GENERAL PATHOLOGY AN INTRODUCTION TO THE STUDY OF MEDICINE GENERAL PATHOLOGY An Introduction to the Study of Medicine BEING A DISCUSSION OF THE DEVELOPMENT AND NATURE OF PROCESSES OF DISEASE BY HORST OERTEL Strathcona Professor of Pathology and Director of the Pathological Museum and Laboratories of McGill University and of the Royal Victoria Hospital, Montreal, Canada NEW YORK PAUL B. HOEBER 1921 * COPYRIGHT, 1921 By PAUL B. HOEBER Published, June 1921 Printed in the United States oj America THE FOLLOWING PAGES, A RECORD OF THE COMBINED EFFORTS OF ALL NATIONS TO ARRIVE AT THE TRUTH IN ONE BRANCH OF SCIENCE, ARE DEDICATED TO THE PRINCIPAL, GOVERNORS, MEDICAL FACULTY AND STUDENTS OF MCGILL UNIVERSITY, AT ITS ONE HUNDREDTH ANNIVERSARY. Vivat, Crescat, Floreat! 451511 FOREWORD AN effort has been made in the following pages to bring together, in what I hope is a concise and at the same time comprehensive, connected and readable form, those facts and considerations upon which modern pathology rests. Care has been taken to impress upon the reader that path- ological processes are not to be regarded, as they often enough are, as a personal conflict in which man defends himself by a special endowment with purposeful processes of defense. Pathological definitions and conceptions unfortunately still abound in metaphysical and teleological ideas, even though it is sixty-two years after Virchow's effort to lift pathology to the rank of other sciences. Thus the student is easily misled in his conceptions of patho- logical processes and he frequently separates what he has learned in biology and physiology from his pathological studies and ideas. My purpose, therefore, was to convey to my readers that pathology must be approached within the frame of modern biology, and that in the study of disease, no less than in the study of health, scientific vision is possible only if we divest ourselves of all metaphysical and teleological conceptions of use, harm, defense, vital forces, conscious purpose, etc., and treat pathological processes entirely as expressions of physico-chemical laws. We must, in other words, with Kant, lay down the rule that the mechanical method, by which natural phenomena are brought under general laws of causation and so explained, and without which there can be no proper knowledge of nature at all, should in all cases be pushed as far as it will go, for this is the principle of "determinant judgment." In those cases in which this is insufficient and in which we accept purposiveness, we must remain conscious that this purposiveness is not identical with the metaphysical conception of a purpose residing outside of the organism itself, vif viii FOREWORD but meant in so far as it relates to the cause and effect in the or- ganism by which it brings together the required matter, forms it and puts it in its appropriate place. This is an internal purpose, not a means to other ends in which purposiveness is relative and its cause external. It is a heuristic principle. My second aim was to furnish to the reader an appreciation of present ideas by tracing their historic development. The history of a science is an essential part of it, and, should be presented, not as a simple recital of sequences, but in the bearing and influence which one step of thought exerts upon the next. This possesses not only great educational value, but is the only way of arriving at proper valuation and understanding of current ideas, and furthermore cultivates a critical judgment for the future. My third purpose was to visualize as much as possible patholog- ical occurrences, and therefore great emphasis has been put on the anatomic-histological, formal side from the dynamic standpoint. Lastly, I have thought it essential to include a somewhat more extensive discussion of certain subjects, (e. g. heredity and disposi- tion), than is usually devoted to them in textbooks of pathology. This, I think, is justified by their great pathological importance. The instruction in pathology* as at present pursued at McGill University is preceded by a course in general cell physiology, in which the fundamental physical and colloidal phenomena of normal cell life are discussed, so that the course in pathology may follow in its footsteps and presupposes knowledge of the normal. The chapter on bacteria and infection is not intended to take the place of textbooks of bacteriology, but those parasitic types have been selected which seemed to serve best as examples of pathogenic actions and their relations to processes of immunity. For the same reason matters of technique are not fully presented. In order to keep the volume within reasonable limits and not to confuse the reader, I have omitted an extensive bibliography. For the same reasons controversial matter has been reduced to what appeared a necessary minimum. The book is intended as an introduction and general outline of the subject. It is difficult FOREWORD ix to strike always the proper course in these regards. Illustrations have been omitted, because the emphasis has been put on dis- cussion of the nature and development of pathological process and it is assumed that laboratory experience will supplement the use of the book. My thanks are due to Professors Lloyd, Willey, Tait and Bruere of McGill for much valuable information. The ever-willing kind- ness of the Governors, the Superintendent, Mr. H. E. Webster, and of my colleagues on the Staff of the Royal Victoria Hospital, to put at my disposal its rich material, has been of considerable help in the preparation of this volume. To the publisher I owe thanks for unselfish interest and speedy publication. My thanks are also due to my personal staff, especially Drs. Crowdy and Gross. Should this attempt meet with friendly reception, I contemplate a second volume on the diseases of special organs and systems. H. O. McGiLL UNIVERSITY, MONTREAL. March, 1921. PREFACE IT is the custom to commence the study of a science with a defi- nition of its scope and, in a manner not unlike that of the actio finium regundorum in Roman law, to draw boundary lines between it and its neighbors. Such a method of approach is an imperfect one and leads to erroneous concepts, for a definition, in order to be exact, must repeat the whole matter of a subject and endeavor to systematize it; but to repeat the whole contents of a science in a definition is manifestly impossible, and it is equally impossible to isolate, by sharp boundary lines, one branch of science from another. The mental and moral disciplines are in a somewhat better position in this respect, for being a product of the mind, they deal with the mediate a purely created world. Thus, for example, in law or in mathematics more or less permanent agreement of cer- tain values may be reached and these may then be readily classified. But in the study of biology we are confronted by reality the immediate world. All biological sciences deal, therefore, with phe- nonema and processes of life directly. These are so intimately connected, related, dependent upon each other and are so elastic, that strict limitations and separations are not possible. Influenced by innumerable, often unknown conditions, processes of life defy strict classification and codification. It is only the finished, dead subject which may be so* treated. But our knowledge and views regarding these processes are constantly changing and fluid. And how many times is one subject treated by more than one science? True specialization consists in focusing all available rays of light upon a matter. In fact, it is only when all boundary lines have vanished that we obtain true scientific vision. In Lord Bacon's words: "Let this be the rule that all partitions of knowledge be accepted rather for lines and veins than for sec- tions and separations." Or as a great historian, Gibbon, puts it: xi xii PREFACE "The roots of all intellectual departments are interlaced, although, as in a forest, every one appears at first sight isolated and separate." These difficulties confront us at once in an attempt to define pathology and to draw boundary lines between it and its nearest neighbor, physiology. For while we may say that pathology is the science of disease, the more thoroughly we investigate this appar- ent distinction between health and disease the more we become convinced that essential differences between health and disease do not exist. "If we reflect," says Goethe, "upon our own life, we rarely find ourselves well, physically and mentally: we are all suffering from life." The same material and forces and the same processes underlie health and disease. Only their relations and relative importance differ. Thus, in the development of the embyro and in the post- natal progressive and regressive evolutionary changes which shape and characterize the various age periods from birth to old age are found the physiological prototypes of all pathological processes. But they remain physiological by their orderly restriction within the general individualistic evolution. It is the loss of orderly corre- lation, the breaking of the ensemble by the exaggerated value of one or the other part in relation to the rest that constitutes patho- logical life and leads, by upset of the normal evolution, to death. "Disturbances in relativity of values" is, therefore, the first and most important principle of pathological occurrences. For these reasons we cannot express our conception of disease by a short, concise formula. We can form an accurate estimate of this con- ception only by tracing the history of our ideas of disease; for a proper appreciation of present ideas is only possible by following the evolution of human thought. The division of health and disease was primarily based on sub- jective (simple personal) observations. It was the altered feeling, the pain, the dis-ease, which first drew attention to pathological states. Amongst primitive peoples this physical state of pain and ill feeling was connected with the experiences of corporal punish- ment, and, as the infliction of this punishment could not be traced to visible beings, it was attributed to invisible beings, gods, PREFACE xiii demons, evil spirits. Thus resulted the early and close relation between medicine and religion. Even the first reflective thought in medicine was most impressed and guided by subjective factors and symptoms. Of these certain body fluids early attracted attention on account of the frequency with which their disturbances are apparent in various diseases. These are blood, mucus, yellow and black bile. Blood, mucus and bile were readily recognized by the flow of blood from wounds, ulcers, etc., of mucus from the nose, mouth, throat, and bile by its appearance and taste in vomit. The black bile is somewhat problematic; it was regarded as the product of the spleen. These four body fluids, or humors, were supposed to combine in certain proportions and to constitute the normal make-up of the body. Their normal mixture was termed crasis. Disturbances of the mixture produced dyscrasis of various types and thus accounted for the different diseases. These were the teachings of Hippocrates, the celebrated Greek physician, born on the Island of Cos about 460 B.C., and of Galen, D.A. 130 to 200, of Greek derivation, but practicing in Rome. The authority of this teaching controlled medical ideas not only of its own time, but throughout the Middle Ages and even to modern periods of pathological thought. It was known as humoral patho- logy, inasmuch as it regarded disturbances of body fluids as the essence of all diseases. The almost slavish adherence to humoral pathology and the lack of progress in medicine up to the sixteenth century was due to the general belief in authority, and also during the early periods of the Christian era to the abhorrence of bodily ills as works of devils and demons. Attention became centered around mental and spiritual uplift, and the body was looked upon with horror as the work and property of the devil. Treatment consisted, therefore, largely of exorcism driving out of malign spirits and demons. "We are born," laments St. Augustine, "inter urinas et jxces" A revolt against the blind following of Hippocrates and Galen was inaugurated by Paracelsus (Theophrastus Bombastus von Hohenheim, 1493-1541). Paracelsus formulated a much broader conception of the nature of disease as an abnormal process of life xiv PREFACE which results from disturbed chemical changes. According to him life is dependent upon a personal principle, "the Archseus," which resides in the stomach and which separates and eliminates useful from harmful substances. If the Archaeus is paralyzed, harmful "acrimonious" substances accumulate in blood and tissues and create disease. Based on these views Paracelsus was one of the first to recommend the use of eliminants, purges and alteratives as drugs. The great reformation in pathology, as in other spheres of human knowledge, came with the period of the Renaissance. This impor- tant movement, which, towards the end of the fifteenth century, became manifest first in Italy and then swept over the whole world, reestablished three almost forgotten values: (i) rejuvena- tion of classic art, literature and science; (2) objective observa- tions; (3) individuality and tolerance of free thought. In medicine, and especially in pathology, it was ushered in through Andreas Vesalius (1514 to 1564) by the development of anatomy which gave a sounder knowledge than formerly existed of the body and the changes in disease. But it was the merit of Mor- gagni (1682 to 1791) in his great work, "De sedibus et causis mor- borum per anatomen indigatis" (1761), to attempt for the first time a correlation between symptoms of disease and the ana- tomical findings after death. He, therefore, was the first who attempted to give an anatomic explanation of symptoms by localizing diseases in definite organs of the body or, as Virchow once happily termed it, he introduced the anatomical idea into medicine. His great merit was further to consider the usual and unusual with equal care, and thus he gave the first objective basis for the conception of disease. However, knowledge of the nature of diseases still remained very crude as hardly anything was known of the construction of organs in health and disease. In other words, while it was recog- nized that certain gross anatomical changes were associated with certain symptoms, the nature of these changes, their development and their relation to the symptoms remained obscure and vision- ary. An advance in this respect was made possible by Bichat (1771 to 1802), founder of general anatomy, who discovered that or- PREFACE xv gans consisted of general and special tissues and that, correspond- ing to these, diseases produced general and special tissue changes. Herein lay an important progress, for diseases were thus properly regarded as anatomical processes. This gave a great impetus to the study of pathological anatomy in relation to the development of diseases and, therefore, also to symptoms. Laennec and Corvisart, the great French physicians of the early nineteenth century, stood directly on Bichat's shoulders, and to this period belong also the fine clinicians of the English school, Bright, Addison, Hodgkin and others who, by careful record of progress in symptoms and progress in anatomical changes, drew the first concrete histories of diseases. Bright, especially, stands out as a commanding figure, for no one has ever excelled him in power and accuracy of clinical and anatomical observation. A more profound knowledge of the nature of diseases was laid by Rokitansky (1804 to 1878), Professor in Vienna, in the thorough cultivation of pathological histology, which disclosed the finer microscopic changes and thereby revealed the histogenesis of diseased processes in a very accurate and detailed manner. But no matter how much was gained by the industry of investi- gators in collecting such data, the nature of diseases their basic principles ^remained veiled, and dyscrasis and disturbed hypothet- ical "vital forces" were still resorted to as explanations. Thus even to the middle of the nineteenth century medicine lacked a scientific backbone and a uniform biological standpoint. The result of this became disastrous to the practice of medicine, for the various hypothetical ideas on the nature of disease, which were necessarily all speculative, gave rise to opposing and debating "schools" of medicine, such as allopathy, homeopathy, polyprag- masia, eclecticism, Rademacher's and Priessnitz' system of hydro- therapy, bleeding of the patient to unconsciousness, mesmerism, and others, which were entertaining and edifying to their pompous defenders but of no benefit to their patients or to science. Out of this apparently hopeless chaos arose Virchow (1821-1902), Professor of Pathology in the University of Berlin. Virchow may properly be named the founder of modern pathology; nay, much more, his discoveries and ideas are so far-reaching that they extend xvi PREFACE beyond medicine and form the basic structure of modern biology. Virchow is generally spoken of as creator of cellular pathology. What does this mean? Did he discover cells? He did not. Cells (originally regarded as empty partitions, hence the name) had centuries before Virchow, been known to exist and even their importance was fully recognized by Schwann. Malpighi (1628- 1694) of Bologna had first seen them and later the English botanist Grew. Trevirannus already knew that cells combine to form tissues and Schleiden, and especially Schwann (1839) had, shown that all living structures in plants and animals are ulti- mately combinations of cells and that the ovum is a cell. What then was Virchow's merit? Before Virchow the origin, derivation and functional significance of cells had been obscure and hypothetical. Thus, even Schleiden and Schwann still held that cells originated from unorganized matter which precipitated first as a nucleus surrounded by a mem- brane. Through this membrane matter diffuses from outside and thus cells are formed. Similarly in pathology, cancer cells and cells of scar tissue were supposed to arise through "vitalization" of exuded fibrin, and this was held to explain the close relation between inflammation and cancer. Virchow, in a celebrated course of lectures delivered during the winter semester of 1858 in the Charite Hospital in Berlin, de- veloped the following cardinal doctrines of "cellular pathology:" (i) the cell is the unit of life; (2) all cells develop from preexisting cells (omnis cellula e cellula); 1 (3) diseases are pathological cell changes and disturbed cell relations; (4) anatomical changes thus produced constitute the disease. Thus he discarded all speculative and fantastic systems in medicine and created the modern objective study of disease and the anatomical (visual) conception of pathological processes as cell changes. Whatever scientific thought has been produced since Virchow has only enlarged, never contradicted, these principles. While cells are then properly regarded as the most important 1 This principle had already been proclaimed by Remak in 1852 in regard to the formation of embryonic cells. PREFACE xvii vital unit, it must be remembered that cells in higher organisms, commonly spoken of as metazoa, are not only building material, but stand in biological relation to each other. It is the merit of Hertwig to have emphasized this side of higher cell life. For this biological relation is one of the most important cell functions. It shows itself in altruism and antagonism of different cell territories and organs. This has become most important from the pathological standpoint, for diseases represent not only local cell disturbances, but disturbed biological cell relations, and these are frequently of far greater importance and consequence than the local cell changes. The disturbances of internal secretion, the independent growth of tumor cells, the changes of parenchyma cells to new abnormal cell types in inflammations, are examples in point, for their effect is not only local, but reflects generally on the whole state of cells which constitutes the individual. Thus, disease of one part means disease of the whole by upset of physiological balance and creation of pathological relations. If, then, as we have seen, it is not possible to give an exact and all-embracing definition of health and disease, what are the most important fundamental characteristics and outstanding points in each? First, what comes within the term of health? By health we under- stand relative stability in cell, tissue and organ structure, function and coordination. These depend upon proper relation of stimuli to cell reaction and adjustment of cells to stimuli. Secondly, what is disease? By disease we understand the pro- longed loss of cell, tissue and organ stability and coordination, which results from disturbances in the relation of stimuli to cell reactions beyond physiological adaptation. It, therefore, leads to more lasting cell alterations and cell and tissue injury. It is essential to appreciate that the loss of stability must be prolonged in order to come within the range of disease, for a short or temporary upset may still be considered physiological. For in- stance, when an individual by severe muscular exercise upsets his heat regulation and even raises his temperature, he may for a short time present the phenomena of fever. This is not regarded as fever as long as there is a rapid return to normal conditions and xviii PREFACE the production of body heat is still carried on by physiological methods. It is in every instance the more lasting loss of physio- logical stability and adaptation which marks a process as patho- logical a loss which leads to derangement and perversity of cell activities. General pathology deals with the processes of disease in their own general relations. It neglects the special organ or anatomical structure in which the disease occurs; disregards, as much as pos- sible, the expressions of disease from a particular locality, and endeavors to lay bare the origin, development and common charac- teristics of diseased processes. It is convenient and customary to treat general pathology under two headings: I. Etiology, the causes of disease, which may be divided into two groups: i. The external factors. 2. The internal factors. The external factors may, again, be subdivided into two divisions: (i) Bacteria and infection; the higher parasites. (2) Physical agents; heat, cold, air, pressure, electricity, light rays. Chemical agents; poisons. II. The Pathological Processes themselves. These, again, fall under two intimately connected subjects: 1. Pathological anatomy and histology, or, the morphological changes of disease. 2. Pathogenesis, the manner by which these changes develop, and the nature of the lesion. It is to be noted that pathological anatomy and histology differ from normal anatomy and histology in being not only descriptive but eminently explanatory of the character of a disease. For, being representative stages of a disease at a certain time, they col- lectively disclose the whole formal genesis, that is, the manner of development and the history of a disease. CONTENTS BOOK ONE ETIOLOGY PART I THE EXTERNAL FACTORS SECTION I BACTERIA AND INFECTION CHAPTER PAGE I. INTRODUCTION. HISTORICAL. GENERAL CONSIDERA- TIONS i II. STAPHYLOCOCCI, STREPTOCOCCI AND BACILLUS PYOCANEUS. . .... |; . . 1 . . . . . . . 14 III. DIPLOCOCCUS PNEUMONL-E 25 IV. DIPLOCOCCUS INTRACELLULARIS MENINGITIDIS. GONOCOCCUS AND MlCROCOCCUS CATARRHALIS . 28 V. BACILLUS COLI COMMUNIS 34 VI. BACILLUS TYPHOSUS 39 VII. PARATYPHOID BACILLI 44 VIII. BACILLUS DYSENTERIC 47 IX. CAPSULATED BACILLI BACILLUS LACTIS AERO- GENES THE PROTEUS GROUP 49 X. BACILLUS DIPHTHERIA. DIPHTHEROIDS 51 XI. BACILLUS TUBERCULOSIS 62 XII. THE BACILLUS OF LEPROSY 70 XIII. ACTINOMYCOSIS 72 XIV. BACILLUS MALLEI (GLANDERS) 75 XV. ANTHRAX 77 XVI. THE PLAGUE BACILLUS 82 xix xx CONTENTS CHAPTER PAGE XVII. THE TETANUS BACILLUS. BACILLUS OF MALIGNANT EDEMA BACILLUS AEROGENES 84 XVIII. TYPHUS EXANTHEMATICUS 90 XIX. INFLUENZA 92 XX. THE SPIRILLA 95 XXI. THE PATHOGENIC PROTOZOA 103 XXII. IMMUNITY 108 Definition and classification. Infection Acquired Im- munity Natural Immunity Passive Immunity Anaphylaxis Theories. SECTION II PHYSICAL AND CHEMICAL FACTORS AS THE CAUSE OF DISEASE XXIII. TEMPERATURE HEAT AND COLD 137 XXIV. AIR PRESSURE 141 XXV. ELECTRICITY, X-RAYS AND RADIUM 143 XXVI. POISONS (TOXICOLOGY) k ... 147 PART II THE INTERNAL FACTORS XXVII. DISPOSITION AND IDIOSYNCRASY 151 XXVIII. HEREDITY 160 BOOK TWO PATHOLOGICAL ANATOMY, HISTOLOGY AND PATHOGENESIS I. INTRODUCTION 173 II. PATHOLOGICAL CHANGES IN THE CELLS (NUTRITIVE DISTURBANCES) 176 REGRESSIVE CHANGES Atrophy Degenerations Ne- crosis. PROGRESSIVE CHANGES Hypertrophy and Hyperplasia Regeneration Wound Healing Metaplasia Trans- plantation. CONTENTS xxi CHAPTER PAGE III. PATHOLOGICAL CHANGES IN LOCAL CELL RELATIONS 2 1 8 INFLAMMATION Degenerative Exudative Productive Course and Terminations Inflammatory Tissue For- mation Conclusions. Infective Granulomata Tuberculous Inflammations Syphilitic Inflammations Leprous Inflammations Actinomycotic Inflammations Glanders Rhino- sclerma Blastomycosis Infective Granulomata of Unknown Etiology. TUMORS General Characteristics Metastasis General Histology and Diagnosis General Constitutional Effects Classification : Histoid Fibroma, Myxoma, Lipoma, Xanthoma, Chon- droma, Osteoma, Lymphoma, Myeloma, Melanoma or Chromatophoroma, Myomata, Leyomyoma, Rhab- domyoma, Glioma, Neuroma, Sarcomata. Organoid Papillomata, Adenomata, Cystadenomata, Cancers, Carcinomata, Hypernephroma, Chorio- epithelioma. Endotbeliomata Angiomata, Hemangiomata, Lymph- angiomata, Angiosarcomata, Mesotheliomata. Mixed Embryonic Teratoid, Teratomata, Embryomata. ETIOLOGY AND HISTOGENESIS OF TUMORS. EXPERIMENTAL STUDY OF TUMORS. IV. PATHOLOGICAL CHANGES IN GENERAL CELL, TISSUE AND ORGAN INTERRELATIONS 298 DISTURBANCES IN BLOOD AND LYMPH CIRCULATION Disturbances in Blood Circulation Pathological Changes in the Amount and Quality of the Blood Local Changes in Blood Circulation Thrombosis Embo- lism Hemorrhage Shock. Disturbances in Lymph Circulation Edema. DISTURBANCES OF INTERNAL SECRETION AND OF SPECIFIC METABOLISM General considerations Afunc- tion, Hypofunction, Hyperfunction Dysfunction. FEVERS (Febris. Pyrexia) Cause of Fever and of the Rise in Temperature Nature and Significance of Fever. V. GENERAL SOMATIC DEATH 362 EPICRISIS . 331 INDEX 333 BOOK I ETIOLOGY Part I The External Factors SECTION ONE BACTERIA AND INFECTION CHAPTER I INTRODUCTION HISTORICAL. Originally the source of all infection (from inficere = to contaminate) was seen in the air as that common medium which came into most intimate contact with everything and everybody, and so could be regarded as the most probable source of infection. Such contaminated air was spoken of as miasma, which literally means putrid or noxious stain. This idea of mias- matic, air-born diseases persisted until the middle of the nineteenth century As late as 1860 as good an observer and physician as Murchison still believed that sewer gas was the cause of typhoid fever. When in 1871 King Edward VII, then Prince of Wales, contracted typhoid fever at Sandringham, the chance escape of sewer gas into his apartments was considered the cause. Explana- tion of sudden appearance of infectious diseases and of epidemics was found in outside factors, more especially geographical and heavenly conditions and these, in certain favorable combinations, were supposed to form a constitutio epidemica, and account for the outbreak of epidemics. The idea of infection was later contrasted with contagion after it was found that certain infections were conveyed directly from man to man. This became clear after the frightful and interesting epidemic of syphilis at the end of the fifteenth century (Fracastor in 1546). It is probable that the Jesuit Kircher, about 1660, was the first to observe lower types of life in pus and in material from pest patients and putrefying plants. More definite were the ob- servations of van Leeuwenhoek, a Dutch lens maker, who, with the aid of his lens, saw some of the larger micro-organisms in decomposing infusions of plants (1675). He spoke of these as "animalcules." He also, with this aid, in 1677, although priority 2 GENERAL PATHOLOGY of this discovery was claimed by Nicholas Hartsocker, of Rotter- dam, discovered spermatozoa in the seminal fluid. The first ideas of a parasitic character of diseases were ad- yji'iiced byooo of an inch. 6 GENERAL PATHOLOGY It has been asserted and denied. Recent observations seem to indicate that while a definite nuclear unit is not demonstrable, chromatin is irregularly distributed through the bacterial body, and that metachromatic granules are also present. The question of a cell membrane is also uncertain. A cellulose envelope, characteris- tic of vegetable cells, is absent. Motility. Many bacterial forms are actively motile, that is, possess the ability of translation in space. This genuine motility must be differentiated from quivering, oscillating, Brownian move- ments, which are physical, surface tension phenomena. Locomotion depends upon the presence of flagellae whip-like, filamentous ap- pendages, which by contraction and expansion propel the body. Growth and division of bacteria into equal halves occur in one, two or three planes and by elongations. Maturity of individuals is almost immediate. Spore Formation. So called spores are means of preserving and reproducing bacteria by resistant forms. They are much less sus- ceptible to those outside influences, which ordinarily kill bacteria. They tolerate heat (7OC.-iooC.) and poisons to much higher degrees for the following reason: Heat and antiseptics kill bac- teria by coagulating the contents of their protoplasm, for they contain considerable water and salts; but spores, being poor in salt contents and containing only hygroscopic water, are much less susceptible to coagulation; being simply dry they are, therefore, more resistant. Spores are compact and highly refractive. They stain with difficulty. They form in any part of the cell, usually at the poles in the anaerobes, and are generally of the same diameter as the cell. Occasionally they cause the cell body to bulge and such a spore-bearing organism is known as a clostridium. Spores give rise to new bacterial forms by growth from the spore body. The new organism escapes by breaking through the capsule and then divides in ordinary fashion. Spore propagation is more frequent in bacilli than in cocci. Occasional bud-like constrictions in rods and cocci are named arthrospores. Their true spore char- acter is doubtful. Spores are formed under the influence of unfavorable environ- ment where the bacterial life is in danger. The spore represents a INTRODUCTION 7 resting stage which preserves the organism during an unfavorable period. This state may, in a way, be compared to hibernation oi higher animals. Fortunately many pathogenic .bacteria are not spore formers, which makes their destruction easier. But some of the most important and malignant organisms are, such as the bacilli of anthrax, tetanus and malignant edema. Capsule. Bacteria possess mucoid coverings in the form of a transparent halo. This is sometimes very plain and these micro- organisms are then termed capsulated. The capsule may surround either individuals or characteristic groups. Almost all of them are capsulated only in the natural state, not in culture except by special methods. The capsule is a product of the bacterial ectoplasm. Opinions as to the nature and significance of the capsule differ: some regard it as protection, others as indication of degeneration. It is certain that some capsulated micro-organisms are very virulent. (6) MORPHOLOGY OF GROUPS OF BACTERIA. All bacterial forms, when suitably planted, grow in colonies and these exhibit, even to the naked eye, characteristic behavior on the culture medium. Gelatine, agar and bouillon are the most common media used. On these media the various types of bacteria show differen- tial manners of growth and these are, as Koch first pointed out, diagnostic of bacterial species. Thus they may or may not liquefy the solid culture media, produce acid or alkali, various enzymes, pigments and other distinguishing metabolic products, derived from their own body or by disintegration of the medium. We shall now shortly review some of these common characteristics of bacterial growth and life. Temperature. Bacteria grow only within certain variable temperature limits. If these are exceeded, on one or the other side, action and life ceases. Below the minimum temperature, life is not destroyed, but only becomes latent; high temperatures, however, lead speedily to disintegration of the bacterial body. Between the two lies what is known as the optimum temperature of growth, provided other conditions of life and nutriment are also supplied. Bacteria, like other living beings, owe their existence to chemical cleavage processes by which the high unstable molecules of the cell 8 GENERAL PATHOLOGY protoplasm are converted to simpler compounds by saturation of affinities. Thus energy is liberated. This self-disintegration is known as internal respiration (end product is CO 2 ), and depends upon the instability of the plasma. It proceeds apparently spon- taneously, as in an explosive, but in reality is due to surrounding heat waves. The motion of heat waves is necessarily greater in higher tem- peratures and is communicated to the unstable molecules of the protoplasm, which disintegrate somewhat like a high, unstable pyramid crumbles when exposed to the force of the wind. Below the point of temperature which is required to set heat waves in motion, molecules remain necessarily intact, but life also ceases, remaining latent. If, on the other hand, heat waves, as in high tem- perature, move and act violently, the plasma is injured, because restitution by synthesis becomes impossible. Hunger, therefore, is also a gradual destroyer of life. Thus warmth is the carrier of life, while food sustains it. Generally speaking the optimum tempera- ture of life for bacteria is about 37C., hardly ever above 42C. The optimum limits, however, are wide for the pest bacillus about 3OC., while for the bacillus of avian tuberculosis about 43C. Few, if any, grow below 2OC.; some (like the gonococcus) not below 3OC. Some of the non-pathogenic bacteria are exceptions to this general rule, growing up to 75C. and at 2oC. Air and Oxygen. Bacteria are divided into three groups as regards behavior towards atmospheric air and oxygen. 1. Obligatory aerobes, needing air or uncombined oxygen. 2. Facultative or optical anaerobes, which grow in the presence of air or uncombined oxygen. 