages covered with hairs, the normal function of which is to carry the eggs. The effect of the parasite in the male is that the abdomen is broader, the copulatory styles reduced, and biramous hairy appendages are developed similar to those of the female, but smaller. In the female the abdomen remains broad, but the appendages are much smaller than in the normal female, about equal in size to those of the 'sacculinised' male. Smith interpreted the alteration in the male as a development of female secondary characters, but it is obvious from the condition in Macrura or tailed Decapods, like the lobster or crayfish, that the abdomen or tail of the male originally carried appendages similar to those of the female, and that the male character is a loss of these appendages. The absence of the male character therefore necessarily involves a development of these appendages, and there is not much more reason for saying that the male under the influence of the parasite develops female characters, than for saying that the male character is absent. There is no evidence in the facts concerning parasitic castration for Geoffrey Smith's conclusion that the female characters are latent in the male, but the male characters not latent in the female: both return to a condition in which they resemble each other, and the primitive form from which they were differentiated. By his studies of parasitic castration Geoffrey Smith was led to formulate a theory for the explanation of somatic sex-characters different from that of hormones. He found that in the normal female crab the blood contained fatty substances which were absorbed by the ovaries for the production of the yolk of the ova. When _Sacculina_ is present these substances are absorbed by the parasite; the ovary is deprived of them, and therefore atrophies. In the male the parasite requires similar substances, and its demand on the blood of the host stimulates the secretion of such substances, so that the whole metabolism is altered and assimilated to that of the female. It is this physiological change which causes the development of female secondary characters. He describes this change as the production of a hermaphrodite sexual formative substance, on the ground that in at least one case eggs were found in the testis of a male _Inachus_ which had been the host of a _Sacculina_, but had recovered. It must however be noted that the _Sacculina_ itself is hermaphrodite, with ovaries much larger than the testes. It is possible that while the parasite prevents the development of testis or ovary in the host, it gives up to the body of the host a hormone from its own ovaries which tends to develop the female secondary characters: for the parasite is itself a Crustacean, and therefore the hormone from its ovaries would not be of too different a nature to act upon the tissues of the host. The observation of Geoffrey Smith that eggs may occur in the testis of a crab after recovery from the parasite appears of more importance than his peculiar theoretical suggestions, for it tends to show that sex is not always unalterably fixed at fertilisation. In this case the influence of a parasite predominantly female would seem to be the real cause of the development of eggs in the testis of the host. Geoffrey Smith does not discuss the origin of the somatic sexual characters in evolution, or attempt to show how his theories of sexual formative substance, and of the influence of the gonads by subtraction rather than addition, would bear upon the problem. CHAPTER VI Origin Of Non-Sexual Characters: The Phenomena Of Mutation According to the theory here advocated, modifications produced by external stimuli in the soma will also be inherited in some slight degree in each generation when they have no relation to sex or reproduction. In this case the habits and the stimuli which they involve will be common to both sexes, and the hormones given off by the hypertrophied tissues will act upon the corresponding determinants in the gametocytes. The modifications thus produced will therefore be related to habits, and the theory will include all adaptations of structure to function, but other characters may also be included which are the result of stimuli and yet have no function or utility. The majority of evolutionists in recent years have taught that influences exerted through the soma have no effect on the determinants in the chromosomes of the gametes, that all hereditary variations are gametogenic and none somatogenic. Mendelians believe that evolution has been due to the appearance of characters or factors of the same kind as those which distinguish varieties in cultivated organisms, and which are the subject of their experiments, but they have found a difficulty, as already mentioned in Chapter II, in forming any idea of the origin of a new dominant character. A recessive character is the absence of some positive character, and if in the cell-divisions of gametogenesis the factor for the positive character passes wholly into one cell, the other will be without it, will not 'carry' that factor. If such a gamete is fertilised by a normal gamete the organism developed from the zygote will be heterozygous, and segregation will take place in its gametes between the chromosome carrying the factor and the other without it, so that there will now be many gametes destitute of the factor in question. When two such gametes unite in fertilisation the resulting organism will be a homozygous recessive, and the corresponding character will be absent. In this way we can conceive the origin of albino individuals from a coloured race, supposing the colour was due to a single factor. In Bateson's opinion the origin of a new dominant is a much more difficult problem. In 1913 he discussed the question in his Silliman Lectures. [Footnote: _Problems of Genetics_, Oxford Univ. Press, 1913.] He considers the difficulty is equally hopeless whether we imagine the dominants to be due to some change internal to the organism or to the assumption of something from without. Accounts of the origin of new dominants under observation in plants usually prove to be open to the suspicion that the plant was introduced by some accident, or that it arose from a previous cross, or that it was due to the meeting of complementary factors. In medical literature, however, there are numerous records of the spontaneous origin of various abnormalities which behave as dominants, such as brachydactyly, and Bateson considers the authenticity of some of these to be beyond doubt. He concludes that it is impossible in the present state of knowledge to offer any explanation of the origin of dominant characters. In a note, however, he suggests the possibility that there are no such things as new dominants. Factors have been discovered which simply inhibit or prevent the development of other characters. For example, the white of the plumage in the White Leghorn fowl is due to an inhibiting factor which prevents the development of the colour factor which is also present. Withdraw the dominant inhibiting factor, and the colour shows itself. This is shown by crossing the dominant white with a recessive white, when some birds of the F(2) generation are coloured.[Footnote: Bateson, _Principles of Heredity_, p. 104.] Similarly, brachydactyly in man may be due to the loss of an inhibiting factor which prevents it appearing in normal persons. It is evident, however, that it is difficult to apply this suggestion to all cases. For example, the White Leghorn fowl must have descended from a coloured form, probably from the wild species _Gallus bankiva_. If Bateson's suggestion were valid we should have to suppose that the loss of the factor for colour caused the dominant white to appear, and then when this is withdrawn colour appears again, so that the colour factors and the inhibiting factors must lie over one another in a kind of stratified alternation. And then how should we account for the recessive white? In his Presidential Address to the meeting of the British Association in Australia, 1914, Bateson explains his suggestion somewhat more fully with a command of language which is scarcely less remarkable than the subject matter. The more true-breeding forms are studied the more difficult it is to understand how they can vary, how a variation can arise. When two forms of _Antirrhinum_ are crossed there is in the second generation such a profusion of different combinations of the factors in the two grandparents, that Lotsy has suggested that all variations may be due to crossing. Bateson does not agree with this. He believes that genetic factors are not permanent and indestructible, but may undergo quantitative disintegration or fractionation, producing subtraction or reduction stages, as in the Picotee Sweet Pea, or the Dutch Rabbit. Also variation may take place by loss of factors as in the origin of the white Sweet Pea from the coloured. But regarding a factor as something which, although it may be divided, neither grows nor dwindles, neither develops nor decays, the Mendelian cannot conceive its beginning any more than we can conceive the creation of something out of nothing. Bateson asks us to consider therefore whether all the divers types of life may not have been produced by the gradual unpacking of an original complexity in the primordial, probably unicellular forms, from which existing species and varieties have descended. Such a suggestion in the present writer's opinion is in one sense a truism and in another an absurdity. That the potentiality of all the characters of all the forms that have existed, pterodactyls, dinosaurs, butterflies, birds, etc. etc., including the characters of all the varieties of the human race and of human individuals, must have been present in the primordial ancestral protoplasm, is a truism, for if the possibility of such evolution did not exist, evolution would not have taken place. But that every distinct hereditary character of man was actually present as a Mendelian factor in the ancestral _Amoeba_, and that man is merely a group of the whole complex of characters allowed to produce real effects by the removal of a host of inhibiting factors, is incredible. The truth is that biological processes are not within our powers of conception as those of physics and chemistry are, and Bateson's hypothesis is nothing but the old theory of preformation in ontogeny. Just as the old embryologists conceived the adult individual to be contained with all its organs to the most minute details within the protoplasm of the fertilised ovum or one of the gametes, so the modern Mendelian, because he is unable to conceive or to obtain the evidence of the gradual development of a hereditary factor, conceives all the hereditary factors of the whole animal kingdom packed in infinite complexity within the protoplasm of the primordial living cells. That man is complex and _Amoeba_ simple is merely a delusion; the truth according to Mendelism is that man is merely a fragment of the complexity of the original _Amoeba_. Mendelism studies especially the heredity of characters, and only incidentally deals with recorded instances of the appearance of new forms, such as the origin of a salmon-coloured variety of _Primula_ from a crimson variety. The occurrence of new characters, or mutations as they are called, has been specially studied by other investigators, and I propose briefly to consider the two most important examples of such research, namely, that by Professor T. H. Morgan, which deals with the American fruit-fly _Drosophla_, and the other which concerns the mutations of the genus of plants OEnothera, exemplified by our well-known Evening Primrose. Professor T. H. Morgan informs us [Footnote: _A Critique of the Theory of Evolution_ (Oxford Univ. Press, 1916), p. 60] that within five or six years in laboratory cultures of the fruit-fly, _Drosophila ampelophila_, arose over a hundred and twenty-five new types whose origin was completely known. The first of these which he mentions is that of eye colour, differing in the two sexes, in the female dark eosin, in the male yellowish eosin. Another mutation was a change of the third segment of the thorax into a segment similar to the second. Normally the third segment bears minute appendages which are the vestiges of the second pair of wings; in the mutant the wings of the third segment are true wings though imperfectly developed. A factor has also occurred which causes duplication of the legs. Another mutation is loss of the eyes, but in different individuals pieces of the eye may be present, and the variation is so wide that it ranges from eyes which until carefully examined appear normal, to the total absence of eyes. Wingless flies also arose by a single mutation. These were found on mating with normal specimens to be all recessive characters, thus agreeing with Bateson's views. The next one described is dominant. A single male appeared with a narrow vertical red bar instead of the broad red normal eye. When this male was bred with normal females all the eyes of the offspring were narrower than the normal eye, though not so narrow as in the abnormal male parent. It may be pointed out that this is scarcely a sufficient proof of dominance. If the mutation were due to the loss of one factor affecting the eye, the heterozygote carrying the normal factor from the mother only might very well develop a somewhat imperfect eye. Morgan arranges the numerous mutations observed in _Drosophila_ in four groups, corresponding in his opinion to the four pairs of chromosomes occurring in the cells of the insect. After the meiotic or reduction divisions each gamete of course contains in its nucleus four single chromosomes. One of the four pairs consists of the sex-chromosomes. All the factors of one group are contained in one chromosome, and it is found in experiments that the members of each group tend to be inherited together--that is to say, if two or more enter a cross together, in other words, if a specimen possessing two or more mutations is crossed with another in which they are absent, they tend to segregate as though they were a single factor. This fact agrees with the hypothesis that the factors in such a case are contained in a single chromosome which segregates from the fellow of its pair in the reduction divisions. Exceptions may occur, however, and these are explained by what is called 'crossing over.' When one chromosome of a pair, instead of being parallel to the other in the gametocyte, crosses it at a point of contact, then when the chromosomes separate, part of one chromosome remains connected with the part of the other on the same side and the two parts separate as a new chromosome, so that two factors originally in the same chromosome may thus come to lie in different chromosomes. In consequence of this, two or more factors which are usually 'coupled' or inherited together may come to appear in different individuals. Morgan emphasises the statement that a factor does not affect only one particular organ or part of the body. It may have a chief effect in one kind of organ, _e.g._ the wings or eyes, but usually affects several parts of the body. Thus the factor that causes rudimentary wings also produces sterility in females, general loss of vigour, and short hind legs. The facts to which I shall refer concerning _Oenothera_ are for the most part quoted on the authority of Dr. Ruggles Gates, and taken from his book _The Mutation Factor in Evolution_ (London, 1915). The occurrence of mutations in _Oenothera_ was first noticed by De Vries, the Dutch botanist, in the neighbourhood of Amsterdam in 1886. He found a large number of specimens of _Oenothera Lamarckiana_ growing in an abandoned potato-field at Hilversum, and these plants showed an unusual amount of variation. He transplanted nine young plants to the Botanic Garden of Amsterdam, and cultivated them and their descendants for seven generations in one experiment. Similar experiments have been made by himself and others. The large majority of the plants produced from the _Oe. Lamarckiana_ by self-fertilisation were of the same form with the same characters, but a certain percentage presented 'mutations'--that is, characters different from the parent form, and in some