/ it J; if 
 
 Issued November 2;!, 1908. 
 
 U.S. DEPARTMENT OF AGRICULTURE, 
 
 BUREAU OF PLANT INDUSTRY— Circulai No. 18. 
 K. T. GALLOWAY, Chief of Bureau! 
 
 REAPPEARANCE OF A PRIMITIVE CHARACTER 
 IN COTTON HYBRIDS. 
 
 (). V. COOK, 
 
 BlONOMIST, BUEEAI OF Pi, AM InDI 
 
 59001 -Clr. is 08 
 
 WASHINGTON : GOVERNMENT PRINTING Of-Fi. I 
 
 
 
BUREAU OF PLANT INDUSTRY. 
 
 ' Pathologist, and Chief of Bureau, Beverly T. Galloway. 
 Physiologist and Pathologist, and Assistant Chief of Bureau, Albert F. Woods 
 
 Laboratory of riant Pathology, Erwin F. Smith, Pathologist in Cha 
 
 Investigations of Diseases of Fruits, Merlon P.. Waite, Pathologist in Charge. 
 
 Laboratory of Forest Pathology, Haven Metcalf, Pathologist in < barge. 
 
 Cotton an<i TrucJc Diseases and Plant i" ea fill ' 0r1 m athologlsl in 
 
 Charge. 
 Plant Life i westigations, Walter T. Swingle, Physiolo harge. 
 
 gallons, Archibald D, Shamel and Daniel N Sho ma ei Physiolo- 
 gists in Cha) 
 Tobacco Investigations, Archibald D. Shamel, Wightman W. Garner, and Ernest II. 
 
 MathSwson, in Charge. 
 Corn Investigations, Charles r. Hartley, Physj i arge. 
 
 Ulcali and Drought i ; tt Plant Breeding Investigations, Thomas H. Kearney, Physl 
 ologist in Cha i 
 
 \logy and Water Purification Investigations, Karl F. Kellerman, Physiologist 
 in < 'barge. 
 Bionomic Investigations of Tropical and Subtropical Plants, Orator F. Cook, IKonomist 
 
 in Charge. 
 Drug and Poisonous Plant Investigations and Tea Culture Investigations, Rodney H. 
 
 True, Physiologist in Charge. 
 Physical Laboratory, Lyman J. Briggs, Thysicist in Charge. 
 
 Crop Technology and Fiber Plant Investigations, Nathan A. Cobb, Crop Technologist in 
 Charge. 
 
 nvestigations, Frederick V. Covill iisi in Charge. 
 
 ment ! - ations, William .1. Spillman, Agriculturist in charge. 
 
 , ations, Mark Alfred Carleton, Cerealist in Chai 
 
 Hon Experimental Farm, I." i t, Horticulturist in Charge. 
 
 Vegetable Testing Gardens, William W. Tracy, sr., Superintendent. 
 Sugar-Beet Investigations, Charles 0. Townsem gist in charge. 
 
 :,:,,.,,<„ a l Extension Agriculturist in Charge. 
 
 Di ' ; culture In Chilcott, Agriculturist in Charge. 
 
 Pomological Collections, Gustavus 13. Brackett, Pomologist in Charge. 
 Field in in Pomology, William A. Taylor and G. Harold Powell, Penologists 
 
 in Charge. 
 
 Gardens and Grounds, Edward M. Byrnes, Su] lent. 
 
 Foreign Seed and Plant Introduction, David Fairehild. Agricultural Explorer in Charge. 
 
 ,, Crop Investigations, Charles V. Piper, Agrostologisi in Charge. 
 Scat Laboratory, Edgar Brown, B i Charge. 
 
 lands i lation, John D. Shanaban, Crop Technologist in Charge. 
 Suui Ernst A. Bessey, Pal In Charge. 
 
 , ,, ;,,.,/, Hon Garden, Chico, Cat., W. W. Tracy, jr., Assistant in Charge. 
 
 i-een, Pomolog t i CI 
 Farmers' Cooperative Demonst ati n, Worl an A. Kn, ent in Cha 
 
 Seed Distribution (Directed by Chief of Bureau), Lisle Morrison, Assistant in General 
 Charge. 
 
 Editor, .1. E. Rockwell. 
 
 Chit ( Cirri;, .lames E. Jones. 
 
 ICir. 181 
 2 
 
REAPPEARANCE OF A PRIMITIVE CHARACTER IN 
 COTTON HYBRIDS. 
 