3. Obligatory anaerobes, which do not grow in the presence of air or uncombined oxygen. The first group fails to grow and functionate when oxygen is reduced below the optimum tension. If oxygen is still further de- creased, bacteria are injured and spore formation is prevented. To the second group belong a large number of pathogenic bac- teria, such as anthrax, typhoid, bacillus coli, cholera, bacillus aerogenes capsulatus, etc. They grow in the presence of air, but also may do so on its exclusion. INTRODUCTION 9 The third group is a very interesting one and was brought to light by Pasteur. It includes a number of important pathogenic micro-organisms, such as the bacillus of tetanus, of malignant edema, etc., and also many putrefactive bacteria. While their life is generally maintained on exclusion of oxygen, they may adapt them- selves to minute quantities of oxygen. They do not live by oxida- tion but derive their energy from cleavage (reduction) processes only. (It will be remembered that cleavage precedes oxidation, but in oxidation oxygen combines rapidly with cleavage products to form the end-products (H 2 O and CO 2 ), thus liberating much energy. In anaerobes, this second step is omitted. Other Gases. Facultative organisms and strict anaerobes grow well in H and N. Many do not grow in CO 2 at all; anthrax, bacillus subtilis, bacillus glanders and cholera bacillus are quickly killed by it and so are others. H 2 S is also poisonous. Culture Media. For culture media organic foodstuffs are em- ployed, chiefly proteids and carbohydrates, the latter to supply carbon and energy. The reaction of culture media suitable for most bacteria is a weak alkalescence. Culture media are of very great diagnostic importance, for bacteria possess characteristic manners of growth and produce characteristic chemical substances on them. Culture media are of very great diagnostic importance, for bac- teria possess characteristic manners of growth and induce char- acteristic chemical changes in them. Products of bacterial growth are of two kinds: (i) Those resulting from disintegration of the culture medium; (2) those resulting from bacterial secretion, ferments and enzymes. i. Reduction Processes, (a) Splitting O from culture medium through metabolic products. (6) The formation of H 2 S from pro- teins and peptones in the presence of nascent H. (c) Reduction of nitrates to nitrites, ammonia and free N and the formation of basic, alkaloidal substances known as ptomaines. Formation of Aromatic Compounds. The most important of the aromatic compounds is indol, which is derived by certain bacteria from peptone: CeH 4 \ /CN. It is important diagnostically, as io GENERAL PATHOLOGY some bacteria, like colon and cholera, are active indol producers, while others, like bacteria of typhoid, are not. (Easily demonstrated in broth culture by adding concentrated H 2 SO 4 + o.oi Sod. ni- trite = red color. More delicate is Ehrlich's test with Paradimethyl- amidobenzaldehyde and Pot. sulfate (Sol. I. The former 4 pts., abs. ale. 380 pts., cone. HCI 80 pts. Sol. II. Pot. sulf. saturat. watery sol.) 5 c.c. of I to io c.c. culture and 5 c.c. of II = red color.) 2. Fermentation and Enzyme Formation. By fermentation and enzyme action is meant chemical decomposition by cell activity, either directly or by a cell product, the enzyme. Of these actions bacteria possess a considerable number of importance, as follows : (a) Simple hydrolytic cleavage, in which the source of energy is diastatic, changing starch to sugar, acid, H 2 O and CO2. (6) Sugar splitting, in which bacteria, like yeasts, are capable of splitting sugar into alcohol and CO2, thus : C 6 H 12 6 = 2C 2 H 5 OH -f 2C0 2 (c) Formation of acids from alcohol and other organic acids: It has been known for a long time that bacterium aceti converts alcohol to acetic acid by oxidation. Acids are also formed by splitting sugar or glycerine. Higher alcohols, like dulcite and man- nite, may also be converted into acids alone, or acids and gas. These reactions are useful in the identification of bacterial species. Only few bacteria produce alkali reaction in culture media by syn- thetic processes. According to Theobald Smith all aerobes or facul- tative anaerobes form lactic acid from sugar. (d) Invertive changing cane sugar to dextrose. (e) Peptonizing and proteolytic changing albumen to peptone and liquefying proteids, especially gelatine. (/) Coagulating rennin action. (g) Splitting urea CO(NH 2 ) 2 + 2H 2 O = CO 3 (NH 4 ) 2 (Micro- coccus ureae). Aerobes produce alkaline substances from proteids. (b) Nitrification is a very important process for the mainte- nance of life in nature and is an excellent example of useful or al- truistic activity of bacteria. It represents the oxidation of ammonia to nitrites and nitrates. This maintains the proper circulation of N in nature, for it puts it into a form suitable for reconsumption by INTRODUCTION 1 1 plants and thus counteracts the constant reduction of proteids to nitrates, nitrites and ammonia. Nitrification is accomplished by a special group of bacteria, knowledge of which we owe to Wino- gradsky and Warrington. It occurs in the soil and is the work of two organisms, one converting ammonia into nitrites, the other converting nitrites into nitrates, as follows : X H ,OH N^H NA)H H 2 O = O = N OH X H X OH Ammonia Normal Nitric acid Nitrous acid O + o =|| N OH II O Nitric acid Nitrates, thus formed, are taken up by the chlorophyl bearing plants and, in the energy of sunlight, are transformed into pro- teins with H 2 O, CO 2 , phosphates, etc. VARIATIONS AND ADAPTABILITY IN BACTERIA. This subject has been a matter of active discussion in relation to specificity and pathogenicity of bacterial strains. In bacteria, as in other forms of life, races, strains and even indi- viduals vary, but inasmuch as bacteria are the simplest form of unicellular organisms without differentiation, and without any nucleus, dividing by fission only, they are more open to environ- mental influences than higher differentiated multicellular organ- isms of complicated construction which possess specific nucleated sex cells. In other words the tendency to generic and individual stability increases with ascending animal evolution (see later under heredity). Bacteria, however, for the reason just stated, adapt themselves to their habitat in culture medium, temperature, etc., to such an extent that a sufficient deviation from the original may occur to impress us as a new species. Whether this is due to the acquisition of new characters or suppression of certain old 12 GENERAL PATHOLOGY ones, or the survival of forms originally endowed with what now seem to be new characteristics of the whole strain, it is not possible to determine exactly and cannot be fully entered into here. It is sufficient to appreciate that bacteria are variable and not absolutely fixed in type, as was thought in the early days of bac- teriological research. If only slight, variable and temporary changes occur, often compared to the ripples on the surface of water, we speak of them as fluctuations; if, on the other hand, the changes are profound, definite and continuous, we speak of them as sports or mutations. A strict classification of bacteria is, for these reasons, very difficult and there is often no direct relation between cultural characteristics and pathogenicity. In the diphtheria bacillus, for example, we cannot tell whether we are dealing with a mild or viru- lent strain from appearance and culture. We must resort to inocu- lation (biological test). The subject of parasitism and saprophytism, is, therefore, inti- mately connected with the question of variability and adaptation, and it is customary to differentiate between three groups of bacteria: 1. Pure saprophytes, or micro-organisms which can under no circumstances develop or grow in other living organisms. These may, however, become pathogenic through their toxines as, for instance, the bacillus causing botulism, a form of food poisoning. 2. Pure parasites, organisms such as the influenza bacillus, the meningococcus, gonococcus, the pneumococcus, etc., which rapidly gain foothold, thrive and spread in living organisms. They suc- cumb rapidly outside of a living body. 3. Optional or facultative parasites, which under suitable condi- tions are infective, but may also lead a saprophytic existence. They are not, as a rule, as virulent as pure parasites. However, here, as in other bacterial properties, no sharp and permanent class division can be made. It has only recently been well estab- lished that by careful, gradual cultivation on living organisms, ordinary pure saprophytes may become converted into parasites, and that by gradual sensitization of the host to the micro-organisms the latter may acquire considerable virulence. Thus Charrin and de Nittis found that the bacillus subtilis, ordinarily a harmless INTRODUCTION 13 organism (saprophyte) of the soil, may become a parasite, by cultivation on blood media and repeated passage through animals. Embleton and Thiele showed that the harmless bacterium my- coides of garden soil, which is ordinarily destroyed by body heat, developed pathogenic properties if repeatedly injected into animals, within periods of a week or ten days. Recovering it from animals thus infected, they gradually increased its virulence by passing it through other animals of the same species. They made another very interesting observation in finding that this acquisition in virulence was associated with morphological changes in the bacillus itself, and that this motile bacillus lost its flagellae, formed a capsule and became more stumpy, so that it could no longer be differenti- ated from anthrax. Similar observations have been made in other bac- teria, especially in the large group of streptococci. Briefly then, we see that by favorably timing inoculation, animals may, by sensitizing them, be made susceptible to an originally harmless organism. The latter acquires parasitic properties, and may even develop specific affinity for certain tissues and localities. However, the conditions prevailing in the host are also of greatest importance, for, as will be more fully entered into later, the disease which re- sults from a successful infection is a complex anatomical change in the tissues of the host, into which enter many other factors besides the pathogenicity of the invader. Moreover, the disposi- tion of the host towards an infecting agent is variable. This depends upon external factors, such as cold, fatigue, hunger, etc., and upon as yet poorly understood, internal conditions which are collectively grouped as resistance (see under Internal Factors as Causes of Disease, page 151). Thus, while the colon bacillus, for example, is ordinarily a normal saprophyte of the large gut, invasion and disease by it are possible under lowered resistance, or as a partner with other organisms. CHAPTER II STAPHYLOCOCCI; STREPTOCOCCI AND BACILLUS PYOCYANEUS STAPHYLOCOCCI. Cocci arranged in groups and bunches. The history of infection with staphylococci is practically identical with that of wound infections. Since 1870 investigators had seen cocci in pus, but their significance became clear only after Koch's methods and work created a new era in bacteriology (1878). In 1888 Richet and Hericourt made the further important discovery that the serum of immune dogs ( no longer susceptible to staphylo- coccus action after recovery) conferred passive immunity when injected into another dog. The prototype of pathogenic staphylo- cocci is the Staphylococcus pyogenes aureus, a pus-producing organism, which on culture brings forth a golden-yellow pigment. The individual organism is a small globe, about 0.7-0.9/1. The size varies according to favorable medium and temperature. It is positive to Gram's method of staining. The individuals occur in recent state in pus in small groups or bunches of two, or three or more, 9-10 individuals; often four members combine as tetrads, and even short chains occur. The optimum temperature of growth is 24C. to 28C., but much higher (42C). and lower (8 or 9C. even 6C.) temperatures are tolerated. It is a facultative aerobe, that is, grows with O and H. The best reaction for growth is alkaline, but even a weakly acid medium is compatible with it. It grows well in broth, also in 20 per cent, dextrose bouillon, when its virulence is lessened. It hemolyses rabbit's blood. Growth is also active in milk, which slowly coagulates with the formation of lactic acid. In solid gela- tine stab cultures it liquefies the medium from above downward. On gelatine plates, small yellowish points surrounded by a peri- pheral liquefying zone appear after two days. In from 24 to 60 hours there occur circular, flat depressions with sharp, sometimes slightly 14 STAPHYLOCOCCI 15 elevated edges and in the center a yellow colony the size of a pin- head. On slant agar a supple, smeary, yellowish fiber is formed with a grayish periphery. Pigment is also produced in abundance on potato, but best and most rapid on coagulated blood serum. The staphylococcus aureus is quite resistant to heat, to drying and even to burial for about four weeks. Staphylococci occur normally on the human skin, the staphylo- coccus aureus not quite so abundantly as the staphylococcus albus, which does not produce pigment and, on the whole, is much less virulent. A number of other types occur which vary in slight cul- tural differences and in their hemolytic properties. Besides being abundant on the skin, they float about in air. The culture broth filtrate of Staphylococci is toxic to other tissue cells, besides erythro- cytes. The rabbit is the most susceptible of all laboratory animals. The virulence of different strains is very variable, but it may be increased by continual passage through animals of the same species. Rabbits are usually killed by o. i c.c. of a broth culture in four to eight days with the formation of multiple small abscesses in the heart, kidneys, joints, muscles and bones. Sometimes pericarditis and pneumonia occur without abscesses, especially after large doses which produce staphylococcus septicemia or bacteriemia. Subcuta- neous injection in rather large doses produces erysipelas; injection into the mediastinum causes purulent inflammation. The periton- eum seems less susceptible, but the eye is very much so. Man is, generally speaking, more susceptible to staphylococcus infection than animals. Here the staphylococcus is one of the most important and frequent pus and abscess producers. Garre, experi- menting on himself by rubbing cultures into the skin, or after subcutaneous injection, caused abscesses and furuncles. Applica- tion of the bacteria-free, filtered broth to the skin causes dermati- tis. Loci minoris resistentia? (trauma) are particularly exposed to the staphylococcus and thus the staphylococcus frequently acts with or follows infection by other bacteria, such as pneumococci, streptococci, meningococci, etc. The frequent localization of Staphylococci in the osseous system is important, especially in the bone marrow of young, growing individuals. Here it is the frequent cause of osteomyelitis. It may 16 GENERAL PATHOLOGY also give rise to liver and subphrenic abscesses and middle ear infections. In man, general staphylococcus invasion in the form of a septicemia or bacteriemia with verrucose endocarditis is observed occasionally, but it is rare, except in infants. It may then be re- covered from the blood. (In blood cultures there is always danger from contamination by skin organisms, therefore care should be used in interpretation of findings.) The staphylococcus pyogenes aureus is the typical pus and abscess producer. Its pus is rich in polymorphonuclear leucocytes, but poor in fibrin. As already stated the organism takes advantage of a primary injury or previous entrance of other bacteria. The injury may be mechanical or chemical. From the original port of entrance it spreads by the lymph streams (lymphangitis) and then by blood. Septic emboli thus result (multiple abscesses, pyemia). Besides causing pus formation the staphylococcus leads to death (necrosis) and solution of the invaded tissue (cell lysis). Healing of the abscesses occurs usually by a break to the outside, rarely by resorption of pus. The defect heals with formation of granulation tissue (see page 210). Of other less important staphylococci, men- tion should be made of the staphylococcus albus and the staphylococcus ureae which breaks up urea into ammonium carbo- nate: CO(NH 2 ) 2 + 2H 2 O = (NH 4 ) 2 CO 3 . STREPTOCOCCI : Cocci arranged in chains. The history of strepto- cocci commences with Ogsten (1881), who was the first to differenti- ate between staphylococci and streptococci in pus. Streptococci are round cocci arranged in necklace-like chains. In size the individual coccus is about i/i, but this varies with the culture medium. Indi- viduals are often slightly flattened at the points of attachment. Characteristic is the tendency to grow only in one direction of space, but occasional tendency to growth in two directions occurs in the formation of tetrads. The chains also vary in length. They may be short, straight, or long and curved. These characteristics depend upon the strain and environment. Streptococci grow best on weakly alkaline broth, with 0.2 to 2 per cent, dextrose. Ordinarily the organism has no definite capsule, but some especially virulent strains show capsulation of chains with indentation at the point of union of individuals. One STREPTOCOCCI 17 of these strains, formerly spoken of as the streptococcus mucosus, is now classed with the pneumococci, which are intimately related to the streptococci. Very useful for the differentiation of strepto- cocci strains is cultivation on blood agar plates (i c.c. defibrinated blood + 6 c.c. agar). On this medium some streptococci exhibit marked hemolytic properties. Each colony is surrounded by a pale halo, hence the name streptococcus hemolyticus. Another strain pro- duces in similar manner a characteristic green pigment which encir- cles each colony. This is termed streptococcus viridans. Streptococci grow on agar as grayish points, sometimes as a faint diffuse layer. They usually do not liquefy or peptonize gelatine, unless irregu- larly. The optimum temperature of growth is the usual one of incubation, and the extreme limits are 43C. and 12 to I5C. They are facultative aerobes and grow well on exclusion of air. Some streptococci form lactic acid from milk and coagulate it, eventually checking their growth, unless neutralized; others only attack the glucose in milk with no clotting. Cultures remain transferable for months, particularly those coming from pus and erysipelas. Throat and intestinal cultures are usually less resistant. The usual patho- genic streptococci are Gram positive. Gram-negative streptococci are generally saprophytes. STREPTOCOCCUS DISEASES OF SKIN AND SUBCUTANEOUS TISSUES. The most important is erysipelas, a disease recognized since ancient times and well known to the Hippocratic school as epidemic. Hunter and Gregory, in the eighteenth century, recognized its contagiousness, and Volkmann established the disease in 1869 as a most important wound infection. Erysipelas is a migrating, sharply demarcated inflammation of the skin, easily recognized by its red color and saltatory progress. It may be either superficial or deep, extending through the rete Malpighii and deeper. The inflammatory exudate is serous, raising blisters, or it may become phlegmonous, purulent, and even gan- grenous. In these severe cases it may extend to the mucous mem- branes, the serous cavities or joints. The period of incubation (time from infection to outbreak of disease) varies. In animals it is only 15 to 61 hours, in man much longer, 6 to 14 days, on an 2 1 8 GENERAL PATHOLOGY average one week; the duration is from 10 to 14 days. Abortion of an attack is possible. Streptococci are not found in the reddened parts, but in the lymphatics and tissue spaces of the periphery not in the blood vessels. The reddened central parts contain a hemorrhagic serous exudate within necrotic tissue. This may give way to purulent infiltration and even abscess formation. The original .idea of Fehleisen that erysipelas is excited by a specific streptococcus is no longer entertained, since it is known that streptococci from many foci, from abscesses, throat in scarlet fever, tonsillar affections, etc., may be responsible. Not all persons are equally disposed to the disease. The skin of persons in certain trades, as blacksmiths, bakers and cooks, seems more susceptible. The same applies to the skin of blond individuals, while brunettes are less liable to infection. Individual idiosyncrasy towards the disease is great. Moreover, once having occurred it is liable to habitual recurrence (cocci doi/ not die, but attenuate and gain new virulence). Before the times of antisepsis erysipelas was a gravely feared disease of surgical wards and hospitals. Since the introduction of antisepsis and asepsis it has lost much of its previous horror. Streptococci frequently combine with staphylococci in abscess formation or phlegmonous inflammations of the skin. In dirty wounds they associate themselves with putrefactive bacteria. There are numerous other skin lesions in which streptococci are found, especially in impetigo contagiosa, also erythema multiforme, scar- let fever, etc. Here are concerned not only the micro-organisms themselves, but their toxines. OF THE THROAT. Mucous membranes, especially of mouth and throat, are favorable places for lodgment, growth and penetration of streptococci. The same applies to the lymphoid tissue in these situations, especially the tonsils. Up to 45 per cent, of healthy tonsils show the presence of streptococci, and, generally speaking, there exists a rich bacterial flora in the mouth and gastro-intes- tinal tract. Streptococci grow well in the alkaline secretions of mucous membranes, especially when the secretion is abundant and contains many desquamated and necrotic cells. Thus a catarrhal condition of mucous membranes favors the growth of streptococci. STREPTOCOCCI 19 Very important also is any injury to the mucous membrane, either by physical or chemical agents, or by other bacteria, such as the diphtheria bacillus, or, as it occurs in measles, typhoid fever, etc. Here streptococci invade through the injured mucous mem- brane, often directly with the original cause of the injury and con- tribute to a mixed infection. The streptococcus infection may then even exceed the importance of the primary infection, increase its virulence, or give it a new character (necrosis of tissues and gen- eral septicemia). Streptococci, therefore, are found in practically all inflammations of the throat, from the mildest to the most severe. IN BRONCHI AND LUNGS. Streptococci cause disease either alone (aspiration pneumonia, pyemia) or, more important, as secondary infection. In this connection the relation to tuberculosis deserves special mention. Koch himself showed as early as 1884 the impor- tance of streptococci in the progress of tuberculosis of the lung. Streptococci follow the path of the tubercle bacillus, may even precede it, and are largely responsible for the rapid fusion of tuber- culous tissue, ulceration and cavity formation. OF THE GASTROINTESTINAL TRACT. Here they are as abundant as in the throat. They seem to have etiological relation to some diar- rheas, especially of children. They may either enter through the mu- cous membrane or reach the gut by way of the lymphatics, even from remote foci. Thus appendicitis is thought by some to be due to lymphatic extension from a tonsilar focus. Similar views are held as to the origin of some streptococcus types of dysentery. OF BONES AND JOINTS. Streptococci have not the same impor tance in osteomyelitis that staphylococci have, but their affinity is greater for joints. They are responsible for purulent synovitis and arthritis as parts of a general pyemic process, and also seem to settle in joints as the primary focus of infection. Some investiga- tors hold that certain specific strains of streptococci are responsible for acute articular rheumatism and that this disease, with its fre- quent accompanying endocarditis, is to be regarded as a strepto- coccus pyemia. IN PUERPERIUM. Very important are the puerperal infections with streptococci. They take their origin from the wounds and injuries of the uterus during or after confinement. That puerperal 20 GENERAL PATHOLOGY fever was of contagious, transmitted origin was suspected by Oliver Wendell Holmes in 1843, but a substantial support of this idea was not furnished until Semmelweiss showed, in 1861, that the puerperal mortality could be greatly reduced by cleanliness and care of operator and instruments. His observations, however, were scorned and disregarded. Actual proof of Semmelweiss' contention came with the advent of bacteriology. The typical, pronounced infec- tion is a purulent gangrenous inflammation of the mucous mem- brane of the uterus (septic endometritis). It may penetrate to the musculature of the uterus and the surrounding connective tissue (septic metritis and parametritis). Infective thrombi are formed in the large, exposed blood channels and lymphatics of the uterus and in the parametrium. Extension of the parametritis leads to peritonitis and through lymph and blood stream to pleuritis, pericarditis and mediastinitis. By entrance of micro-organisms into large veins (vena spermat- ica interna), opportunity for a general pyemia is given. In no other infection does the streptococcus possess greater importance or greater virulence, and nowhere are the anatomical conditions more favorable for its location (necrotic tissue) and invasion (large bleeding surfaces). Severe complications with other, especially pu- trefactive bacteria, increase the danger. Streptococci are conveyed to the exposed, susceptible parts, in at least the majority of cases, from the outside by hands, instruments, bandages, tampons, etc. The question of autoinfection by streptococci normally present in the vagina has also been raised. While this possibility cannot be absolutely denied, it is certainly not as important a source of infection as introduction from outside, and only possible under unusual circumstances. It is true that streptococci occur in the vagina, but, as the observations of Doderlein and others showed, these are rendered innocuous by the strongly acid secretion of the vagina. Only the pathological secretion in catarrh, especially in gonnorhea, becomes weakly acid or alkaline. In these reactions mucus would be a good culture medium. Under such conditions the development and increase in virulence of vaginal streptococci is conceivable, but not proved. 1 1 Von Herff figures for 10,000 labors one hematogenous puerperal infection, that is, not caused by local infection. STREPTOCOCCI 21 SEPTICEMIA AND PYEMIA. Reference has already been made sev- eral times to generalization of streptococci throughout the body. Such a condition is known as septicemia or bacteriemia. The latter name is now preferred by some as being more definite. When under such conditions local manifestations are added, as joint lesions, multiple abscesses, inflammation of serious membranes, etc., the process is termed pyemia. Entrance of the micro-organisms may occur either directly or indirectly through the lymph cir- culation (lymphangitis). When only small numbers are thus swept into the blood stream, they are usually made innocuous by the antibacterial properties of the blood. In large numbers, however, they overgrow the body, or as already stated, locate in parts, either through mechanical arrest or through special anchoring affinities of certain tissues (receptors, chemical and biological relation of tissues to invading organism see page 108). In general infections blood culture shows the presence of strepto- cocci. This may be taken as indication of the inability of the host to fix and destroy bacteria locally. In withdrawing blood for culti- vation in broth, conveniently from a larger, peripheral vein of the arm, 5 to 10-20 c.c. are taken and ^volume of a 2 per cent, solution of sodium citrate added to prevent coagulation and bactericidal action. Otherwise a small volume of blood must be diluted with a relatively large amount of broth (several hundred c.c.) in order to avoid any bactericidal action of the blood serum, whereby growth is inhibited. General streptococcus infections present the picture of an intoxication with remittant, so-called septic temperature. SPECIFICITY OF STREPTOCOCCUS DISEASES. Originally, under the influence of early bacteriological teaching, it was held that every disease had its specific micro-organisms and that these were fixed in type and pathogenicity. It has already been mentioned that Fehleisen considered his so-called streptococcus erysipelatos entirely distinct from others. It was found, however, that one type may cause erysipelas, phlegmon and general sepsis, even in the same host, and that these various manifestations of streptococcic in- fections depend upon certain variable factors in the streptococci strains and in the host. These variables, which, it may be added, apply not only to streptococcus infections, but to infections with 22 GENERAL PATHOLOGY other micro-organisms as well, determine occurrence, location and character of the disease and may, therefore, be spoken of as "rela- tive determinants." Recent investigations have further confirmed these views and have especially emphasized the great variability in cultural characteristics and virulence of streptococci strains as influenced by their source and previous history. The following table summarizes the factors entering into the formation of relative determinants: TABLE I FACTORS DETERMINING CHARACTER AND, VIRULENCE OF STREPTOCOCCUS INFECTION (Relative Determinants) A. In the Streptococcus. Fluctuations and variations in type. These depend upon (1) Source (Animal, etc.). Virulence increased by successive passage through animals of the same type. (2) Soil, (a) Quantitative: nutrition of host, good: virulence, plus. nutrition of host, bad: virulence, minus. (6) Qualitative: affinity for tissues previously inhabited (re- ceptors) such as joints, skin, etc. B. In the Host: (1) Local Determinants, (a) Anatomical structure (mechanical arrest by capillary loops in kidney glomeruli, or in spleen, etc.). (6) Pathological lesions: blocking of paths of travel by exudate, etc. (2) General Determinants, (a) Antibactericidal action (a) general. (|8) specific as re- sponse to a particular invasion. (6) Individual organization (a) age period, (as suscep- tibility t o bone infec- t i o n in youth, etc.) (/3) s p e c i fi c, gro uped collective- ly as dis- position. BACILLUS PYOCYANEUS 23 This table explains the possibility of a large number of easily variable and fluctuating streptococcus strains, both pathogenic and saphrophytic. This is borne out by facts. Even saphrophytic strains may thus acquire pathogenic properties and mild or severe virulence. An attempt has been made of late to classify and differentiate the various streptococcus strains by their behavior towards various sugars, but this is still in the experimental stage. Another method of streptococcus classification is that of Avery, and depends upon their acid production. The acid production differs apparently in bovine, human and saprophytic strains. Thus milk streptococci produce more acid than those from the throat. While of interest, this method is at present not sufficiently advanced to allow a classification for pathological use. Recently it has been claimed by Rosenow that streptococci may be "trained" to the production of specific diseases, for instance for gastric ulcer, and that this property once acquired remains fixed in the strain. Substantiation of this assertion by others has not been forthcoming and, when it is considered upon how many different and variable factors a disease depends besides the in- fecting agent, this claim requires confirmation before it can be entertained. BACILLUS PYOCYANEUS. This organism, which produces, as its name implies, blue or green pus, is conveniently considered as an appendix to the foregoing pus producer, although it is not a coccus, but a rod. It was of much greater importance in the days before antisepsis and asepsis, for it was quite common to observe it in suppurating wounds with bluish or greenish pus. The cause of this peculiar pigment was discovered in 1882 by Gessard in a pig- ment-producing bacillus. This organism is a short rod, I to 2ju in length, small, slender, actively motile and does not form spores. It stains easily with the ordinary dyes, but is negative to Gram. In culture it is a faculta- tive anaerobe, but its pigment is produced only in the presence of oxygen. It grows well on practically all media in acid or alkaline reaction in the form of an abundant, grayish glistening layer on the surface of the solid medium and produces pigment in about a 24 GENERAL PATHOLOGY day. On broth it also grows on the surface as a thick pellicle. It coagulates milk. The pigment is called pyocyanin, and is originally a colorless base which becomes green or blue only on exposure to oxygen. Some strains produce a fluorescent pigment. The organism by itself possesses only mild pathogenic properties and often lives only as a harmless saprophyte on the skin or in the gut. It exhibits pathogenic properties only in feeble, reduced and senile individuals and in infants. In unclean wounds it is often a secondary invader with other pus-producing organisms, such as staphylococci and streptococci, giving the pus a faint to deep bluish or greenish color. CHAPTER III DIPLOCOCCUS PNEUMONIA THE DIPLOCOCCUS PNEUMONIA. This organism, closely related to the streptococci, is, as the name implies, the most frequent cause of pneumonia. The disease was originally considered the result of cold and prolonged chilling of the body, which were sup- posed to drive and congest the blood into the internal organs and especially the lungs. But Skoda and Jiirgensen were al- ready convinced of the infectious nature of the disease. After several investigators had found the presence of cocci in the sputum and exudate of pneumonic patients, Frankel and Weichselbaum independently identified this capsulated diplococcus as an almost constant concomitant of pneumonia, and further found that the organism cultured from human sputum and injected into animals caused septicemia. While the pneumonoccus is found in perhaps the majority of cases of straightforward pneumonia, it must be emphasized that it is by no means the only cause. Other organisms may also be con- cerned, such as ordinary streptococci, staphylococci, the influenza bacillus, the typhoid bacillus, the diphtheria bacillus and others. Inflammation of the lung does not, therefore, differ in this respect from other inflammations. It may be caused by a variety of organ- isms. On the other hand the pathogenic effects of the diplococcus pneumoniae are by no means entirely confined to the lung. On the contrary it may be responsible for inflammations elsewhere, in the meninges, middle ear, peritoneum, etc. These may either follow a pneumonia or may occur without it. In other words while the diplococcus pneumoniae possesses a special affinity for anchorage in the lungs, this property is not exclusive and illustrates, as in other organisms, lack of absolute etiological specificity. The pneumococcus presents in recent state a typical mor- phology. It is somewhat elongated, lancet-shaped, in pairs, hence 25 26 GENERAL PATHOLOGY called diplococcus lanceolatus. It is occasionally arranged in short chains which always display close union of two (diploid) organisms. Characteristic is its distinct capsule, a clear halo which surrounds either one, frequently two organisms. If short chains are found, which is common in the type of pneumococcus formerly spoken of as the streptococcus mucosus, the capsule is indented at the point of junction of pairs. The capsule disappears usually on artificial cultivation and is regarded as an indication of strong virulence. It is retained only under very favorable conditions of cultivation (in fluid sera and non-coagulated albuminous fluids). Cultures ferment inulin with the production of acid, which is a distinguishing reaction from streptococci. (Streptococcus mucosus ferments inulin, putting it into the pneumococcus class.) The pneumococcus dies rapidly on culture, being an obligatory para- site. Its death is hastened by strong acid formation. Frequent transplants are, therefore, necessary to keep it going even for a short time. These may fail. In sputum and blood the virulence is maintained longer. The