cases identical with those of plants occurring occasionally among those growing wild in the field where the observations began. Nine of these mutants have been recognised and defined, and distinguished by different names. The characters are precisely described and in many cases figured by Gates in the volume cited above. The first mutant to be recognised--in 1887--was one called _lata._ It must be explained that the young plant of _Oenothera_ has practically no stem, but a number of leaves radiating in all directions from the growing point which is near the surface of the soil. The plant is normally biennial, and in the first season the internodes are not developed. This first stage is called the 'rosette.' From the reduced stem are afterwards developed one or more long stems with elongated internodes, bearing leaves and flowers. In the mutation _lata_ the rosette leaves are shorter and more crinkled than those of _Lamarckiana,_ and the tips of the leaves are very broad and rounded. The stems of the mature plant are short and usually more or less decumbent with irregular branches. The flower-buds are peculiarly stout and barrel-shaped, with a protrusion on one side. The seed-capsules are short and thick, containing relatively few seeds, and the pollen is wholly or almost wholly sterile. It is to be noted here, a fact emphasised by DeVries in his earliest publications on the subject, that in nearly all, if not all cases, a mutation does not consist in a peculiarity of a single organ, but in an alteration of the whole plant in every part. In this respect mutations as observed in _Oenothera_ seem to be in striking contrast to the majority of Mendelian characters. Mutation in fact seems to be a case of what the earlier Darwinians called correlation, while Mendelian characters may apparently be separated and rejoined in any combination. For example, in breeds of fowls any colour or any type of plumage may be obtained with single comb or with rose comb. In my own experiments on fowls the loose kind of plumage first known in the Silky fowl, which is white, could be combined with the coloured plumage of the type known as black-red. At the same time it must be borne in mind that since the factor, whether a portion of a chromosome or not, is transmitted in heredity as a part of a single cell, the gamete, and since every cell of the developed individual is derived by division from the single zygote cell formed by the union of the two gametes, the factor or determinant must be contained in every cell of the soma, except in cases where differential division, or what is called somatic segregation, takes place. Thus the factor which causes the comb to be a rose comb in a fowl must be present in the cells that produce the plumage or the toes or any other part of the body. Morgan, as mentioned above, finds in _Drosophila_ that factors do affect several parts of the body. It is, however, curious to consider that the factor which produces intense pigmentation of the skin and all the connective tissue in the Silky fowl has no effect on the colour of the plumage in that breed, which is a recessive white. The plumage is an epidermic structure, and therefore distinct from the connective tissue, but it is difficult to understand why a pigment factor though present in every cell has no effect on epidermic cells. The Mendelians, when the mutations of _Oenothera_ were first described, endeavoured to show that they were merely examples of the segregation of factors from a heterozygous combination. They suggested in fact that _Oenothera Lamarckiana_ was the result of a cross, or repeated crosses, between plants differing in many factors, that the numerous mutations were similar to the variety of different types which are produced by breeding together the grey mice arising from a cross between an albino and a Japanese waltzing mouse in Darbishire's experiment. Since that time, however, the natural distribution and the cultural history of _Oenothera_ has been very thoroughly worked out. _Oenothera Lamarckiana_ is the common Evening Primrose of English gardens. The species of the sub-genus _Onagra_ to which _Lamarckiana_ belongs were originally confined to America (Canada, United States, and Mexico), but _Lamarckiana_ itself has never been found there in a wild state. Attempts, however, to produce it by crossing of other forms have not succeeded, and a specimen has been discovered at the Muséum d'Histoire Naturelle at Paris, collected by Michaux in North America about 1796, which agrees exactly with the _Oenothera Lamarckiana_ naturalised or cultivated in Europe. The plant was first described by Lamarck from plants grown in the gardens of the Muséum d'Histoire Naturelle, under the name _OE. grandiflora_, which had been introduced by Solander from Alabama, but Seringe subsequently decided that Lamarck's species was distinct from _grandiflora_, and named it _Lamarckiana_. Gates states that Michaux was in the habit of collecting seeds with his specimens, and that it is therefore highly probable that Lamarck's specimens were grown directly from seeds collected in America by Michaux. Gates considers that the suggestion of the hybrid origin of _Lamarckiana_ in culture is thus finally disposed of. By the year 1805, _Lamarckiana_ was apparently naturalised and flourishing on the coast of Lancashire, and in 1860 it was brought into commerce, probably from these Lancashire plants, by Messrs, Carter. The cultures of De Vries are descended from these commercial seeds, but the Swedish race of _Lamarckiana_, as well as those of English gardens, differ in several features and must have come from another source or been modified by crossing with _grandiflora_. This last remark is quoted from Gates, but it seems improbable that the Dutch plants should be derived from those of Lancashire, and those of English gardens from a different source. The fact seems to be, according to other parts of Gates's volume, that there are various races of _Lamarckiana_ in English gardens and in the Isle of Wight, as well as in Sweden, etc., and that these races differ from one another less than the mutants of De Vries and his followers. An important point about these mutations is that their production is a constant feature of _Lamarckiana_. Whenever large numbers of the seeds of this plant are grown, a certain proportion of the plants developed present these _same_ mutations; not always all of them--some may be absent in one culture, present in another, but four of them are fairly common and of constant occurrence. The total proportion of mutant plants compared with the normal was 1.55 per cent. in one family, 5.8 per cent. in another. It would appear therefore, supposing that mutations arose subsequently in the same determinate way from previous mutations, that evolution, though in a number of divergent directions from one ancestral form, would proceed along definite lines, and that there would be nothing accidental about it. We should thus arrive at a demonstration of what Eimer called orthogenesis, or evolution in definite directions. The mutation _lata_ cannot be said to breed true, as the pollen is almost entirely sterile. It has therefore been propagated by crossing with _Lamarckiana_ pollen, with the result that both forms are obtained with _lata_ varying in proportion from 4 per cent. to 45 per cent. _Rubrinervis_ is a mutation from _Lamarckiana_, chiefly distinguished by red midribs in the leaves and red stripes on the sepals. When propagated from self-fertilised seed it produced about 95 per cent. of offspring with the same characters, and the remaining 5 per cent. mutants, one of which was _laevifolia_ which had been found by De Vries among plants growing wild at Hilversum. Gates obtained a single plant among offspring of _rubrinervis_ in which the sepals were red throughout, and to this he gave the name _rubricalyx_. When selfed this plant gave rise to both _rubricalyx_ and _rubrinervis_, and in the second generation when the _rubricalyx_ was selfed again the numbers of the two were approximately 3 to 1. _Rubricalyx_ is therefore a dominant heterozygote, and this fact was further confirmed in the third generation when a selfed plant gave 200 offspring all _rubricalyx_, the mother plant having evidently been homozygous for the red character. In this case, therefore, we have what Bateson was seeking, the origin of a new dominant character under observation, the original mutation having arisen in a single gamete of the zygote which gave rise to the plant. It is claimed by mutationists that mutations are not new combinations or separations of Mendelian unit characters already present, but are themselves new characters, though not always necessarily, as in the case of _rubricalyx_, new unit characters in the Mendelian sense. Perhaps the most interesting of the researches on the phenomena of mutation are those concerning the relation of the characters to the chromosomes of the cell, in which Gates has been a pioneer and one of the most industrious and successful investigators. The behaviour of the chromosomes in meiosis or reduction division both in the pollen mother-cells and in the megaspore mother-cells which give rise to the so-called embryo-sac are fully described by Gates. Here it is only necessary to refer to the abnormalities in the reduction division which are related to mutation, and the results of these abnormalities in the number of chromosomes. The original number of chromosomes in _OEnothera_ is 14. In the mutation _lata_ this has become 15, and also in another mutation called _semilata_. The chromosomes before the reduction division are arranged in pairs, each pair consisting, it is believed, of one paternal and one maternal chromosome. One of each pair goes into one daughter-cell and the other into the other, but not all maternal into one and all paternal into the other. Thus each daughter-cell after the first or heterotypic division in normal cases contains 7 chromosomes. A second homotypic division takes place in which each chromosome splits into two as in somatic divisions, and thus we have 4 gametes with 7 chromosomes each. Now when _lata_ is produced it is believed that in the heterotypic division one pair passes into one daughter-cell instead of one chromosome of the pair into each daughter-cell, the other pairs segregating in the usual way. We thus have one daughter-cell with 8 chromosomes and the other with 6. This 6+8 distribution has actually been observed in the pollen mother-cell in _rubrinervis_. When a gamete with 8 chromosomes unites in fertilisation with a normal gamete with 7 the zygote has 15. The _lata_ mutants having an odd chromosome are almost completely male-sterile, and their seed production is also much reduced: but this partial sterility cannot be attributed entirely to the odd chromosome because _semilata_, which has also 15 chromosomes, does not show the same degree of sterility. Other cases occur in which the number of chromosomes in the somatic cells is double the ordinary number--namely, 28--and others in which the number is 21. The normal number in the gamete, 7, is considered the simple or haploid number, and therefore the number 28 is called tetraploid. This doubling of the somatic number of chromosomes is now known in a number of plants and animals. It occurs in the _OEnothera_ mutant _gigas_. The origin of it has not been clearly made out, but it must result either from the splitting of each chromosome or from the omission of the chromosome reduction. In many cases the more numerous chromosomes are individually as large as those in normal plants, and consequently the nucleus is larger, the cell is larger, and the whole plant is larger in every part. But giantism may occur without tetraploidy, and vice versa. In the _OEnothera gigas_ the rosette leaves are broadly lanceolate with obtuse or rounded tips, more crinkled than in _Lamarckiana_, petioles shorter. The stem-leaves are also larger, broader, thicker, more obtuse, and more crinkled than in _Lamarckiana_. The stem is much stouter, almost double as thick, but not taller because the upper internodes are shorter and less numerous. It is difficult to avoid the conclusion that the stouter character of the organs in this plant is causally connected with the increased number of chromosomes. Where the number of cells formed is approximately similar, as in two allied forms of plant in this case, the greater size of the cells would naturally give a stouter habit, but it is clear that large cells do not necessarily mean greater size. The cells of _Salamander_ and _Proteus_ are the largest found among Vertebrates, but those Amphibia are not the largest Vertebrates. It is curious to note how different are these discoveries concerning differences in the _number_ of chromosomes from the conception of Morgan that a mutation depends on a factor situated in a part of one chromosome. More copious details concerning mutations will be found in the publications cited. The question to be considered here is how far the claim is justified that the facts of this kind hitherto discovered afford an explanation of the process of evolution. It seems probable that mutations are of different kinds, as exemplified in _Oenothera_ by _gigas_ and _rubricalyx_ respectively, the former producing only sterile hybrids, the latter behaving exactly like a Mendelian unit. There can be little doubt that, as Bateson states, numerous forms recognised as species or varieties in nature differ in the same way as the races or breeds of cultivated organisms which differ by factors independently inherited. There are facts, however, which prove that all species are not sterile _inter se_, and that their characters when they are hybridised do not always segregate in Mendelian fashion. John C. Phillips, [Footnote: _Journ. Exper. Zool._, vol. xviii., 1915.] for example, crossed three wild species of duck, _Anas boscas_ (the Mallard) with _Dafila acuta_ (the Pintail) and with _Anas tristis_. In the former cross he states that except for one or two characters there seemed to be no more tendency to variation in the _F2_ generation than in the _F1_. An _F1_ Pintail-Mallard [female] was mated with a wild Pintail [male]. According to Mendelian expectation the offspring of this mating should have been half Pintail and half Pintail-Mallard hybrids, but Phillips states that on casual inspection the plumage of all the males appeared pure Pintail although the shape was distinctly Mallard-like. The statement is, however, open to criticism. The question is, what were the unit characters in the parent species? If the unit characters were very small and numerous, an individual in which all the characters of the Pintail existed together among the offspring of the hybrid mated with pure Pintail would be rare in proportion to the individuals presenting other combinations. Of the _F2_'s obtained from crossing _Anas tristis_ [male] with _Anas boscas_ [female] Phillips obtained 23 females and 16 males. The females were all alike and similar to _F1_ females. Of the males one was a variate specially marked, about half-way between the _F1_ type and the Mallard parent. This, according to Phillips, was a segregate. The rest showed a range of variation but no distinct segregation. It is somewhat surprising that Mendelian experts, who seem to believe that species are distinguished by Mendelian characters, have not made systematic experiments on the crossing of species in order to prove or disprove their belief. For my own part I cannot help thinking that the origin of varieties in species in a domesticated or cultivated state is in a sense pathological. Such variation doubtless occurs in nature, but not with such luxuriance. The breeds of domestic fowls differ so greatly that Bateson and others refuse to believe that they have all arisen from the single species _Gallus bankiva_. It seems to me from the evidence that there cannot be any doubt that they have so arisen. One fact that impresses my mind is that if we consider colour variations in domesticated animals, we find that a similar set of colours has arisen in the most diverse kinds of animals with sometimes certain markings or colours peculiar to one group, _e.g._ dappling in horses, wing bars in pigeons. Thus