 INTRODUCTION. 
 
 The facts considered in this brief report arc incidental result 
 experiments undertaken for the purpose of acclimatizing in the 
 United States weevil resistant varieties of cotton from Central 
 America and of hybridizing them with our United States varieties. 
 The experiments have not yet been carried far enough to determine 
 the agricultural value of these varieties in the United States, but they 
 have already afforded several facts of scientific and practical ini 
 
 li is demonstrated that hybrids may differ from both parents in 
 showing undesirable primitive characters in the first generation and 
 yet may be free from such characters in the second generation. An 
 explanation of this strange behavior is round in the fact that the first 
 generation of hybrids represents an intermediate stage in the pr< 
 of conjugation begun h\ the original germ cells, while tin 
 general ion is formed a fter a plete conjugation has taken place. 
 
 Thus breeders have an additional reason for growing their hybrids 
 for a; least two generations. To reject lie I ation hybrid: be 
 
 cause they appear unpromising is to judge them b( •■ oeri 
 
 mcni of crossing is really complete. It i- like throwing away young 
 plants or animal- because tiny do not have all the proper! i 
 adult-. In-tead of being accepted a- evidence regarding the agri- 
 cultural value id' hybrids between two specie- or varieties the 
 acters of the first generation ma\ be merely temporary. Hybrids 
 which do not yield a desired combination of parental characters in 
 the first generation may siill do so in the aeration. 
 
 PRIMITIVE CHARACTERS SHOWN IN REVERSION AND 
 RECAPITULATION. 
 
 Any character which appear- to have been attained i'ar hack in the 
 developmental history of a species or variety may he described as a 
 primitive character. The name i- applied re especially to char- 
 acters which have ceased '" be regularly expressed, hut come to light 
 onl\ in i d individual- which are -aid to " lake after '" remote 
 ancestoi id of resembling their immediate parents. 
 
 Fad- -how ing the pei istence of primitive characters in plant- and 
 animals are commonly recognized as constituting two distinct group? 
 of phenomena, called reversion and recapitulation. The behavioi ol 
 [Clr :■ 
 
4 A PRIMITIVE CHARACTER IN COTTON HYBRIDS. 
 
 our cotton hybrids serins to show that the relation between these 
 phenomena is very intimate, and that one may pass into the other 
 us a result of hybridization. 
 
 Reversion is the reappearance of a character which has been trans- 
 mitted in latent form — that is. without being brought into expression 
 in the parent generation or in a previous series of generations. 
 Recapitulation may be described as the following over of the ances- 
 tral paths of descent in each generation. Studies of the embryology 
 of the higher vertebrates have shown that many primitive features 
 are brought into temporary expression in the course of development 
 of each individual. Mammalian embryos still show gill clefts and 
 rudiments of other ancestral features which have not served as adult 
 characters for many geologic ages. 
 
 Reversion and recapitulation have no limits in years or in numbers 
 of generations. They give us a vivid indication of the all-embracing, 
 all-enduring power of transmission. Darwin has aptly associated 
 the permanence of latent characters with the persistence of rudi- 
 mentary organs : 
 
 There is no more inherent improbability in each domestic pig, during a thou- 
 sand generations, retaining the capacity and tendency to develop great tusks 
 under fitting conditions, than in the young calf having retained fur an indefinite 
 number of generations rudimentary incisor teeth, which never protrude through 
 the gums." 
 
 In this, as in many other passages. Darwin recognizes a distinction 
 which many subsequent writers have overlooked, perhaps because 
 no definitely contrasted terms were used to define it. The distinc- 
 tion is between (1) the process of transmission which conveys to 
 successive generations of organisms the '"capacity and tendency" to 
 reproduce and transmit the characters of their parents and ancestors, 
 and (2) the process of expression, by which characters are actually 
 " developed " or worked out in visible form. These two processes, 
 transmission and expression, give us the facts commonly known as 
 " heredity." 
 
 Recapitulation may be described as a temporary or partial expres- 
 sion of a primitive character, while reyersion is the expression of a 
 character which is usually transmitted in latent form without coming 
 into expression at all. Recapitulation may never be visibly com- 
 plete: many ancestral characters are not brought into expression, but 
 the power of such characters to reappear shows that they continue 
 to he transmitted. The '•capacity and tendency" remain in the 
 protoplasm, even when no visible tissues are formed. The many 
 different reversions shown by members of the same stock indicate 
 thai all the ancestral characters are probably transmitted ami con- 
 
 " Darwin, Charles. Variation of Animals and Plants under Domestication, 
 ■hapter 13. 
 