recent observations, especially of Dochez and other workers at the Rockefeller Institute in New York, have shown that the pneumococcus occurs in a number of strains. Of these four may be recognized as distinct in certain cultural characteristics and virulence. The first two are the common, typical pneumococcus forms; the third is the organism spoken of as streptococcus muco- sus; the fourth is a relatively virulent form which is common in the mouths of healthy persons. Of these four forms, the third is the most virulent; then comes Nos. i and 2, and finally No. 4. Mix- tures of these are not infrequently encountered in infections. Besides in the mouth pneumococci occur on other normal mucous membranes, such as those of the nose, throat, pharynx and conjunctiva, apparently waiting for an opportunity to invade. The investigations of Weichselbaum demonstrated this organism in 94 cases of 129 pneumonias. The diplococcus pneumoniae is most abundant at the beginning of the inflammation in the lung and in the earliest inflammatory areas. In older or healing lesions they become scarcer, lose the capsule and disappear. They are seen in the alveoli, lymph and blood vessels, free or in leucocytes. DIPLOCOCCUS PNEUMONIA 27 They travel by means of the lymphatics to the pleura and to the glands at the hilus of the lung, enter the general circulation and disseminate through the rest of the body as pneumococcus septi- cemia. Pneumonia should, therefore, be regarded not simply as an inflammation of the lung, but rather as a septicemia or bacteri- emia, with local manifestations in the lung. This explains the other, frequent complications in the disease. The occurrence of the dip- lococcus in pneumonic sputum is constant. Mixed infection with other micro-organisms is, on the whole, rare, but may occur with bacillus influenzse, streptococci and staphy- lococci, rarer with putrefactive bacteria in unresolved and stagnant inflammatory exudates. Broncho-pneumonia may be excited by this diplococcus, but is more frequently due to other organisms. Complications of pneumonia, such as pleuritis, pericarditis, menin- gitis, etc., are the results of lymphatic extension and generalization of the infection. But pneumococcus pleuritis, peritonitis and menin- gitis may occur without any involvement of the lungs. In primary pneumococcus meningitis the organism enters probably directly from the accessory cavities of the nose or middle ear. Rarer pneu- mococcus diseases are arthritis, periarthritis and pyemia. The pneumococcus produces a characteristic thick, creamy pus, slightly greenish, but clear, which compares with the dirty, serous, hemorrhagic exudate in streptococcus infections. In animals the pneumococcus does not, under ordinary circum- stances, cause pneumonia, but a septicemia only. Wadsworth, how- ever, has succeeded in inducing in rabbits pulmonary lesions by direct intratracheal introduction, after partial immunization against the diplococcus through previous attenuated small doses of the organism. This may have enabled the animals to fix or an- chor the pneumococcus in the lungs. CHAPTER IV DIPLOCOCCUS INTRACELLULARIS MENINGITIDIS, GONOCOCCUS AND MICROCOCCUS CATARRHALIS DIPLOCOCCUS INTRACELLULARIS MENINGITIDIS. Also known as meningococcus. This organism is the cause of epidemic cerebro- spinal meningitis. Next to the pneumococcus and tubercle bacillus it is the chief etiological factor in this disease. After Klebs, Eberth, Marchiafava and Celli had observed cocci in the exudate of epidemic cerebrospinal meningitis, Weichselbaum, in 1887, described as the diplococcus intracellularis meningitidis, an organism distinct from the pneumococcus, and this finding was later confirmed by others. Morphologically this organism is similar to the gonococcus (see later). It appears in pairs or tetrads, even in groups, and has a great tendency to lie in leucocytes, hence "intracellularis." It divides in two planes, so that the name micrococcus is preferred by some. It is non-motile and forms no spores. An important difference from many other pathogenic cocci is its Gram-negative character, which it shares with the gonococcus and the micrococcus catarrhalis of Pfeiffer. In culture it grows only feebly at temperatures from 37 to 42C. On agar plates grayish colonies 2 mm. in diameter, with smooth, slightly elevated edges appear in 24 hours. These, on mag- nification, are finely granular. On blood and serum agar growth is more luxuriant, so that in 24 hours colonies of about 3 to 4 mm. in diameter appear. The addition of i per cent, dextrose seems to favor growth. On slanted agar growth is uncertain and poor. In broth slight turbidity is produced. It grows in milk without coagu- lation. It does not ferment to acid mannose, saccharose and levu- lose, but only dextrose and maltose. Neutral reaction is most favorable. The meningococcus is essentially an aerobe, and does not grow on exclusion of air. Frequent transfers (from 2 to 3 days) in culture are necessary to have it retain its viability. It is a strict parasite, and dies easily on culture media, and when exposed to drying 28 GONOCOCCUS 29 (in about 24 hours). Its pathogenicity to animals is low. White mice are more susceptible than other animals, but even subcuta- neous injection is tolerated by them. Subdural introduction into monkeys is followed by meningitis. The organism is a constant finding in epidemic meningitis. It produces a fibrinous or sero-fibrinous inflammation of the pia arachnoid which not infrequently extends to the cerebral substance. The number of cocci in the inflammatory exudate varies. They are usually scarce and lie mostly in leucocytes. The path of entrance to the brain is not quite clear. It is held that this is probably through the nose and accessory skull cavities (Flexner) where the micrococcus meningitidis has been found in healthy subjects, who may act as carriers of the disease. 1 These findings have not always been beyond all doubt, because of the possibility of confusing the meningococcus with the micrococcus catarrhalis of Pfeiffer, with which it has some similarity (see later). General dissemination through the body, that is, a septicemia, seems to be rare. The diagnosis can usually be made during life of the patient by spinal lumbar puncture and withdrawal of some of the exudate for microscopic examination and culture. GONOCOCCUS. The venereal, purulent inflammation of the ure- thra can be traced with certainty, much better than syphilis, to the remotest periods of antiquity. The works of the ancient physi- cians give ample proof that the disease was generally recognized very early amongst peoples of all cultures. Even its infectious character and contagiousness by contact had been fully recognized and during the Middle Ages efforts were made to prevent its spread by police regulations, such as examination of prostitutes, etc. But during the last part of the fifteenth century (about 1490) there occurred that remarkable epidemic of syphilis which obscured and even lost everything that had been recognized of gonorrhea as an affection sui generis. During this period there occurred a number of extraordinary events of most unfortunate consequences for the whole of Europe, and these made possible a marvelous epidemic 1 Embleton has recently shown that these cocci may be carried deep into the mucous membrane so that their detection may be missed in superficial swabs. 30 GENERAL PATHOLOGY and spread of another veneral disease, syphilis, throughout the western hemisphere. All attention became centered upon it and all other venereal diseases were disregarded, or identified with it. For several years bad seasons in Italy, France and Germany had brought poor harvests and famine. Other epidemics, plague, typhus, etc., overran the south and west of Europe. Social con- ditions were at lowest ebb, but the corruption of morals amongst both sexes had reached an extraordinary height. Added to these came the turmoil of war. The army of licentious, lawless bands of Charles VIII returning from Italy overran France, Switzerland, Germany and the Netherlands. They carried with them, according to cred- itable contemporary writers, the germs of syphilis ("Morbus gallicus, the French pocks"). Thus the disease spread rapidly from Southwest to North and East, carried by loafers, unscrupulous gentry and even the better classes. Under the impression of this venereal epidemic, all other vener- eal diseases were regarded as manifestations of it. The identity of syphilis and gonorrhea was established and remained. As great a man as John Hunter still supported it and endeavored to prove it by self-sacrificing self-inoculation. It was Ricord's merit (1832) to succeed in establishing once more gonorrhea as distinct from syphilis, but while he regarded it as an independent infection, he did not recognize it as a specific disease, but as a simple catarrh of the urethral mucous membrane, excited only by a non-specific irritation of the vaginal secretion. Further investigation by others soon showed the fallacy of this conception, for it was impossible to produce typical gonorrhea with ordinary pus. Finally, in 1879 Neisser succeeded in discovering the specific cause of the disease. He described the organism as a diplococcus of biscuit form and situated with preference in leucocytes. For a time the organism withstood attempts at cultivation. Bumm finally succeeded in this difficult task by employing human blood serum as medium. He also proved its infectiousness by direct inoculation on the human urethra. The coccus is about i.6ju in size, or less, 0.8 to o.6/z. Cocci lie in the pus cell body (usually polymorphonuclear and plasma cells) sometimes in great numbers. It appears that in the acute stage GONOCOCCUS 31 the cocci are mostly intracellular. In the chronic, they are more apt to lie outside of cells. But this behavior is only to be observed in the exudate on the surface of the urethral mucous membrane, not in the tissues. This phenonemon, known as phagocytosis, repre- sents active cell action and not an invasion by the gonococci, for they are taken up rapidly by leucocytes on artificial media and the organisms themselves are non-motile. The gonococcus stains with ordinary dyes, but is Gram negative. It is extremely difficult to cultivate, and grows only in the presence of uncoagulated protein, i.e., human serum. No growth takes place on broth or gelatine. A successful culture medium is the agar serum of We'rtheim, which consists of 2 to 3 parts broth peptone agar and i part serum or pleuritic, cystic or serous fluid. The cultured or- ganisms have been found to reproduce the disease in human beings. The temperature limits are 30 to 38C., the optimum 37C. The colonies appear in 16 to 20 hours, and in 24 hours are of pin- head size, light grayish, mucoid, tenacious. In ascetic fluid broth only superficial growth occurs, no turbidity. The organism is a strict parasite; it succumbs easily, even in culture, after a few days. Transplantation is difficult. Towards outside agents it is very susceptible, especially to silver salts. These are, therefore, best suited for treatment. The gonococcus is almost entirely pathogenic for man. Although local inflammations and reactions have been occasionally produced by endotoxic action of the bacterial bodies in animals, there is never any growth. While the urethral mucous membrane seems most susceptible, others are open to infection, especially that of the conjunctiva (gonorrheal ophthalmia), vagina, cervix, uterus and tubes. The bladder is somewhat less susceptible. Infection occurs by direct contact, as the organism is strictly parasitic. The gonococcus grows principally on the surface of the mucous membranes and between the epithelial layers, but also penetrates into the deeper tissues and extends by continuity to adjoining structures, Cowper's glands, prostate, epididymis. Its growth leads to an edematous imbibition of the mucous membrane, quickly associated with a marked purulent exudate on the surface. The lining epithelium is loosened, desquamated and lost. The sub- 32 GENERAL PATHOLOGY mucous tissue appears infiltrated with leucocytes and lymphocytes (plasma cells). As the infection and inflammation become attenuated the lining cylindrical epithelium regenerates, but flattens, and the gonococci continue to grow around the glands and in the crypts. Thus chronicity is established. It is most important to remember, however, that the organism retains its virulence and that the body does not acquire protection against it. The attenuation of the affection and the decline in the disease are, therefore, not due to any real immunity, but rather to the local changes in the mucous membrane and the gradual adaptation of the mucous membrane and a particular gonococcus strain to each other. For if these chronic cases are revaccinated with another type, a superinfection results which generally is milder. It is possible that the local ana- tomical changes may be of some mechanical importance, as the gonococci can no longer adhere so readily to the altered surface of the mucous membrane. 1 It is important to appreciate that chronic gonorrhea is as infect- ive and virulent as the acute, so that a husband with chronic gonorrhea may infect his wife and then may himself in time be reinfected by his wife. The time limit of infectiousness in gonorrhea is difficult to determine, but it may extend for years, especially in women. Gonococci disappears from the urethral secretion in man after about a year, but even then infection cannot be ex- cluded, as cultivation is so difficult (Elser). MacKenzie gives about three years as the probable time limit in men. While gonorrheal infections are more frequently local and only spread to neighboring glands (buboes), general infection (septi- cemia, endocarditis) may follow. This occurs, according to Neisser, in about 0.7 per cent, of cases. Other lesions, such as neuritis, are still rarer. Somewhat more frequent is monoarticular arthritis. The importance of gonorrhea lies in its great frequency and dis- tribution as well as its general neglect. Women particularly suffer in more ways from the consequences than men. According to Erb about 50 per cent, of a population suffer at one time or an other from the disease. It is most frequently contracted in early life. 1 What has been reported of antibody formation and successful vaccine treatment with attenuated organisms is very uncertain. MICROCOCCUS CATARRHALIS 3 3 Amongst 386 infected husbands, 85 had acquired the disease before the twenty-fifth year. A direct estimate of the number of cases in a community is difficult, as many cases are, of course, never reported. In armies and various professions the figures vary from 1.5 to 3 per cent, and even much higher, 10 to 20 per cent. MICROCOCCUS CATARRHALIS (PJeiffer). This diplococcus, which morphologically and in staining qualities resembles the meningo- coccus and gonococcus, was isolated by Pfeiffer in certain catarrhal inflammations of the respiratory tract, hence the name. It is Gram negative and grows, as contrasted to the gonococcus, easily on the common media. It differs from the meningococcus by a heavier and coarser growth. It develops at a temperature below 2OC, while the micrococcus meningitidis does not below 25C. The meningococcus produces acid in milk without coagulation. The micrococcus catarrhalis leaves the reaction of milk unchanged or produces slight alkalinity. The following are the chief points of difference between gono- coccus, meningococcus and micrococcus catarrhalis: Gonococcus grows poorly or not at all on Loftier 's blood serum, the meningococcus somewhat better and the micrococcus catar- rhalis even upon plain agar. Meningococcus produces acid in dextrose and maltose, the gonococcus only in dextrose, and micrococcus catarrhalis no acid in dextrose or maltose. CHAPTER V BACILLUS COLI COMMUNIS BACILLUS COLI COMMUNIS. This bacillus, the most representa- tive of the so-called colon group, is perhaps the most important member of the intestinal flora. The importance of the intestinal flora was recognized after Pasteur had demonstrated bacterial relation to fermentation and putrefaction. Since Koch's discoveries it became possible to separate, identify and study the intestinal bacteria. Bienstock was the first to attempt to trace intestinal decomposition to bacterial activity. It is curious that he missed the discovery of this, the most important, inhabi- tant of the intestinal tract. It was reserved for Escherich ( 1 886) to recognize it in the stools of breast-fed children, together with the bacterium lactis aerogenes and other, more or less inconstant, bacterial forms. He found the bacterium coli in increasing quantity towards the lower parts of the gut, while the bacterium lactis aerogenes inhabited the small intestines. This organism is a greater gas former than the bacillus coli, fermenting sugars into CO2 and H. These investigations of Escherich established the regular occur- rence .of bacillus coli in the gut and also, as in the bacteria lactis, the relationship of certain intestinal organisms to decomposition of foodstuffs. Further investigations demonstrated that the bacil- lus coli is not an absolutely fixed type, but rather a group, variable within certain limits, in which the members differ from each other in culture and pathogenicity. In a broad sense the colon group comprises the colon members, the typhoid bacillus and the various types of so-called paratyphoid bacilli. Of the colon members there are two common forms which may serve as a basis for descriptions; the bacillus coli communis and the bacillus coli communior, differing only in very slight cultural points (acid and gas production from saccharose). The latter is more common in the gut, hence the name. 34 BACILLUS COLI COMMUNIS 35 The colon bacillus is a plump, straight rod with rounded edges. The length exceeds the breadth by three to four times. The average length is 1-5/4 or 2-4/*, the breadth 0.4-0.71*. Some individuals display bright, refractive polar bodies or pseudo- spores. These are really vacuoles or degenerative products. True spore formation is absent, and the organism does not ordinarily possess any capsule. It stains easily with the ordinary aniline dyes, especially with fuchsin, but is Gram negative. The staining is not always uniform, sometimes irregular, granu- lar (nuclear chromatin). The bacillus does not grow in characteris- tic arrangement. Occasionally two rods hang end to end (division forms) and even short chains may then be formed, especially in media with high sugar contents in which its motion is diminished. Ordinarily the bacillus coli is actively motile in varying degree. The movement of translation in space is usually lazy and sluggish; it never acquires the rapid movement of the typhoid and paraty- phoids, although when virulent the motion is greater. Its flagellae, which can be demonstrated by suitable staining methods, are shorter, fewer and more delicate than in the typhoid forms. Bacillus coli grows well on gelatine without liquefaction. Colonies are characteristic, leaf-like, irregular, white or milky. It resembles in this respect the typhoid, but grows more coarsely and thickly. On agar and serum it also grows somewhat like the typhoid, but more luxuriantly, yellowish, often homogeneous. Its growth on fresh potato is quite characteristic, 3 to 4 mm. broad, peasoup- like, with undulating edges (important differential from typhoid see later). It develops well on milk, which it coagulates (typhoid does not). In broth bacillus coli produces a strong turbidity (more so than typhoid) in an alkaline reaction. The odor of the culture is cheese-like, but not foul. It ferments glucose, mannite; some strains also saccharose, dulcit and glycerine with the production of organic acids. Important is the production of CO 2 and H gas with possible traces of CH 4 . This gas production commences early in culture (24 to 48 hours) and is most marked and constant on glucose and lactose. Saccharose is fer- mented to acid and gas in about 60 per cent. (bac. coli communior). It appears that this is a true fermentation and not a simple hydro- 36 GENERAL PATHOLOGY lytic cleavage. It takes place under anaerobic conditions and is more complex than ordinary yeast fermentations. Bioses (sac- charose) are probably first converted into mono-saccharides. This gas production is an important differentiation of the colon members in contradistinction to entire lack of gas formation by the typhoid bacillus. Gelatine is never liquefied; the bacillus is, therefore, not proteo- lytic, but it possesses the ability to split, by cleavage, simpler com- pounds from the protein molecule. Upon this property depends the important formation of indol and skatol, mercaptans, ammonia and H 2 S. In anaerobic environment, the organism grows in the presence of glucose (not lactose) with the formation of H. Generally speaking bacillus coli is antagonistic to other putrefactive bacteria. It is also resistant to drying (150 to 200 days). It is readily killed by gastric juice and fresh blood. The great variability in virulence of this micro-organism is well shown in its different behavior towards animals, so that a general rule cannot be laid down. In moderately large doses (2 to 3 c.c. of fresh broth culture) it is pathogenic to, and even kills, animals with symptoms of severe gastro-enteritis, somewhat similar to those of typhoid fever, but less pronounced. Types which are re- covered from intestinal diseases are reported by some as more virulent than others; the virulence is gradually diminished by cultivation. The general distribution of bacillus coli is necessarily a very wide one, since fields, waters, lakes, rivers are almost always con- taminated by it. Even pure water usually contains a small number. All foodstuffs, especially milk and vegetables and those that under- go much handling, as well as clothing, are contaminated with it. In infants on the breast the bacillus coli forms almost the only intestinal organism. It is absent in the upper parts of the gut, while abundant in cecum and colon. From these earliest times of life it persists throughout. Every intestinal catarrh favors its develop- ment and increase. Ordinarily it leads only a saprophytic existence in the gut. The pathogenic importance of the colon bacteria in man lies in BACILLUS COLI COMMUNIS 37 its ability to pass, under certain conditions, through the gut and invade the surrounding structures (peritoneum, kidney, etc.) and even the circulation. This occurs frequently during agony and immediately post-mortem when circulatory stasis and tissue death provide no longer any obstacles. In these cases the appearance of colon bacilli in the blood and organs is of no particular significance. But similar favorable opportunities for invasion may prevail under certain other pathological conditions than in agony and death. Thus, in either general or local lowered resistance, entry of the colon bacillus in large numbers through the gut becomes possible, and it may then acquire pathogenic importance, either by itself or as partner in a mixed infection. This pathogenic importance of the colon bacillus was formerly overrated, for, as we have already seen, its presence in a body after death may be the result of agonal or post-mortem invasion. It is the merit of Gruber to have pointed out that agonal or post- mortem invasion can be differentiated from true infection by a peculiar behavior of the blood serum towards a diluted broth cul- ture of the bacillus. In true infection the blood serum acquires the ability to arrest motion and agglutinate (clump) freshly culti- vated colon bacilli in very high dilutions. This can be observed in hanging drop under the microscope. These dilutions are active when the normal bactericidal and agglutinative properties of blood serum would fail and thus prove true interaction between micro- organism and animal body by presence of specific agglutinative properties. Gruber discovered here an important immunological phenomenon and principle which will be discussed fully later, and which has been elevated to diagnostic dignity in various other diseases, more especially in typhoid fever by Widal (see later). The following possible infections by the colon bacillus show its varied pathogenic relations: 1. Septicemia, more particularly in infants or complicating other infections. 2. Diarrheas and enteritis, infectious colitis, especially in chil- dren. 3. Peritonitis, after severe insults (nutritive or inflammatory or traumatic) to the intestinal wall. 38 GENERAL PATHOLOGY 4. Cholecystitis and production of gall stones; bile stagnation is favorable to infection and colon bacilli may form precipita- tion nuclei for concretions. They may involve the liver in purulent inflammations (liver abscess). 5. Inflammation of genito-urinary tract, pyelitis, cystitis; in- fection is favored by urine stagnation. Infection occurs through the blood stream, but also directly through migration from the gut. (Importance of intestinal stasis.) 6. Pus producer especially in already inflamed and infected organs with other putrefactive organisms. 7. In eye (conjunctivitis), skin, and mouth diseases. CHAPTER VI BACILLUS TYPHOSUS BACILLUS TYPHOSUS. The disease now known as typhoid fever has been recognized from very early times, but it was not well defined and differentiated, as the term ruos (fog) was given to a number of infectious diseases which were associated with clouded consciousness. The infection was considered miasmatic till about 1860 (Murchison). Later it was the belief that bad (sewer) gases made the body at least more susceptible to the disease. The bacil- lus was discovered by Eberth in 1880 in the mesenteric glands and spleen of typhoid patients. The first cultures were obtained by Gaffky in 1884. The chief difficulty in its recognition was the simi- larity to the colon bacillus and to the members of the so-called paratyphoid group, and in 1890 Koch declared that an absolute differential between these types did not exist. Since then bacteri- ological and especially immunological progress has cleared these points. Of greatest importance is here the phenomenon of specific serum agglutination, which Gruber used in establishing true colon infections and which was further strengthened by the observation of Pfeiffer, who showed that the serum of animals made immune to a disease possessed the property of killing and dissolving these bacteria (Bacteriolysis Pfeiffer's phenomenon). Widal finally demonstrated that in typhoid fever specific agglutination proper- ties against typhoid bacilli develop so early in the blood of typhoid patients that this reaction acquires great diagnostic significance in doubtful cases (Widal reaction). The bacillus is a short, plump rod of varying dimensions, but less so than the bacillus coli. Like the colon bacillus it is negative to Gram. Important is its great motility, which, however, is depend- ent largely upon a suitable culture medium, especially serum, peptonized 3 per cent., glycerine bouillon and dextrose bouillon. Its motion is oscillating, serpentine and somersaulting, and is 39 40 GENERAL PATHOLOGY executed by from 10 to 12 flagellae, which are, therefore, more numerous than in the colon bacillus. It forms no spores and grows in aerobic and anaerobic environ- ment. As a general differentiation the tyhoid bacillus grows on cul- ture media less luxuriantly and more delicately than the bacillus coli. Gelatine is not liquefied. On gelatine plates, small, circular, oval circumscribed colonies appear in 24 hours, colorless at first, but after 48 hours darker, almost brownish. Later it grows somewhat in the leaf-like extension of the colon bacillus, but always more delicately and with a characteristic eccentric dark umbilication. In bouillon moderate turbidity is produced, Especially important is its behavior on potato, which was emphasized by Gaffky and before the days of serology was one of the most reliable differentiations. It grows on potato only as a fine, delicate, often hardly visible, membrane or film. Furthermore it does not, as Kitasato first pointed out, produce indol (see above). The typhoid bacillus grows on litmus milk, but produces less acid (bluish red) with very often a terminal alkalinity, and leaves the milk clear as contrasted with the colon bacillus which produces much acid (bright red) and turbidity in milk (coagulation). Very important is the lack of gas fermentation on sugar, not even in traces (differentiation from paratyphoid bacilli). The only other bacillus with which it may be confounded in this respect is the bacillus fecalis alkaligenes. Lactose and saccharose are not influenced by the typhoid bacillus, but glucose, maltose, levulose, galactose and mannite are fermented to acid, but without gas formation. The typhoid bacillus must, therefore, show the following charac- teristics: (i) active motility, (2) Gram negative, (3) growth on gelatine without liquefaction, (4) faint growth on potato, (5) no indol production, (6) no gas fermentation on any sugar, (7) growth on litmus milk with only feeble acid formation without coagulation. Quite difficult at times may be its identification from the bacillus fecalis alkaligenes of the gut. This organism resembles the typhoid very closely, but shows coarser growth on potato and does not form acid from any sugar. The paratyphoid bacilli also do not pro- duce indol, but generally ferment sugar with the formation of gas. Very characteristic, as already stated, are the typhoid reactions BACILLUS TYPHOSUS 41 with the serum of patients or convalescents. Of these the aggluti- nation (Widal reaction) has practically become the most important. The serum of immunized individuals possesses in large dilutions (i :ioo or even more) the power to clump freshly cultivated, active typhoid bacilli. Characteristic are only high dilutions, as even nor- mal serum has, in concentrated form, the same ability. The serum is diluted accurately with a graduated pipette with physiological salt solution and then added to a measured quantity of fresh active broth culture of typhoid bacilli to obtain the desired proportions. In positive agglutination the activity of the bacilli is soon dimin- ished, they aggregate, hang together, lose their motility entirely (considered by some the essential characteristic of the reaction) and finally immobile clumps of agglutinated organisms remain. This is the end-reaction, which ought to occur rapidly, but, of course, is dependent somewhat upon the degree of dilution. In practice one usually employs dilutions of from 1 150 to I :ioo when agglutination should be complete in about 20 minutes to one-half hour. To-day the diagnosis by blood culture is often easily made during the life of the patient and may be obtained in about 80 to 90 per cent, of the cases during the first week of the disease. Gradually the bacilli disappear in the course of the illness. Three to five c.c. of blood from a vein of the arm should be immediately transferred to a relatively large amount of culture medium (200 to 400 c.c. of broth), to prevent bactericidal inhibitory action of the blood, and incubated without delay. Coleman and Buxton have introduced the useful method of cultivation from blood on ox bile, glycerine and peptone. PATHOGENICITY. The typhoid bacillus is not infectious to ani- mals in the same degree as it is to man. Its growth in animals is ex- tremely limited. Dead, sterile cultures have about the same effect as living micro-organisms. The action on animals is, therefore, only a toxic one. The bacilli disappear quickly from the blood and do not grow in internal organs. Local infections follow injections of large doses of virulent forms, while small doses are rapidly destroyed. For man the bacillus typhosus is truly pathogenic. Its chief focus of action and port of entrance is the lymphoid tissue of the lower ileum, near the ileo-cecal valve. There it produces swelling, 42 GENERAL PATHOLOGY especially of Peyer's patches, due to lymphoid and endothelial cell proliferation and edema. This is followed by necrosis, sloughing anddesquamationofthe parts, leaving a bleeding ulcer in the longi- tudinal direction of the gut. The bacilli enter the mesenteric glands and produce similar changes in them. They are also abundant in the blood, spleen, bile and bone marrow and in the characteristic skin roseola. Lymphoid cell foci undergoing necrosis are also to be found in liver and kidney. Typhoid fever is, therefore, a true septicemia or bacteriemia. Practically of importance is the frequent localization of typhoid bacilli in the urinary tract. They occur in the urine in from one-fourth to one-third of all typhoid cases. The earliest is towards the end of the second week, often later, but they may persist during convalescence and even after. This appearance is frequently very abrupt, so that the urine may be clear one day and the next turbid or cloudy with bacilli. Albumin and blood may be present, but not necessarily, and the acid urine may contain only few leucocytes. Rarer are cases of defi- nite typhoid cystitis and pyonephritis. The urine as well as the feces is, therefore, an important source for spreading the disease. The bacilli have been reported to persist in urine for several years (up to five years by Young). Urotropine is efficient in clearing up these cases, in doses of from 1.5 to 3.0 gm. per day. In the gall bladder the typhoid bacilli occur frequently and grow well, especially when the bile flow is interfered with. They may then produce a true cholecystitis and this may not make its appearance until after the fever itself is over. The bacilli, like bacillus coli, serve also as a precipitation nucleus for gall stones. They are very persist- ent in the gall bladder and have been recovered 7, 15 and even 17 years after a typhoid attack. So-called "typhoid carriers" who may spread the disease are persons of this type. Typhoid bacilli may cause complications in the respiratory tract in the course of typhoid fever, i.e., bronchitis and pneumonia. The typhoid septicemia may take on the character of a pyemia in the form of inflammatory metastases and multiple abscesses. These may be of two kinds: (i) Due to the typhoid bacillus itself; (2) mixed infections with cocci as secondary invaders. The first BACILLUS TYPHOSUS 43 are most frequent in the osseous system in the form of typhoid periostitis, arthritis or osteomyelitis; also as cause of tibial abscesses and of necrosis of frontal bone in the skull. These may occur late in the disease, even in convalescence. Much rarer, according to Curschmann, are subcutaneous and muscular abscesses, and, very rare are inflammations of the nervous system. The old idea that the typhoid bacillus is never a pus producer is no longer tenable, al- though it is not a common pus former. Mixed infections in typhoid fever are rare. These may occur either as more or less independent complications, or are secondary on the ground paved by the typhoid infection. They may involve all organs: ear, pleura, parotid gland, peritoneum, testicle and prostate. Typhoid bacilli are here absent in the pus ; only strepto- cocci or staphylococci are found. Typhoid infections, like others, vary greatly in virulence and in the extent and character of anatomical lesions. The intestinal lymphoid swelling and ulcerations may be very slight, or limited, sometimes more prominent, or entirely confined to the large gut (colo-typhoid). Perforation of intestinal ulcers is frequent. An important feature is that the extent and severity of the intestinal lesions bear no relation to the severity of the disease. Many very severe cases show relatively slight local intestinal changes (ina- bility to anchor bacilli in gut), being, in fact, only grave typhoid septicemias. The manner of transmission and infection in typhoid is by direct ingestion of substances contaminated by it, usually foodstuffs. The importance of disinfection and proper disposal of feces and urine is plain, and the possibility of infection through dejecta of "carriers" must also be recognized. Persons long recovered and quite well but who harbor typhoid bacilli in the gall bladder or urinary bladder may for many years spread the infection wherever they go. It has not been possible to demonstrate a particular toxic secretion in typhoid bacilli, which, as in diphtheria, is distinct and separable from the bacillary body (esotoxine). The typhoid toxemia is evidently, at least largely, dependent upon toxines liberated by disintegration of the bacilli themselves (endotoxine). CHAPTER VII PARATYPHOID BACILLI IT is now well established that diseases occur which clinically, anatomically and bacteriologically are closely allied to typhoid, but differ in certain respects. Bacteriologically this group stands between the colon and typhoid bacilli with similarities and slight morphological differences between the members of each group. Clinically they show often a lighter, more irregular course than typhoid, with a mortality of below i per cent. Two main cultural characteristics distinguish generally paratyphoid from typhoid and colon bacilli. They ferment sugars to gas, as opposed to ty- phoid, but do not produce indol, as opposed to colon bacilli. In their motility they resemble closely the typhoid. TABLE II B. COLI TYPHOID PARA- TYPHOID Motility Sluggish Active Active Gas production from sugar +4- o + + (Not from lactose) Acid production from sugar . . 