in various kinds of Mammals and Birds we have white and black, red or yellow, chocolate with various degrees of dilution, and piebald combinations. Why should forms originally so different, as the cat with its striped markings and the rabbit with no markings at all, give rise to the same colour varieties? It seems probable that the reason is that the original form had the small number of pigments which occur mixed together in very small particles, and that in the descendants the single pigments have separated out, with increase or decrease in different cases. It is true that historical evidence tends to show that the greatest variations, such as albinism in one direction or excess of pigment in the other in the Sweet Pea, were the first to arise (see Bateson, Presidential Address to British Association, Australia, 1914, Part I.), and the splitting appears often to be intentionally produced by crossing these extreme variations with the original form, but the possibility remains that the conditions of domestication, abundant food, security and reduced activity, lead to irregularity in the process of heredity. In any case the mere separation among different individuals of factors originally inherited together in one complex does not account for the origin of the complex or of the factors. This is somewhat the same idea as that of Bateson when he states that it is easy to understand the origin of a recessive character but difficult to conceive the origin of a dominant. The point, however, which I desire most to emphasise is that the investigations we have been discussing are concerned with variations which have no relation whatever to adaptation, and afford no explanation of the evolution of adaptations. These variations perform no function in the life of the individual, have no relation to external conditions, either in the sense of being caused by special conditions or fitting the individual to live in special conditions. A still more important fact is that they do not explain the origin of metamorphosis. They do not arise by a metamorphosis: in the case of the rose comb of fowls the chick is not hatched with a single comb which gradually changes into a rose comb, but the rose comb develops directly from the beginning. Mutationists and Mendelians do not seem in the least to appreciate the importance of metamorphosis or of development generally in considering the relation of the mutations or factors which they study to evolution in general, because they have not grasped the fact that there are two kinds of characters to be explained, adaptational and non-adaptational. T. H. Morgan, for example, [Footnote: _A Critique of the Theory of Evolution_, p. 67 (Princeton, U.S.A., and London, 1916).] describes a mutation in _Drosophila_ consisting in the loss of the eyes, and triumphantly remarks: 'Formerly we were taught that eyeless animals arose in caves. This case shows that they may also arise suddenly in glass milk-bottles by a change in a single factor.' As it stands the statement is perfectly true, but it is obvious that the writer does not believe that the darkness of caves ever had anything to do with the loss of eyes. It is almost as though a man should discover that blindness in a certain case was due to a congenital, i.e. gametic, defect, and should then scoff at the idea that any person could become blind by disease. Some of those who specialise in the investigation of genetics seem to give inadequate consideration to other branches of biology. It is a well-established fact that in the mole, in _Proteus_, and in _Ambtyopsis_ (the blind fish of the Kentucky caves), the eyes develop in the embryo up to a certain stage in a perfectly normal way and degenerate afterwards, and that they are much better developed in the very young animal than in the adult. Does this metamorphosis take place in the blind _Drosophila_ of the milk-bottle? The larva of the fly is, I believe, eyeless like the larvae of other Diptera, but Morgan says nothing of the eye being developed in the imago or pupa and then degenerating. There is therefore no relation or connexion between the mutation he describes and the evolution of blindness in cave animals. It is a truth, too often insufficiently appreciated by biologists, that sound reasoning is quite as important in science as fact or experiment. Loeb [Footnote: _The Organism as a Whole_, p. 319 (New York and London, 1916).] also endeavours to prove that the blindness of cave animals is no evidence of the influence of darkness in causing degeneration of the eyes. He refers to experiments by Uhlenhuth, who transplanted eyes of young Salamanders into different parts of their bodies where they were no longer connected with the optic nerves. These eyes underwent a degeneration which was followed by a complete regeneration. He showed that this regeneration took place in complete darkness, and that the transplanted eyes remained normal when the Salamanders were kept in the dark for fifteen months. Hence the development of the eyes does not depend on the influence of light or on the functional action of the organs. But it must be obvious to any biologist who has thoroughly considered the problem, that this experiment has little to do with the question of the cause of blindness in cave animals. No one ever supposed that cave fishes became blind in fifteen months, or in fifteen years. The experiment cited merely proves that in the individual the embryonic or young eye will continue developing by heredity even after it is transplanted and in the absence of light. But the eye of the Mammal normally develops in the uterus in the absence of light. In his remarks concerning _Typhlogobius_, a blind fish on the coast of southern California, Loeb seems to be mistaken with regard to the facts. He states that this fish lives 'in the open, in shallow water under rocks, in holes occupied by shrimps.' According to Professor Eigenmann the same species of shrimp is found all over the Bay of San Diego, and is accompanied by other genera of goby, such as _Clevelandia_ and _Gillichthys_, which have eyes; but these fishes live outside the holes, and only retreat into them when frightened, while the blind species is found only at Point Loma, and never leaves the burrows of the shrimp. It would appear, therefore, that _Typhlogobius_ lives in almost if not quite complete darkness, instead of being, as Loeb states, 'blind in spite of exposure to light,' while the closely allied forms which are exposed to light are not blind. Loeb states, on the authority of Eigenmann, that all those forms which live in caves were adapted to life in the dark before they entered the cave, because they are all negatively heliotropic and positively stereotropic, and with these tropisms would be forced to enter a cave whenever they were put at the entrance. Even those among the Amblyopsidae which live in the open have the tropisms of the cave dweller. But these latter are not blind, and the argument only tends to show that the blind fish _Amblyopsis_ entered the caves before it was blind. Nocturnal animals generally must be said to be negatively heliotropic, but these usually have larger and more sensitive eyes than the diurnal. It is said, however, that _Chologaster agassizii_, which is not blind, lives in the underground streams of Kentucky and Tennessee, but I think it is open to doubt whether it is a species entirely confined to darkness. Another point which Loeb omits to mention is the absence of pigment in cave animals, especially Vertebrates such as _Amblyopsis_ and _Proteus_. If absence of light is not the cause of blindness in these cases, how is it that the blindness is always associated with absence of pigment, since we know that the latter in Fishes and Amphibia is due to the absence of light? It has been shown that _Proteus_ when kept in the light develops some amount of pigment, although it does not become pigmented to the same degree as ordinary Amphibia. We have here, I think, an example of the essential difference between mutations and somatic modifications. Absence of the gametic factor or factors for pigmentation results in albinism, and no amount of exposure to light produces pigmentation in albinos, _e.g._ albino Axolotls which are well known in captivity. Absence of light, on the other hand, prevents the development of pigment. The question therefore is whether the somatic modification is inherited. The fact that _Proteus_ does not rapidly become as deeply coloured when exposed to light as ordinary Amphibia shows that the gametic factors for pigmentation have been modified as well as the somatic tissues. Loeb attributes the blindness of cave fishes to a disturbance in the circulation and mutation of the eyes originally occurring as a mutation. But how could an explanation of this kind be applied to the case of _Anableps tetrophthalmus_, in which each eye is divided by a partition of the cornea and lens into an upper half adapted for vision in air and a lower half for vision in water? This fish lives in the smooth water of estuaries in Central America, and swims habitually with the horizontal partition of the lens level with the surface of the water. It is impossible to understand in this case, firstly, how a mutation could cause the eyes to be divided and doubly adapted to two different optic conditions, and, secondly, how at the same time a convenient 'tropism' should occur which caused the animal to swim with its eyes half in and half out of water. Are we to suppose that the upper half of the body or eye had a positive heliotropism and the lower half a negative heliotropism? The fact is that the fish swims at the surface in order to watch for and feed on floating particles. The tropism concerned is the food tropism, but what is gained by calling the search for food common to all active animals a tropism, and how is the search for food before the food is perceptible to the senses, before it can act as a stimulus on a food-sensitive substance in the body, to be compared to a tropism at all? Loeb undertakes to prove that the organism as a whole acts automatically according to physicochemical laws. But he misses the question of evolution altogether. For example, he quotes Gudernatsch as having proved that legs can be induced to grow in tadpoles at any time, even in very young specimens, by feeding them with thyroid gland. Loeb writes: 'The earlier writers explained the growth of the legs in the tadpole as a case of an adaptation to life on land. We know through Gudernatsch that the growth of the legs can be produced at any time by feeding the animal with the thyroid gland.' Obviously he thinks that these two propositions are contradictory to each other, whereas there is no contradiction, between them at all. Loeb actually supposes that the thyroid is the cause of the development of the legs. Logically, if this were the case it would follow that if we fed an eel or a snake with thyroid it would develop legs like those of a frog, and if a man were injected with extract of the testes of a stag he would develop antlers on his forehead. It will be obvious to most biologists that the thyroid, whether that of the tadpole itself or that which is supplied as food, only causes the development of legs because the hereditary power to develop legs is already present. The question is how this hereditary power was evolved. Legs _are_ an adaptation to life on land. What we have to consider and to investigate is whether the legs arose as a gametic mutation or as a direct result of locomotion on land. The general result of clinical and experimental evidence is to show that the hormone of the thyroid is necessary to normal development. The arrest of development in cretinous children is due to some deficiency of thyroid secretion, and is counteracted by the administration of thyroid extract. Excess of the secretion produces a state of restlessness and excitement associated with an abnormally rapid rate of metabolism and protrusion of the eye-balls (Graves' disease). The physiological text-books, however, say nothing of precocity of development in children as a result of hyperthyroidism. This, however, is undoubtedly what occurs in the case of tadpoles. The legs would naturally develop at some time or other, after a prolonged period of larval life. Feeding with thyroid causes them to develop at once. I have repeated Gudernatsch's experiment with the following results:-- This year I had a considerable number of tadpoles of the common English frog, which were hatched between March 26 and March 29. On April 12, when they had all passed the stage of external gills and developed internal gills and opercula, I divided them into two lots, one in a shallow pie-dish, the other in a glass cylinder. To one lot I gave a portion of rabbit's thyroid, to the other a piece of rabbit's liver. They fed eagerly on both. Afterwards I obtained at intervals of a week or so the thyroid of a sheep. I have seen no precise details of Gudernatsch's method of feeding tadpoles, but my own method was simply to put a piece of thyroid into the water containing the tadpoles and leave it there for several days, then to take it out and put in another piece, changing the water when it seemed to be getting foul. April 22. Noticed that the non-thyroid tadpoles were larger than those fed on thyroid. Changed the former into the pie-dish and the latter into the glass jar, to make sure that the difference in size was not due to larger space. May 3. Only eighteen of the non-thyroid tadpoles surviving, owing to the water having become foul, but these are three times as large as those fed on thyroid. In the latter no trace of hind-legs was visible, but the abdominal region was much emaciated and contracted, while the head region was broader. May 4. Noticed minute white buds of hind-legs in the thyroid-fed tadpoles. May 6. A number of the thyroid-fed were dying, and the skin and opercular membranes were swollen out away from the tissues beneath. Largest normal tadpole, 2.7 cm. long. body, 1.0 " tail, 1.7 " Largest thyroid-fed tadpole, 1.1 cm. long. body, 0.5 " tail, 0.6 " May 10. A great number of the thyroid-fed dead and the rest dying, lying at the bottom motionless. They now had the tail much shorter, and the fore-legs showing as well as the hind, but the latter not very long, and without joints or toes. Period from first feeding with thyroid, thirty days. I now decided to feed the controls with thyroid, expecting that as they were large and vigorous they would have strength enough to complete the metamorphosis and become frogs. May 15. Fed the controls with thyroid for first time. The smallest of them was in total length 1.7 cm. body, 0.7 " tail, 1.0 " The largest measured was in total length 2.2 " body, 0.8 " tail, 1.4 " May 25. All but two of the tadpoles dead. The tails were only half the original length, all had well-developed hind-legs, some with toes, but the fore-legs were beneath the opercula, not projecting from the surface. Smallest total length, 1.2 cm. body, 0.5 " tail, 0.7 " Largest total length, 1.8 " body, 0.7 " tail, 1.1 " These last measurements were made after the tadpoles had been preserved in spirit, and were therefore doubtless somewhat less than in the fresh condition. Making allowance for this it is evident that the tails had undergone reduction as part of the metamorphosis, but the body was also shorter. There is some reason therefore for concluding that actual reduction in size of body occurs as the result of metamorphosis induced by thyroid feeding. As in the other case the skin and opercular membranes were distended by liquid beneath them. The total period of the change in this second experiment was ten days. I conclude that the amount of thyroid eaten was so excessive as to cause pathological conditions as well as precocious metamorphosis, so that the animals died without completing the process. On June 10 I still had four tadpoles which had never had thyroid, but only pieces of meat, earthworm, or fish. These were very much larger than any of the others, were active and vigorous, and the largest one showed small rudiments of hind-legs, the others none at all. CHAPTER VII Metamorphosis And Recapitulation As one of the most remarkable examples of metamorphosis and recapitulation