 [Cir. isj 
 
\ PRI&IITIV1 CTEB CI , 11\ BRIDS. 5 
 
 tinue to be capable of regaining expi'ession if some unusual condi- 
 tii n interferes with more normal com ses of development. Hybridi- 
 zation and transfer to new conditions are the most familiar meai 
 calling forth the latent characters. 
 
 The course of development followed by any individual plant or 
 animal is chosen, as it were, from many ancestral alternatives. 
 Though only tin' chosen characters are brought into expression, the 
 process of transmission remains inclusive and impartial. Each gen- 
 eration is to be thought of as passing along to I essors a com- 
 plete genealogical chart, (ialton's law of regression shows that each 
 generation tends to follow the route-, used by the parents and other 
 recent ancestors, but under normal conditions of descent there is a 
 wide liberty of choice Individual diversity rsistently shown, 
 even when organisms of the same ancestry develop under the same 
 condition-. 
 
 REAPPEARANCE OF GREEN FUZZ IN COTTON HYBRIDS. 
 
 Reversion is often reckoned as a rare and exceptional phenomenon, 
 not to be understoo I from the standpoint of normal inheritance; but 
 the fact is that many reversions are as definite and uniform as any 
 other es of descent. Thus there are no characters in which 
 
 hybrids between the Kekchi cotton of Guatemala and the Sea-Island 
 or Egyptian cotton- are in better agreement than in the very large 
 size of the seeds and in the det e coat of bluish green fuzz with which 
 eeds arc covered underneath the long, while lint. These ch 
 
 the seeds of the hybrids abruptly different from those 
 of the parent typ< . 
 
 The removal of the lint leave- the seeds of the Kekchi cotton i 
 ered with a dense white fuzz, while the seeds of the Sea-Island and 
 Egyptian cottons are black and naked. Thus the green fuzz of the 
 hybrid seed is not a blend or other combination of the parental char- 
 acter-, though it may be viewed as a compromise between the paren- 
 tal condition- if considered in relation to other facts of n 
 and recapitulation. Examples of green fuzz are found in many dif- 
 i : pes of cotton, including those which are native in the Old 
 World, and especially in wild or unimproved varieties. Thus it 
 probably represents an ancestral condition from which both of tic 
 parental types have diverged. No wild cottons with white fuzz seem 
 i" I" known, hut most of the naked-seeded cotton- have a small tuft 
 of green or brown fuzz at the base of tl itemalan cot 
 
 ton of dp Sea-Island -eric- has the lower half of the seed coated 
 with green fuzz, the Inn being confined to the upper half, which 
 has no fuzz. 
 
 Cook, O. r. Weevil Resisting Adaptations of the Cotton I'ftuit, [Juliet iu 88, 
 mi of 1 'lu 111 Industry, l . S. Dept "i ure, \<. 32. 
 
b A PRIMITIVE CHARACTER IK COTTOK HYBRIDS. 
 
 The reappearance of the green fuzz in these hybrids need not be 
 considered as a turning back from the characters of the parent 
 varieties, as the word reversion seems to imply. These hybrids do 
 not follow either of the parental routes of development, but com- 
 promise on a primitive character which appears to represent common 
 ancestral ground. A stage of development which is quickly passed 
 by or entirely latent in the parent varieties remains as a definitely 
 expressed character of the hybrids. Abortive seeds are often found 
 with green fuzz, even when normally matured seeds in the same 
 locks have white fuzz. Thus reversions can be viewed as conditions 
 of arrested development— failures to pass beyond stages marked by 
 primitive characters. 
 
 DIFFERENCES BETWEEN FIRST AND SECOND GENERATIONS. 
 
 The recali to expression of the ancestral green-fuzz character is not 
 permanent. The next generation shows a wide diversity of combina- 
 tions and intergradations between the characters of the parent types, 
 but there is no such failure to attain the parental characters as in the 
 first generation, though the green color sometimes remains in the 
 second and even in the third generation. Why an ancestral character 
 should so regularly appear in the first generation and almost as regu- 
 larly disappear in the second is not easiby understood until we remem- 
 ber that the second generation is the first that represents a completion 
 of the conjugation begun by the original germ cells." 
 