4- + 4- (Not from lactose) (Not from lactose) Indol 4-4- o o Milk coagulation + o Growth in potatoes Luxuriant Delicate Variable Agglutination Specific Specific Specific Gram Negative Negative Negative Two groups of paratyphoid bacilli are recognized, A and B. B occurs in the larger number of cases of paratyphoid. These groups differ in relation to alkali production in milk and sugar fermen- 44 PARATYPHOID BACILLI 45 tations. Type A produces alkali in litmus milk (after slight pri- mary acidity) more slowly than type B (14 days in A; four to five days in B). A ferments xylose and dulcite slowly. B ferments xylose and dulcite rapidly. A does not blacken lead acetate in 18 to 24 hours. Pathogenetically A resembles closely typhoid, and is less toxic to animals. Some paratyphoids seem to be able to lead a saprophytic exis- tence in the gut. Their exact biologic relation to typhoid and colon bacilli has not been determined. BACILLUS ENTERITIDIS OF GARTNER. This is one of the im- portant paratyphoid members, and is responsible for many meat infections. It has been known for a long time that the ingestion of apparently healthy, non-putrefied meat, may produce serious gastro-enteritis, often with marked nervous symptoms and other evidence of general infection. The disease commences about six to twelve hours after ingestion with nausea, vomiting, and diar- rhea. A number of cases result fatally, and autopsy then discloses the anatomical lesion of a severe gastro-enteritis with swelling of the lymphoid tissue of the gut and spleen and degenerative nephritis. The disease is much more apt to arise after partaking of raw or insufficiently cooked meat, although it occurs some- times even after eating cooked meats (toxine action). Gartner succeeded, in 1888, in isolating a pathogenic organism from the meat of a cow, the ingestion of which had been followed by toxic symptoms. He obtained an identical organism from the spleen of a person who died after eating this meat. Both resembled the typhoid bacillus in some respects, and the colon bacillus in others. A similar bacillus was identified in subsequent epidemics of meat poisoning in 1 890 and 1 892, and further studies showed its close relation to certain other animal diseases, notably pneumo- enteritis of calves, and hog cholera. The most impressive epidemic caused by Gartner's bacillus took place in Ghent, Belgium, in 1 895, and was thoroughly studied by van Ermengem. The inspector of an abattoir, who himself was an expert veterinarian, had been ordered by the police to examine a number of smoked, so-called, "Cervelat" sausages, because suspicion had become strong that these sausages had been respon- 46 GENERAL PATHOLOGY sible for disease in several consumers. The inspector was under the belief that only putrefied meat was dangerous and when he saw the perfectly fresh, sweet material, passed it as safe, himself ate some of it, and also distributed it amongst employees. All were taken ill; the inspector with fatal results. He died in five days, with all the symptoms of meat poisoning. From the body of this veterinarian and from the sausages van Ermengem isolated Gartner's bacillus. 1 In an epidemic occurring in 1892 in Paris, observed by Leichten- stern, Nocard isolated a paratyphoid organism. The disease was a pneumonia with typhoid symptoms and probably conveyed to man by parrots. It has, therefore, been named psittacosis. In a number of cases of infections with paratyphoid bacillus B, ulcerative lesions in the large gut resembling dysentery have been observed. 1 This form of meat infection must be strictly distinguished from botulism, which is excited by another organism, the bacillus botulinus, a pathogenic saprophyte and strict anaerobe. This Gram-positive bacillus does not grow in the living body, but thrives on dead organic material, which has been contaminated by it, under exclusion of air (insufficiently sterilized canned meat, fish and vegetables). In them it produces an extremely toxic poison which is fatal in many instances in which such food insufficiently cooked, has been consumed. The poison affects the nervous system producing dyspnea, delirium and paralysis. One to two drops from a gelatine culture are suffi- cient to kill an ordinary monkey, 0.0003 to o.ooi c.c. is sufficient to kill a rabbit, and from o.oooi to 0.0005, a guinea pig. The poison seems to be related, and acts similar, to that of certain mushrooms and the tetanus toxine. CHAPTER VIII BACILLUS DYSENTERIC BACILLUS DYSENTERI/E. There exist a number of infective organisms in relation to dysentery, some of which are not even bacteria, but protozoa. Since the discovery of the ameba coli by Koch and Kartulis in Egypt, which was later confirmed by Osier, Councilman and Lafleur, and others, amebic dysentery has come to be recognized as a tropical disease. In 1898 Shiga, however, described a bacillus which has acquired great importance in its relation to the dysentery of Northern countries. This organism was first identified by Shiga in an epidemic in Japan ; by Kruse, two years later, in a similar epidemic in Rhenish Westfalia, and, finally, by Flexner and Strong in the Philippines. While all of the bacilli which were recovered in various parts of the world were held at first to be identical, it is now known that they represent various types and are, as a class, closely related to the colon typhoid group. Anatomically dysentery is characterized by a necrotic diphthe- ritic inflammation of the large gut (ulcerative colitis). The inflam- mation is first catarrhal, but soon becomes intense and leads to necrosis of the inflamed parts and, by sequestration, to irregular ulcerations. In amebic dysentery the ulcers are said to show a char- acteristic undermining of edges, while in bacillary dysentery the ulcers are flat and irregular. These ulcers heal with abundant scar formation and are often followed by contraction and stenosis of the gut. Other viscera are hardly involved in bacillary dysentery, whereas in the amebic type liver abscess is a frequent sequel. The Shiga bacillus, which is the prototype of the bacillus dysen- teriae group, is a short rod, which resembles the typhoid bacillus, but is plumper and polymorphous in culture. It is Gram negative, but stains well with aniline dyes. It was originally thought by Shiga and Flexner that the organism was motile, but later investigations 47 48 GENERAL PATHOLOGY iave demonstrated that the motility is probably only active kownian movement. Flagellae have not been demonstrated. ic dysentery bacilli grow well on the usual culture media under aerobic and anaerobic conditions. Growth on potato is similar to typho| d. Gelatine is not liquefied ; indol is not formed by the Shiga, but by some other types; glucose is not fermented to gas. Milk is slightly acidified, but not coagulated. The growth on gelatine shows a leaf-like extension, not unlike that of typhoid, and quite delicate. Differentiation of the various types of dysentery bacilli is largely based on their behavior towards sugars and specific agglutination reactions. The Shiga bacillus does not produce acid on mannite, the Flexner-Strong bacillus, recovered in Manila, and some others, do. Some produce also acid from maltose and saccharose. All mem- bers of the group produce acid from glucose. Life in culture is short and the organism is easily overgrown by other bacteria; it also suc- cumbs to drying in 12 to 17 days. In moist ground, if protected from direct sunlight, it may remain viable for months. In the human body it seems also to persist for a long time. It is found in the gut of persons ill with the disease, in the ulcers and mesenteric glands, but not in the spleen, blood, urine or milk. Its action seems, therefore, to be largely local and not invasive. The importance of dysentery lies in its epidemic occurrence. Wherever masses of people aggregate (armies) under unsanitary conditions, there exists danger of outbreak of dysentery. It attacks with predilection the weak, reduced and decrepit. It is easily con- veyed by intestinal discharge and soiling of clothing, bedding, etc.; possibly also by flies. Drinking water and rivers are easily polluted (carriers). Infection occurs probably by mouth. Strong and Musgrave re- port direct infection of a criminal who swallowed a 48-hour broth culture after neutralization of his gastric contents by weak sodium hydrate. He developed symptoms and the discharge of dysentery in 36 hours. The organism was isolated from the stools. Similar re- sults were obtained by Ravant and Dopter in feeding monkeys. CHAPTER IX CAPSULATED BACILLI BACILLUS LACTIS AEROGENES -THE PROTEUS GROUP CAPSULATED BACILLI. A number of capsulated bacilli, more or less related to the colon typhoid group, are of importance. The prototype of this class is the following: Bacillus Mucosus Capsulatus. Also called Friedlander's bacillus. It was found in 1882 by Friedlander in cases of pneumonia and described as pneumonic bacillus. Only a relatively small num- ber of pneumonias, however, are caused by it (8 to 10 per cent.), the bulk being due to the pneumococcus. It is very virulent and the pneumonic exudate is more serious, tenacious, but less fibrinous than that caused by the pneumococcus. The bacillus is a short, plump rod (0.5 to 1.25/x broad and only 0.5 o o.6ju long), sometimes as broad as long, coccoid bacilli. It is non-motile, does not form spores, is easily cultivated, grows under aerobic and anaerobic conditions (better aerobic),- and possesses a definite broad capsule in recent state. Artificially culti- vated, the capsule is retained only during the first generation, but may be reproduced by renewed animal inoculation. The organism is Gram negative. Cultivation is possible between 10 to I2C. and 56C. The colonies show a characteristic slimy, tenacious, stringy appearance. Gelatine is not liquefied. Indol is not produced and milk may or may not be coagulated. Cultural behavior towards sugars is variable. Bacillus Rhino-Scleroma. This organism is morphologically closely related to Friedlander's bacillus and is by some believed to be identical with it. Rhino-scleroma is a slowly progressing granulomatous inflammation of the external nares and mucosa of nose, mouth and larynx. Microscopically it is characterized by thick, connective tissue formation with bright, hyaline cells within its meshes which contain the bacilli. Rare in America. 4 49 50 GENERAL PATHOLOGY BACILLUS LACTIS AEROGENES. This has already been mentioned in connection with the colon bacillus. It was first described by Escherich, in 1885, with the colon bacillus, as occurring in the upper intestinal tract of infants. It produces gas energetically on sugar broth and invariably coagulates milk. It is found constantly in the human intestine. It is a facultative anaerobe and produces acid on lactose media. Gas production in the gut may be strong enough to give rise to flatulence. THE PROTEUS GROUP. This is a very widely distributed group which is not of very great pathogenic importance, except for its activity in the intestinal tract. The members of the group bear a certain resemblance to the bacillus coli, but are longer and slender, with a tendency to form filaments. They are motile and possess numerous flagellae. The prototype of the group is bacillus proteus vulgaris, discovered by Hauser. It is Gram negative. On gelatine growth takes place from a center in characteristic radiating threads. Gelatine is liquefied, somewhat less readily under anaerobic condi- tions. On solid agar colonies grow in irregular sausage, corkscrew- like streamers over the surface, giving the growth somewhat of a stellate appearance. The chief function of the bacillus proteus is putrefactive, split- ting the proteid molecule into its simplest radicles. Its pathogenic importance rests mainly in some diarrheal diseases. CHAPTER X BACILLUS DIPHTHERIA, DIPHTHEROIDS THE disease now recognized as diphtheria is of importance not only as a disease of wide distribution, but because it was the first infectious disease in which modern science established practical control by an enormous reduction in morbidity and mortality. Moreover, it was this disease which led to the foundation of modern conceptions of immunity. For the first eventful study of bacterial toxines and anti-toxines was carried on in diphtheria and serum therapy was introduced. While the malignant diseases of the throat have been known for generations, and have frequently occurred in severe and devastat- ing epidemics, it was Bretonneau of Tours who recognized diph- theria in the modern sense of an infectious, pseudo-membranous angina or croup. Until the work of Bretonneau, croup and diph- theria were regarded as two distinct affections. Napoleon the first, after the death of his nephew, had offered a prize for the best essay on the nature and treatment of croup. Thus, following an epidemic in Tours, Bretonneau (1818-1820) disclosed by autopsy the essential anatomical similarity and relationship between all the pseudo-membranous inflammations of the pharynx and larynx and, on account of the general presence of a false membrane made up of exuded fibrin, which fuses with coagulated dead masses of mucous membrane, gave these inflammations the term diphtherite (from bl$Qkpa = membrane). Later Virchow employed the terms croupous and diphtheritic purely in a general anatomical, not in an etiological, sense. He spoke of "croup" as an inflammation of mucous membranes in which a fibrinous exudate is precipitated on a necrotic surface, and of "diphtheritic inflammation " when this is accompanied by death of, and fusion with, deeper layers of the mucous membrane. 51 52 GENERAL PATHOLOGY Diphtheritic inflammation is, therefore, anatomically, the se- verer, more destructive process of the two. Virchow attached to these terms purely a descriptive anatomical meaning without reference to a particular etiological factor or any particular locality. A good deal of confusion has arisen in their use since the discovery of a specific micro-organism by Loffler, called, unfortunately, the diphtheria bacillus. This, it has been found, is etiologically con- cerned in some, but not all pseudo-membranous, croupous or diph- theritic inflammations of the throat and elsewhere, and it does not always produce a pseudo-membranous inflammation, but occasion- ally only a simple angina of the pharynx. The suggestion has, therefore, been made to drop the name diphtheria for the specific anginas or pseudo-membranous inflammations of the throat, caused by Loffler's bacillus altogether, and to speak of them as was done centuries ago as synanche contagiosa (Senator, Orth). The term diphtheria appears, however, so deeply rooted in lay and medi- cal usage that this has met with no success. The organism was definitely identified by Loffler in 1 884, but had already been noted by Klebs in 1883 in pseudo-membranous exu- dates. It is, therefore, sometimes spoken of as Klebs-Loffler bacillus. The organism is, as the name signifies, a rod, straight or partly curved and often with a club-shaped swelling at one extremity. It is about 6/-1 long and i.6/x thick, non-motile and stains particularly well with alkaline methylene blue (Loffler's Solution): Saturated alcoholic Sol. of methylene blue, 30 gm. Sol. of caustic potash, 1.10,000, 100 c.c. Characteristic is its pleomorphism and the marked irregularity with which it takes stains. The rod is pale, often colorless, while at the poles appear deeply staining points, or paler granules espe- cially in bacilli which have been grown on blood serum. Neisser has introduced the following staining method for demonstration of these granules. i. Stain one to two seconds in a solution of i gm. methylene blue (Griibler), dissolved in 20 c.c. 96 per cent, alcohol. Add 950 c.c. H 2 O + 50 c.c. glacial acetic acid, filter. (2) Wash in water. (3) Stain for three to five seconds in a solution of Bismarck brown, (Vesuvin) 2 gm. in 100 c.c. of boiling H 2 O. (4) Wash and mount. BACILLUS DIPHTHERIA 53 The bacilli appear as pale brown rods, bearing bluish black (metachromatic) granules, usually of an oval shape and of some- what greater diameter than the rod. While they are generally polar, they occur also in the center of the bacillary body and are spoken of as Babes-Ernst granules. The character of these granules has been a source of discussion. Originally Ernst regarded them as spores, but to-day it is generally held that this differentiation of the bac- terial plasma with the formation of the granules has nothing to do with propagation, but is an expression of cell metabolism. Culture. For a reliable diagnosis of this organism, culture on an appropriate medium is indispensable. The bacillus is in need of much O. It grows best, therefore, on the surface of slanted, solid media containing protein at usual temperature and alkaline reac- tion. The blood serum recommended by Loffler is best. On this, bacilli grow rapidly in 12 hours to small, opaque colonies. After 24 to 48 hours these fuse to a thick, white mantle on the solid serum. Growth on agar is also good, especially with blood serum and glucose. On nutrient gelatine development is slower and less luxuriant. In nutrient broth flocculent turbidity occurs in 12 to 24 hours, and precipitation with acid formation in 48 hours. The acidity in- hibits the formation of the toxine. On milk, growth is as good as in broth producing no coagulation. On potato, development is, on ac- count of strong acid production, poor. Blood serum culture is, there- fore, best for diagnosis and can be made in about 12 to 20 hours. But it must be remembered that in about 10 per cent, of advanced or older cases in which the pseudo-membrane is about to desquamate the bacilli can no longer be recovered by culture. The earlier bacteriological examination of a suspected throat is made, the better. Resistance of bacilli on blood serum is great. LofHer succeeded in growing them in full virulence for 27 months in 77 replantations. Membranes containing bacilli retain them long (3 to 4 months) even when dry but not exposed to light. In dry air they die in a few days, even hours. Small pieces or fragments of membrane coughed upon objects like toys, chairs, clothing, etc., or attached to spoons, knives, forks, or even dust may carry the infection. The organism is very susceptible to heat (killed by 6oC.) and oxidizing agents, 54 GENERAL PATHOLOGY notably H 2 O 2 and formaldehyde (these are, therefore, valuable disinfectants). Virulent bacilli may remain in the nasopharynx for a long time after desquamation and cause infection in others. It is the custom in some hospitals for infectious diseases to discharge no patient until swabs from the throat are shown to be bacilli free. It is in this connection important, that, especially during an epidemic, nurses, orderlies and others in contact with patients may harbor and carry bacilli in their mouths, although themselves not ill (carriers). Even other persons, not directly in contact with pa- tients, may do so. Thus, Park found that i per cent, of healthy throats examined in New York during an epidemic carried bacilli. Great care must, therefore, be exercised to prevent spread of this infection. The virulence and consequent local and general effects of the bacillus also show great individual differences. In some the disease may, as already stated, produce only a slight angina with little constitutional effects, in others it appears as a severe, septic pseudo- membranous inflammation of the throat, larynx and trachea, extend- ing to the bronchi. One and the same strain may cause in one person only slight reaction and in another malignant fatal results. Here, as elsewhere, secondary infections, especially with streptococci, play a large role. Patbogenicity. The pathogenic action of this bacillus is partic- ularly characteristic in guinea pigs. After subcutaneous injec- tion of 3^ to i c.c of a 24-hour broth culture, these animals become visibly ill, lose their appetite and succumb in two to three days. At the place of inoculation a gelatinous, edematous hemorrhagic inflammation of the subcutaneous tissue, containing numerous bacilli, is found which often extends deeper, involves the musculature and assumes a general extension (abdomen and chest) . The inguinal glands are swollen and hemorrhagic and the abdominal cavity contains serous, hemorrhagic exudate. Especially character- istic is the great inflammatory enlargement of the suprarenal gland. It is deeply reddened and shows numerous hemorrhages. The omen- turn also shows abscesses with bacilli, and the pleurae are the seat of a double exudative pleurisy, sometimes sufficient to float both BACILLUS DIPHTHERIA 55 lungs in the fluid. Besides these acute fatal manifestations the infection may pursue a more chronic course. In other animals, notably rabbits, inoculation into the trachea leads to a pseudo-membranous inflammation with dyspnea and death or a late paralysis. In man it is possible to recognize three expressions of this infection, (i) the localized diphtheritic lesion; (2) the general diphtheritic infection; (3) the septic and gangre- nous diphtheria. 1. Localized Lesion. It has already been emphasized that infec- tions with the so-called diphtheria bacillus of Loffler does not necessarily lead to what is anatomically a diphtheritic inflamma- tion. All grades and transitions, from angina pharyngis to severe necrotic exudative inflammations in which the exuded fibrin fuses with the necrotic masses to form a densely adherent pseudo-mem- brane, may occur. Characteristic of the latter is often rapid development and extension. This was already recognized by Bretonneau. 2. General Infection. The general diphtheritic infection de- pends upon poisoning with a toxine set free by the bacilli (eso- toxine). The earlier investigators, among them Loffler himself, had already concluded that the severity of the symptoms and even some of the anatomical changes in the body could hardly be due to local bacterial action, and suspected a poison. Loffler even succeeded in extracting with glycerine and subsequent precipi- tation by alcohol, a poisonous substance from broth cultures which produced local inflammatory reactions. But it was the work of Roux and Yersin to put the knowledge of diphtheritic toxine on a sound basis. They filtered a fresh broth culture through a Chamberlain filter, thus rendering the filtrate germ free. This ster- ile filtrate was injected into guinea pigs and rabbits in relatively large doses, up to 35 c.c. with very definite toxic results; loss of appetite, dyspnea and death in five to six days. Autopsy disclosed the characteristic inflammatory involvement of the suprarenal gland and serous pleurisy. Animals which sur- vived showed later paralysis. Older broth cultures were more active and fatal even to larger animals like dogs. White mice, which are ordinarily not susceptible to the bacilli themselves, are 56 GENERAL PATHOLOGY killed by toxine doses which are sufficient to kill 80 guinea pigs (relative immunity). The poison develops best in alkaline broth with free access of air. Acid reaction is detrimental to its production. The observations of Roux and Yersin have subsequently been generally confirmed and enlarged. Especially important in this respect is the fact that the formation of the poison is proportional to the virulence of the bacilli. It is destroyed by a temperature of 6oC. but not by evaporation at 5OC., or treatment with HCI. It is, therefore, no ferment or enzyme. It is precipitated by NH4OH or NaSO4 from bouillon cultures and may be cleaned by dialysis (Brieger and Frankel). On account of certain protein reactions it was formerly regarded as a toxalbumen, but it has been found that the albuminous contents are only an admixture and that the poison may be freed from the albumen complex. It is, moreover, easily oxidized. The chemical nature of the poison is at present quite obscure. Unlike the action of ferments, the quantity adminis- tered stands in direct proportion to the poisonous properties. Kossel has shown that the poison is originally intimately connected with the bacillary body and gradually dissolves in the culture medium by maceration, so that it is present in greatest quantity when the bacilli decline in growth and activity. 3. Septicemic Type. Loffler had already appreciated that the diphtheria bacilli pave the way for the entrance of other bacteria, notably streptococci. Thus the septicemic form of diphtheria follows, really a mixed infection in which the local diphtheritic lesion has opened blood and lymph channels for invasion by other bacteria. The diphtheria bacilli themselves remain superficial, do not penetrate and do not, at least in any quantity, enter the blood stream or permeate the viscera. In these mixed infections the deepest and most extensive involve- ment of the respiratory passages occur. Nose, ear, the accessory sinuses and trachea and bronchi may be covered by a thick pseudo- membrane and this may, by desquamation, become really dangerous as a mechanical impediment to breathing, and kill through as- phyxia (this occurs sometimes in neglected, advanced diphtheria after a large dose of antitoxine, when the pseudo-membrane is rapidly loosened). Broncho-pneumonia occurs in about 50 per cent. BACILLUS DIPHTHERIA 57 of fatal cases. There is danger of myocarditis with sudden heart paralysis and it may even later lead to trouble in causing ex- tensive myocardial scarring (sudden death). Diphtheritic con- junctivitis occurs in about 3 per cent. The skin is rarely the seat of diphtheritic inflammation. Sometimes diphtheria pursues a more chronic course, but is not less dangerous. The late results of the poison are shown by various forms of neuritis and paralysis. The differentiation of true diphtheria from other pseudo- membranous inflammations of mucous membranes not caused by Loffler's bacillus is important. This is especially true of scarlet fever, which also goes along with simple angina pharyngis or diph- theritic inflammation in the anatomical sense. In this instance the pseudo-membrane appears more slimy and disconnected, but at times may be indistinguishable from the diphtheria by Ldffler's bacillus. In some of these cases Loffler's bacillus is actually present, so that we are dealing with a combination of scarlet fever and diph- theria; in many, however, Loffler's bacillus is not etiologically concerned. This combination may also occur in measles, erysip- elas, etc. Finally, as in every infectious disease, it must be remembered that, although in general the contagiousness of diphtheria is high, the disease develops in infected persons only on the basis of a specific disposition to this micro-organism. Certain age periods, especially childhood and adolescence, are more susceptible than later life, but even amongst individuals of the same age disposition varies tremendously (see Schick reaction). The ultimate solution of this problem lies probably largely in differences of anatomical tissue organization and body construction. Thus, the different organization of the various age periods creates differences in susceptibility to infections by changes in tissue soil and environment which are essential for anchorage and develop- ment (biological affinity) of bacteria (see more fully under disposition). The bacteriological diagnosis of the Loffler bacillus must be made by culture, even if the microscopic examination of the fresh spread shows characteristic forms. For it will presently be shown that there are strains, so-called "diphtheroids," which are very 58 GENERAL PATHOLOGY prevalent in the mouth and elsewhere, but vary in cultural charac- teristics and especially in virulence from the Loffler bacillus. It is convenient to use for this purpose a sterile wire, the end of which is wrapped into absorbent cotton, known as a swab. This is carried in a sterile tube. It is introduced, cotton wrapping foremost, into the throat and gently touched to, and moved over, the surface of the affected mucous membrane (bacilli are superficial). Then it is withdrawn and gently smeared over the surface of several slant serum tubes which are incubated for 12 hours. Colonies are then visible on the surface of the slant serum. These may be examined microscopically. But even definite cultural results are no proof of the pathogenicity of the organism. For it has only recently been shown that there exist in throats and wounds bacilli which morphologically and culturally answer to the Loffler bacillus, but are avirulent (Adami) . It is, therefore, necessary to follow the culture by inoculation into a guinea pig for the characteristic anatomical lesion and general toxic effects. PSEUDO DIPHTHERIA BACILLI: (DIPHTHEROIDS). In the fore- going discussion it has been made clear that the group of the diph- theria bacillus is represented, as in other more or less specific bacterial types, by several members which exhibit differences from the main representative of the group, morphologically, culturally and pathogenetically. This was already appreciated by Loffler. Hofmann later studied one of these forms which goes by his name. This organism is somewhat shorter, thicker and stains more homogeneously with Neisser stain. It grows luxuriantly on ordinary culture media; does not ferment sugar, nor dextrose and is non-pathogenic. Bacillus Xerosis. This is a diphtheroid which is found in conjunctivitis, but also on the normal conjunctiva. It resembles the bacillus of Loffler closer in morphology and cultural characters than Hofmann's bacillus, but differs in behavior towards sugar media; it ferments sacharose with production of acid, while the bacillus of Loffler does not; on the other hand, the bacillus xerosis does not ferment dextrin to acid, while Loffler's bacillus does. It is, if at all, weakly pathogenic. The relation of these diphtheroids, of which there are still DIPHTHEROIDS 59 others, to the bacillus of Loffler is not clear. The fact that even in the true Loffler form pronounced variations in pathogenic effects occur, so that its mere discovery is no proof of its infectious charac- ter, makes the close relation of all these forms as modifications of one type very probable. Diphtheroids are of wide distribution and their presence in tissues and lesions does not, for reasons given above, establish a necessary etiological relationship to the focus in which they are discovered unless corroborated by animal experiment. ANTITOXINE. It has been stated that the investigations of Roux and Yersin demonstrated that the pathogenic effect of Loffler's bacillus lay mainly in a toxine, a poison dissociable from the body of the bacilli, and, therefore, an esotoxine. But it was the merit of Behring with Kitasato to show that inoculation of animals (horses and guinea pigs) by repeated injection of first attenuated and gradually stronger, virulent bacilli, rendered them resistant and that this artificial resistance to the disease was due to the presence of a neutralizing substance or property (antibody to the poison) in the blood of the animals thus treated. In other words, repeated injection of doses of the poison too small to be fatal, stimulate the body to the production of a neutralizing substance which is contained in its blood and protects it against further infection with even virulent cultures or stronger poison. This antibody is contained in the serum, and its protective influence may be transferred through injection into another animal. Injected after the disease has developed, it aborts and shortens the infection. The serum containing the antibody is spoken of as antitoxine. It is important to appreciate here that the antitoxine is not de- structive to the bacilli themselves, but neutralizes their product, the toxine. We can thus passively immunize (protect) an animal against this infection, or, once established, overcome or ameliorate it by injection of the serum (antitoxine) of another animal pre- viously immunized. Thus antitoxine immunity differs, as will be shown in detail later, from vaccination, in which the introduction of attenuated or dead bacillary bodies actively stimulates an organism to the formation of substances directed against a later 60 GENERAL PATHOLOGY infection with stronger, more virulent forms, to destruction of bacteria themselves. It is fortunate in this regard that the bacilli in diphtheria do not penetrate deeply and do not invade throughout the whole body. Consequently neutralization of the poison is relatively more easily accomplished in comparison to diseases in which bacteria diffuse, grow and disintlgrate throughout the body (Bacteriemia). Im- mediately upon discovery of diphtheria antitoxine by Behring in 1893 its tremendous practical importance was apparent and soon established. Consequently on account of its wide use and applica- tion as a prophylactic and curative measure, it became necessary to find a system of accurate measurement for dosage. Here, however, existed the apparently hopeless difficulty of ignorance of the chemical or physical constitution of either diphtheria toxine or antitoxine and inability to isolate either in sufficient purity to allow exact measurement. Behring and Ehrlich, therefore, devised a very ingenious method of calculation based on the biological effects and affinity of toxine and antitoxine. It is possible by this method to establish accurate values of the antitoxine strength of an immune serum. It is first necessary to determine the strength of the toxine: 1 . As a simple fatal dose Ehrlich regards that quantity of poison, expressed in c.c., which kills a guinea pig of 250 gms., in 4 to 5 days. 2. A normal poison, according to Behring, is one which contains in i c.c. 100 fatal doses (DTNM 250 ). These arbitrary values are used for standardizing antitoxine, as follows: i. A simple serum is one of which i c.c. exactly neutralizes the effects of i c.c. of normal poison, i.e., one hundred fatal doses. .2. This value, of i c.c of a simple serum, is the antitoxic unit or unit of immunity, I. E., is used as such to express antitoxine strength or dosage. Thus antitoxine is administered in antitoxic units (usually 500 to 10,000, depending upon the purpose). These values, however, apply only to the relationship of antitoxine to fresh toxines. It has been found that if the diphtheria toxine is allowed to stand, its toxic property diminishes, while its ability to combine with antitoxine persists. Bodies which lose their toxic properties DIPHTHEROIDS 61 while retaining power of combination with their antitoxines are spoken of by Ehrlich as toxoids or toxones. To study this peculiar phenomenon quantitatively, Ehrlich introduced two new values Lo (zero limit) and L -f- (fatal limit). Lo is the quantity of poison + unit of immunity which is completely physiologically neutralized by it, L -f- is the quantity of poison whch + unit of immunity is just sufficient to produce death in a guinea pig. This mixture con- tains, therefore, a fatal dose in free state and gives us the toxicity. (Lo - L + = D (difference, fatal dose). In pure poisons D = i, but in reality it is generally higher on account of what Ehrlich believed to be the presence of toxoids or toxones. In older poisons L o is lowered. D is, therefore, the indica- tion (measure) of toxone contents (weakening) in a poison. Scbick Reaction. It has been pointed out that infection with Loffler's bacillus occurs only on the basis of a specific disposition to the organism. It appears that certain persons possess normally a sufficient antitoxic property in their blood to withstand possible infection. In order to test the antitoxic quality of the blood and thus save individuals the occasionally unpleasant results of pro- phylactic immunizing doses of antitoxin (serum sickness, anaphy- laxis; see immunity), Schick designed the following reaction. An amount of diphtheria toxine equivalent to Jo the minimum fatal dose for guinea pigs, is made up to 0.2 c.c. with sterile salt solution and injected subcutaneously, or better, intracutaneously into the flexor surface of the arm. A positive reaction, signifying absence of sufficient antitoxine, appears within 24 hours and con- sists in swelling and diffuse reddening of an area of about 2^ to 3 cm. around the point of injection. It fades within a we^k. If the reaction is absent the antitoxine property of the body may be deemed sufficient. It has been calculated that when the reaction is positive the blood contains less than %Q of antitoxic unit per c.c., in a faint reaction Y to J^o of antitoxic unit per c.c. Individuals giving a negative reaction may be considered sufficiently immune to infection, but those in which the reaction is faint or definite should receive immunizing doses when exposed to the danger of a diph- theritic infection. CHAPTER XI THE BACILLUS TUBERCULOSIS THE disease, or better diseases, which are now collectively recog- nized as tuberculosis, have been known for centuries under differ- ent names, especially as phthisis. In the writings of the Hindus the disease is described. The Greeks already regarded the air as carrier of infection and the idea of contagiousness has persisted ever since. Morgagni declared his dislike of sectioning tuberculous cadavers for fear of infection. The conception of tubercle (a nodule) was originally, as in diphtheria, an anatomical one and laid down by Sylvius (1614- 1672). Tuberculous inflammations were later thoroughly studied by Laennec and Virchow. But their etiologic identity and relations remained obscure. Villemin (1855) gave the first experimental proof of its infectiousness by inoculation of tuberculous material into rabbits. These experiments were discredited when it was found that other foreign material produced similar nodular swellings at the point of inoculation. The question was settled by Cohnheim in conclusive experiments in which he demonstrated that tubercu- lous infections were not only followed by local lesions at the point of inoculation, but generalization from the original focus. Even after the infectious nature of tuberculosis had thus been established the cause remained unknown until Baumgarten and Koch (1882) almost simultaneously saw the organism in tubercu- lous material and tissues. Koch's work remained the more impor- tant on account of its classic presentation and the completeness with which he traced the history and characteristics of the bacillus through difficult cultivation to reinfection in animals. By repeated cultivation (iiooth generation) he obtained pure cultures, and by inoculation into monkeys, rabbits and guinea pigs regularly produced the lesions of tuberculosis. 