in connexion with adaptation we will consider once more the case of the Flat-fishes which I have already mentioned in an earlier chapter. These fishes offer perhaps the best example of the difference between gametogenic mutations and adaptive modifications. In several species specimens occur occasionally in which the asymmetry is not fully developed. [Footnote: See 'Coloration of Skins of Fishes, especially of Pleuronectidae,' _Phil. Trans. Royal Soc_., 1894.] These abnormalities are most frequent in the Turbot, Brill, Flounder, and Plaice. The chief abnormal features are pigmentation of the lower side as well as of the upper, the eye of the lower side, left or right according to the species, on the edge of the head instead of the upper side, and the dorsal fin with its attachment ceasing behind this eye, the end of the fin projecting freely forwards over the eye in the form of a hook. Such specimens have been called ambicolorate, but it is an important fact that they are also ambiarmate--that is to say, the scales or tubercles which in the normal Flat-fish are considerably reduced or absent on the lower side, in these abnormal specimens are developed on the lower side almost as much as on the tipper. Minor degrees of the abnormality occur: in Turbot with the hook-like projection of the dorsal fin the lower side of the head is often without pigment, while the rest of the lower side is pigmented. Less degrees of pigmentation of the lower side occur without structural abnormality of the eye and dorsal fin. There is no evidence that these abnormalities are due to abnormal conditions of life. One specimen of Plaice of this type was kept alive in the aquarium, and it lay on its side, buried itself in the sand, and when disturbed swam horizontally, like a normal specimen. The abnormalities are undoubtedly mutations of gametic origin. The development of one of these abnormal specimens from the egg has not to my knowledge been traced, but there is no reason to suppose that the fish develops first into the normal asymmetrical condition and then changes gradually to the abnormal condition described. On the contrary, everything points to the conclusion that the abnormality is an arrest or incomplete occurrence of the normal process of development, _i.e._ of the normal metamorphosis. T. H. Morgan, in a volume published some years ago, [Footnote: _Evolution and Adaptation_.] put forward the extraordinary view that the Pleuronectidae arose from symmetrical fishes by a mutation which was entirely gametogenetic and entirely independent of habits or external conditions, and then finding itself with two eyes on one side of its head, and no air-bladder, adopted the new mode of life, the new habit of lying on the ground on one side in order to make better use of its asymmetrically placed eyes. According to this view habits have been adapted to structure, not structure to habits. We are thus to believe that Amphibia came out of the water and breathed air because by an accidental mutation they possessed lungs and a pulmonary circulation capable of atmospheric respiration. Such is the result of applying conclusions derived from phenomena of one kind to phenomena of a totally different kind. One of the chief differences between structural features and correlations which are adaptive from those which are not is the process of metamorphosis, where we see the structure changing in the individual life history as the mode of life changes. The egg of the Flat-fish develops into a symmetrical pelagic larva similar to that of many other marine fishes. The larva has an eye on each side of its head and swims with its plane of symmetry in a vertical position: it has also colour on both sides equally. When the skeleton begins to develop the transformation takes place: the eye of one side, left in some species, right in others, moves gradually to the edge of the head and then on to the other side. The dorsal fin extends forward, preserving its original direction, and so passes between the eye that has changed its position and the lower side of the fish, on which that eye was originally situated. In some cases this extension of the fin takes place earlier and the eye passes beneath the base of the fin to reach the other side. Any one who takes the trouble to make himself acquainted with the facts will see that the three chief features of the Pleuronectid--namely, the position of the eyes, the extension of the dorsal and ventral fins, and the absence of pigment from the lower side--are not structurally correlated with one another at all as changes in different parts of the organism in a mutation are said to be, but are all closely related to their functions in the new position of the body. A mutation consisting in general asymmetry would be comprehensible, but the head of the Pleuronectid is not asymmetrical in a general sense, but only so far as to allow of the changed position of the eyes. The posterior end of the skull is as symmetrical as in any other fish, and in some cases the mouth and jaws are also symmetrical, entirely unaffected by the change in the position of the eyes. In other cases the jaws are asymmetrical in a direction opposite to that of the eyes, there is no change of position but a much greater development of the lower half of the jaws, reduction, with absence of teeth, of the upper half. In the latter case the fish feeds on worms and molluscs living on the ground and seized with the lower half of the jaws, in the former the food consists of small fish swimming above the Flat-fish and seized with the whole of the jaws (Turbot, Halibut, etc.). I contend, then, that the mode in which the normal Flat-fish develops is quite different from that in which mutations arise. T. H. Morgan [Footnote: _A Critique of the Theory of Evolution_ (1916), p. 18.] states that a variation arising in the germ-plasm, no matter what its cause, may affect any stage in the development of the next individuals that arise from it. In certain cases this is true, that is to say, when there are very distinct stages already. For example, a green caterpillar becomes a white butterfly with black spots. A mutation might affect the black spots, an individual might be produced which had two spots on each wing instead of one, and no sign of this mutation would be evident in the caterpillar. But my contention is that when this mutation occurred, the original condition of one spot would not be first developed and then gradually split into two. Morgan proceeds to state clearly what I wish to insist upon concerning mutations. He writes that in recent times the idea that variations are discontinuous has become current. Actual experience, he tells us, shows that new characters do not add themselves to the line of existing characters, but if they affect the adult characters, they change them without as it were passing through and beyond them. Now in the case of the ancestors of the Flat-fish the adult and the larva must have had the same symmetry with regard to eyes and colour and the dorsal fin terminated behind the level of the eyes. Thus the variations which gave rise to the Flat-fish were not discontinuous but continuous. In each individual development now, not merely hypothetically in the ancestor, the condition of the adult arises by an absolutely continuous change of the eyes, fins, and colour. Such a continuous change cannot be explained by a discontinuous variation, _i.e._ a mutation. The abnormalities above mentioned on the other hand, although they doubtless arise from the same kind of symmetrical larva as the normal Flat-fish, and develop by a gradual and continuous process, do not presumably pass through the condition of the normal adult Flat-fish and then change gradually into the condition we find in them. As compared with the normal Flat-fish they arise by a discontinuous variation, they are mutations, whereas the normal Flat-fish as compared with its symmetrical ancestor arises by a continuous change. In order to make my meaning clear I must point out that I have been using the word continuous in a different sense from that in which it is used by other biologists, Bateson for example. The word has been applied previously to variations which form a continuous series in a large number of individuals, each of which differs only slightly from those most similar to it. No two individuals are exactly alike, and thus such continuous variations are universal. According to the theory of natural selection the course of evolutionary change in any organ or character would form a similar continuous series, the mean of each generation differing only by a small difference from that of the preceding. According to the modern mutationists such small differences are to be called fluctuations, and have no effect on evolution at all, are not even hereditary, are not due to genetic factors in the gametes. Discontinuous variations, on the other hand, are as a rule differences in an individual from the normal type and from its parents of considerable degree, and are conspicuous: these are what are called mutations. The mutationists and Mendelians have not shown how the essential characteristics of mutations are to be reconciled with the facts of metamorphosis, or with recapitulation in development which is so often associated with metamorphosis. T. H. Morgan is the only mutationist, so far as my reading has gone, who has attempted to do this, and he seems to me to have failed to understand the difficulties or even the nature of the problem. He points out that the embryos of Birds and Mammals have gill slits representing the same structures as those of the adult Fish, but the young stage of the Fish also possessed gill slits, therefore it is 'more probable that the Mammal and Bird possess this stage in their development simply because it has never been lost.' He concludes therefore that the gill slits of the embryo Bird represent the gill slits of the embryo Fish, and not the adult gill slits of the Fish, which have been in some mysterious way pushed back into the embryo of the Bird. Morgan evidently does not realise that the Birds and Reptiles must have been derived from Amphibia, and that the embryo Reptile or Bird with gill slits and gill arches is merely a tadpole enclosed in an egg shell. The Frog in its adult state differs much from a Fish, while the larva in its gill arches and gill slits resembles a Fish. Morgan contends that the new characters do not add themselves to the end of the line of already existing characters. But in the case of the Frog this is exactly what they have done. The existing characters were in this case the gill arches and slits. Those who believe in recapitulation do not suppose that the animal had to live a second life added on to the life of its ancestors and that the new characters appeared in the second life. They believe that in the ancestor a certain character or general structure of body when developed persisted without change throughout life like the gill arches and slits in a Fish. At some stage of life before maturity this character underwent a change, and in the descendants the development of the original character and the change were repeated by heredity. There is no 'mysterious pushing back of adult characters into the embryo,' although it is possible or even probable that in some cases the change gradually became earlier in the life history: it is the new character which is pushed back, not the adult character of the ancestor. It is perfectly true, as Morgan says, that new characters which arise as discontinuous variations--in other words, those kinds of variation which are called mutations--do not add themselves to the line of already existing characters, but 'change the adult characters without as it were passing through and beyond them.' The mutations which Morgan describes in his own experiments on _Drosophila_ illustrate this in every case. In no case is the original organ or character, _e.g._ wings, of the normal Fly first developed and then changed by a gradual continuous process into the new character. It might perhaps be said that this took place in the pupa, but that seems impossible, for the complete wing is not fully developed in the pupa. The same truth is equally apparent in the mutations described in _OEnothera_. It follows, therefore, that none of the evolutionary changes which have produced what are called recapitulations can have been due to changes of that kind which is known as mutation. The abnormalities in Pleuronectidae to which I have referred are of the kind usually regarded as due to arrested development. But closer consideration gives rise to doubt concerning the validity of this explanation. It might be supposed that the attached base of the dorsal fin is unable to extend forward because the eye on the edge of the head is in the way, but if the metamorphosis is arrested, why should the fin grow forward in a free projection? I have described a very abnormal specimen of Turbot in a paper communicated to the Zoological Society of London, [Footnote: _Proc. Zool Soc._, 1907.] and in that paper have discussed other possible explanations of these mutations. In the specimen to which I refer the pigmentation instead of being present on both sides was reversed: the lower side was pigmented from the posterior end to the edge of the operculum (Plate II, fig. 2), while the upper side was unpigmented excepting a scattering of minute black specks and a little pigment on the head (Plate II., fig. 1). [Illustration: PLATE II, Fig. 1 and Fig. 2, Abnormal Specimen Of Turbot] I have suggested that the explanation here is that in the zygote the primordia of a normal body and a reversed head have been united together. We may suppose that different parts of the body are represented in the gametes by different determinants or factors, and therefore it is possible that these factors may be separated. In the specimen we are considering the body is normal or nearly so, with the pigmentation on the left side, which is normal for the Turbot, while the head has both eyes with some pigment on the right side and the left side unpigmented. Reversed specimens occasionally occur in many species of Pleuronectidae, and if the determinants for a reversed head and a normal body were united in one zygote, the curious abnormality observed might be the result. It is just a possibility that if this fish which was only 4.4 cm. long had lived to adult size, the upper side would have become pigmented under the influence of light, while the strong hereditary influence would have prevented the disappearance of the pigment from the lower side. In that case the adult condition would have been similar to that of ordinary ambicolorate specimens, but reversed, with eyes on the right side instead of the left. Other explanations of the more frequent ambicolorate mutation are possible: the body may consist of two left sides instead of a left and right, joined on to a normal head. But the first suggestion seems the more probable, as two rights or two lefts would not be symmetrical. Supposing the head and body not properly to belong to each other, one being reversed and one normal, we can in a way understand why the dorsal fin does not form the usual connexion with the edge of the head, because the determinants would not be in the normal intimate relation to each other. In thus writing of reversed and normal it must be understood that the former word does not mean merely turned over, for in that case right side of the body would be joined to the left side of the head, and the dorsal fin would be next to the ventral side of the head, which is not the case. What is meant is that a left side of the body which is normally pigmented is joined to a left side of the head which instead of having both eyes has neither, the two eyes being on the right side of the head which is joined to the right side of the body, and this is normal and unpigmented. The dorsal fin belonging to the normal sinistral body would therefore have a congenital tendency in the metamorphosis to unite with the head on the outer side of the original lower or right eye after it has moved to the left side. Actually, however, in this abnormal specimen it finds itself on the outer side of the left eye which has passed to the