 The first generation is formed during the preliminary stages of 
 conjugation, so that the temporary expression of an ancestral char- 
 acter in the first generation may not be essentially different from 
 other phenomena of recapitulation in which temporary expression of 
 characters takes place. Instead of an intermediate average between 
 the divergent parental characters or the dominance of one over the 
 other, the green fuzz may represent a third method of adjusting 
 the parental differences, by compromising upon a common ancestral 
 character. 
 
 If we think of the green fuzz as in the nature of a chemical com- 
 bination of the parental characters, its failure to become "fixed" 
 appears very mysterious; but when we associate it with the phe- 
 nomena of reversion and recapitulation it is easy to understand that 
 the disappearance of the green in the second generation accords with 
 the very frequent result that the second generation of a hybrid differs 
 from the first. An intermediate and nearly uniform first generation 
 often produces an extremely diversified second generation. 
 
 The experiments of Mendel and his successors have made us 
 familiar with the fact that parental characters which are suppressed 
 
 "Cook, <». !•'.. and Swingle, W. 'I'. Evolution of Cellular Structures, Bulletin 
 81, Bureau of Planl Industry, '■'• S. Dent, of Agriculture, 190.". 
 [Clr IS] 
 

 RIMI I IVl. cil ai: \c ill; I :• CO! - i^ BR1DS. i 
 
 in the first generation commonly reappear in th< ' generation. 
 
 of a Mendelian hybrid shows only oi • of a 
 of contra irental characters (called the dominant chara< 
 
 btil the other characl a part of the 
 
 generation. The fuzz character may be de- 
 
 scribed a typical . for a ■ 
 
 linen! in th< ration tends to disappear in I 
 
 itions. I true c. i • tween the wiii 
 
 Kekchi cotton a pland \ . like the 
 
 Truitt. Though the \ linates in the first 
 
 ation, it gradually hird genera 
 
 I simila dendelian behavior is shown 
 
 in a hybrid in which th i to be 
 
 dominant in i ion, while about two-thirds of the plains 
 
 of thi I generation have tl different degrees. 
 
 In a lev. of them the fuz h, but none have the vivid green 
 
 usually shewn when the color appears in the fii ation. 
 
 EXPRESSION OF CHARACTERS IN FIRST AND SECOND 
 GENERATIONS. 
 
 Diffi between the first and second generations of hybrids are 
 
 the externa] evidence of the fact that th esses of reprodui 
 
 followed by the higher plant- and animal- have two critical points 
 or periods of adjustment of the internal relations which govern the 
 expressions of the character-. One adjustment is made when conju- 
 gation begins by the union of the outer protoplasm and nuclei of the 
 two germ cells. A second adjustment is made when conjugation is 
 completed by the fusion of the chromatic material of the cells (mitap- 
 sis) before the formation of the gi ; is which give rise to the sec 
 
 ond generation. The adjustn lade when the conjugation of the 
 
 germ cells begins are usually less profound than those accomplished 
 when i n n is completed. 
 
 The first adjustment has the single result of determining the ex- 
 pression of characters in the fir i generation— that in which the con- 
 jugation begin-. The r< suits of the second adjustment are not shown 
 until the second generation, which i- in reality the first generation to 
 be formed after conjugation has been completed by mitapsis. The 
 second gi hows a very different series of adjustments, 
 
 and often a widely varied series. Individual members of (his gen 
 (•ration frequently differ as much from each other as from the 
 parental ty] 
 
 If characters combined like other physical or chemical substances 
 we might expect that like ingredient- would produce like results, 
 whereas hybrids of the same parentage may be endlessly diverse. 
 
 [Cil 
 
8 A PRIMITIVE CHARACTER IN COTTON HYBRIDS. 
 
 The facts of reversion and recapitulation enable us to look upon these 
 diversities of hybrids as corresponding to the normal diversities of 
 descent of the parental groups intensified by the recall to expression 
 of ancestral peculiarities, such as the green fuzz of the cotton hybrids. 
 
 If the green-fuzz character behaved in a truly Mendelian manner 
 half of the second generation would have green seeds. The theory of 
 Mendelism holds that characters are transmitted as separate " units " 
 and that the units which represent definitely contrasted parental 
 characters pass into separate germ cells at the end of the first genera- 
 tion. Thus the germ cells formed by the green-seeded first genera- 
 tion would carry either the black-seeded Egyptian character or the 
 while-seeded Kekchi character. Half of the germ cells would con- 
 jugate with others of their own kind and half would find mates of the 
 opposite kind. The contrasted pairs would give rise to green-seeded 
 plants, while the other half of the second generation would be equally 
 divided between white seeds and black seeds. 
 