62 THE BACILLUS TUBERCULOSIS 63 Morphology. Koch and Baumgarten saw the bacillus first in unstained tissues after clearing them in KOH. Koch described it as a slender, short, non-motile rod. Stained, it appears delicate with rounded extremities, 2 to 4/j long (about % to Y of size of a red blood corpuscle) and 0.3 to 0.5/4 broad. Frequently it is slightly curved. The bacilli are found isolated or in small groups lying across each other. In tissues they are generally in cells. Spore formation is still questionable. Some points are in favor of it. It is also stated that the bacilli show at times nuclear contents. Characteristic is pleomorphism, i.e., great variation in form, shape and arrangement. Bacilli appear in certain strains, long, thick, filamentous or linked to threads, branches, forks; in others they are short, thin or thick, isolated rods. They approach, therefore, a higher botanical order and are related to actinomyces and the hyphomyces. Staining Properties. To demonstrate the bacilli, solid, grayish particles of tuberculous sputum or tuberculous pus are well suited. These are thinly spread on a cover glass or slide with a platinum needle, dried and fixed by passing them through a flame rapidly about three times, or gently waving them over the flame to coagu- lating temperature. If the suspected material is very thick and tenacious or con- taminated with other bacteria, it is well to emulsify it with a solution of potassium hydrate. For this purpose antiformin 1 is used. This solution destroys organic substances through liberation of chlorine, but leaves intact acid-fast bacilli, on account of their waxy capsule. The suspected material is therefore mixed with 25 to 50 per cent, of antiformin in a tube (depending upon thickness of ma- terial) and well shaken until all solid matter is thoroughly disin- tegrated and the contents appear as a turbid, homogeneous fluid. The disintegration is hastened by incubation for 30 minutes at 37C. The fluid is then centrifugalized at high speed. The super- natant fluid is pipetted off, the test tube filled with sterile water and again centrifugalized. This is repeated. The sediment is injected 1 Antiformin has nothing to do with formalin, but consists in equal parts of liquor sodii chloratis and sodium hydrate. 64 GENERAL PATHOLOGY into guinea pigs for development of tuberculous lesions. If only microscopic slides are to be prepared, shake with petroleum ether, or chloroform, centrifugalize, and then prepare the slide film from the surface of the fluid if petroleum ether is used, and from the bottom if chloroform is used. In films thus prepared the tubercle bacilli are demonstrated by a specific staining quality which they have in common with some other bacteria. This depends upon the fact that the bacilli, although taking aniline stains with diffi- culty, discharge the stain with equal difficulty when treated with acids and alcohol. They are, therefore, spoken of as acid-fast. This quality depends upon the presence of a waxy capsule. The method consists, therefore, in overstaining in an aniline dye (preferably acid fuchsin) and then decolorizing with a dilute mineral acid and alcohol. In this way other bacteria discharge the stain, while tubercle bacilli retain it. The stain employed for this purpose in ZiehPs solution of i gr. fuchsin, dissolved in 10 c.c. absolute alcohol and 90 c.c. 5 per cent, carbolic acid. The latter acts as a mordant and keeps the solution durable. An excess of the solution is placed on the fresh film and the slide heated to just within the boiling point, and kept steaming, but not boiling for a few minutes. The stain is then poured off and, without washing in H 2 O, the film is thoroughly decolorized by alternate immersion in a 25 per cent, solution of a mineral acid and absolute alcohol, until all stain is apparently extracted. Then wash in H 2 O. Counter-stain in methylene blue, wash in H 2 O, dry and mount. Examine with oil immersion. Shorter and more condensed methods have been recommended, such as Gabbet's (see books on bacteriological technique), but they are neither so exact nor so reliable as carefully conducted, consecutive steps of procedure. It has been pointed out and emphasized by Much that not all tubercle bacilli are acid-fast. Certain forms and phases of develop- ment, especially of the bovine type, lack the acid-fast property. They may subsequently become acid-fast in culture. Cultivation. The tubercle bacillus is cultivated with difficulty, owing to its slow development and consequent easy overgrowth by other bacteria. Koch finally succeeded by employing solid THE BACILLUS TUBERCULOSIS 65 blood serum. Not until the 4th and 5th day may delicate points be recognized with the magnifying glass. They grow very gradually to the fourth week. It was later found that glycerine cultures with acid reaction are better adapted than pure serum. Subsequently Hesse introduced a much employed useful medium consisting of nutrose 10 gm., sod. chlor. 5.0 gm., glycerine 30 gm., normal sol. of cryst. soda (28.6 per cent). 5 c.c., H 2 O 1000 c.c. On this pure cultures grow in about 4 to 5 days in loops and pigtail fashion. More recently Dorset's egg medium and Smith's dog serum have been employed in cultivation from tissues directly. The tubercle bacillus requires much air for its growth and it is susceptible to temperature. The human type does not grow at temperatures over 42C. or below 3OG; only the avian type endures somewhat higher temperatures. Other outside influences are better tolerated. It is resistant to drying for several months (three), also to cold and heat. Thus a temperature of iooC. is tolerated for one hour. But steam kills it in about 30 minutes and boiling in five minutes. In beef it persists unless thoroughly cooked. Rare beef still contains viable bacilli. Disinfection of tuberculous material, such as sputum, is best accomplished by sulphurous acid or formalin, not by bichloride of mercury or other precipitants of albumen which, on account of their precipitating quality do not sufficiently penetrate. A five per cent, carbolic acid solution kills in about 24 hours; absolute alcohol in about ten hours. Pathogenic Effects. These are first, local; secondly, general. They are the results of the irritating influence of the bacilli and their toxine which appears to be derived from the destruction of the bacillary body and not well separable from it. It is, therefore, an endotoxin. The local manifestations consist of the tubercle, a nodular granulomatous inflammation, caused by pro- liferation of fixed, endothelial and connective tissue, cells mixed with, and surrounded by, lymphocytes (granuloma). Character- istic is the presence of giant cells and, more especially, the tendency to complete necrosis and cheesy disintegration of the tubercle and the tissue in which it is seated. This is the result of 5 66 GENERAL PATHOLOGY the toxines liberated from the disintegrating bodies of the bacilli and it varies in different strains in quantity, and possibly quality, so that the extent and degree of the so-called "caseation" of the tissues vary in different tuberculous infections. The same is true of the exudative processes which surround the tubercle. Secondary infections, especially with streptococci, acquire great importance; they follow close upon the path of the tubercle bacilli (see under Infective Granulomata, page 236). Paths of Injection. This is still a much discussed question. Tubercle bacilli may reach an organ through the blood and lymph stream, especially the latter. Aerogenous infection of the lungs, that is due to direct inhalation, was formerly believed to be a very common method of introduction. Recently, however, it has be- come very doubtful whether it ever occurs, because the anatomical distribution, formerly thought to be characteristic of aerogenous infection, is closely simulated and reproduced by lymphatic infec- tion and extension. Generally speaking the tubercle bacillus produces a nodule at the point of entrance and then creeps along lymph channels to the regionary glands which it involves. Tuberculous infection may occur, however, without leaving a trace at its port of entrance (for instance through the mucous membrane of gastro-intestinal tract or skin) and it may even pass glands, before its final lodgment. This makes it difficult and at times impossible to determine in a given case the mode and path of infection. There is not an organ which is immune to tuberculosis. Skin, digestive apparatus, respiratory tract, bones, joints, serous mem- branes, brain and spine and cord, ductless glands and even the organs of the special senses may be primarily or secondarily in- volved. Frequently the primary focus may remain small and rela- tively unimportant, but may give rise to a serious fatal, consequent infection, such as tuberculous meningitis following upon tubercu- losis of bones or joints, etc. The pathogenic importance of the acid-fast waxy capsule of the tubercle bacillus has attracted much attention, especially since it is known that the bacillus is not always acid-fast. Theobald Smith has advanced the hypothesis that the capsule is really a THE BACILLUS TUBERCULOSIS 67 protection to the bacillus and that it remains attached to the or- ganism until this finds a suitable soil for growth. Then it is re- moved by solvent action of fluids, and the organism becomes active. Thus it happens that young tubercle bacilli are, as Much pointed out, usually not acid-fast. If this hypothesis is correct, it would explain the latency of certain tuberculous infections. The neces- sary lipase for the solution of the capsule is supposed to be derived from lymphocytes and mononuclear leucocytes and certain parenchyma cells which are apparently rich in it. The tubercle bacillus exists in several group types and it is pos- sible, besides the type mostly found in human beings, to distinguish three types of practical interest, the avian, the bovine, and a form occurring in cold-blooded animals. The Avian Type. This is closely related to the human type. It occurs in hens, pheasants, pigeons, turkeys, wild ducks and geese. In an investigation of 600 chickens, 62 were found tubercu- lous. Koch first regarded it as identical with the human form, but differences were found. It grows at higher temperatures, 45 to 5OC. and does not readily affect rabbits and guinea pigs, and it is also more easily cultivated. Some birds, like the parrot, are susceptible to both avian and human tuberculosis. Other animals show varying behavior towards both forms. In man infection is practically unknown, it having been observed only in very few instances. The Bovine Type (Perlsucht). This type is the cause of tuber- culosis in cattle, and also infects sheep, pigs and goats. Its mani- festations are coarser, gross, nodular, and with predilection affect serous membranes. The tendency to caseation and cavity formation is less than in the human type. Morphologically and culturally the differences are extremely slight. Acid glycerine broth is rendered gradually alkaline by the bovine type. The question of the possibility of human infection by the bovine form has been actively discussed without as yet full agreement. Koch admitted the possibility, particularly in early life, but denied its general importance in man, as compared to infection with the human type. It is also held by some that many milk infections are really due to contamination with human tubercle bacilli. On the other hand others strongly contend that the bovine type is patho- 68 GENERAL PATHOLOGY genie to man, that it plays a large role in the glandular tuberculosis of children, and that it may also be recovered in a certain number of genuine cases of tuberculosis of adults. Investigations by Weber of 628 cases which covered 284 children, 335 adults and 9 of unstated age, all of whom had been exposed to the effects of milk from cows with tuberculous udder, showed that only two very young children had apparently been infected with the bovine type. The exact observations of Park and Krummwiede make it appear that bovine infection is relatively common in youth to 16 years, but uncommon in adults. The matter needs still further investigation, especially in view of the history of some of these apparent bovine infections in youth, which in later life present the characteristics of human infection. Are these independent occur- rences or in any way related? Do tubercle bacilli change in charac- teristics in different animal environment? These are still unsolved questions. Tuberculosis of Cold-Blooded Animals. Tuberculosis occurs in carp, lizards, snakes, and turtles, and seems to be insignificant in relation to human infection. IMMUNIZATION. Koch attempted to establish an immunity against tuberculosis; but this is a different and in a way more difficult problem than in diphtheria. We have already seen that the tubercle bacillus does not produce a definitely recognizable toxine which, as in the case of the LofHer bacillus, diffuses easily through the body. The tuberculous toxine is not easily separated and widely disseminated from the bacillary bodies, but seems to be generated by their disintegration and in varying amounts and quality in different strains. Its effects are local, or at least close to its origin (Cheesy pneumonia). Moreover almost all cases of well-established tuberculous infection are mixed infections. We have already seen that streptococci are responsible for much of the secondary and late manifestations connected with the breaking down, fusion and cavitation of the infected tissues. Koch endeavored to induce immunity by making a glycerine, extract of dead tubercle bacilli and injecting it. It was his effort to stimulate the body to greater reaction against the tuberculous THE BACILLUS TUBERCULOSIS 69 infection, that is, the bacteria themselves. This was tuberculin. Its office was to be active immunization of an individual, contrasted to the passive neutralizing action of diphtheria antitoxine. For the reasons given above, the results were not uniformly satis- factory and, of course, useless in active general and advanced tuberculous infections in which the body is already overloaded with all sorts of dead bacilli. It is, however, suited for localized, chronic, slowly progressing tuberculous infections, especially of the glandular, bone, joint and skin type, and in children. The dose has to be carefully adjusted. McKenty found the best results with bacillus emulsion in doses of from ;H}0ooo mg. to Hooo mg. in children and Ko.ooo mg. to Ksoo m g- m adults. Tuberculin is now extensively employed for diagnostic purposes. (1) Intravenously. The old tuberculin of Koch in doses of o.i to 0.2 mg. is followed, in positive reaction, by rise of temperature in from 12 to 48 hours, at least J^ over the previous; constitutional effects, accentuation of T.B.C. symptoms, swelling of glands, etc. (2) Ophtbalmo. Tuberculin reaction of Wolff- Eisner and Calmette. Apply drop of tuberculin to conjunctiva. In positive reaction followed by sharp congestion. (3) von Pirquet's cutaneous reaction. Solution made up of 25 per cent, old tuberculin in salt solution and carbolic acid. Place 2 drops on skin and scarify. After 24 to 48 hours in tuberculous patients small papules and vesicles appear. This, however, is not always an indication of active tuberculous lesions and, especially in adults, may be due to an old, latent focus. OTHER ACID-FAST BACILLI. Smegma bacillus occurs in preputial and vaginal secretion. Morphologically it resembles the tubercle bacillus closely, but is much less resistant to the action of acid and alcohol. It is apt to occur in urine and feces and give rise to diagnos- tic error. This can be excluded by prolonged decolorization with absolute alcohol after acid, overnight or at least 1 2 hours. Butter bacilli are also somewhat similar to the tubercle bacillus, but also less acid-fast. Timothy or bay bacillus is found in hay infusions (grass bacillus) is even more easily decolorized by hot water. In all doubtful cases animal inoculation (guinea pig) is necessary. CHAPTER XII THE BACILLUS OF LEPROSY LEPROSY is a very ancient disease, known to the Egyptians and Greeks many centuries before Christ. It was early transported to Italy and the rest of Europe. Leprosy hospitals were established in A. D. 636 in Italy, France and Belgium. In 757 and 789 Charle- magne made it a cause for divorce and declared such marriages unlawful. Leprous patients were considered dead and a requiem mass was celebrated on their entrance to a hospital. During the Crusades the disease became even more prevalent, as many con- tracted the disease in the Orient. In 1229 there were in France 2000 leper hospitals and 19,000 in the whole of Europe. In England the first hospital was put up in A.D. 1 100, but the disease was already known in the tenth century in Wales. Later, 1 1 2 leprosy houses were founded in England. In Norway the disease was recognized in the thirteenth century and from Germany it spread to Denmark, Sweden and Finland. To-day the disease has almost disappeared except in Spain, Italy, Russia, Finland and Sweden. It is still relatively frequent in Norway and Iceland. Foci exist in South America, China and Africa; in India the number of lepers is esti- mated at 100,000, in Japan 40,000. In the United States were reported 150 cases in 1909 as against 278 in 1902, mostly in Louisiana, and 750 in the Hawaiian Islands. It is endemic still in the Philippines and Sandwich Islands. Morphology. The bacillus of leprosy was discovered by Hansen of Norway, in 1872, in characteristic round or oval clear cells of the leprous granuloma. It is a small rod of 6/i which in staining qualities closely resembles the tubercle bacillus. The leprous lesions resemble the tuberculous nodule, but they lack the characteristic caseation and display greater tendency to scar tissue formation. The bacilli are often present in the leprous tubercle in enormous numbers and lie mostly intracellular. 70 THE BACILLUS OF LEPROSY 71 Cultivation and Inoculation. Recent investigators have claimed cultivation and inoculation (Duval, Clegg) but these are doubtful. The bacilli are supposed to develop in the presence of other bacteria which possess the ability to split albumen into amino-acids or in the presence of tryptic enzymes. It is also held by these investiga- tors that the disease can be reproduced in monkeys and rats. Patbogenesis. Two forms of leprosy are known in man, the nodular and anesthetic. The first occurs in tumor-like, deforming growths over the whole skin and also the larynx, and slowly leads to death (lepra tuberosa). The second is merely an anesthetic neuritis with erythematous discoloration of the skin. The two forms may combine. How infection occurs is not known. The idea of fish infection is now abandoned. Nurses and physicians in contact with leprous patients are rarely infected. Flies have been held as carriers. The disease shows, besides external manifestations, the result of general infection in fever attacks and leprous nodules in spleen, kidney and other parenchymatous organs; also on the mucous membranes of the mouth, throat, nose and larynx. One case which I saw autopsied on Blackwell's Island, New York, died after years of laryngeal involvement. Saliva and nasal secretions contain bacilli. The disease is, in the temperate climates at least, very slowly but persistently progressive, lasting decades. CHAPTER XIII ACTINOMYCOSIS ACTINOMYCOSIS is a specific, purulent and granulomatous infec- tious disease of animals and man, caused by the ray fungus. It was discovered in carious bones of the spine and jaw and in the tongue. Bellinger, in 1877, properly recognized and described it in cattle. Harz defined its botanical position. The name is derived from axrts (ray) and nvKrjs (fungus). Ponfick identified the disease in man and cattle, and Johne, in 1882, traced it to tonsilar infection. As the name implies, actinomyces belongs to the filamentous fungi, is closely related to the hyphomyces or molds, and, there- fore of a higher botanical order than bacteria proper (Schizomy- ces). It belongs to the order of trychomyds, (0pt = hair), or streptothrix group, all of which are delicate filamentous branching or pseudo-branching organisms. Very near to these stand the tubercle, leprosy and glanders bacilli which at times also exhibit tendency to filamentous growth. The recognition of actinomyces is relatively easy; the purulent detritus in this infection contains fine rice granule-like particles which are largely composed of colonies of the fungus. These gran- ules are o.ooi to 0.2 mm. and even to 0.75 mm. large, and are grossly easily visible. Examination under the microscope discloses a characteristic radiating arrangement of the hyphens (hence the name). The hyphens carry at their ends long, club-shaped, bright cells, while in the center they exhibit a diffuse, filamentous inter- woven network. The admixture of other cell and purulent detritus sometimes obscures this picture, but the addition of 30 per cent. NaOH clears the field. The club-shaped filaments are of gelatinous consistency. The nature of the clubs have been an object for discus- sion. Originally held to be spores, they are now considered to be involution forms and depend for their formation on a gradual inhibition in growth of the filaments which leads to a gelatinous 72 ACTINOMYCOSIS 73 expansion of the extremity. The size and arrangement of the fila- ments vary. They are always more or less wavy, somewhat spirillar and the fungus sheath may contain small cocci-like granules. They exhibit true branching. Coccoid central borders have been regarded as spores, but this is recently denied (Jordan). The older the colonies, the more convoluted their center, while the filaments at the periphery are long and extend by characteristic radiation. The club-shaped extremities do not make their appearance until late and the gradual formation of the clubs in different filaments may be noted. Culture. Culture is made with difficulty, but may be done on gelatine, agar, glycerine agar, potato and watery egg solution. The organism is a facultative anaerobe and resistant to drying (over one year). It is, however, susceptible to temperature, being killed at 6oC., more readily at 75 to 8oC. On the other hand, it stands sunlight well. Method of Injection. In cattle and pigs the infection occurs mostly from contaminated grass and grain, especially when feeding in swampy districts and in wet years when cattle are fed on barley coming from flooded districts. Thus Johne found in 1882 that the tonsils of pigs contained barley grain studded with active mycotic granules. Bostrom found such grains in the gums of actinomycotic cattle. They may also occur in corn and other grain and hay, maize and straw. Direct communication from barley or ears of corn to man has been demonstrated through swallowing or chewing of grain stalks. While the infection occurs mostly through the tonsils or carious teeth, it is also possible through the intestinal tract. Pathogenicity. Actinomycotic lesions of the bones of the jaw are frequent in cattle. For this reason the disease has long been popu- larly named "lumpy jaw." The involvement of the jaw is less frequent in man. It produces tumor-like swellings, which break down, and undergo purulent softening with destruction of the bone. The ray fungus grows into the soft tissue through the mucous membrane of the mouth, leads to the formation of nodular inflam- matory masses with necrosis and a purulent peripheral mantle. A localizing scar formation occurs around such areas. But while 74 GENERAL PATHOLOGY cicatrizing in one part it progresses to another and produces secondary actinomycotic inflammations in heart, kidneys, brain, etc. Characteristic is its progress by fistulous canals with tendency to break through to the surface, especially through the skin. In man secondary involvement of lung, appendix, and diaphragm is not infrequent. A closely related type of organism is found in Madura foot. Various other members of the streptothrix or nocardia (Nocard, French veterinarian) group possess pathogenic interest. These are practically important, because their lesions are, especially in the lung, very similar to tuberculosis. They are widely distributed in soil, water and foodstuffs. Morphologically they are pleiomor- phous, short or long, thick rods or coccoid bodies or branching long filaments (mycelia). They do not form radiating clusters as actino- myces do. A member of this group is cladothrix, another try- chomyces, which exhibits only pseudo-branching and is generally non-pathogenic. Crowdy has, however, described one case of a pro- bable enteric infection and indolent ulceration in a debilitated subject. True molds (mucor-corymbifer, aspergillus; sporothrix) are rarely, but occasionally concerned in pulmonary infections, indo- lent gastrointestinal ulcerations and skin affections. They simu- late tuberculosis. Blastomycosis. Pathogenic yeasts have recently been brought into prominence. Generally, yeasts are harmless saprophytes. They are round ovoid, sometimes capsulated cells with bright eccentric granules which propagate by budding. They occur in the stomach and gut, where they ferment carbohydrates. There have been described granulomatous, ulcerative and purulent inflamma- tions of the skin, lungs and glands in which pathogenic yeasts appear to be the cause and can be demonstrated in the inflamma- tory lesions. CHAPTER XIV BACILLUS MALLEI (GLANDERS) GLANDERS is a disease of horses which can, however, be trans- mitted to man. It is a dangerous, easily transmittible disease which, while long recognized, was not accurately known until the nineteenth century, when Rayer injected horses with material obtained from human glanders. The cause of glanders, the bacillus mallei, was discovered by Loffler and Schiitz in 1882 and the disease fully described by Loffler in 1886. The disease runs an acute or chronic course which easily merges one into the other. In the acute forms the horses develop a high fever, chills and great prostration. The mucous membranes are early injected and reddened. After one to three days appear the local manifestations on the mucous membrane of the nose, ec- chymoses, confluent nodules and pustules which rupture and dis- charge a seropurulent fluid. The mucous membrane then ulcerates and the lesion extends to the larynx (difficult, sterterous breathing). Skin lesions appear as pustules. The lymph glands are enlarged. The name farcy applies to cases in which lymphatics thicken and form farcy buds. Death occurs in from 8 to 30 days from asphyxia and intoxication. The chronic infection is much more frequent (90 per cent.). It develops insidiously, slowly and may last for months or years. The lesions and symptoms are less pronounced and less active and the skin or nasal manifestations are most prominent. In man glanders in very similar and involves all viscera. The bacillus is a small rod, straight or slightly curved, of about the same length as the tubercle bacillus, but shorter and thicker. It is non-motile, forms no spores, but is apt to stain irregularly. Larger filaments with swollen ends and branching forms have been observed. It stains with the ordinary dyes, especially when con- taining alkalis or carbolic acid, which act as mordant. It is Gram negative and decolorized by alcohol. 75 76 GENERAL PATHOLOGY Cultures. Cultures may be made on ordinary media, particu- larly in the presence of glycerine. The growth on potato is rather characteristic; it is tenacious, from light to dark brown color and honey-like. Cultures are easily destroyed. Patbogenicity. The micro-organism is pathogenic to all car- nivora, horse and man, while cattle and the house rat are immune. The port of entrance is probably through erosions in the mucous membrane. The bacteriological diagnosis of glanders infection, which is often important, is made by inoculation of the material into a guinea pig, by the so-called mallein test, and by agglutination. The character- istic lesion of the glanders bacillus in the guinea pig is orchitis with marked testicular swelling. This is followed by general infection and pyemia. The value of this test, however, is not absolute. It must, therefore, be supplemented by the other two: The mallein test consists in the injection of mallein (glycerine) broth of dead glanders bacilli (prepared after the fashion or tuberculin) into the suspected animals. In glanders occurs rise in temperature (increase of from 1.5 to 2.5C.), pronounced local swelling at the point of injection, and constitutional symptoms. Agglutination is performed in infected animals in dilutions of one to 3200; 1:500 is still un- certain. Serum of normal horses agglutinates to 1 :2oo. CHAPTER XV ANTHRAX ANTHRAX, splenic fever, wool-sorter's disease, or malignant pus- tule, is a disease which affects with equal virulence all higher verte- brates and man. Since olden times it has been prevalent, destruc- tive to agriculture and dangerous to certain trades which come in contact with animals or parts of animals subject to the disease. The disease played an important part in Rome. Ovidius and Seneca mention it and two Roman Consuls, Rufus and Bassus, are said to have died of it. From Middle Ages to modern times serious epidemic outbreaks have from time to time taken place and destroyed ani- mals and man. A restraint and prevention of the disease became possible after Koch had fully described the causative micro-organ- ism and its methods of growth and infection. In Russia the'disease is known as Siberian Pest. Anthrax seems to be bound, more or less, to certain localities; swampy moors, turfy ground and wet soils, are particularly favor- able to it, especially when in heated condition, as, for instance, drying swamps or moist ground immediately after a draught. The disease is, therefore, more liable to occur in early spring or autumn. It affects the majority of domestic and wild animals. Cattle, goats, deer, rabbits, hares, buffaloes, dogs, cats, lions, tigers, etc., are all liable to it, while it occurs more rarely in birds, chickens, ducks and geese. In the Zoological gardens at Copenhagen infected horseflesh was fed to wild animals with the results that two leop- ards, two pumas, three coons, four bears, three polecats and one beech marten contracted the disease. A similar observation was made in Posen, where two silver lions, one jaguar, one hyena, three coons and one large tiger were made acutely ill, but survived. Amongst domestic animals the disease may be contracted through infected straw. 