right side, and it has no tendency to unite with this part of the head. At the same time it has no tendency to bend over at an angle to reach the outer side of the right eye, and therefore it grows directly forward without attachment to the head at all. It will be seen, therefore, that what is changed in relative position in these mutations is not the actual parts of the body, but merely the _characters_ of those parts. In a sinistral Flat-fish, whether it is normally sinistral like the Turbot or abnormally like a 'reversed' Flounder, the viscera are in the same position as in a dextral specimen: the liver is on the left side, the coils of the intestine on the right. Thus in a reversed or sinistral Flounder, which is normally dextral, the left side which is uppermost is still the left side, but it has colour and two eyes, whereas in the normal specimen the right side has these characters and not the left. Thus we are forced to conceive of the determinants in the chromosomes of the fertilised ovum which correspond to the two sides of the body, as entirely distinct from the determinants which cause the condition or 'characters' of the two sides, unless indeed we suppose that determinants of right side with eyes and colour occur in some gametes and of right side without eyes and colour in others, and vice versa, and that homozygous and heterozygous combinations occur in fertilisation. On this last hypothesis the mutation here considered might be a heterozygous specimen, with the dextral condition dominant in the head and the sinistral in the body. Or it might be somehow due to what Morgan and his colleagues have called crossing over in the segregation of heterozygous chromosomes, so that a part corresponding to a sinistral body is united with a part corresponding to a dextral head. My conclusion from the evidence is that any process of congenital development may in particular zygotes exhibit a mutation, a departure from the normal. We need not use the term heredity at all, or if we do, must remember that in the present argument it does not refer to any transmission from the parent. The factors in the gametes of the normal Flat-fish egg cause the normal metamorphosis to take place after the larval symmetry has lasted a certain time. In occasional individuals the factors whatever they are, portions of the chromosomes or arrangement of the chromosomes or anything else, are different from those of the normal egg, and in consequence the abnormalities above described are developed. But the chief fact which I cannot too strongly emphasise is that the development of the abnormality from the symmetrical larva is direct, whether it is merely an arrest of development or an abnormal combination of reversed and normal parts. The abnormal development is not due to a change occurring _after_ the normal asymmetry has been developed. These abnormalities are true mutations. The evolution of the normal Flat-fish, on the other hand, was obviously due to a change of a different kind. Here we are dealing with the change from a symmetrical fish to the asymmetrical. Judging from what takes place in other mutations, it was quite possible for asymmetry to have developed directly from the egg, in consequence of some difference in the chromosomes of the nucleus. It has been shown that placing a fish egg for a short time in MgCl[2] [Footnote: Stockard, _Arch. Eut. Mech._, xxiii. (1907).] causes a cyclopean monstrosity to be developed in which the two eyes are united into one: but the two eyes do not develop separately first and then gradually approach each other and unite, the development of the optic cups is different from the first. In the normal Flat-fish the evolution that has occurred is the original development of the symmetrical fish, and the subsequent _continuous gradual_ change in eyes, fin, and colour to the adult Flat-fish as we see it. All the evidence accumulated by the experiments and observations of mutationists and Mendelians goes to prove that this change is of an entirely different kind from those variations which are described as mutations, or as loss or addition of genetic factors. This being the case, we have to inquire what is the explanation of the evolution of the normal metamorphosis. The important fact is that the original symmetrical structure of the larva and the asymmetrical structure of the adult Flat-fish correspond to the different positions of the body of the fish in relation to the vertical, the horizontal ground at the bottom of the water, and incidence of light. The larva swims with its plane of symmetry vertical like most other fishes; its locomotion requires symmetrical development of muscles and fins; the two sides being equally exposed to light, it requires an eye on each side, and the pigment on each side is also related to the equal exposure to light. The adult lying with one side on the ground has its original plane of symmetry horizontal and parallel to the ground, and only the other side exposed to light, and on this side only eyes and colour, _i.e._ pigment. The change of structure corresponds with the change of habit. It consists in the change of position of the lower eye, the extension of the dorsal fin forwards, and the disappearance of pigment from the lower side. In the actual metamorphosis these changes take place as the skeleton develops, before the hard bones are fully formed, while the fish is still small, but the young Turbot reaches a much larger size before metamorphosis is complete, namely, about one inch in length, than the young Plaice or Flounder. It is of little importance to consider whether at the beginning of the evolution the change of position occurred late or early in life. It may have become earlier in the course of the evolution. The important matter is to consider the evidence in support of the conclusion that the relation to external conditions has been the cause of the evolutionary change. We have already seen that the nature of the change and the relation of the change of structure to the change of conditions necessarily tend to the inference that the latter is the cause of the former. But we have to consider the particular changes in detail. To take first the loss of pigmentation from the lower side. I have shown experimentally that exposure of the lower sides of Flounders to light reflected upwards from below causes development of pigment on the lower side. At the same time the experiments proved that the loss of pigment in the fish in the natural state and the development of it under exposure to light were not merely direct results of the presence or absence of light in the individual, for in some cases the young fish were placed in the apparatus before the pigment had entirely disappeared from the lower side, and the metamorphosis went on, the lower side becoming quite white, and the pigment only developed gradually after long exposure to the light. In the principal experiment four specimens were placed in the apparatus on September 17, 1890, when about six months old and 7 to 9 cm. in length. One of these died on July 1, 1891, and had no pigment on the lower side. The other three all developed pigment on that side. In one it was first noticed in April 1891, and in the following November the fish was 22 cm. long and had pigmentation over the greater part of the lower side (Plate III.). Microscopically examined, the pigmentation was found to consist of black and orange chromatophores exactly similar to those of the upper side. Some hundreds of young Flounders were reared at the same time under ordinary conditions and none of them developed pigment. It is clear, therefore, that exposure of the lower side to light and reduction of the amount of light falling on the upper side (for the tops of the aquaria used were covered with opaque material) does not cause the two sides to behave in the same way in respect of pigment, as they would if the normal condition of the fish was merely due to the difference in the exposure to light of the two sides in the individual life. There is a very strong congenital or hereditary tendency to the disappearance of pigment from the lower side, and this is only overcome after long exposure to the light. On the other hand, if the disappearance of the pigment were due to a mutation, were gametogenic and entirely independent of external conditions, there would be no development of pigment after the longest exposure. To prove that an inherited character is an acquired character is quite as good evidence as to show that an acquired character is inherited. The latter kind of evidence is very difficult to get, for the effect of conditions in a single lifetime is but slight, and is not likely to show a perceptible inherited effect. The theory that adaptations are due to the heredity of the effects of stimulation assumes that the same stimulus has been acting for many generations. [Illustration: PLATE III - Flounder, Showing Pigmentation Of Lower Side After Exposure To Light] It is necessary, however, to consider how far the conclusions drawn from these experiments are contradicted by the mutations occurring in nature, some of which have already been mentioned. We will consider first ambicolorate specimens. If the absence of pigment from the lower side in normal Flat-fishes is due to the absence of light, how is it that the pigmentation persists on the lower side of ambicolorate specimens, which is no more exposed to light than in normal specimens? The answer is that in the mutants the determinants for pigmentation are united with the determinants for the lower side of the fish. My view is that the differentiation of these determinants for the two sides was due in the course of evolution to the different exposure to light, was of somatic origin, but once the congenital factors or determinants were in existence they were liable to mutation, and thus in the ambicolorate specimens there is a congenital tendency to pigmentation on the lower side, which would only be overcome by exclusion of light for another series of generations. Mutations also occur in which part or whole of the upper side is white and unpigmented. Several such specimens are mentioned in the memoir by myself and Dr. MacMunn in the _Phil. Trans._ already cited, one being a Sole which was entirely white on the lower side, and also on the upper, which was pigmented only over the head region from the free edge of the operculum forwards. Since the upper sides in these specimens are fully exposed to light in the natural state and yet remain unpigmented, it would appear impossible to believe that the action of light was the cause of the development of pigment on the lower sides of normal specimens in my experiments. To some it may be so, but in my own opinion the one fact is as certain as the other. I believe the two facts can be reconciled. I had one specimen of Plaice in the living condition which had the middle third of its upper surface white, and the whole of the lower side white as usual. This specimen was kept for 4-1/2 months with its _lower_ surface exposed to light and the upper side shaded. At the end of that period there were numerous small patches of pigment scattered over the lower side principally in the regions of the interspinous bones, above and below the lateral line. In the area of the upper side, which was originally unpigmented, there were also numerous small pigment spots. I believe, therefore, that in this case there were determinants for absence of pigment not only on the lower side but on part of the upper side also, and that so long as light was excluded from the lower side the patch on the upper side remained unpigmented in sympathy. When the congenital tendency of the determinants on the lower side was overcome by the action of light, the white patch on the upper side also began to develop pigment. Lastly, I may refer again to the specially abnormal Turbot mentioned above. In this case the lower side was over the greater part pigmented and the upper side white, and this would appear to contradict the conclusion just drawn concerning the piebald Plaice. But this Turbot was only 4.4 cm. long, and is the only case known to me where so much of the lower side was pigmented with the upper side almost entirely white. The theory of sympathy or correlation might apply here since the lower side of the head was unpigmented, but from the small size of the specimen and the amount of pigment on the lower side, it seems to me most probable that if the specimen had lived to be adult the upper side would have developed pigment under the action of light and the specimen would have become ambicolorate. When we compare the results reached by the mutationists with those obtained by the Mendelians we find that they tend to two different conceptions of the relation between the gametes and the organism developed from them. The effect of a change in the determinants of the gametes according to the mutationists is evident in every part of the plant. A factor in Mendelian experiments usually affects only one organ or one part of the organism. The factor for double hallux in fowls, for instance, may coexist with single comb or rose comb. The general impression produced on the mind by study of Mendelian phenomena is that the organism is a mosaic of which every element corresponds to a separate element in the chromosomes. Thus we know that what we call a single factor may cause the whole plumage of a fowl to have the detached barbs, which constitutes the Silky character, but we also know that an animal may be piebald, strongly pigmented in one part and white or unpigmented in another. So we find in these Flat-fish mutations mosaic-like forms which evidently result from mosaic-like factors in the gametes, or in the chromosomes of the gametes. Experimental evidence concerning the movement of the lower eye to the upper side and of the forward extension of the dorsal fin has not been obtained, though years ago I made some attempts, at the suggestion of Mr. G. J. Romanes, to obtain such evidence with regard to the eye by keeping young Flounders, already partially metamorphosed, in a reversed position. I did not succeed in devising apparatus which would keep the young fish alive in the reversed position for a sufficiently long time. We can only consider, therefore, whether those other changes can reasonably be attributed to the conditions of life. Anatomical investigation shows that the bony interorbital septum composed principally of the frontal bones, which in symmetrical fish passes between the eyes, is still between the eyes in the Flat-fish, but has been bent round through an angle of 90 degrees on the upper side, while in the lower side a new bony connexion has been formed on the outer side of the eye which has moved from the lower side. This connexion is due to a growth from the prefrontal backwards to join a process of the frontal, and is entirely absent in symmetrical fishes. It is along this bony bridge that the dorsal fin extends. The origin of the eye muscles and of the optic nerves is morphologically the same as in symmetrical fishes. On the theory of modification by external stimuli we must naturally attribute the dislocation of the eye of the lower side to the muscular effort of the fish to direct this eye to the dorsal edge, but something may also be due to the pressure of the flat ground on the eye-ball. There is little difficulty in attributing the bending of the interorbitl septum to pressure of the lower eye-ball against it, pressure which is probably due partly if not chiefly to the action of the eye muscles. The formation of the bony bridge outside the dislocated eye is more difficult to explain, as I have never had the opportunity to study the relation of this bridge to the muscles. It is worth mentioning that in the actual development of Turbot and Brill the metamorphosis takes place to a considerable degree while the young fish is pelagic, before the habit of lying on the ground is assumed, but of course this is no evidence that the change was not originally caused by the habit of lying on the ground. With regard to the extension of the dorsal fin there is no difficulty in discovering a stimulus which would account for it. Symmetrical fishes propel themselves chiefly by the tail; in shuffling