 The general disappearance of the green seeds in the second genera - 
 tion indicates that the germ cells which produce this generation do 
 not have the same expression relations as those which produced the 
 first generation, for there is not the same tendency to recall the green 
 fuzz into expression. Development no longer halts at this earlier 
 stage, but brings back the white fuzz and the smooth seeds of the 
 parent types and many intermediate conditions. The parental charac- 
 ters are not only united with each other in varying combinations, but 
 also in combination with occasional traces of the green fuzz or of 
 brown fuzz, a character which also appears in primitive types of 
 cotton. Traces of green or brown fuzz may even arrive without 
 hybridization, as when the Kekchi cotton is being raised for the first 
 time in. the United States, or when our Upland varieties are grown in 
 new localities. Exposure to new conditions disturbs the usual course 
 of development and brings many latent diversities into expression, 
 often the same diversities that are found among the hybrids. 
 
 Different crosses between the same stocks may show different de- 
 crees of expression of the green character. Sometimes it does not 
 appear in (he first generation and sometimes it lingers in a large 
 proportion of the second generation. The strongest tendency to 
 retain the green fuzz has been noticed in a hybrid which had the 
 Jannovitch Egyptian cotton Tor the female parent and the Kekchi 
 cotton for the male parent. In one planting of thirty second-genera- 
 tion individuals raised from a green-seeded plant of the firsl genera- 
 tion, twenty show at least a trace of green in the fuzz, five have the 
 seeds nearly smooth, and five others have them densely covered with 
 white fuzz. Among the twenty reckoned as having green seeds there 
 are many gradations in the color as well as in the amount of fuzz 
 on the seeds. 
 
 fCiv. IS] 
 
a PRIMITIVK CHAKACTER IN COTTOfl HYBR 9 
 
 EXPRESSION OF CHARACTERS DETERMINED BY ADJUSTMENTS. 
 
 It is not necessary to suppose that the return of the parental char 
 acters in the second generation of the cotton hybrids is caused l>y a 
 mere reversal or undoing of the internal adjustments which led to 
 the formal ion of the green seeds, as the theory of Mendelism 
 sumes. The probability is rather thai the parental characters return 
 because further and more complete adjustments have been reached. 
 Even from the standpoint of Mendelism it has to be recognized for 
 the 6rs1 generation that the expression relations of the characters are 
 determined by adjustment. 
 
 There is no reason to believe that either of the germ cells which have 
 formed one of the green-seeded hybrids was adjusted to bring the 
 green-seed character into expression. The green-seed character 
 would have continued to remain in abeyance if either of the germ cells 
 which give rise to a green-seeded hybrid had conjugated with a part- 
 ner of its own kind. Bui after the conjugation began, the tendencies 
 o\' expression we] i changed and the green-seeded character appeared. 
 
 I rider the theory of .Mendelism two different assumptions are i 
 in attempting to explain the two changes of characters, away from the 
 parents and then back again. It has to be considered that the char- 
 acters of the first generation are determined, as stated, by a readjust- 
 ment of the internal relations which govern the expression of the 
 characters. But when the end of the generation is reached and new 
 ,:i cells arc' to be formed .Mendelism assumes that the expression 
 relations oil iie new cells are determined in another and very different 
 way. by the segregation of the "units" of the contrasted parental 
 characters in distinct germ cells. 
 
 The assumptions of Mendelism, that the characters are represented 
 by "• unit- " and that these are segregated and are transmitted by dif- 
 ferent verm cell-, become unnecessary as soon as we consider that the 
 expression relations of germ cells may be determined by adjustment. 
 The fact that the expression relations of germ cell- are capable of 
 being readjusted after conjugation should lie considered as evidence 
 that the relations they have before conjugation are also reached by 
 adjustment rather than by exclusion. If char icters are to be thoughl 
 ented in the germ cell- by definite particles or material 
 "units" ; kind, it is more in accord e fads to think of 
 
 hanging some positional, chemical, or other rela- 
 tion among themselves than a- being separately transmitted in dif 
 ferent germ cells. 
 