77 78 GENERAL PATHOLOGY A number of investigators, notably Da vain and Rayer in 1850 and PoIIender in 1 855, had observed bacilli in the blood and organs of animals ill of splenic fever, but the proof of the relation of this organism to the disease, its isolation and manner of infection was furnished by Koch in his earliest work, in which he laid the founda- tion for modern bacteriological technique. The discovery of in- fection by persistent anthrax spores in instances in which the bacilli themselves were not responsible established the pathogenic impor- tance of spores even though the bacilli had been killed by heat or antiseptics. In appearance the anthrax bacillus is a large rod of 4-5, even lo/u and of i-ij in. thickness. It is non-motile and large enough to be easily recognized, even unstained in the blood or organ juice (spleen). The rods lie between red blood cells as clear, cylin- drical elements in pairs, short chains or isolated. They stain easily with the usual anilin dyes and are positive to Gram. Fixa- tion is preferably done by pouring alcohol on a slide and rapidly burning this off. The bacilli appear then well in detail. In arrangement they often show an end to end, joint-like attach- ment, and as their extremities are not flat, but depressed in form of a concave curve, several joints give the impression of a bamboo cane. Noticeable is a capsule in recent state, but not in culture. Anthrax bacillus is an aerobe and grows well only in air, although existence under anaerobic conditions is possible. The temperature limits are pretty wide, from I5C. to 43C., but growth at low temperature is much slower. Growth takes place on the ordinary culture media, best in alkaline reaction, but acid reaction is tolerated. It also develops well on barley, corn, maize, wheat and hay infusions which are excellent culture media. It liquefies gelatine and grows in the form of long, wavy filaments which project in every direction and form thickly coated masses. Milk is coagulated, and eventually digested, litmus reduced and some acid is formed. Spores develop in the presence of nascent oxygen only they are, therefore, not found in the animal organism. This can be readily observed in the hanging drop where the spores only make their appearance in about 24 hours. In culture they are found only ANTHRAX 79 where the growth has overstepped the height of its development, that is, in change from favorable to unfavorable environment. They are, like other spores, highly refractive oval bodies, are surrounded by a dense membrane and can be stained by special methods, which is hardly necessary to recognize them. New bacilli develop from the spores, under favorable conditions, in several hours, through a polar opening and divest themselves of their spore membrane in snake-like fasion. While the anthrax bacilli themselves are no more resistant than many other micro-organisms the spores are extremely resistant (10 to 12 years), and this resist- ance seems to vary in different strains. A 5 per cent, carbolic acid solution kills the spores in from two to forty days, steam in from three to twelve minutes, boiling water in over five minutes. The bacilli themselves succumb at 55C. Sunlight and air kill the spores in 2% hours. Air excluded, they remain viable 50 hours. 1:1000 bichloride of mercury kills spores in about half an hour. It is important that certain other bacteria, especially staphylococci, streptococci, bacillus pyocyaneus and the pneumococcus are antagonistic to bacillus anthracis. The blood serum of certain animals, especially of white rats, is said to be destructive to it. Pigs and dogs on the other hand are very sus- ceptible, cold-blooded animals less so. Poor nutrition, cold and hunger favor infection. Methods of Injection. Infection may occur through three ports of entrance. First, by direct contact or vaccination through abra- sions or scarification before a protecting granulation tissue is formed (frequent in butchers). Second, by feeding, when infection takes place through the intestinal tract. Koch showed that in this method the bacilli are probably all destroyed, but the spores mature in the intestinal tract and penetrate into the mucous membrane. Thus characteristic ulcerations are formed. The third method is through inhalation. This was first demonstrated by Biichner and occurs through direct inhalation of anthrax spores. This in- fection involves the lungs and probably requires a large quantity of spores. Infected animals continue in apparent health some hours after inoculation, then suddenly, in from one to two days in rabbits and 8o GENERAL PATHOLOGY guinea pigs, show signs of acute illness. They fall down, have con- vulsive movements and die rapidly, usually without fever. Autopsy discloses an edematous, gelatinous exudate at the point of inocula- tion and anthrax bacteriemia, that is, all organs are swarming with bacilli. The blood is thick and tarry; its CO 2 is increased; O diminished. The spleen is much enlarged, soft, pulpous (splenic fever). Hemorrhages and necroses occur in other organs. In man the lesions are similar although the splenic swelling is less. In the intestinal anthrax occur edematous infiltrations hemorrhages and carbuncles of the mucous membrane. In respira- tory anthrax (wool-sorter's disease) is found hemorrhagic infiltra- tion of the nasal mucous membrane, larynx and trachea. Infarcts of the lung, serous pleuritis. Rigor mortis may be absent. Putre- faction is rapid. In man hemorrhagic meningitis develops some- times very rapidly and early leads to death. The cutaneous infection is characterized by the so-called malig- nant carbuncle or pustule. This may be either primary and con- stitute the principal picture of the disease or skin lesions may follow or accompany an internal infection. Prophylaxis. Destruction of the cadaver by rapid, deep burial (6 feet under ground where spores cannot form) is the only safe prevention. The disease is spread only by free, not buried, bacilli, and the ground is easily contaminated by secretions of infected animals from mouth and nose. In man the disease is contracted almost entirely by those in contact with animals susceptible to the disease or their hides or hair. Such are butchers, horse-hair weavers, wool packers, shepherds, meat inspectors, longshoremen carrying hides, glove and brush makers, etc. Isolated cases due to infected shaving brushes have been reported. Protective vaccination against anthrax infection in animals is now practiced with attenuated bacilli. Good results have been reported from this method, and also from a serum. Symptomatic Anthrax. A disease known as symptomatic anthrax occurs chiefly amongst sheep, cattle and goats. It also goes under the name of quarterevil or black leg. It does not occur in man, but in animals it may be confused with anthrax on account of a superficial similarity. It is due to a spore-forming bacillus, residing in the soil, BACILLUS SUBTILIS 81 (bacillus cbauvei), with rounded ends, motile and possessing oval spores which are larger than the rod, giving somewhat the impres- sion of a " whetstone. " Sometimes they are distinctly spindle shaped, and the immature spores are seen in the center of the bacil- lary body (clostridium). The organism is an anaerobe, grows easily and is Gram negative. It produces a soft, puffy swelling in the legs, which spreads and is accompanied by fever. The bacilli remain mostly local and are scarce in other parts of the body. Infection occurs through skin abrasions and wounds of extremities. BACILLUS SUBTILIS. There exist a number of bacilli which resem- ble the anthrax bacillus morphologically and may give rise to some confusion. Most important of this groups is the bacillus subtilis or hay bacillus. It differs from anthrax by being motile and by equatorial instead of polar development from the spores. Culturally it rapidly liquefies gelatine and forms a pellicle on the surface of broth. The members of the bacillus subtilis group are generally inhabit- ants of the soil, widely distributed, and generally non-pathogenic, being bacteria of decomposition. There exist, however, some patho- genic varieties which lately have been recognized in impor- tance in relation to inflammations of the eye and various, often severe, ophthalmias (contamination of water in operating rooms and wards). CHAPTER XVI THE PLAGUE BACILLUS BUBONIC plague or black death, has always been a much-feared disease, especially in Oriental countries, on account of its devastat- ing epidemic character. Repeatedly it has swept over the whole world and decimated it. To-day it is almost entirely confined to the Orient, particularly China, whence it is occasionally brought to the Western continent. The bacillus was discovered in cadavers of victims and in the pus of glands by Kitasato and Yersin, inde- pendently, in 1893. An accidental infection with a laboratory cul- ture occurred in Vienna in 1898. The bacillus is short, thick, with rounded ends (1.51* by 0.511), mostly single, rarely united or in chains. Older cultures show many involution forms and pleomorphism. It is non-motile and does not form spores. It stains well with aniline dyes and in pus shows polar staining after fixation in alcohol (no heat) and is negative to Gram. In the tissues some of the bacilli are capsulated, a feature which is not very common. Cultures are easily obtained on meat media between 20 to 38C. in neutral or slightly alkaline reactions. Agar and gelatine are better suited than broth. It grows compact with granular, indented margin. Milk is slightly acidified without coagulation. The bacilli are easily killed by several hours of drying. Dry heat destroys them in one hour; steam in a few minutes, but cold is withstood for years (10 years in an ice chest). To direct sunlight and antiseptics they succumb readily. Patbogenicity. The bacilli enter the animal body through the skin or the respiratory tract. Thus originate lymphatic (bu- bonic) or pneumonic plague. The bacilli are then generally dis- seminated through the body (bacteriemia), and cause wherever they anchor severe hemorrhagic, necrotic and gangrenous inflam- mations. The sputum contains an abundance of bacilli and is, 82 THE PLAGUE BACILLUS 83 therefore, a dangerous source of infection. All patients suffer from, and die with, severe cardiac depression. Most susceptible are rats and guinea pigs, and in rats the disease occurs spontaneously and is epidemic, hence they are an important factor in infection of docks and ships. Rats show the same autopsy findings as man: marked hemorrhagic bubo formation (necrotic, purulent inflammation of glands) and other evidences of a severe septicemia. Squirrels have also been found infected in epidemics. The disease may easily spread through contaminated clothing, linen and other objects with which dying vomiting and coughing rats come in contact. The rats themselves are reinfected from other rats' excretions and human dejecta. Infection from man to man is also common. One attack confers immunity. Artificial immuniza- tion by vaccines (attenuated bacilli) has been reported successful in some instances. CHAPTER XVIII THE TETANUS BACILLUS, BACILLUS OF MALIGNANT EDEMA, BACILLUS AEROGENES TETANUS : Lockjaw. While this disease is ordinarily of less fre- quency than other wound infections, it acquires great importance in times of war, where it is apt to carry off a large number of victims. Certain localities, moreover, are more exposed to tetanus infection than others, especially where the soil has long been culti- vated and fertilized, when the ground abounds in anerobic bac- teria. That tetanus is eminently a wound infection has been recog- nized for generations, and its peculiar nervous manifestation, were formerly attributed to peripheral nerve irritations. Thus Dupuy- tren described a case in which a piece of a whip cord was found in the scar of a wound around the ulnar nerve. But it remained unsettled why such foreign bodies should cause lockjaw in one case and not in another. The endemic frequency in certain loca- tions was also peculiar. When later the infectious character of hydrophobia and of the wound fevers were generally recognized it was possible to assume a similar etiology for tetanus. Gradually this view was strengthened, especially after the direct transmission of the disease by material from tetanic patients to animals had been demonstrated. The cultivation of the bacillus of tetanus was finally accomplished by Kitasato in Koch's laboratory by anaerobic methods. Morphology. Very recent gelatine cultures show the bacillus 2 to 4^ long, 0.3 to o.5ju broad, free or in threads. In 10 to 14 days a very characteristic spore formation takes place. The spore is a round, polar body of I to 1.5/4 diameter, which, like a head, sits on the end of the bacillus giving it the appearance of a drumstick. The bacilli are actively motile, are easily stained and are Gram positive. Kitasato cultivated it on agar plates in an atmosphere of hydrogen after he had, by previous culture and heating to 8oG, THE TETANUS BACILLUS 85 succeeded in fractional sterilization of the culture from other contaminating bacteria. The success of the cultivation depended, therefore, upon the resistant spores. On gelatine the culture con- sists of thicker central masses with radiating or straight streaky extensions. The culture medium is softened by the formation of small gas bubbles. Peptonization and gas formation are character- istic. The gas is methane and CO 2 . The blood serum is not a good culture medium. The organism is strictly anaerobic. O is bacteri- cidal to it. Pathogenicity. The bacilli occur superficially in cultivated fertil- ized soil in the form of spores and, if protected from the air, persist a long time. They are probably also introduced into the animal gut through products of the soil. The bacillus is not, strictly speaking, parasitic. It easily succumbs to the bactericidal properties , of blood and remains at the point of inoculation (mostly introduced in wounds, through the umbilicus in infants or by vaccination). More- over infection takes place only when bacilli are introduced in large numbers and especially where extensive trauma and death of tissues (compound fracture) have occurred. These furnish a good culture medium and lessen antibactericidal action of blood and tissues. Tetanus neonatorum occurs by infection through the umbilicus. The period of incubation is days to weeks (latent spores). There may be local factors interfering with bacteriolysis favoring in- fection (see under Bacillus Aerogenes and Immunity). Clinically the disease is characterized by an increasing and progressing muscular rigidity. The muscles of the jaw and neck are primarily affected, then those of the chest and abdomen. Hands and fore- arms remain free. The rigidity is increased by temporary exacerba- tions or crises. Consciousness remains clear. Profuse perspiration is frequent. The prognosis is bad, the mortality being about 88 per cent. The chronic form gives a somewhat better prognosis. Death occurs from asphyxia and heart paralysis. Autopsy does not disclose characteristic lesions. The local confinement of the bacilli, their rapid disappearance at port of entrance and the symptoms show that the disease is eminently a toxic one and not dependent upon a bacteriemia or septicemia. 86 GENERAL PATHOLOGY The toxine of the organism is obtained from anaerobic broth cultures. It is very highly poisonous, but in a different degree to different animals. For example, the horse is twelve times more susceptible than the mouse, but this is 30,000 times as susceptible as the hen, 0.000,005 c.c. is sufficient to kill a mouse. The tetanus toxine has a strong affinity for the cells of the nervous system. Wassermann and Takaki, in a fundamental study, found that the poison is made innocuous when mixed first with the brain substance of a pig and subsequently injected. In other words the toxine has been bound by the nerve cells of the pig's brain. It is not unlikely that other cells of the body possess, at least to some vary- ing degree, the ability to fix tetanus toxine. The different suscepti- bility of animals may depend upon this phenomenon. An important feature is that the toxine is not transported by the blood or lymph stream, but seems to be adsorbed by the end organs of the motor nerves and then is diffused through the axis cylinders to the ganglion cells of the central nervous system. Antitoxine. Antitoxine formation is similar to that of diphtheria and has acquired considerable importance in the prevention of tetanus. Its curative value is, however, almost nil, except in the chronic form, partly because the toxines travel by the axis cylinder of nerves, being thus protected from antitoxine contact, partly on account of a very firm union of toxine to nervous cells and finally because the regeneration of the nervous system, after being once injured, is very poor or impossible. Antitoxine is prepared, as in diphtheria, by injection of very small doses of attenuated toxine with iodine bichloride into horses. This is followed by gradual appearance of antitoxine in the blood. In the recent war its prophy- lactic value has been conclusively demonstrated. BACILLUS OF MALIGNANT EDEMA. This micro-organism was first seen by Pasteur, and then more thoroughly studied by Koch, who, in 1881, proposed the name on account of its characteristic, local inflammatory action. It is very widely distributed in the soil and, therefore, exists also in the intes- tines of animals and man. Morphology. Long, slender rod, somewhat like the anthrax BACILLUS AEROGENES 87 bacillus, but longer and thinner (normally 3 to 8ju long). Frequently it occurs in long threads or more or less homogeneous filaments. The bacillus is motile. Spores form at 2oC. and are oval. They are either polar or equatorial. Generally the organism is reported as Gram negative, by some as positive. Cultivation. Like most bacteria of the soil the bacillus of malig- nant edema is a strict anaerobe. It grows well on most culture media, especially in the presence of glucose. Characteristic is a radiating manner of extension which on gelatine and glucose is attended with gas (bubble) formation. Milk is slowly coagulated, and growth is good on potato. It is, on the whole, not very sensi- tive to the reaction of the culture media. Patbogenicity. The bacillus is pathogenic for mice, guinea pigs, rabbits, horses, sheep, pigs, cattle, some birds and man. Inoculation produces at the site of entrance in about a day a marked edema- tous (watery) hemorrhagic inflammation, extending into the deeper tissues and to the neighboring lymph glands. Gas is formed and the tissues become thereby elastic and crepitant (emphysema). The disease is primarily local, only shortly after death bacilli invade generally and diffusely through the body. The disease is rare in man, but occurs occasionally after extensive, dirty trauma (com- pound fractures) and accompanies extensive suppuration. It has been observed after abortion in women. Protection is conferred by the disease or artificially filtered sera of infected animals. THE BACILLUS AEROGENES Bacillus Aerogenes Capsulatus (Welcbii). Is the cause of gase- ous edema or gangrene, and acquired great importance in the late war. The organism was discovered by Welch (1892) in the body of a man dying from aortic aneurysm, who at autopsy showed a peculiar gaseous emphysema of the skin, internal organs and blood. It is probably identical with Frankel's bacillus phlegmones em- phymatosae (1893). Subsequently the organism has been found to be a common inhabitant of the soil and intestines. Morphology. This bacillus is a large organism, from 3 to 5/x long, occurs in pairs, groups, but not in chains, occasionally also 88 GENERAL PATHOLOGY in coccoid forms. It is non-motile and produces spores. It stains well with the ordinary dyes and with Gram, sometimes more or less irregularly. Characteristic is its broad capsule when in tissues. 1 Capsule is not seen in artificial cultivation, except in blood serum. The bacillus is an anaerobe, but, under certain conditions may exist as an aerobe. It grows on neutral or alkaline gelatine, better with the addition of glucose. Here a very characteristic strong, stormy, gas production occurs. Colonies are grayish white or brownish; at end of 24 hours about 0.5 to i.o mm. in size and later as large as 2 to 3 mm. In broth it grows only anaerobically, also in milk which is coagulated. The resistance of the bacillus is not great. It dies at a temperature of 58C. Spores, of course, persist. Patbogenicity is ordinarily very limited and mostly only a ter- minal or even post-mortem invasion. The organism cannot grow in living, circulating blood. But in wounds into which earth has been forced, as in compound fractures or by prolonged contact of crushed wounds with the soil (soldiers or aviators on field of battle) the organism is apt to show an alarming malignant virulence. In the last war it was, therefore, a much feared battle-field infection, producing local swelling, reddening, and abundant gas formation with hemorrhagic necrosis of skin and muscles. Extension occurs often very rapidly and sometimes involves the whole body, in- creasing after death. The body may then show a disfiguring skin bloating and emphysema. But even under reduced, weakened conditions and in shock, infection occurs only in a relatively small number of cases and, as in tetanus, a special concatenation of cir- cumstances seems required for its pathogenic action. Bullock and Cramer have recently shown that the presence of calcium salts artificially injected at the site of inoculation or elsewhere (but then not so readily) prevents normal lysis of these bacteria and makes the animal susceptible to infection. Contamination with an earth containing calcium salts may, therefore, render an animal susceptible by breaking down the normal l To demonstrate, spread, dry and fix. Pour on a drop of glacial acetic acid for a fe.w moments, drain and cover at once with strong solution of gentian violet. Best examined fresh in drop of a solution of sodium chloride. BACILLUS AEROGENES 89 resisting powers. Magnesium, on the other hand, exerts a protec- tive action. A similar combination of circumstances is apparently required for the production of tetanus. The mechanism of action is not yet clear, but seems to depend upon a local change brought about by the calcium salts at the site of injection (see under Immunity). Autopsy in gas gangrene shows frothy blood and organs with extensive hemorrhagic necrotic breakdown, especially at the point of entrance. Besides its local importance, this bacillus seems to be concerned in certain troublesome intestinal putrefactions with much butyric acid formation and may cause, according to Herter, general anemia. CHAPTER XVIII TYPHUS EXANTHEMATICUS TYPHUS EXANTHEMATICUS is a highly contagious, fatal, epidemic disease with a short incubation period (8 to 15 days), characterized by high fever, a scarlatiniform and purpuric rash, skin sloughs and large spleen. The disease has long been recognized as one making its appearance and ravages in dirt and filth with hunger and famine. In the Middle Ages it was an important pestilence. The last war brought it again to the attention of the world by wide occurrence in the East and Near East. The disease is brought to the Western World by immigrants and possibly exists in the United States in a milder, aborted form under the name of Brill's disease, although this is not settled. Etiology. The infecting agent exists in the circulating blood of infected persons and may be transmitted to monkeys. It is stated that inoculation with blood filtered through a Berkefeld filter renders monkeys refractory to further infection. Until recently attempts to isolate a specific micro-organism have failed. In 1915 Plotz found by anaerobic cultivation a bacillus which he and some others believed to be the cause of the disease. By incubating 2 c.c. of freshly drawn blood in serum glucose ag& r (5 c - c - serum, 20 c.c. 2 per cent, glucose agar), deep colonies develop in 16 days of a small pleomorphous, Gram-positive bacillus, straight or slightly curved. It does not form spores, but shows occasional polar bodies. It produces acid on dextrose, malt- ose, galactose and inuline, but no gas. It is an obligatory anaerobe. Confirmation of its etiological relation seemed to be supported by the specific agglutination test and pathogenic effect on guinea pigs which develop high fever and a large spleen. But whether this is a true typhus infection is uncertain and agglutination tests in typhus appear unreliable. Against it is the negative evidence of Zinsser, Sellards, Hopkins and others who failed to isolate Plotz's organ- ism and especially the observations of Ricketts, Wilder (1910), 90 TYPHUS EXANTHEMATICUS 91 Helger and Prowazeck, (1913) Rocha Lima (1915), Toepfer Schiissler, Noeller, Weigle, and Walbach and Todd, who have discovered a plesiomorphous coccoid and bacillary organism in the alimentary epithelial cells of the body louse and in the vascular endothelium of typhus patients. It is apparently identical with forms seen by Ricketts in Mexican typhus. Rocha Lima introduced the term "Rickettsia Prowazecki" for it to honor the two pioneer investigators of typhus who themselves succumbed to the disease. The " Rickettsias " seem to constitute a group of so far poorly understood forms of which one other has been found in trench fever. Others, however, have been seen without diseases, but never intercellular, in body lice. Their relations, nature and position are quite uncertain. They have not been definitely identi- fied, much less cultured. Strong is, therefore, still of the belief that the etiology of typhus is undetermined. E. W. Schultz regards the "Rickettsias" as protozoa. Whatever organism may be the cause, it is certain that the infection occurs principally through the body louse, although infection through saliva (cough) is by some con- sidered possible. NicoIIe and others succeeded in transmitting the disease by the feces or crushed remains of infected lice and their bite is either infected or becomes infective through fecal contam- ination. The most important louse is here the body louse, not the head louse. Monkeys and guinea pigs are, as stated, susceptible and the latter develop characteristic brain lesions (Endothelial cell swelling and proliferation, thrombosis and perivascular cell infiltrations). Prophylaxis. The only efficient prophylactic measure is ex- tinction of vermin. No other disease has demanded so many victims among doctors and nurses. Silk underwear has been recommended as repugnant to lice. Isolation of garments for about a week kills the lice by starvation. The same can be accomplished more quickly by heat and kerosene. The great Serbian epidemic of 1915 was controlled by cleanliness. An antityphus serum has been prepared by NicoIIe from the blood of asses by injection of an emulsion of leucocytes and spleen of infected guinea pigs. It is said to be effective. CHAPTER XIX INFLUENZA THE name influenza has been given to an infectious epidemic disease, which, occurring in waves lasting several years and spread- ing over the whole world from east to west is characterized by mild or very severe, often rapidly fatal, catarrhal and serous hemor- rhagic inflammations of the respiratory tract, severe constitutional disturbances and long-continued marked prostration. It is not certain whether all the epidemics which have been regarded as influenza are of uniform etiology, or even one and the same disease. In a severe epidemic from 1890 to 1892, Pfeiffer discovered a bacillus, now bearing his name, which since then has been regarded as the cause of the disease. PJeiffer's Bacillus. This is a very small organism, rarely larger than 1.5/1 long and 0.3/1 thick. It does not form spores, is non-motile and possesses no capsule. It has little affinity for aniline stains in aqueous solution. It is best stained by carbol fuchsin diluted 1:10, 4 to 5 minutes without decolorization. It is Gram negative. Culture is best done on dilute blood agar. The presence of hemoglobin is indispensable and necessary. Recently culture media containing an oleate have been employed. Colonies appear as minute, trans- lucent, round, discrete points in about 18 hours. They are not viable long and have very little power of resistance to drying and antiseptics. According to Grassberger the Bacillus influenzas grows more luxuriantly on ordinary blood agar (5 to 10 per cent, blood) in the vicinity of colonies of pyogenic cocci and especially of staphy- lococcus aureus. Bruere recommends a medium consisting of nu- trient agar, made with a dead twenty-four hours' staphylococcus aureus broth to which i per cent, defibrinated blood has been added while the agar is still hot (9OC). Patbogenicity. The exact pathogenesis of this bacillus has always been somewhat uncertain. Pfeiffer cultivated the micro- organism from the bronchial secretions of influenza patients. In 92 INFLUENZA 93 subsequent investigations Wassermann, Clemens, Koppen, Pick and others had great difficulty in demonstrating its presence even in the acute stage, and Kretz and others showed its occurrence in non-pathogenic strains and as partner in mixed infections. Even among virulent types strains seem to vary greatly. The bacillus does not generally penetrate deeply into the tissues and blood cultures have been generally negative, but influenza infections of joints have been reported by Franke. Specific agglutination with high serum dilutions of infected persons has not been successful in general experience. Fichtner says: "My hope to find a clinically useful diagnostic method by the agglutination test has been much lowered. Genuine agglutina- tion may occur, butapositive result must be interpreted with great care." Recent investigators claim better results in some instances. Animals are refractory to the infection, but its toxine (extracted with chloroform) is fatal to rabbits. Intratracheal injection and rubbing a pure culture of the bacillus upon the unbroken nasal mucosa produces influenza symptoms in monkeys. Here also the reaction is probably largely toxic. Immunity is slight and short. The bacterial toxine is a strong nervous depressor. The most recent influenza epidemics (1918, 1919) have been extremely severe, but have so far not allowed an absolutely clear definition of the etiological question. As cultural methods and experience have improved, the influenza bacillus has been found in increasing numbers, rarely, however, alone; generally with the pneumococcus, but also streptococci and staphylococci. It is held by some that the strain of the last epidemic is a particularly virulent one. It is possible that we are dealing with symbiotic infections of several pathogenic bacteria, but so far very little is known about symbiotic infections. 1 Kocb-Weeks Bacillus. Closely related to the bacillus of Pfeif- fer is the Koch- Weeks bacillus which occurs in a form of contagious conjunctivitis. Most influenza epidemics have been associated with, or fol- lowed by, peculiar cases of encephalitis, i.e., inflammations of 1 Olitsky has isolated lately a filtrable virus and this has been confirmed by Loewe. 94 GENERAL PATHOLOGY the brain (perivascular cell infiltration, thrombosis, hemorrhages and softenings). Sometimes meningitis is present. The pontine location is preferred and purpuric hemorrhages may be visible in the brain substance. In earlier epidemics gross softenings had been observed. In the last sweep of influenza softenings (infarcts) were microscopic. Leichtenstern, Nauwerck and others look upon it as an influenza infection. The latter cultivated (1895) bacilli similar to Pfeiffer's, from the ventricular fluid in one case. Others, Flexner, for example, deny any direct relation and believe that influenza simply prepares a suitable soil for another infection. Emulsions of the diseased brain injected into rabbits produce the disease in them. Loewe and Strauss claim isolation of an organism. It is, according to them, a filtrable virus. CHAPTER XX THE SPIRILLA SPIRILLA and SPIROCHETES are, as compared to bacteria, higher types of micro-organisms. They are tapering, filamentous threads, very motile and flagellated. Some discussion has arisen as to their exact biological position. They stand close to the lowest animal forms, protozoa, more especially the spirochetes. Occasionally they are identified with them. But the modern view distinguishes spirilla from protozoa by lack of nucleus, blepharoplast and of an undulating membrane and by a different method of division. Moreover, some spirilla appear during certain phases of their development as bacilli. The following are the most important: CHOLERA. By cholera we understand an epidemic disease which was confined to Asia before the nineteenth century. Since then it has visited Europe and America. In 1817 a severe epidemic com- menced in India, involved the whole peninsula and spread over the whole world. Since that time there have occurred five great epidemics: 1817 to 1823; 1826 to 1837; 184610 1862; 186410 1875; the last commenced in India, in 1883 went, by way of Egypt, Asia Minor and Russia to Germany, which it reached in the sum- mer of 1892. It increased in intensity to 1894, reached Hamburg and from there England, and, in isolated cases the United States of America. The origin of all of these epidemics was the mouth of the Ganges River, where the disease is endemic. At the beginning of the last epidemic, in 1883, Koch was commissioned by the Ger- man Government to proceed to Egypt and to investigate this disease. Koch recognized it as an intestinal infection and saw this organism, later named the comma bacillus, in the intestinal contents and wall of victims. He succeeded in its cultivation, established its etiological relation and traced the source to polluted water tanks. Thus it was possible successfully to prevent spread of the infection and later to establish immunity by protective vaccination. 95 96 GENERAL PATHOLOGY Cholera is primarily, as Koch found it, an intestinal infection and the chief evidences are in the gut. If the duration of the disease is only very short (hours) the intestinal contents are of "rice water" consistency, with mucous flakes of reddish tint. The mucosa appears injected. In later stages the lining epithelium of the gut desquamates, the intestinal wall appears turbid and in spots pinkish, especially in areas rich in lymphoid tissue. The intestinal contents show an almost pure culture of "comma" bacilli and these may penetrate into the mucosa after necrosis of the lining epithelium. Then other organisms, such as bacillus coli, follow in its path. Very severe, late lesions resemble somewhat those of typhoid (so-called cholera typhoid). The mucous membrane appears dark, almost black, necrotic, hemorrhagic, especially in the region of the ileo-cecal valve. The intestinal contents are then foul and bloody. Morphology. The organism is a very motile, flagellated, non- spore-forming spirillum. It stains by the ordinary methods, but not by Gram. The motility is so great that Koch compared it to a swarm of midgets. The germ appears as a short rod with a distinct curve, comma-shaped, occasionally in an S curve. Koch regarded it originally as a pure bacillus, but it is now known that the bacil- lary form is only a phase of the spirillum or vibrio. The spirillum develops from the so-called bacilli. Both are, therefore, frequently found together. Under difficult conditions of existence, however, only spirals are found. Each spirillum possesses a single flagellum attached to one end. Cultivation is easy. It grows luxuriantly on the usual media. On gelatine appear small white spots growing from below towards the surface. Gelatine is liquefied, so that in older cultures the plate appears studded with small holes caused by evaporation of the liquid gelatine. Later the colonies become granular and yellowish. This is its characteristic manner of growth. A pellicle is formed on the surface of bouillon. On milk this spirillum is only short lived, as it is destroyed by acidity. Characteristic is indol formation in bouillon and the reduction of nitrates to nitrites, so that only the addition of a few drops of H 2 SO 4 is required for the production of the rose-red color, the so-called "nitroso indol reaction." To THE SPIRILLA 97 develop indol it is best to use a i per cent, solution of Witte's peptone + 0.5 per cent. NaCI. The medium must be alkaline. Resistance. The organism is very susceptible to drying. Bouillon cultures are thus killed in two hours. Infection through dust and air, therefore, is not possible. Moreover inhalation into the lung does not seem to be pathogenic. Boiling is immediately destructive, a temperature of 3OC. kills in five minutes. Antiseptics are poorly tolerated; i to 23,000,000 bichloride solution kills in from five to ten minutes. Even distilled water destroys in 24 hours. The growth of the spirillum is retarded by putrefactive bacteria. Sewage kills it in 24 hours. Dry food also does not preserve it and fluids must be of alkaline reaction to preserve it at all. Patbogenicity. Spontaneous cholera is a disease of man and not of animals. Animals, however, may be made more or less suscepti- ble if the gastric juice, which is antagonistic, is neutralized. Its infectious character in man has been established, not only bacterio- logically, but experimentally, by accidental means. In 1884 a worker in Koch's laboratory was infected with one of the cultures from India. Severe infections occurred in Pfeiffer himself and in Pfuhl in the Berlin Institute for infectious diseases. In 1895 an assistant in the bacteriological laboratories of Hamburg infected himself with a drop of a culture intended for a guinea pig, and died. Pettenkofer and Emmerich experimented on themselves after first neutralizing their gastric juice and then drinking water con- taining some cholera bacilli. In Pettenkofer resulted a severe diarrhea and Emmerich almost died of a typical cholera attack. The disease runs in man a characteristic course, with abdominal cramps, rice-water stools, great prostration, anuria, subnormal temperature, collapse and death. Infection seems to occur largely by polluted water, and outbreaks of the disease are, on account of the short period of incubation, explosive. When in 1892 the city of Hamburg became infected through its drinking water by pollution through the river Elbe, the contiguous city of Altona, which filtered its water, escaped entirely. Important is the carrier, who himself may be spared, but who spreads the infection from place to place. During an epidemic the number of carriers is increased. 