over the ground or swimming a little above it. Flat-fishes move by means of undulations of the dorsal and ventral fins. Increased movement produces hypertrophy, and according to the theory here maintained, not merely enlargement of parts existing, but phylogenetic increase in the number of such parts, here fin rays and their muscles. In Flat-fishes the dorsal and ventral fins extend along the whole length of the dorsal and ventral edges: the dorsal from the head, in some cases from a point anterior to the eyes, to the base of the tail, the ventral from the anus, which is pushed very far forward, to the base of the tail, and in some species of Solidae these fins are confluent with the caudal fin. Formerly it was dogmatically maintained that the effect of an external stimulus on somatic organs or tissues could have no influence on the determinants in the chromosomes of the gametes to which the hereditary characters of the organism were due. As we have tried to show, this dogma is no longer credible in face of the discoveries concerning hormones. The hormone theory supposes that the somatic modifications due to external stimuli--in the case of the Flat-fish the disappearance of pigment from the lower side, the torsion of the orbital region of the skull, and the extension of the dorsal fin--modify the hormones given off by these parts, increasing some and decreasing others, and that these changes in the hormones affect the determinants, whatever they are, in the gametocytes within the body. Here arises an interesting question--namely, how does the hormone theory explain the phenomenon of metamorphosis any better than the mutation theory? It might be agreed that if the determinants are stimulated or deprived of stimulation, the effect of the change should logically show itself from the beginning of development, and that therefore the process of metamorphosis or indirect development does not support the hormone theory any more than the theory of gametogenic mutations. This objection may be answered in the following way. The reason why the determinants give rise to the original structure first and then change it into the new structure is probably the same as that which causes secondary sexual characters to develop only at the stage of puberty. By the hypothesis the new habits and new stimuli begin to act at some stage after the complete development of the original structure of the body. The differences in the original hormones of the modified parts are therefore acting simultaneously with the hormones, that is, the chemical substances derived from all other parts of the body in its fully developed condition. It is very probable that in the early stages of development the metabolism of the body would be considerably different from that of the adult stage, and the same combination of hormones would not be present. We may suppose, therefore, that the determinants of the zygote have acquired a tendency to produce the increases and decreases of tissue which constitute a certain modification, _e.g._ the change in the position of the eyes in a Flat-fish, but the stimulus which caused this tendency has always acted when the adult combination of hormones was present. In consequence of this the developed tissues do not undergo the inherited modification until the adult combination is again present. In this way we can form a definite conception of the reason why an adaptive modification is inherited at the same stage in which it was produced, just as the antlers of a stag are only developed when the hormone of the mature testis is present. At the same time it is probable that the age at which the inherited development takes place tends to become earlier in later generations, to occur in fact as soon as the necessary hormone medium is present. The diagnostic characters, of some of the species of Pleuronectidae have been mentioned in an earlier part of this volume, in order to point out that they have no relation to differences of habit or external conditions. Here it is to be pointed out that there is no evidence that they arise by metamorphosis. The scales, for example, afford distinct and constant diagnostic characters both of species and genera, but their peculiarities have not been found to arise by modification of a primitive form. The rough tubercles of the Flounder, and the scattered thornlike tubercles of the Turbot, develop directly, not by the continuous modification of imbricated scales. There is, however, one scale-character among the Pleuronectidae which appears to stand in direct contradiction to the conclusions drawn by me concerning scales in general. It not only develops by a gradual change, but it is a secondary sexual character developing in the males only at maturity. The character was described by E. W. L. Holt in specimens of the Baltic variety of the Plaice, _Pleuronectes platessa_, [Footnote: _Journ. Mar. Biol. Assn._, vol iii. (Plymouth, 1893-95.)] and consists in the spinulation of the posterior edges of the scales, especially on the upper side, in mature males. The same condition, but to a much slighter degree, was afterwards shown by myself to occur constantly in Plaice from the English Channel and North Sea. [Footnote: _Ibid._, vol. iv. p. 323.] It occurs also in _P. glacialis_, the representative of the Plaice in more northern seas. I have shown that the spinules develop in the mature males not as a modification of the scale, but as separate calcareous deposits the bases of which afterwards become united to the scale. It would seem that the development of this character is dependent on the hormone from the mature testis, and in order to conform with the arguments used by me in other cases, the spinulation should have some definite function in relation to the habits of the sexes, and this function should involve some kind of external stimulation restricted to the mature male. So far, however, no evidence whatever of such function or such stimulation has been discovered. It is possible that the case differs from other secondary sexual characters as the antlers of stags in one respect, namely, that the Dab (_P. limanda_), the Sole, and other species of _Solea._ and several other Pleuronectidae have what are called etenoid scales--that is, scales furnished with spines on the posterior edge--and since the ordinary scales of the Plaice are reduced, the spinulation of scales in the mature male Plaice is not a new character but the retention of a primitive character. Then the question would remain why the scales in the mature female and immature male have degenerated, or rather why the primitive character develops only in the mature stage of the male. There is one point in which this sexual dimorphism in the Plaice appears to differ from typical cases, and which suggests that the greater spinulation of scales in the males has no function at all in the relations of the sexes, and is therefore not subject to and external stimulation. This point is the remarkable way in which the degree of development of spiny armature differs in different regions and in local races, and seems to correspond to different climatic conditions. Both Plaice and Flounders in the Baltic are much more spiny than in the North Sea, although in the Flounder no sexual difference in this respect has been noted. On the east coast of North America occurs _P. glacialis_, in which the scales of the male are strongly spinulate and those of the female smooth. On the coast of Alaska females of this species seem to be more spinulate than elsewhere. The Flounder does not occur in the Arctic, but on the west coast of North America occurs a local form called _P. stellatus_, scarcely distinct as a species, which has a strong development of spiny tubercles all over the upper side. The Flounders of the Mediterranean are much less spinous than those of the North Sea or Channel. The Dab (_P. limanda_) occurs on the American coast in a local form called _Limanda ferruginea_, and in the North Pacific there is a rougher form called _L. aspera_. In these three species therefore, apart from mutations, the northern forms all show a greater development of spines on the scales. Whether this is an effect of colder temperature it is difficult to say. It is possible that the difference is due to external conditions, of which lower temperature of the water is the most obvious, and it may be that these conditions have a greater effect on the male than on the female in the Plaice. Sexual differences in scales, which have a function in the relations of the sexes, occur in a few other fishes, and these can be attributed with good reason to mechanical stimulation. For example, in the Rajidae among Elasmobranchs the males possess on each 'wing' or pectoral two series of large, recurved, hooked spines. It has been stated, [Footnote: Darwin, _Descent of Man_ (2nd edit., 1885), p. 331.] apparently by Yarrell, that these spines are developed only in the breeding season. It is doubtful if there is any marked breeding season in these fishes, but it is probable that the spines are absent in the immature male, as it is known that in _Raia clavata_ the adult male has sharp pointed teeth, while the young male and the female at all ages have broad flat teeth. It is supposed that the spines and perhaps the sharp teeth are used for holding the female, but it seems equally probable that these structures are really used by the males in fighting with each other. The habits of these marine fish have not been much observed, but there is little reason to doubt that these differences in scales and teeth correspond with differences of mechanical stimulation. This does not at all imply that the scales and teeth themselves have been produced by mechanical stimulation, or that the difference between the dermal denticles of Elasmobranchs and the scales of Teleosteans correspond to differences of stimulation. But the degree of development of a structure whose presence is due to gametic factors may very probably be modified by external stimulation, and the modification may become hereditary. If the views here advocated are true, the two processes mutation and modification must be always acting together and affecting the development not only of the individual but of any organ or structure. Thus the peculiarities of antlers in stags, it seems to me, prove that the mechanical stimulation due to fighting was the cause of the evolution of antlers, that without the habit of fighting in the males antlers would not exist. At the same time each species of the _Cervidae_ has its special characters in the antlers, in shape and branching, and it would be impossible to attribute these to differences in mode of fighting: they are due to mutation. In connexion with the metamorphosis of Amphibia the case of the Axolotl has always been of very great interest. In the few small lakes near the city of Mexico where it occurs it has never been known to undergo metamorphosis but is aquatic throughout its life and breeds in that condition. Yet in captivity by reducing the quantity of water in which it is placed the young Axolotl can be forced to breathe air, and then it undergoes complete metamorphosis to the abranchiate condition. The same species in other parts of North America normally goes through the metamorphosis, like other species of the Urodela. It is evident, therefore, that the Mexican Axolotls, although they have been perennibranchiate for a great number of generations, have not lost the hereditary tendency to the metamorphosis which changes the larvae of _Amblystoma_ elsewhere into an air-breathing terrestrial animal. This may be regarded as evidence that the conditions of life which prevent the metamorphosis in the Mexican Axolotl have produced no hereditary effect. The fact, however, that Axolotls require special treatment to induce metamorphosis seems to show that they have distinctly less congenital tendency to metamorphosis than larvae of the same species, _Amblystoma tigrinum_, in other parts of North America, and this difference must be attributed to the inherited effect of the conditions. The most important of these conditions seems to be abundance of oxygen in solution in the water, and the next in importance abundance of food in the water. Recently it has been shown that the metamorphosis may be induced by feeding Axolotls on thyroid gland. But there is no reason to suppose that a congenital defect of thyroid arising as a mutation was the original cause of the neoteny, _i.e._ the peisistence of the larval or aquatic, branchiate condition. Such a supposition would imply that the association between Axolotls and the peculiar Mexican lakes, supplied with oxygenated water by springs at the bottom, was purely accidental. Moreover, there is no evidence that there is any deficiency of thyroid in the Axolotl. The secretion of the thyroid gland is necessary for the normal growth and development of all Vertebrates, and we are only beginning to understand the effects of defect or excess of this secretion. There is nothing very surprising in the fact that excess in the case of the Axolotl causes the occurrence of the metamorphosis which had already in numerous experiments been produced by forcing the animals to breathe air. Metamorphosis, as in the development of gill arches and gill slits in the embryos of Birds, Reptiles, and Mammals, exhibits a recapitulation of the stages of evolution of certain organs. But in the case of other organs the absence of recapitulation is remarkable by contrast. If, as I believe, the development of lungs and disappearance of gills was directly due to the necessity of breathing air, it is difficult to avoid the conclusion that the terrestrial legs were originally evolved from some type of fishes' fins by the use of the fins for terrestrial locomotion. Yet neither the amphibian larva nor the embryo of higher Vertebrates develops anything closely similar to a fin. There is no gradual change of a fin-like limb into a leg, but the leg develops directly from a simple bud of tissue. The larva of the Urodela is probably more primitive than the tadpole of the Frogs and Toads, and in the former the legs develop while the external gills are still large, long before the animal leaves the water. It is possible that the limbs were transformed to the terrestrial type before the animal itself became terrestrial, the habit of swimming having been partly abandoned for that of crawling or walking at the bottom of the water, and the tail being used merely for swimming to the surface to obtain air. But the condition of the Dipnoi, which possess lungs but do not walk on land, does not support this supposition, for they possess fins which are either filamentous or fin-like, having a central axis with rays on each side. There can be little doubt that the digits of the terrestrial limb are homologous with endoskeletal fin-rays, but the evolution of the axis of the limb is not to be ascertained either from development or palaeontology. The absence of metamorphosis here may perhaps be due to the fact that the lateral fins ceased to function in the earlier aquatic stages, only the caudal fin being used for swimming. If this were the case the absence of metamorphosis in the legs is itself an adaptation, the disuse of the paired limbs in the larva having caused the earlier fin-like stages of these limbs to disappear, while the terrestrial leg was developed later by heredity, just as the legs have disappeared in the larvae of many insects, though fully developed in the adult. Metamorphosis of structure in Amphibia and in Flat-fishes corresponds to the change of conditions of life in the free-living animal. In the case of the eyes of the Cave-fishes the conditions in respect of absence of light are constant throughout life, and we find only an embryonic development of the eye taking place by heredity. The question arises whether, when there is no embryonic recapitulation, it must be concluded that apparent adaptations are due to mutation and not to function or external conditions. One case of this kind is that of the limbs of Snakes, where, if we except the vestiges of hind limbs in the Pythons, there is no trace of limbs either in the embryo or after hatching. There are several similar cases among Reptiles and Amphibia. The Slow-worm (_Anguis fragilis_) is limbless, and so are the members of the sub-class Apoda among the Amphibia. In these also rudiments of limbs are entirely absent in the embryos or larval stages. Considering the recent evolution of Snakes as compared with the origin of lungs and loss of gills and gill slits in terrestrial Vertebrates in general, we have here a remarkable contrast which shows in the first place the difference resulting when the change in habits and conditions in the one case takes place from one stage of life to another, and in the other case the new habits are constant throughout life from the moment of hatching. It seems to me that in the present state of our knowledge we cannot form a decisive opinion on the question whether the absence of limbs in such cases is the result of mutation or of disuse--that is, absence of functional stimulation. The power of flight is an excellent example of adaptation. It has been evolved independently in Pterodactyls, Bats, and Birds. In the two first groups, and to a slight degree in the third, the expanse of the wing is formed by an extension of the skin into a thin membrane, supported by the fore-limbs. It is not necessary to argue in detail that the evolution of this membrane and of the modifications of bones and muscles by which it is supported and moved, can be satisfactorily explained on the theory that modifications due to mechanical and functional stimulation are ultimately inherited. In birds, however, the surface of the wing is supplied chiefly by feathers, and consideration of the matter affords no reason for supposing that the evolution of feathers was due to any external or functional stimulation. It is often stated that the feathers of birds are a modification of the epidermic scales of reptiles, but investigation does not fully confirm this statement. The reptilian scales are retained on the tarso-metatarsal region of the leg in the majority of birds, and it would be expected, if the view just quoted were correct, that a transition from scales to feathers would be visible at the ankle-joint. This, however, is not the case. In fowls some breeds have scaly shanks and others feathered. In those with scaly legs I have found cases in winch, in the chicks, there were two or three very minute feathers, and I have examined these microscopically by means of sections of the skin. The result was to show that the minute feathers were not a prolongation of the tips or edges of the scales, but arose from follicles between the scales. The scale is flat and is a fold of the epidermis not arising from an invaginated follicle. The feather, on the other hand, is a tubular structure arising from a papilla at the base of a deep follicle extending inwards from the surface of the skin. As the feather grows the papilla grows with it. This papilla consists of vascular dermal, _i.e._ mesodermic tissue, and if the feather is pulled out during growth bleeding occurs. The epidermic horny tube splits posteriorly towards the apex of the feather, and is divided into rachis and barbs, and thus the dermal tissue within, by this time dead and dry, is exposed and is shed. Every feather is in fact an open wound, and is perhaps the only other case, in addition to that of the antlers of stags, in which vascular mesodermic tissue is normally shed in such considerable quantities. When the development of the feather is complete, growth gradually ceases, the proximal part of the feather remains tubular and does not split, and the vascular tissue within dies, shrivels, and dries up, forming the pith of the quill When the papilla recommences to grow the old feather is pushed out, and this process causes the moult. It would appear, therefore, that the feather must have been evolved, not by a continuous modification from the scale but by a development of a new kind between the scales. I have been unable to discover hitherto any evidence suggesting an external stimulus which could cause this remarkable process of development in feathers, or indicating that the function of flight would involve such a stimulus. For the present, therefore, we must conclude that feathers are not an adaptation, and not due to somatogenic modification, but must be result of a gametogenic mutation. Feathers, having been evolved, served in the wings and tail as important organs of flight. There is reason to believe that, once present, the growth of feathers was modified greatly by the degree of stimulation applied to the papillae at roots by the movement and bending strain of the feathers. The modification of the hones and of the wing, shoulders, and sternum by the functional stimuli involved in flying are obviously adaptations, and in my opinion are only to be explained as the hereditary effects of functional stimulation, like all skeleto-muscular adaptations. The strains produced in bones by muscular contraction produce hypertrophy of the part of the bone to which the muscles are attached and thus we can understand the origin of the carina of the sternum in flying birds, and its absence in flightless forms. In bats and in pterodactyls also the sternum is produced into a carina along the median line. The reduction of the digits of the wing in birds to three, with the bones firmly united together, would follow from their use in flight and their disuse as digits, and it would seem, from the fact that the flight-feathers must have been always on the posterior edge of the wing, and that the ulna is larger than the radius, that the three digits which have persisted are the 3rd, 4th, and 5th, and not the 1st, 2nd, and 3rd as usually taught. A comparison of the hind-limbs of birds with those of bats and pterodactyls suggests strongly that the patagium flyers have arisen from arboreal or climbing animals, while the birds arose from terrestrial forms which acquired the bipedal habit, as certain reptiles have. An arboreal animal would necessarily use all four limbs, as climbing animals actually do. The wings of birds, on the other hand, would have arisen, from the endeavour to increase speed by movements of the fore-limbs. The perching birds would therefore have arisen by later adaptations after the power of flight had been evolved. Complete recapitulation does not occur in the development of the digits of the wing. Only a rudiment of a fourth digit has been found in the embryonic wing, not, as might be expected, rudiments of five digits of which two disappear. The metacarpals are free, not united as in the adult, and there are separate distal carpals, which in the adult are united with the metacarpals. In other respects the modifications of wings and sternum are so obviously adaptive that it is difficult to believe that the reduction of digits was not due to disuse. This is another of those cases in which the function to which structure is adapted is constant from the beginning of independent life to the end, and there is some ground for believing that in course of time in such cases embryonic recapitulation may be much diminished or disappear. The period of time since birds were first evolved is in all probability immensely greater than that which has elapsed since the blind fish, _Amblyoysis_, was modified by cave-life, so that we can understand why the eye is developed to a certain stage in the embryo of the blind fish, although it lives in darkness all its life, while embryonic recapitulation in the wing of the bird is very incomplete. In another class of adaptations the embryonic or larval stage is adapted to new conditions, while the adult condition is either less changed or not changed at all. One of the most obvious examples of this is the allantois in the Amniota. The embryos of Reptiles, Birds, and Mammals all develop two embryonic or foetal membranes, the amnion and the allantois. Of the function or origin of the amnion little is known: to state that it is protective affords little explanation. It seems possible that it is merely the mechanical result of the weight of the embryo and the development of the allantois. The latter is a precocious hypertrophy of the cloacal bladder found in Amphibia, with the function of embryonic respiration. In the water the amphibian larva respires by means of gills and gill slits. In adaptation to terrestrial life it is necessary, if the free aquatic larval stage is to be eliminated, that the embryo should be able to breathe air before hatching. Various Amphibia show how this requirement was met in various ways. In the South American tree-frogs of the genus _Nototrema_ the eggs are developed in a dorsal pouch of the skin of the female, and within this pouch the respiration of the embryo is carried on by a membranous expansion of the second and third external gills on each side. In the Reptilia the bladder is expanded for the same function, and absorbs oxygen and gives off carbon dioxide through the pores of the shell. It is impossible to reconcile the conception of mutation with the adaptive relation between this allantois and the expulsion of the egg enclosed in a shell on land. The transition probably came about gradually from the deposition of the eggs in moist places but not in water. In the midwife toad (_Alytes obstetricans_) the male carries the eggs about attached to his legs, respiration is effected by enlarged external gills, and the larvae are hatched in water. In the ancestral reptiles external gills may have helped at first, until by the enlargement of the bladder they were rendered unnecessary. In all such cases the absorption of oxygen must be regarded as the stimulus which caused the enlargement of the respiratory membrane. As the allantois could not be absorbed or retracted again into the abdomen, the umbilicus was evolved--that is to say, the scar formed by the union of the folded edge between the body wall and amnion surrounding the stalk of the allantois. It would he difficult for a mutationist to explain how a mutation should affect the development of the cloacal bladder to such an enormous degree, just when it was required for embryonic respiration, and cause the sides of the body to unite ventrally at the time of hatching, cutting off the allantois and the amnion. T. H. Morgan [Footnote: _A Critique of the Theory of Evolution_, p.18.] states that a mutation of gametic origin may affect any stage in the development of the individual. This may be true when there are already distinct stages in the life history. The more important question is whether distinct stages can be caused by mutation. It is true that in heterozygous individuals characters may develop more fully in the adult stage than in the young. But when we find different stages evidently adapted to different modes of life, it is impossible to explain them by mutations affecting different stages of life. In such cases as the larval stages of Insects we find the larvae have become adapted to new habits while the adults have remained unchanged, or have evolved quite independent adaptations. For example, the adults in the chief orders of Insects have the typical three pairs of legs, while the maggots or grubs of the Diptera or Hymenoptera have no legs at all, the caterpillars of Lepidoptera have evolved pseudo-legs on the abdomen, and the larvae of Coleoptera have the ordinary legs and no more. This is the reverse of recapitulation: in the case of legless maggots, and caterpillars with pro-legs, the adult is more similar to the ancestor than the larva. But the same principle holds, that where functions and habits are different, there organs are different. No mutationist has yet produced by breeding experiments a caterpillar without the three pairs of thoracic legs and yet developing into a moth that had normal three pairs. Morgan, with all his mutations of the adult _Drosophila_, says nothing of mutants possessing legs. The only rational conclusion is that legless larvae have lost the disuse, since those larvae which are destitute of legs do not go in search of food but either live in the midst of it or are fed by others, and that the pro-legs of the caterpillar have been developed by the muscular action of the insect in clinging to leaves. Here again the hormone theory, although we cannot pretend to understand the matter completely, helps us to form a conception of the process of heredity and evolution. The disuse of legs in the larva affects the determinants, so that they remain inactive in the presence of the hormones produced in the body generally in this stage. In the adult stage activity of the legs produces hormones which influence the same determinants in the gametes to develop legs, but again in the presence of the different hormones which are present in the body generally in the adult stage. As the habits of larva and adult became more specialised and contrasted, the change became less and less gradual, and the intermediate stage, not being adapted to any transitional mode of life, became an inactive pupa in which the adult organs develop. In conclusion I will briefly consider the attempts which have been made to prove the influence of somatic modifications or characters on the gametes by direct experiment. The method of Kammerer of inducing changes of habit or structure by conditions, and then showing that the change is in some degree inherited, has already been mentioned. One obvious criticism of this evidence is that it seems to prove too much, for it is difficult to believe that a change produced in individuals would show so much hereditary effect in their immediate offspring. Two other methods are conceivable by which the influence of somatic hormones might be evident. One of these is to graft ovaries or testes from one animal into another which possesses a certain somatic character, and then to see if the offspring produced from these gonads shows any trace of the character of the foreign soma in which it was nourished. C. C. Guthrie [Footnote: _Journ. Exper. Zool._ (1908), v.] claimed to have done this in his experiments on hens. He grafted the ovaries of two Black Leghorn pullets into two White pullets of the same breed, and vice versa. The black and the white birds bred true when mated to cocks of their own colour. The black hen with white ovary mated with black cock produced four black chicks and two black chicks with white legs, the white hen with black ovary mated with white cock produced some white chicks, some black and some white with black spots. This is held to prove that the transplanted ovaries were functional, because they produced evidence of the character originally belonging to them. On the other hand, the black hen with white ovary mated with white cock produced nine white chicks, and eleven chicks which were white spotted with black, and the white hen with black ovary mated with black cock produced not black chicks but white chicks spotted with black. This was held to prove that the somatic characters of the "foster mothers" were transmitted. Davenport repeated Guthrie's experiments on different fowls, grafting the ovary from a cinnamon-coloured hen into a white hen, and mating her with a cinnamon-coloured cock. The chicks were exactly similar to those obtained from crossing such a cock with a normal white hen, and Davenport concludes that the engrafted ovary was not functional but had degenerated. It is known to be almost if not quite impossible to remove the ovary completely from a hen, owing to its close attachment over the great post-caval vein. At the same time it is difficult to see how Guthrie could have obtained black and spotted chicks from a white hen mated with, a white cock if the grafted ovary from a black hen had not been functional. One point which Guthrie does not mention, and of which apparently he was not aware, is that the white of the White Leghorn is dominant to colour, the heterozygotes not being pure white but white with spots. Thus when he mated a black cock with a white hen with grafted ovary and obtained spotted chicks, this would have been the result if the original white ovary was functional. None of his results prove conclusively the influence of the soma of the hen into which ovaries were grafted, but would all be explained if some eggs were derived from the part of the original ovary not removed in the operation, and others from the grafted ovary. The grafting