7 98 GENERAL PATHOLOGY One attack of cholera usually leaves an individual immune from future attacks. The organism does not produce a readily dissociable toxine, like diphtheria or tetanus, but only an endotoxine, bound to the body of the spirillum and liberated by its destruction. It seems to remain largely local, in the gut, the cholera vibrios not penetrating into the body. The nature of the poison is not at present under- stood. Agglutination with the patient's serum is irregular and uncertain and here not of diagnostic value. Immunization has been attempted and lately practiced with what appears to be good results. Immunized animals develop a bacteriolytic (dissolving) property in their serum, which seems to be specific. The serum has preventive, but no curative value, unless injected almost immediately after infection. KoIIe advised prophy- lactic vaccination with cultures killed by heating to 5OC. This has been successfully used in an epidemic in Japan. Closely related spirilla or vibrios occur in large number. They differ biologically in virulence and are not bacteriolysed by cholera- immune serum. VINCENT'S ANGINA. This is an ulcerating membranous angina pharyngis and stomatitis, sometimes closely simulating diph- theritic inflammations. It is apparently caused by a constantly present, long, slender, spindle-shaped or fusiform organism, which is non-motile and Gram negative. Spreads show at the same time a variable number of spirilla with the bacilli. Their relationship has been a matter of question. It is now held that, as in cholera, bacilli and spirilla represent phases in the development of one organism (Tunnecliffe). Similar spirilla and bacterial forms have been found in other ulcerating and necrotic stomatitis. RELAPSING FEVER. This has been of great interest because Obermeier demonstrated in 1868, long before the days of bacteri- ology, a living organism as the cause of the disease. He published his investigations in 1873 and in the same year died of cholera. He described the organism, which now bears his name, as a fine, motile thread. Its infectious nature was fully corroborated by subsequent observers, especially through the direct inoculation of infected blood into man and monkeys. THE SPIRILLA 99 Relapsing or recurrent fever is characterized by attacks of fever separated by completely afebrile intervals. The attack commences with a chill, the temperature rises to 39, 40, 4iC. and drops in a few days by crisis, usually below the normal. After a few days of complete rest follows another attack, and this is repeated three to four times. The fever chart becomes, therefore, quite characteristic so that the diagnosis is easy. The spirillum is always present in the blood in the fever attacks, appears with the rise in temperature and disappears with the crisis. It is absent during the intervals. Occasionally jaundice is present. Mortality is not high, 2 to 5-10 per cent. The spleen is large and, post-mortem, shows marked lymphoid swelling. Morphology. The spirillum of Obermeier is a fine, spiral, taper- ing thread of no more than ifj, in thickness and loto 20-4 io/* in length. It possesses between 6 to 20 curves or convolutions. The organism does not show a particular structure or differentiation. In fresh blood the motility is so rapid and active that individual movements are seen with difficulty. They are boring (motion around longitudinal axis), to side or lateral, and forward and back- ward. The boring movement seems most frequent. Flagella have not been definitely demonstrated. Individuals are generally free, inde- pendent, solitary, not in groups. Spores have not been discovered. Schaudinn maintained that the organism does not belong to the bacteria, but is a protozoon, and in possession of a nucleus, bleph- aroplast and undulating membrane. Novy and Knapp deny this and claim, in addition, that multiplication occurs by trans- verse, not longitudinal, division. However, morphology, biology and pathogenic characters put it very close to the protozoa. The spirillum of Obermeier stains with the ordinary aniline dyes, but not by Gram's method. Preferable are basic methylene blues, as Romanowsky's, Giemsa's, Wright's or Leishman's stains or impregnation with a silver salt. It does not grow on ordinary media, but Noguchi succeeded in culture by adding infected blood to sterile ascitic fluid containing pieces of fresh rabbit's kidney. Method oj Injection. It had been recognized for many years that recurrent fever is essentially a disease of unclean, dirty surroundings. In Russia, inhabitants of prisons, barracks, tene- ioo GENERAL PATHOLOGY ments and tramps were well known to contract it. In Africa Europeans were infected frequently along caravan roads. Dutton and Todd showed then that the African form of relaps- ing fever is transmitted through the horse tick. This resides in dry ground and under the roof of inns and road houses. The female is especially dangerous. It attacks at night, sucks itself full of blood and retires again. Spirilla thus taken in pass the stomach, develop in the alimentary tract at rather high temperatures from 30 to 35C. and reach the ovaries. They infect the eggs and these, when hatched, remain infective to the next generation. The excreta of the tick also contain the spirillum and the tick remains infective for 1 8 months. Infection occurs probably by the bite contaminated with the excretions of the tick. Of greater importance in the European method of transmission is the body louse. The lice infect their eggs and infection in man is brought about by crushing the louse, the bite apparently being ineffective. Eggs may carry the infection 12 to 30 days after inges- tion of the parasite by the louse. It is generally held that immunization occurs during the fever attack through a powerful lytic substance which appears in the blood and dissolves the organism. After crisis the organism can only be found in the bone marrow and, possibly, other protected parts of the body. But there is some evidence supporting the view that during the afebrile intermissions the spirillum passes through a developmental cycle and alters its form. WEIL'S DISEASE. In 1914 Inada and Ido demonstrated a spiril- lum or spirochete in the liver of patients with infectious jaundice (Weil's disease) : Spirochaeta ictero-hemorrhagica. It is transmitted through the urine and the rat. Similar organisms have been demonstrated by Noguchi in yellow fever. SYPHILIS. The interesting history of this most important infection has already been referred to in connection with gonor- rhea. It is, according to old testimony and the recent historical researches of Sudhoff of great antiquity and general occurrence. But it was first brought prominently before the world in the great epidemic at the end of the fifteenth century. THE SPIRILLA 101 The name syphilis was introduced by Fradaktpr (^485 t6, 1553), in a poem in which Syphilus, a mythical king's son y was afllicted with the disease for blasphemy of Apol.ta. ,Alf attempts tt> find the etiological factor failed, until Schaudinn with Hoffman (1905) in following up the claims of Siegel of the discovery of another organism in the secretions of syphilitic sores, discovered a delicate spirochete, the relation of which to syphilis is now well established. The disease is practically always acquired by direct contact, sexual or otherwise, with a syphilitic sore or secretions. Extrageni- tal infection has been much exaggerated, but certainly occurs as by kissing, tattooing, etc. The organism is relatively easily dis- covered in the recent state in India ink preparations, in which the spirochetes stand out as clear, delicate, fine spirals against the dark background (mix fluid India ink with a drop from a syphilitic sore, let dry and examine with oil immersion). Even better is the fresh preparation with the dark field illumination in which their motility may be clearly observed. They may be demonstrated in fixed, very thin films by Giemsa's stain (stain for 1 6 to 24 hours, after fixation with absolute ethyl or methyl alcohol). Spirocheta pallida or Treponema pallidum is an exceedingly fine, weakly refracting screw-shaped body, characterized by steep narrow curves. Its length is from 4 to 10 to 14^ and it is, therefore, decidedly smaller than other spirochetes. The individual possesses 6 to 14 curves, but there are forms with 20 to 24 curves. Towards the ends the body shows attenuation. Movement in the fresh specimens is pronounced, principally, as in other spirochetes, rotation around its longtitudinal axis, also forward and backward and sideways. Actual locomotion hardly occurs, so that an organism remains in the field of vision for a long time. Both extremities possess flagella. The finer structure is not quite settled. Schaudinn regarded it as a protozoon. It is important to remember that other spirillar parasites occur frequently in and around the genitals and in the mouth. From these spirocheta pallida is easily distinguished by much finer forms, lesser refraction and numerous delicate curves (especially from the common Spirocheta refringens). 102 GENERAL PATHOLOGY Cuifivia'on.w/is jfipli Accomplished pure by Noguchi, after Schere- sche^^yJaad, obtained impure cultures. The method is essentially th&tf nipfo : yd ihitbfe. cultivation of the spirilla of relapsing fever. It has been possible to reproduce the disease in monkeys by inocula- tion with pure culture, also in rabbits, especially in the testicle. Occurrence. The spirocheta pallida is a pure parasite, and so far has only been found in syphilitic lesions, especially abundant in the chancre, mucous patches and skin lesions. But late syphilitic gummatous affections have also disclosed its presence, sometimes, however, only after very prolonged search and in very scarce number. In sections they are, even in active, early lesions, more difficult to find. In late lesions they often disappear, being either destroyed or assuming another phase form. This is still uncertain. In syphilitic embryos, or fetus, or premature infants, they are very abundant in the liver. The organisms lie in endothelial cells of vessels and in the syphilitic inflammatory infiltrations around blood vessels and lymph spaces. They probably travel in the peri- vascular lymph sheaths. So-called parasyphilitic, or late nervous, manifestations of syphilis (paresis and tabes dorsalis) aie now known to be truly syphilitic by demonstration of the spirocheta pallida in the inflamed meninges (Noguchi). Although the syphilitic lesions are generally local in expression the spirochetes are found generalized in most organs (Warthin). Well adapted for the demonstration of the Spirocheta pallida is the silver method of Levaditi (impregnation of small blocks after formalin fixation with a silver salt nitrate of silver and pyridine solution, then reduction with pyrogallic acid; tissues appear bright yellow; spirochetes are dark brown or black). Immunity in syphilis and the serological diagnosis by comple- ment fixation (Wassermann reaction, see Immunity, page 117). CHAPTER XXI PATHOGENIC PROTOZOA TRYPANOSOMES. Trypanosomes (from rpinravov = to bore) are free, swimming protozoa which occur as parasites in the blood and other fluids of man and animals. They have of late acquired great importance in relation to certain tropical disease, especially sleeping sickness. They are transferred from one animal to another through the bite of leeches, insects or vermin. A large number, about sixty, have been described. The most important of these protozoa is Trypanosoma. Gambi- ense (Dutton, 1902). This is spindle-shaped, about 17 to 28/i long and 1.4 to 2ju broad. From the anterior end, that is, the end which moves forward as the animal swims, projects a whip-fashioned flagellum, about one-half the length of the organism. It is terminal and free. The proximal two-thirds of the body are connected by a band of body substance which is continued like a ruffle along the side of the organism to within a short distance of the blunt posterior end and terminates abruptly where the flagellum ends in the blepharoplast. This is the undulating membrane. The blepharo- plast is a sort of second nucleus, the real nucleus being situated in the center of the protozoon. Multiplication takes place by longi- tudinal division. Transmission and Patbogenicity. For a long time a peculiar sickness has been prevalent in the tropics, known as sleeping sick- ness. It is characterized by headache, lassitude, later profound lethargy, muscular weakness and tremor. As the disease progresses the patient wastes, utter exhaustion follows, bedsores and finally exitus. The disease runs a course of about three years and in its last stages resembles the ending of the general paralysis of the insane. Physically here is only noted enlargement of lymphatics (Sir Patrick Manson). The trypanosome was first seen by Dutton in the blood of a sea captain of a steamer from the Gambia, who was supposed to be suffering from malaria. This patient died in 103 104 GENERAL PATHOLOGY England in 1903. In the same year Dutton and Todd examined other individuals in the Gambia and found trypanosomes among 1000 persons in .six natives and one quadroon. The true relation of the trypanosomes to sleeping sickness was first established by Castellani, who found them in the cerebro- spinal fluid of patients. This was later confirmed by Bruce, Nabarro, Laveran and others. The disease was already well known to the explorer Livingstone in 1857, who recognized that the so-called "tsetse fly" seemed to have some relation to it. It was then sup- posed to be due to a poison of the fly. The exact connection between the fly and the disease was worked out by Bruce in 1895 to 1 897. Flies were fed on infected animals kept in captivity for days and placed on healthy dogs. These flies were not infective, but, if flies were fed on infected animals and immediately transferred, or within 24 to 48 hours, infection occurred. This disproved the infectious nature of the fly and demonstrated that it only acted as a carrier. With the discovery of the trypanosome the role of the fly became even clearer, for the fly is simply the transmitter of the trypanosome. The fly, the so-called "tsetse Ry,"Glossina palpalis, is a large brown insect with a loud, humming sound. It lives in the soft mud on the banks of the stream and feeds on crocodiles. Kleine is of the opinion that the method of transmission is not a direct one, but that the micro-organism undergoes a develop- mental cycle in the body of the fly. Thus, he found that the insect does not become infective until about 18 hours have elapsed from the time of feeding. This is still an unsettled point. Numerous other trypanosomes or related organisms have been discovered. Some relatively harmless, others the cause of severe tropical diseases. Among the latter the trypanosome of Leishman- Donovan is of importance in the production of so-called kalar- azar, dum dum or black fever. MALARIA. Since antiquity malaria has been an extremely com- mon disease in the tropics and hot northern countries. It is preva- lent in Italy, Central America and the Southern States of the United States. The disease is characterized by a high intermittent, remittent or continuous fever with severe constitutional disturb- ances, headaches, even delirium and coma. PATHOGENIC PROTOZOA 105 The fever is generally preceded by definite chills. In the interval patients enjoy relative health. In 1880 Laveran, of France, in Algiers, announced the discovery of a parasite, the plasmodium malariae, in the blood of patients suffering from the disease. Nothing much was known of the organism and the manner of infection until in 1890 Golgi, of Italy, described the cycle of develop- ment in the human blood. In 1895 Sir Ronald Ross discovered its cycle in, and mode of transmission through, the mosquito (anopheles) and in 1898 W. G. MacCallum showed the sexual fer- tilization of the parasite. Infection through an insect, and particularly the mosquito, had already been suspected by Sir Patrick Manson, and he also sus- pected that swamps might act as medium of transmission. The organism occurs in several types, each with a cycle of development of its own and thus leading to different fever attacks which are essentially expressions of discharge of spores into the circulating blood. Thus, we can distinguish: PARASITE DISEASE | HOST | TRANSMITTING INSECT Plasmodium Malariae. . . Plasmodium Vivax Plasmodium Falciparum Quartan fever Tertian fever Aestivo-autumnal fever Man Man Man [ Anopheles (mosquito) Besides these most important pathogenic types for man, others occur which use monkeys and birds as intermediate hosts and other mosquitoes (culex) as final habitat. All are sporozoa and live in the red blood cells of the infected animals. They possess a double life cycle: (i) The asexual in the warm-blooded intermediate host; (2) a sexual, permanent cycle in the cold-blooded host, a mosquito. The mosquitoes are infected in sucking blood of the warm blooded host and these, in turn, are reinfected with bite of the mosquito. i. Asexual, Human, Cycle. Sporozotes which are harbored in the salivary glands of the mosquito (i.5ju long and o.2/x broad) enter the bitten individual. They attach themselves to red blood corpuscles and become spherical (Schizonts). Schizonts appear as a small ring with an eccentric chromatine spot. They grow steadily, 106 GENERAL PATHOLOGY feeding upon the hemaglobin of the red blood cell, breaking the hemoglobin into clumps. In varying time, (PL falciparum in 24 or 48 hours; PL malariae in 72 hours; PL vivax in 48 hours), the schizont matures, reaches the size of the blood corpuscle and the parasite then divides into equal-sized spores or merozoits (8 in PL malarise; 15 to 25 in PL vivax; 8 to 25 in PL falciparum). When they burst the cell and are discharged into the circulation, the fever paroxysm occurs. Spores reenter new corpuscles and the cycle recommences. It is observed, however, that after a time not all schizonts change to spores, but some develop into peculiar new forms which were formerly regarded as degenerative, but which are now known to be sexual parasites, so-called gametes. The male is usually small, microgamete; the female much larger, macro- gamete. They are of different shape in the various plasmoidal forms. Of characteristic, striking shape are the crescents of PL falciparum. 2. Actual mating of the two sexes has so far not been observed in the human blood, but occurs in the stomach of the mosquito. Here the microgamete becomes very active and develops long lashing filaments (spermatozoa). These break loose, swim away and conjugate with the macrogamete, fertilizing it. As a result a zygote or ookinete is formed. This attaches itself to the epithelium of the wall of the mosquito. It penetrates and appears on the out- side of the stomach wall, projecting into the body cavity, grows and divides to form the ovocyst, which contains many sporozoites. These find their way to the salivary gland of the host and rest in the epithelial cells. Ultimately they are free in the saliva and are discharged through the insect's proboscis into the blood of the new host, possibly forced out by sneezing attacks of the mosquito, precipitated through the irritating effects of the human sweat. Demonstration of the plasmodia in human blood may be made fresh or in fixed blood films by Wright's, Leishman's or Romanowsky's stains, during the fever paroxysms. The whole developmental cycle in the mosquito consumes from 10 to 14 days. Plasmodia are distinguished morphologically from each other by their size, chromatine contents, sporozoit formation and time of development. The largest is the plasmodium of tertian fever, a PATHOGENIC PROTOZOA 107 relatively mild infection. Most severe and even fatal is the small Plasmodium falciparum of the irregular estivo-autumnal infections. The most important serious effects of the malarial infection is destruction of red blood cells (therefore large spleen). Anemia and cachexia in long continued cases follow. Prophylaxis. Quinine and extermination of mosquito. FILTRABLE VIRUSES. It was found by Loffler and Frosch that there exist micro-organisms which are so minute as to pass through the pores of porcelain or earthen filters which prevent ordinary bacteria from passing. Some of these micro-organisms may be seen with higher optical powers than usually employed, and with the ultramicroscope, in which the object is illuminated intensely with diffracted light, not the ordinary transmitted light, in a dark field (this may be compared to sun rays passing directly into a dark room through a small opening by which particles floating in air, otherwise invisible, may be seen). The ultramicroscope shows thus objects of 0.004/11 which by ordinary transmitted light sight is limited to 9. 1 to o.2/*. To-day about 40 filtrable viruses are known. In some, like polio- myelitis micro-organisms have recently been isolated, but still need confirmation. Other diseases, like measles, scarlet fever, smallpox, etc., are still obscure and await solution. CHAPTER XXII IMMUNITY DEFINITION AND CLASSIFICATION. Immunity is generally de- fined as protection, defense or security against an invasion (im- munis in Roman law means to be tax-free). But this is only partly correct, and apt to convey an entirely erroneous concept of the nature of immunity. It is true that from the practical, medical standpoint those reactions impress us as the most important which tend to preserve the individual against a parasite or its actions. But immunity, in a broad and scientific sense, really comprises the sum total of all those interactive and reactive processes which proceed in an organism as a consequence of an invasion. Some of these may be protective, some are decidedly disadvantageous, even fatal. Thus when an exudate is poured into fixed tissues, as the result of an inflammatory irritant, it has, it is true, a destructive action on the inflammatory irritant, but, also at the same time, on tis- sues and their functions. This is illustrated in the lung, where in pneumonia alveolar spaces are blocked, the circulation interrupted and the lung and its functions dangerously incapacitated by the presence of the exudate. Again, in what is known as anaphylactic shock (see later) the protective, defensive character is quite overshadowed by the injurious effects. In fact, immunity reactions have primarily no particular purpose. But in the evolution of life only those organisms have persisted which, by virtue of certain characters, were able to maintain themselves. All others neces- sarily perished. In other words, animals were not provided from the beginning with purposely defensive measures against outside harmful influences. But only those types survived which were 108 IMMUNITY 109 endowed, amongst others, with processes now called defensive. They were thus enabled to continue existence in the face of ab- normal environments, and their reactions to abnormal environ- ment came to be regarded as protective or defensive. It is, therefore, intelligible that even in those persistent animal forms certain non-protecting and even harmful processes and phases of immunity continued. Protective immunity is, therefore, only relative and a phenomenon of evolution. Here, as elsewhere, only that is preserved which, through a manifold endowment, can adapt itself to many requirements of environment. A teleological conception of immunity as a primarily purposeful, useful and pro- tective institution cannot be entertained. The study of bacterial infections has shown that cause and de- velopment of disease stand not in fixed relations: to the contrary, as was fully discussed in the streptococcus infections, they are vari- able and depend upon relative determinants in the micro-organism and in the host. We saw that these determinants are partly of quantitative, partly of qualitative character. The disease depends, therefore, upon the conditions under which an invasion takes place. Thus, even pathogenic bacteria may live with a healthy host in symbiosis (carrier). The existence of a parasite in a host may be endangered by general environmental factors which are entirely unsuited for its own development. Cold-blooded animals, for example, are re- fractory to infections of warm-blooded animals. Such a state of non-receptiveness to an invader is called natural immunity. This may be absolute, in which the infective agent can nowhere anchor in the body and nowhere grow on the invaded soil; or relative, in which the immunity has limitations either by the quantity of infection, 1 or by conditions under which infection occurs. (Hunger, for example, makes pigeons susceptible to anthrax infection.) A great many instances of natural immunity in higher animals is relative. Syphilis is, for example, less severe in monkeys than in man and exhibits greater tendency to heal. 1 A white mouse may be killed by diphtheria toxine sufficient to 'kill 80 guinea pigs; fowls cannot be killed by the tetanus bacillus itself, but by its toxine. no GENERAL PATHOLOGY INFECTION. Any discussion of immunity must necessarily be preceded by an understanding of infection. Bacteria are, as has already been seen, the most important infecting agents. They produce disease either locally or by invasion, frequently by both. 1 This action is due to toxic substances derived from their bodies (endotoxines) or poisons which are distinct and separable from their bodies (esotoxines). These toxines must not be confounded with ptomaines, which are alkaloidal substances and products of bacterial (saprophytic) life on dead organic matter. Moreover, bacteria possess specific affinities for certain tissues and thus in- fective diseases show a different attitude towards different age periods depending upon the anatomical organization of these periods. Thus, for example, typhoid fever, osteomyelitis and scarlet fever are essentially diseases of youth (see under Disposi- tion of Age). Necessary for infection is, in every instance, (i)the possibility of bacterial growth and multiplication, and (2) the establishment of a definite interrelation between bacteria and body cell. Where no such interrelation occurs bacteria continue harmless: the more intimate the interrelation, the greater the so-called "bacterial viru- lence." The tissue soil is, therefore, as important for infection as bacteria themselves. The exact nature and mechanism of this interrelation is not clear and not thoroughly understood. It is assumed by Vaughan, Emble- ton and Thiele that this is essentially due to cell enzyme action by which bacteria are disintegrated and poisonous proteids set free from their bodies. The greater and more rapid the enzyme action, the greater the bacterial destruction, and the greater the produc- tion of toxic protein products. Virulence is, according to their conception, really an expression of the enzyme action of the host. Non-pathogenic bacteria do not, or only very slowly, excite to enzyme action; therefore, to very little reaction in the body. Furthermore, Embleton and Thiele attribute the change from non- virulent to pathogenic organisms to a gradually developing sen- 1 A general body permeation by bacteria is spoken of as septicemia or bac- teriemia. If in addition to this bacterial generalization, there exist often multi- ple, local inflammatory or purulent foci, it is termed pyemia. IMMUNITY in sitiveness of the cells of the host and to a gradual production of bacteria splitting antibodies. According to Vaughan, the period of incubation in an infectious disease corresponds to the time necessary for the production of the antibacterial enzyme. In his opinion bacterial disease depends upon cleavage of bacterial proteins, similar to what occurs in parenteral digestion of other proteins. Vaughan showed that all proteins, would yield on cleavage with alkaline alcohol a group of toxic and a group of non-toxic products, and he assumes that all pro- teins contain a central, common and toxic chemical nucleus to which are attached non-toxic side chains which give a protein its specific character. Alcohol as well as cell enzymes break up the protein molecule and set free the central toxic nucleus. Accord- ing to this conception the toxic effects of bacteria would be due, not to any specific poisons of their own, but rather to toxic, non-specific, protein cleavage products, and the question of bacterial intoxication would resolve itself into the quantity and rapidity of bacterial destruction. These ideas are attractive and rest on a good experimental basis, but they are applicable only to certain types and phases of infec- tion and they cannot be entertained as an explanation of all phenomena of infection. In the first place some bacteria like the bacillus diphtheria, bacillus of tetanus and bacillus botulinus are true specific poison formers, irrespective of any enzyme action on their bodies. Moreover, the affinity of certain bacteria for, and their localization in, definite anatomical districts, and the consequent differences in anatomical and clinical expressions of infectious diseases, are not readily made clear by this theory. We recognize, for example, a difference in incubation time and in character of a typhoid from a streptococcus or anthrax infection. While these possess some common features, they exhibit charac- teristics of their own. Furthermore, the peculiar acquired symbiosis of some bacteria, either temporary or permanent, with their hosts is not accounted for (erysipelas, gonorrhea, carriers) and the pheno- mena of individual disposition remain obscure. Here the recent observations of Besredka deserve attention. Investigating the mechanism of typhoid, paratyphoid and dysen- ii2 GENERAL PATHOLOGY tery infections, he discovered that the local susceptibility or place of bacterial anchorage is of great importance for subsequent in- fection and immunity. In animals which are usually immune to these infections, the previous administration of ox bile "sensitized" the intestinal mucosa so as to allow bacterial attachment and inter- course with development of a disease similar to that in the human. Such animals remained immune to reinfection, although the blood showed no protective "substances" or "qualities." In this way oral immunity could be established where vaccination failed (Dysentery). Quite apart from the practical interest of these observations, they emphasize a heretofore not sufficiently appre- ciated importance in the relations between bacteria and specific cell territories, and they may lead us to a better understanding of the individuality and specific expressions of bacterial diseases than any theory which explains infection and immunity only on the basis of general cell activities. Finally, even non-pathogenic bacteria are, when introduced into an organism, often rapidly disintegrated, and still in these cases no characteristic effects of specific virulence occur as in pathogenic types, although a good deal of foreign protein must thereby be set free in the animal organism. Thus it is apparent that there must be still other factors besides those put forward by Vaughan which enter into the pathogenic relations of bacteria to hosts. Indeed, considerable evidence has now accumulated which indicates that not only chemical, but physical properties in bacteria and hosts are of very great impor- tance and this will be more fully entered into in the consideration of acquired immunity. ACQUIRED IMMUNITY. Our knowledge of acquired immunity was like all scientific knowledge, originally purely empirical. The first observations were made in 1791 by a country schoolmaster, Plett, near Kiel, on the Baltic, who noticed that persons who had acquired cowpox became immune to smallpox, and he purposely introduced cowpox virus into three children, all of whom escaped infection. But the first extensive and scientific experimental in- vestigation into this matter was carried on by Edward Jenner, who, on May 14, 1796, transferred some of the contents of a cow pustule IMMUNITY 113 on the arm of a milkmaid to the arm of a boy. He subsequently introduced pus from a smallpox pustule into the arm of the same lad and found him unsusceptible to or protected against this artifi- cial smallpox infection. This led him to repeat his experiments and to publish the successful results. Through him the extermina- tion, or, at least, control of smallpox became possible, and the disease was stripped of its horrors. The type of immunity thus produced is an example of active immunity, that is, one in which the organism, stimulated by an attenuated, non-fatal dose of the same or a similar infecting agent (in this instance cowpox) is enabled to tolerate a subsequent more active, virulent infection of the same nature. This acquired immunity usually lasts for several years. The act of conferring immunization in this manner is spoken of as vaccination (from vacca = cow). Eighty years elapsed, curiously enough, before Pasteur took up again the problem of active immunization. He experimented with anthrax. It occurred to him that attenuated (heated) weakened cultures which had lost the power of spore formation and were possessed of only feeble virulent powers might, nevertheless, confer protection against subsequent stronger anthrax cultures. He found on using such "vaccines" that an actual immunity could be established in animals. The same principle guided him later in his famous immunization against hydrophobia (rabies). Here he showed, that, although the infecting virus is unknown, it is localized in the central nervous system and can be attenuated by drying. Thus, by graded attenuation and successive vaccination with gradually stronger virus, he established successful immunity, even after infection had occurred. Later investigations by others have shown that not only attenuated, but dead micro-organisms fulfill the purpose of protective vaccination, and these are generally employed at the present time as prophylactic measures against infectious diseases, especially typhoid fever. Dead bacteria are now pre- ferred, because the dosage can be more accurately determined. The length of such an immunity varies, being from one-half to several years. ii 4 GENERAL PATHOLOGY Present knowledge of acquired immunity may be grouped under three headings or, as being represented by three phases: 1. Immobilization, anchoring of the infecting agent and its annihilation (bacteriolysis, agglutination, precipitation, phagocy- tosis), that is, active immunity. The body takes an active part in its production. 