of ovaries in Mammals has often been tried, but very rarely with success. The introduced ovary usually dies and is absorbed. C. Foa [Footnote: _Arch. Ital. de Bid._ (1901), Tome xxxv.] states that he made bilateral grafts of ovaries from newborn rabbits into adult rabbits, and two months after the operation one of the operated females was fecundated and produced five normal young. In other cases he placed ovaries from new-born young in positions far from the normal position, such as the space between the uterus and bladder, and in one case the female so treated became pregnant, and when killed had a single embryo in one uterus and no trace of the original ovaries in the normal position. But Foa was not investigating the influence of somatic characters on ova in the grafted ovaries, and does not even mention the characters or breed of the rabbits he used or of the young which were produced from the grafted ovaries. Castle [Footnote: W. E, Castle and J. C. Phillips, _On Germinal Transplantation in Vertebrates_, Pub. Carnegie Institution in Washington (1911), No. 144.] carried out seventy-four transplantations of ovaries principally in guinea-pigs. Out of all these only one grafted female produced young. In this case the ovaries of two different black guinea-pigs about one month old were grafted into an albino female about five months old. After recovery the grafted female was kept with an albino male. She produced six young in three pregnancies, first two, then one, and lastly died with three foetus in the uteri. All these were black, with some red hairs among the black. One of the first two young had a white forefoot. In this case black is dominant, and therefore there is nothing extraordinary in the offspring from a black grafted ovary being black. The presence of red hairs and a white foot is no evidence of the influence of the foster soma, but is due to imperfect dominance. When the same male was mated with a normal black female the offspring were black with red hairs interspersed. All these experiments are open to the following criticism. It has been the main argument of this volume that there are two distinct kinds of characters in all organisms--namely, those of somatogenic origin and those of gametogenic origin. Theory supposes that somatic modifications by means of hormones affect the determinants in the gametes. But it is obvious that the black and white of Leghorn fowls and of guinea-pigs are gametogenic characters, and are strongly established in the gametes of their respective varieties. It is not even certain that the black or white hair or feathers are giving off special hormones which would or could influence the gametes. The hormone theory only postulates such influence from hormones issuing from tissues modified by external stimuli. It is quite certain that the black colour in Leghorns or guinea-pigs is not due to any external stimulus or influence. The experiments therefore are entirely irrelevant to what has been called the inheritance of acquired characters. All that they can be said to prove is that an albino soma does not convert ingrafted ova of black race into ova carrying the albino character. It is probably impossible to prove experimentally the influence of a modified soma in one generation. I have endeavoured to find a case which would not be open to the above criticism--that is, to find a character which could be considered somatogenic and which was absent in a closely allied variety. Most of the characters in domesticated varieties are obviously gametogenic mutations, but the lop-ear in rabbits may be, partly at least, somatogenic. Since many breeds have upright ears, we cannot say that disuse of the external ear has produced lop-ears in domesticated rabbits generally, but in lop-eared breeds the ears are much enlarged; and though this may be gametogenic, the increased weight may have been the cause of the loss of the power to erect the ears. I therefore tried grafting ovaries from straight-eared females into lop-eared individuals. The operation was perfectly successful in seven specimens--that is to say, they recovered completely and lived for many months, up to a year or more afterwards, but none of them became pregnant. When killed no trace of ovary was in any of them; in every case it had been completely absorbed, and the uteri and vagina were diminished in size and anaemic. For grafting I used ovaries from young rabbits of various ages from seven days to six weeks or more, but all were equally unsuccessful. Satisfactory evidence by direct experiment of the inheritance of somatogenic modifications due to external stimuli cannot be said to have been yet produced, and, as I have shown, such evidence from the nature of the case must be very difficult to obtain. The indirect evidence, however, which has been considered in this volume is too strong to be ignored--namely, the case of Japanese long-tailed fowls, that of colour on the lower sides of Flat-fishes, and the similarity of the congenital development of the antlers in stags, to the generally admitted effects of mechanical stimulation and injury on the skin and superficial bones of Mammals. The general conclusions which are logically to be drawn from our present knowledge with regard to the problems of heredity and evolution in animals are in my opinion as follows:-- 1. All attempts to explain adaptation by gametogenic mutations, or changes in gametic factors or 'genes,' have completely failed, as Bateson himself has admitted. 2. The facts discovered concerning mutations and Mendelian heredity harmonize with the nature of the majority of specific and varietal characters, and with the diagnostic characters of many larger divisions in classification. 3. Some of the most striking cases of adaptation, such as the organs of respiration and circulation in terrestrial Vertebrates, and the asymmetry of Flat-fishes, are developed in the individual by a metamorphosis which is generally regarded as a recapitulation of the ancestral evolution. No cases of mutation or gametogenic variation hitherto described exhibit a similar metamorphosis or recapitulation. 4. Secondary sexual characters, usually in the male sex, correspond in their development with the development of maturity and functional activity in the gonads, and it has been proved that the latter influence the former by means of 'hormones' or internal secretions. The evidence concerning sex and sex-linked characters and the localisation of their factors in the chromosomes of the gametes has no bearing on the action of hormones. 5. The facts concerning the action of hormones are beyond the scope of current conceptions of the action of factors or genes localised in the gametes and particularly in the chromosomes. According to these conceptions, characters are determined entirely by the genes in the chromosomes, whereas in certain cases the development of organs or characters depends on a chemical substance secreted in some distant part of the body. 6. It was formerly stated that no process was known or could be conceived by which modifications produced in the soma by external stimuli could affect the determinants in the gametes in such a way that the modifications would be inherited. The knowledge now obtained concerning the nature and action of hormones shows that such a process actually exists, and in modern theory real substances of the nature of special chemical compounds take the place of the imaginary gemmules of Darwin's theory of pangenesis or the 'constitutional units' of Spencer. 7. The theory of the heredity of somatogenic modifications by means of hormones harmonises with and goes far to explain the facts of metamorphosis and recapitulation in adaptive characters, and also the origin of secondary sexual characters, their correlation with the periodical changes in the gonads and the effects of castration. At the same time there are some somatic sex-characters, _e.g._ in insects and birds, which do not appear to be correlated with changes in the gonads, and which are probably gametogenic, not somatogenic in origin. 8. The theory of the heredity of somatogenic modifications is not in opposition to the mutation theory. The author's view is that are two kinds of variation in evolution, one somatogenic and due to external stimuli, acting either directly on passive tissues or indirectly through function, and the other gametogenic and due to changes in the chromosomes of the gametes which are spontaneous and not in any way due to modifications of the soma. Adaptations are due to somatogenic modifications, non-adaptive diagnostic characters to gametogenic mutations. It is a mistake to attempt to explain all the results of evolution by a principle. There are two kinds of congenital, constitutional or hereditary characters in all organisms, namely, the adaptive and the non-adaptive, and every distinct type in classification exhibits a combination of the two. To assert that all characters are adaptive is as erroneous as to state that all characters are blastogenic mutations, and therefore in their origin non-adaptive. 9. Finally it may be urged, although the question has not been directly discussed in this volume, that no biologist is justified in the present state of knowledge in dogmatically teaching the lay public that gametogenic characters are alone worthy of attention in questions of eugenics and sociology. Hereditary or constitutional factors are of course of the highest importance, but there exists very good evidence that modifications due to external stimulus do not perish with the individual, but are in some degree handed on to succeeding generations, and that good qualities and improvement of the race are not exclusively due to mutations which are entirely independent of external stimuli and functional activity. It is important to produce good stock, but it is also necessary to exercise and develop the moral, mental, and physical qualities of that stock, not merely for the benefit of the individual, but for the benefit of succeeding generations and to prevent degeneration. INDEX _Abraxas groussularioun_ and _lacticolor_ Adaptations, origin of; evolution of _Agonus entaphractus_ Albinism Allantois Allurements _Alytes obstetricans_ _Amblyopsis_, eyes of _Amblystoma tigrinum_ Amnion _Anableps tetrophthalmus_ _Anas boscas_, crosses of _Anas tristis_, crosses Ancel and Bouin _Anguis fragilis_ _Antilocapra_ _Antirrhinum_, crossing of Antlers of stags Ants, heredity of sex in Aphidae, heredity of sex in Apoda Axolotl, albino; metamorphosis; influence of thyroid feeding Barred plumage in fowls Basoh Bateson Bees, heredity of sex in Bernard, Claude Berthold, A. A. Biedl and Konigstein Bionomies Blindness in cave animals _Bombyx mori_ Boring, Miss Born and Fränkel Brachydactyly Bresslau Brown-Séquard Bühler _Cambarus_, males of Capons Castle, experiments in grafting; on sex Castration; in ducks; of frog; of Lepidoptera Cats, heredity of colour in Cave animals, absence of pigment Cephalopoda Cetacea, absence of scrotum Chelonia _Chologaster agassixii_ Chromosomes; in mutations _Clevelandia_ _Colaptes_ Colour-blindness; heredity of Colours, origin of, in domesticated breeds Comb of fowls, uselessness of Corpora lutea, evolution of; in viviparous lower vertebrates; origin of _Corystes cassivelaunus_ Courtship, organs of Criss-cross inheritance Crossing over Cryptorchidism Cuttle-fishes Cyclostomes, absence of corpora lutea in Cytology Cytoplasm, in heredity _Dafila acuta_ crosses _Daphnia_, heredity of sex in Darwin _Dasyurus_; corpora lutea; lactation Davenport Determinants Determination of sex Dipnoi, fins Dog-fishes, oviparous and viviparous Dominant characters, origin of Doncaster; on heredity in cats _Drosophila_, blind mutation, heredity of sex, mutations Ducks, crosses of Dutch rabbit Earthworms, sex in Eclipse plumage Eigenmann Eimer Elasmobranchs; corpus luteum in Elephants, testes Eugenics Eunuch Evolution, evidence of Factors, origin of Feathers, evolution of Flat-fishes, mutations of Flight, evolution of Flounder Foa, on lactation; on grafting ovaries Foges Fowls, castration of; origin of breeds Fractionation of Mendelian factors Fränkel Frog, thumb-pad _Gallus bankiva_ Gates, Dr. R. Ruggles Geddes and Thomson Gemmules Genital ducts _Gigas, Oenothera_ _Gillichthys Gipsy moth Goltz and Ewald Gonads, hormones of Goodale, H. D. Grafting, of ovaries or testes Graves' disease Gudernatsch Guthrie, C. C. Gynandromorphism Haemophilia Hanau Hegner Herdwick sheep, castration in Heredity; and sex Hermaphroditism Hill, J. P. Horns Houssaye _Inachus scorpio_ Insects, heredity of sex in Interstitial cells Intromittent organs Japanese long-tailed fowls; artificial treatment of Kammerer Kellog Kopec Lactation, dependence on stimulation, in males; regulation of _Laevifolia, Oenothera_ Lamarck Lamarckian theory Lane-Claypon, Miss; and Starling, on ovaries of rabbit Larvae of insects _Lata, Cenothera_ Leghorn, White Lemon-dab Leopold and Ravana Lepidoptera, castration in _Leptinotarsa_ _Limantria dispar_ Limon Linnæus Lode Loeb, on "blind fish; on blindness in cave animals; on tadpoles and thyroid Lop-eared rabbits, grafting experiments Lotsy, Professor; on crossing Lutein, of corpora lutes Male characters in female Mallard crosses Mammary glands; origin of rudimentary in male Marshall; and Jolly Marsupials, relation of foetus to pouch; scrotum of Masked crab Meisenheimer; thumb-pad of frog _Mendel's Principles of Heredity_ Mendelism; and castration Menstruation Metamorphosis; in Flat-fishes; causes of; and hormones; and diagnostic characters Michaux, Midwife toad, Milk glands, Mole, eyes of, Monotremata, origin of milk glands, Morgan, T. H., on blindness in cave animals, on mutations, on sex:, on sex-linked heredity, on sexual dimorphism in _Drosophila_, on variation, Mutations, in antlers, Natural selection, Nuptial plumage, Nussbaum, _Nyssia zonaria_ O'Donoghue, development of milk glands, _OEnothera_, mutations, _grandiflora_, lata_, _Lamarckiana_, Onagra, species of, _Origin of Species_, Darwin's, _Ornithorhyncus_, corpus luteum Orthogenesis, Otariidae, scrotum, Ovaries, position of, Ovary, in birds, Ovulation, Pangenesis, Parthenogenesis, Parturition, Pearson, Karl, Pheasant, male, gynandramorphism in Phillips, John C., _Philosophie Zoologique_ Phoeidae, testes, _Physiology of Reproduction_, Picotee Sweet Pea, Pigeons, Pigment, absence in cave animals, Pile fowls, Pintail duck, crosses, Plaice, _Pleuronectes flesus_, _glacialis_, _platesca_, Plymouth Rock fowl, Pole-dab, Poll, Preformation, _Problems of Genetics_, Prong buck, Pro-oestrus, _Proteus_, eyes of, Prototheria, milk glands in, Rabbits, lactation in, Recapitulation, absence of, and mutations, Reptiles, corpora lutea in, Reversal, in Flat-fishes, _Rhinoderma darwinii_, Ribbert, Rieger, Rodents, testes, Romanes, GJ Röntgen rays, effect on testes, Rose comb, in fowls, Rotifers, heredity of sex in, _Rubricalyx, Oenothera_, _Rubrinervis, Oenothera_, _Sacculina_, Salamanders, transplantation of eye, Sandes, Schuster, Edgar, Scrotum, origin, of, Sea-horse, Secondary sexual characters, Selheim, _Semilata, Oenothera_, Sertoli's cells, Sex, chromosomes; Mendelian theory of, Sex-Linked heredity, _Sexual Dimorphism_, Sexual dimorphism, in Rajidae, in Plaice, Shattock and Seligmann, Silkworm, Silky fowl, plumage of, Sirenia, absence of scrotum, Slow-worm, Smith, Geoffrey, Snakes, absence of limbs, Sociology, Somatic sexual characters, Species, conception of, origin of, characters of, sterility and hybridism, Spermatogenesis, in man, Starling and Lane-Claypon, on lactation, Steinach, heredity of milk glands, Sternum, carina of, Swallows, Sweet Pea, Swifts, Tadpoles, effect of thyroid in Tandler and Gross Taxonomies Teleosteans; corpora lutea in; ovarian follicles Testes, descent of Tetraploidy Thayer Thumb-pad of frog Thyroid-gland feeding Tortoise-shell colour in cats Tosa fowls, Japanese Transplantation of gonads _Typhiogobius_ Uhlenhuth Urodela, larva Variations _Vespa vulgaris_; _germanica_ Vries, De Wallart Wasps; heredity of sex in Weapons, organs used as Weismann Whale, paddle of White Leghorn, crosses Wilson, E. B. Wing, development of Winiwarter, von Witch Wood, T. B., on crossing of sheep Woodland, W. Woodpecker X chromosome _Zeugopterus_ _Zoaea_