2. Neutralization of poisonous products (antitoxic immunity), which may be either active or passive immunity because it may be transferred from one individual to another. 3. The creation of conditions which are locally or generally unfavorable to settlement or growth of infecting agents by modify- ing the physical and, possibly the chemical constitution of the tissues. This last, the importance of which we are only just begin- ning to appreciate, is really quite distinct from the first two, for it is not a direct reaction against an agent at all, but depends upon cell and tissue properties and surroundings which do not allow union of infecting agent with cells. It is the factor which is un- doubtedly of the greatest importance in natural immunity. In acquired immunity the first two are only steps to reach the third. But it must be admitted that in acquired immunity the creation of conditions which are locally or generally unfavorable to settlement or growth of bacteria is not always attained, or only imperfectly. Reference to this phase of immunity, the most interesting and in a way the most important, will be postponed until later, as the problems of acquired immunity are best considered before consi- dering natural immunity. It was in the eighties of the last century when Fliigge, Nuttall and Buchner made the important discovery that normal blood serum possessed the power to kill bacteria, and that this "bactericidal" property of the blood diminished with the age of the serum and could also be destroyed by exposing it to a temperature of 58C. This was followed by the discovery of Pfeiffer that cholera bacilli injected into the peritoneal cavity of cholera-immune guinea pigs were promptly killed and dissolved. This phenomenon, known as Pfeiffer's phenomenon, was later shown to take place in vitro as well, and this much heightened power in cholera immune serum to IMMUNITY 115 dissolve cholera bacilli could be diminished or destroyed, as in normal serum, by heat. Bordet discovered, in addition, the important fact that serum which was "inactivated" by heating, could be "reactivated," so as to regain its original destructive effect on bacteria, by adding any other normal serum. The same was found in regard to other bac- teria, and from these observations it was concluded that these specific, strong bactericidal properties of a serum immunized against specific micro-organisms are due to two phases, or as was believed, substances; the one contained in every serum, which is easily destroyed by heat; the other specific to the immune serum and stable. The first is now commonly spoken of as complement, the second as amboceptor (ambo = both, capio = I take) or antibody. Just how both of these act to produce solution of cells is a matter of discussion and does not directly concern us here. It is sufficient to remember that solution of foreign cells in an immunized body is brought about by a combined action of ambo- ceptor and complement, which, uniting, attach themselves to the specific cell against which they are directed, thereby producing its solution. Any substance which when introduced into an animal organism excites the formation of a specific antibody is known as antigen. Bacteriolysis or solution of bacteria is, therefore, spoken of as an antigen-antibody (amboceptor) complement reaction. It must be fully appreciated at the start that the terms which are employed in the description of immunity reactions must not be understood in the sense of definite compounds which enter into chemical reactions. They are hypothetical conceptions which are useful to visualize and fix in our mind certain immunity phases as processes. None of them has ever been isolated in substance, their constitution remains entirely unknown, but they represent phe- nomena in extremely complex colloidal emulsions and suspensions and they are probably not distinctive chemical compounds for the different immunity reactions in which they take part (see below). Bordet, continuing these researches, found that this principle of bacteriolysis does not only apply to bacteria, but to other foreign cells, and that the repeated introduction of foreign cells, say red u6 GENERAL PATHOLOGY blood cells of one animal into another, increases the ability in the serum of the second animal to dissolve the hemoglobin from the cells injected from the first. Upon this discovery rests the princi- ple of hemolysis. If, for example, we inject a rabbit several times with a few c.c. (3 to 5) of defibrinated sheep's blood, or better still, with washed red blood cells of sheep, the rabbit serum acquires the property of dissolving red blood cells of sheep, and we say the rabbit has been immunized against sheep cells. In such a case the hemoglobin passes into solution and the test-tube fluid assumes a claret-red hue. The process of hemolysis is not a destruction of red blood cells, but simply a solution of hemoglobin from the cell disks. These remain behind, as a pale scaffold, suspended in the fluid. Moreover, the hemoglobin is not chemically altered, but simply assumes another dispersion phase. Hemolysis has been shown to follow es- sentially the laws of bacteriolysis, that is, in our example, the sheep cells, when introduced into the rabbit, lead to the formation of a specific amboceptor (antibody) in the rabbit which in the presence of complement dissolves the hemoglobin from the red blood cells of sheep. If we inactivate the sheep-immune serum of the rabbit by heating it, no solution will take place, but if we should add some normal serum, the solution will again occur, because then we supply the necessary complement to cells already bound to the antibody. Such cells, which are attached to their antibody (amboceptor), but still without complement are called "sensitized. " A further important observation was made by Bordet, in 1901, in what is known as "complement fixation," which since then has assumed very great practical importance. If we take a bacterial emulsion, say of typhoid bacilli, and add its inactivated heated immune serum (serum from a typhoid patient) plus complement (any normal serum) and then to this mixture of antigen-ambocep- tor-complement add sensitized red blood cells, i.e., red blood cells with their specific, but inactivated serum, no hemolysis will result. If, on the other hand, we take a typhoid bacillary emulsion and add normal serum plus complement and then add to this mix- ture of antigen-zero-complement sensitized red blood cells, hemo- IMMUNITY 117 lysis will take place. Plainly, in the first experiment antigen (ty- phoid bacilli) plus amboceptor, plus complement have firmly united so that complement is no longer available for the completion of the added inactive hemolytic system. In the second case, antigen (ty- phoid bacilli) no amboceptor, but only complement, the latter remains free and may then complete the added inactive hemolytic system. In other words one antigen-amboceptor-complement combination fixes the complement firmly so that it is no longer available to complete another added inactivated system. This important discovery of complement fixation has since then been extensively used for diagnostic purposes, that is, to test whether a suspected serum contains a specific antibody or not. The hemolytic system is introduced simply as a convenient color indicator. If a patient's serum plus an antigen fixes complement so that sensitized blood cells which are added do not hemolyze, the serum contains the specific antibody; the patient, therefore, passes or has passed through the suspected disease. If, on the other hand, the patient's serum, plus an antigen, does not fix complement so that added sensitized red blood cells undergo hemolysis, it is plain that the suspected serum did not contain the sought-for amboceptor; the union or fixation of complement is, therefore, not accomplished and it remains in solution to unite with the added sensitized red blood cells to complete their antigen-amboceptor- complement hemolytic system; that is, hemolysis takes place. Upon these observations rests the original rationale of the Was- sermann reaction for syphilis : Wassermann took extracts of syphi- litic organs as a convenient way of furnishing antigen, mixed these with the serum of a suspected case of syphilis in the presence of complement, then, after incubation, added sensitized red cells. It was found that under those conditions syphilitic serum fixed complement, that is, no hemolysis occurred. Absence or occurrence of hemolysis, as an indicator showed thus presence or absence of syphilitic amboceptor (antibody) in suspected sera. There are several points which are plain from the start in relation to this and similar reactions. First, that it is strictly quantitative so that all reagents employed, antigen, amboceptor and comple- ment, must be quantitatively titrated in order to determine their u8 GENERAL PATHOLOGY strength before they can be employed for reaction. Secondly, that certain technical precautions must be taken in order to obtain reliable readings. This applies particularly to the interpretation of what constitutes a positive reaction, for there are many cases in which the hemolysis is only partial or incomplete and in which it is doubtful whether this is produced by unfixed complement or, possibly, by a certain hemolytic property possessed by the human serum to be tested. Only the straight cut, complete occurrence or absence of hemolysis are decisive negative or positive reactions; partial reactions, i.e., partial hemolysis (often indicated by one plus or two plus by laboratory investigators), are not to be regarded as positive Wassermann reactions. In order to avoid these errors and to simplify the procedure various modifications of the reaction have been introduced. It fol- lows that the physician or surgeon should have some intelligent acquaintance with the technique and manner of interpretation of the laboratory worker to understand and apply results properly. These technical considerations important as they are will not be further discussed here, for we are now concerned with the nature of these reactions, their immunological significance and practical applications. We have spoken of antigen, amboceptor and complement as though they were definite chemical substances and reacted as such, and indeed, although the nature of these substance has always been unknown, it was generally believed until very recently that the union between antigen, amboceptor and complement is a definite chemical reaction and Ehrlich's well-known theory of immunity rests entirely on the supposition of the chemical nature of immunity. But continued observations have disclosed facts which have given complement fixation, generally, and the Wasser- mann reaction in particular, a different meaning and significance. In the first place it developed, as regards the Wassermann reaction, that we are not dealing with a specific antigen, antibody, complement union. For not only syphilitic organ extracts, but alcoholic extracts of normal organs serve the purpose of fixing complement in the presence of syphilitic amboceptor. Further experiments disclosed that the essential substance or substances IMMUNITY 119 which fulfill the duties of antigen in these extracts are lipoids, very complex, physically fat-similar substances, many of which contain N and P, such as the lecithins, and that, as shown by R. M. Walker, these lipoids need not even be animal, but vegetable, and enter, quite irrespective of their source, into antibody comple- ment fixation. Moreover, it was found that the fixation of complement is accomplished by colloidal substances like casein, silicic acid, barium sulphate, etc., and Muir has demonstrated the retention of complement by the Berkefeld filter, through which it passed after a time unaltered. From this and other experiments it appears that fixation of complement is influenced by the surface of the substance to which it is fixed and that in the organ extracts which are employed as antigens the surface of the suspended lipoid particles plays an important role in this phenomenon. Clearly, we are not dealing here with chemical reactions, but with physical phenomena, character- istic of colloids, substances which since the time of Graham have been recognized as large molecular complexes which exist in solu- tions either as suspensoids or emulsoids. The antigen or antigens for the Wassermann reaction have then only this in common, that they are colloidal lipoids, but not one uniform chemical compound. It has also been found that the antibody or amboceptor is not strictly speaking a chemical entity, but, on the contrary, it seems to be made up of lipoidal complexes in combination with a proteid of euglobulin nature and, therefore, also behaves as a colloid. Moreover, comparative reactions of antigen, amboceptor, and com- plement do not follow the chemical laws of multiple proportions. The importance of this was early emphasized in the technique of the Wassermann reaction by Noguchi, and recent investigations of R. M. Walker have further shown that the union of comple- ment to so-called antigen and so-called antibody follows essentially the laws of adsorption. Thus, when the concentration is doubled, the amount adsorbed does not equal 2, but less, namely to the formula of 2 to the power ^- Taking all these facts into consideration it is clear that the Wassermann reaction is a colloidal adsorption phenomenon and no 120 GENERAL PATHOLOGY chemical reaction. It depends for its occurrence upon the presence of lipoid proteid complexes in the serum of syphilitics which, when put in contact with other lipoids, extracted from any lipoid-rich organs, possess the ability to adsorb complement. What determines the specific adsorption and fixation of these substances to each other is at present impossible to say. It may be said, as a reminder, that adsorption is essentially bound to surface tension, that is, work may be done by the surface of a liquid when the tension is able to diminish. Substances of great chemical sta- bility only slightly lower surface tension when spread on water; some, like ether, spread widely and greatly lower surface tension. Bayliss suggests that this is due to decomposition at the interface between liquid and air and between solution and a solid, or immiscible liquid. At these interfaces there is, therefore, a local accumulation of free surface energy which can be altered by the deposit of substances at the interface. From the Gibbs-Thompson law of energetics it follows that substances which lower surface tension will be concentrated in this situation because the energy will be lessened thereby. Accordingly, any substance in solution in contact with the surface of another phase will be concentrated on that surface, if thereby the free energy present is decreased. This is adsorption and characteristic in its relation to surfaces of contact. The exact conditions controlling the adsorption of colloids are as yet not well known, nor are the factors determining specific ad- sorption in mixtures. It is possible that related physical configura- tion of molecular complexes are of importance in this respect and electrical relations of substances are certainly concerned. These considerations are not only of theoretical, but great practical importance, for the specificity of the Wassermann reaction has thereby been much limited. We are enabled to understand now better the gradually increasing number of instances in which the Wassermann reaction is positive in non-syphilitics and the lack of the reaction at times in syphilitics. As a result of long-continued observations carefully carried on by Dr. Bruere in these laboratories and by other observers, it may be laid down as a general proposition that agents which either IMMUNITY 121 increase or diminish the lipoid protein contents of the blood may interfere with the specificity of the reaction, rendering the results of doubtful value as a test for syphilis. Under such conditions positive reactions may occur which are not necessarily due to syphilis. Thus, during digestion (particularly after fatty meals) in acidosis, lipemia, and after chloroform or ether anesthesia, the blood may give a strong positive reaction in non-syphilitics, be- cause lipoids are dissolved and thrown into the blood stream. On the other hand it appears that the reaction after long anesthe- sia or alcoholic debauch may become negative in syphilitics, pos- sibly, because much lipoid has been dissolved out of the blood. Thus also, the blood may be negative and the cerebro-spinal fluid positive. The same applies to infectious diseases, especially where, as in pneumonia, rapid resorption of large amounts of inflammatory exudate occurs, or in ulcerating tumors. Here also the blood be- comes rich in euglobulin, which is one of the components of the amboceptor in syphilitic blood and lipoids. This very practical lesson must, therefore, be drawn, that, in order to obtain a reliable test for syphilis with the Wassermann reaction it is necessary to use the following precautions: First, blood must be taken directly from vessels, avoiding the skin, (subcutaneous fat), and not by blister or cupping. Second, blood should never be taken (a) after a meal (but while fasting), (6) during a fever, (c) during any acute infectious disease, (d) during suppurations or resorptions of large inflammatory exudates (pueu- monia, empyema, etc.), or even in ulcerating or necrosing tumors, (e) after narcosis. As a second proposition, it may be put down that a negative Wassermann does not necessarily exclude syphilis. The value of the Wassermann reaction in the diagnosis of syphilis should not be discredited or underestimated, but our experiences, together with those of others, emphasize the necessity of proper precautions in obtaining the material (blood) for the reaction. It also explains relative value. Here, then, theoretical considerations as well as practical results meet, and when combined give us an intelligent understanding and a reliable application of a complicated immu- nity reaction. 122 GENERAL PATHOLOGY The principles underlying the Wassermann reaction have a much wider and general application to immunity. For in- stance, if a given quantity of diphtheria antitoxine is added to the toxine in fractions, neutralization of less toxine occurs than when all is added at the same time. This is also true of ricine, the toxic principle of the castor bean, and antiricine. If ricine is added in separate amounts to antiricine, more antiricine is necessary for neutralization than when all ricine is added at once. It has also been shown in the frog that adsorption of tetanus toxine by the nerve trunk occurs at low temperature, but poisonous effects do not occur until the animal is heated to 2oC. Even the chemical specificity of the amboceptor or antibody in other immunity reactions is not quite certain. It may represent only an increased production or rearrangement of substances normally present in tissues and fluids which under certain condi- tions and influences form large colloidal complexes and by selective adsorptions pose as specific chemical compounds in their reactions. The peculiar successful treatment of certain diseases with non- specific proteins, such as joint infections with typhoid vaccines, are perhaps to be explained in this manner. A similar phenomenon is the formation of precipitines. If we inject at several sittings the serum of an animal A into an animal B, the serum of the latter acquires the power to precipitate the serum of animal A and this precipitation appears to be relatively specific, so that it occurs only in high dilutions with the serum of an animal against which immunization has been made. To detect human blood, for example, it is only necessary to immunize a rabbit or guinea pig against human serum; this im- munized serum will then precipitate in high dilutions (1:1000 and over) a human serum and that of high anthropoid apes only, but no other. This reaction has, therefore, acquired great medico- legal importance. The reaction is given also by the serum in human exudates and transudates, and slight reactions should not be regarded as conclusive, as they are not specific. Moreover, the precipitate is redissolved rapidly in low dilutions (i :ioo). Agglutination of bacteria follows essentially the laws of hemolysis. IMMUNITY 123 From what has been presented, it appears that these phenomena of immunity are, partly, of complicated colloidal character, largely in the nature of adsorption, partly adsorption plus chemical union of at present quite unknown substances. There is another phase of immunity which at first sight appears far removed from the Wassermann reaction, but which careful reflection shows very close relation to it, chemiotaxis and phago- cytosis. Movement and ingestion of foreign particles such as food, bacteria and pigment are fundamental characteristics of life and possessed by all free cells. In higher animals the movement and ingestion of foreign particles appears particularly strong in meso- dermal cells, especially leucocytes, but other, more highly developed cells are also capable of ingesting foreign matter and thus play an important role in consumption and removal of bacteria. Thus Si- mon showed in a case of cerebro-spinal meningitis 7,380,000 organisms per c.c. in leucocytes. Wright and Douglas found that phagocytosis proceeds better in serum, and therefore suggested that this was due to the presence of substances in the serum which made bacteria more susceptible to cell ingestion; prepared them, so to speak for the leucocytes. They termed these hypothetical substances opsonins (from opsonare to make palatable) and observed that vaccination with killed cultures of bacteria in- increased the opsonic contents, i.e., the opsonic index, of the leucocytes towards the particular vaccinated organism. These views, which were at one time very enthusiastically received, have been materially altered by our recent more perfect knowledge of the nature of chemiotaxis and phagocytosis. Both were once regarded as specific of living forms, and in a way, intelli- gent expressions of life and useful efforts of protection. To-day we know that these functions are by no means confined to living cells, that both properties follow essentially the laws of surface tension in cells as in non-living substances suspended in fluid. When a drop of fluid is suspended in another, the particles of each fluid are, as is well known, under a considerable cohesion force, which holds them together. Within the drop suspended in the fluid the force is equalized by each particle being subjected to the same pressure or force from all sides. But the particles on the surface i2 4 GENERAL PATHOLOGY of the drop are exposed to unequal pressure, for that of the outside fluid is different from that of the drop, so that the surface particles are exposed to the pressure of the two fluids, and this is surface tension. The surface tension endeavors to reduce the free surface to a minimum and this is perfectly represented by the sphere. But the cohesion affinity and power varies in fluids, so that some have high, some low surface tension. Again, if substances are dis- solved one in another the resultant surf ace tension equals that of the two substances. If, then, on a point of the surface of a drop sus- pended in another fluid, the tension is lowered, remaining station- ary elsewhere the drop will bulge and flow in that direction. If, on the other hand, the surface tension is increased at a given point, the wall of the drop will be indented, and the whole drop will flow away from this increased tension towards less resistant parts. Thus we have movements closely simulating positive and nega- tive chemiotaxis. If, for example, we take a drop of metallic mer- cury and suspend it in a flat Petri dish in a 10 per cent, solution of HNO 3 , the drop will assume the shape of a sphere. Suppose we now put a crystal of potassium bichromate in the solution close to the mercury. As the crystal dissolves and strikes a point on the surface of the drop of mercury this is oxidized, the surface tension thereby lowered and the drop projects in this direction, sends out pseudo- podia and ultimately moves towards the crystal, around which it will execute the most active and bizarre motions, apparently battling with it until the surface tension has again been equalized by the solvent action of the acid on the oxide; then the mercury assumes once more the quiescent form of a sphere. If we dissolve the potassium chromate first in the acid water and then add a drop of mercury, the motions of the drop are slower, more ameba-Iike. This is, of course, a very simple and, in a way, crude experiment, but we owe to Ludwig Rhumbler most interesting and elaborate observations which show, on the assumption of the colloidal nature of cells, that chemiotaxis and phagocytosis are funda- mentally surface tension phenomena. Ameba, leucocyte or other cells are, physically considered, drops of a colloidal suspension surrounded by a delicate surface layer which is more or less readily permeable to solvents and sub- IMMUNITY 125 stances in solution. In any fluid such a colloid drop is suspended in a liquid of different composition. These conditions may be imitated in a simpler fashion by suspending a drop of clover oil or chloroform in glycerol and weak alcohol, with which it will gradually mix. Such a drop will move about, send out pseudopodia and change its form as an ameba does. If some strong alcohol is added near the drop, the surface tension on this side will be lowered and the drop will flow in that direction (chemiotaxis) . It will also flow to- wards a heated point, because heat lowers surface tension. But further, even the ingestion and choice of food may beartific- ally produced. A drop of chloroform in water or weak alcohol will refuse certain substances, such as glass or wood, and, if introduced, will expel (vomit) them ; but if a piece of thread of shellac, vulcan or paraffin be brought into contact with it, the drop will, in ameba fashion, flow around it. Even more, if a thread which an ameba ingests is too long, it stretches along the thread and, by bending it, crowds the thread into a coil within its body. This looks like a voluntary or instinctive action, but Rhumbler showed that when a long thread of shellac is offered to a drop of chloroform, it proceeds to bend the thread in the middle, sends out pseudopodia along the thread to pull it in, coils it up inside and then digests it. A thread six times as long as the drop of chloroform may thus be taken in. Moreover, if a piece of glass rod is covered by shellac and then introduced into the chloroform drop, the shellac is retained, but the glass rod expelled. Even the formation of shells by certain protozoa (difflugia) has been imitated by Rhumbler by mixing oil with quartz grains and 70 per cent, alcohol. The grains are thrown out to the surface of the oil drops and adhere to one another as they do in difflugia, and these artificial shells remain intact for months. While the ameba and other cells are certainly much more complicated in their make- up and, therefore, in their physical relations to the outside, these experiments strongly suggest that, at least, many of the elementary motions and actions of cells are exhibitions of changes in surface tension. This is also borne out by the observations on the behavior of higher tissue cells towards certain reagents. Thus, B. Fischer found that the injection of Sudanor scarlet red in oil into the ear 126 GENERAL PATHOLOGY of rabbits caused dissociation of the surface epithelium, and growth and migration towards the Sudan. The same influence has been found after the application of coal-tar, ether, and, generally speak- ing, lipoid solvents, as also in artificial parthenogenesis by J. Loeb. The term chemiotaxis is, therefore, strictly not correct, for the attraction of cells does not depend upon chemical affinity, as once believed, but upon physical changes in the environment of cells. It is probable that the emigration of leucocytes in inflammatory exudation depends upon the same phenomena for the products of cell disintegration, and inflammatory irritants lower surface tension in the tissue fluids. When these diffuse into the blood they will nec- essarily attract leucocytes in the direction of the greatest lower- ing of the tension. They pass then through stomata of vessels and move in the tissue fluids until the tension is once more equalized. The changes in size and shape of inflammatory cells after exuda- tion, their polymorphous character and the fusion of cells to giant cells are also largely governed by the physical factors of their environment. If we take small particles of camphor and throw them into water, they exhibit very active motion. If we now cover the surface of the water by a thin film of oil and thus equalize surface tension, the camphor particles come together, agglutinate and form large irregular masses such as occurs in cell agglutination and cell fusion. 1 We may, therefore, conclude that, as the Wassermann reaction depends upon phenomena of surface energy (adsorption) so depend chemiotaxis and phagocytosis upon phenomena of surface tension. 2 It is clear, therefore, that what was called opsonins and opsonic differences are essentially not chemical, but physical phenomena. NATURAL IMMUNITY. At the beginning it was stated that the third phase of immunity, the goal of desirable immunity, is the creation of conditions which are unfavorable to settlement and growth of infecting agents by modifying the physical and chemical constitution of tissues. We have known for a long time that individ- 1 See later under Inflammation. 2 It may be readily conceded that these phenomena show in living cells cer- tain modifications, but these are not, as far as I can see, fundamental differences. IMMUNITY 127 uals may carry after an infection, or even never having undergone any infection, virulent bacteria, and these individuals, so important from the epidemiological standpoint, are spoken of as of "carriers. " Instructive in this regard is especially gonorrhea. For we know that the gradual adaptation of the gonococcus to the urethral mucous membrane is not due to any bactericidal action of the tissues, but that the gonococcus continues fully virulent and that, therefore, the inflammation excited by this irritant does not heal by annihilation or even decreasing the virulence of the invading agent. We also know that venous congestion, although in other respects rather detrimental to cell life by asphyxia and increased H ionization of the tissues, is unfavorable to settlement and growth of bacteria. Bier's famous treatment of tuberculosis depends on this observation. How can these perplexing questions be explained? It would seem that here also complex physico-chemical conditions of the tissues are involved which make an attack, or better expressed, a union of bacteria to cells impossible. It appears, from recent observations in which Dr. Gross and the author are still engaged, that the colloidal state of cells and their physical environment are of great importance here. We have deviated in our studies of natural immunity from the general custom of employing complex animals, and have chosen the simplest kind of protozoal organism, the paramecium, for our studies. This we have been, and are still growing under varying physical in- fluences with pathogenic bacteria. We have observed that the ability of pathogenic bacteria to attack and destroy paramecia depends to a considerable extent upon physical factors, such as salt contents of the media; that, for example, in higher salt con- centrations paramecia are more vulnerable than in lower or saltless media (swelling and hydrops of cells). These studies are not yet sufficiently completed to draw definite conclusions, but they are suggestive of the importance of physical factors in infection. It is possible that the interesting recent observations of Cramer and Bullock belong to the same category. By injection of various substances such as calcium salts and gelatine, they produced what they term kataphylaxis or local break of tissue defense. Organisms like the bacteria aerogenes or tetanus bacillus, which under ordinary I2 8 GENERAL PATHOLOGY conditions are non-pathogenic, may, by such a local break of tissue defense, acquire virulent properties. Bullock and Cramer attribute this "defense break" to disturbance in vascular and lymphatic drainage from injury, but in view of what has been presented here this effect may be, at least partly, of physical nature by creation of conditions which allow interaction between micro-organisms and cells and thereby disease. PASSIVE IMMUNITY. The immunity which we have so far considered is an active, anti-infectious immunity, that is, one in which the immunity depends upon reactions between the body cells and the invading agent. Intimately connected with it is the active, antitoxic immunity in which cells produce substances which enter into union with bacterial products and thereby neu- tralize or immobilize specific bacterial poisons, for example, the toxines secreted by the diphtheria or tetanus bacillus. These antitoxines, the nature of which is still quite obscure, are products of tissue cells, and are poured into the serum of infected animals in excess so that animals (horses, for instance) may then receive 100 to 300 times the fatal dose without fatal results. Behring (see Diphtheria) showed that by artificial immunization of animals against diphtheria the immunity could be transferred to others by injection of the immune serum. The second animal is thus passively immunized; that is, without any action of its own cells it enjoys the work of the first animal. This passive immunity, however, is never as lasting as an active one at the longest only several months, but its advantages are immediate and prophylactic. Passive or antitoxic immunity is limited to specific esotoxines, and cannot be employed with success against endotoxines. In the discussion of diphtheria toxine and antitoxine our knowledge and the principles of toxine and anti- toxine reactions has already been made known. A curious pheno- menon occasionally observed in animals with a very high antitoxine content of their blood is the so-called paradox reaction, in which the immunized animal becomes again susceptible to toxine action. Its cause is unknown. Some suppose that a very large antitoxine content of the blood injures tissue cells and thus makes them once more susceptible to toxine; then, again, it may be that union IMMUNITY 129 (adsorption) of the colloidal antitoxine and toxine complexes is possible only within certain quantitative limits. ANAPHYLAXIS: (From &v&