 Such fact- a- the reappearance of the green fuzz in the first genera 
 tion of these cotton hybrids show that the readjustment of expression 
 relations in the first generation i- not confined to the parental char 
 acters, hut maj involve the recall to expression of primitive charac 
 
 [Or 18] 
 
10 \ PRIMITIVE CHARA< I B ■ COTTON BYBRIDS. 
 
 lers transmitted in latent form from remote ancestors. It. is one of 
 many indications that the changes of expression relations which have 
 to be ascribed to adjustment are quite as great as those which Men- 
 delism has sought to explain by the theory of "character units' 1 and 
 • . heir segregation in " pure germ cells." 
 
 Writers on Mendel ism have sought to connect the idea of a separa- 
 tion of character units with the processes of subdivision by which the 
 germ cells are formed. The fact that four germ cells are formed by 
 ividing one mother cell has led to the s on that a separa- 
 
 tion of antagonistic character units might occur when this subdivi- 
 sion takes place. Two of the germ cells might contain the "unit* 1 
 representing one of the contrasted characters and two other 'germ 
 cells the unit of the other character. This would give equal num- 
 bers of germ cells of the two kinds which the theory of Mendelism 
 lires. Nevertheless it is possible for this equality to be reached 
 in another more practical way. The numbers of germ cells tending 
 to express the contrasted characters will be equal if equal numbers 
 of the mother cells become adjusted in the two ways before subdi- 
 vision into germ cells takes place. Thus all the germ cells from the 
 same mother cell may be of the same kind instead of being of two 
 kinds. This view is more practical because it does not require us 
 to suppose that the mother cells divide into unequal parts in forming 
 germ cells. In view of the frequency of the phenomena of rever- 
 sion and recapitulation it is much easier to suppose that both of the 
 '•ontrasted characters are transmitted, though only one comes into 
 expression, than to believe that then- is any separate transmission of 
 character units in different germ cells. 
 
 SIGNIFICANCE OF PRIMITIVE CHARACTERS IN BREEDING. 
 
 Breeders will appreciate the practical importance of the fact that 
 such a character as the green fuzz of cotton is not necessarily perma 
 nent, even though it may be shown by all the members of the first 
 generation of a hybrid. A> soon as we know that such a character 
 is likely to disappear we recognize the need of carrying our hybrids 
 over to the second and third generations before undertaking to make 
 final determinations of their merits. 
 
 Even among the cotton hybrids it has to be considered that other 
 and more important characters may be affected by the same prin- 
 ciples as the green fuzz. In the first generation all the hybrids be- 
 tween the Central American types of cotton and our improved Upland 
 varieties produced shorter lint than either of the parents. If the 
 short lint had been looked upon as a permanent character, such liv 
 brids would have been rejected as of no value in comparison with 
 the parent varieties. Nevertheless, a series of these hybrids is being 
 retained in order to learn whether the short lint will not behave like 
 
 Kir 18] 
 
A PRIMH IVE CHARACTJ 11 
 
 a primitive character and give place to long lint, in later generations. 
 Indeed, this seems already to he taking place. Though th lint 
 
 - not disappear as promptly a sjreen fuzz, the second and 
 
 third generations of the hybrids are showing examples of much lorn 
 lint than appeared in the first g( neration. 
 
 SUMMARY. 
 
 hi hybrids between the Kekchi ■ temala and varieties 
 
 of tin- Sea-Island and Eg} ptian nly show gr 
 
 fuzz in the ration. This character does not normally app 
 
 in either of the parental varieties, though it is probably an ancestral 
 character of both of them. 
 
 The reappearance of the primitive character in the hybrids is to 
 he associated with other facts of reversion and recapitulation, and 
 io indicate that these groups of phenomena are very closely 
 related. 
 
 The fact that the green fuzz largely disappears in the second gen- 
 eration of the hybrids indicate- that the recall of this character to 
 expression in the firsl generation marks a preliminary stage in the 
 process of conjugation. The complete results of conjugation first be- 
 come visible in the second generation, when the parental characters 
 reappear in many combinations and gradations. By thus recognizing 
 that th" firsl and second generations of hybrids represent different 
 stages of the process of conjugation it is possible to understand the 
 appearance and disappearance of such characters as the green fuzz 
 without resorting to the complicated theory of Mendelism. 
 
 The practical point is that such departures from the parental char- 
 acter- in the first generation of a hybrid may not remain to detract 
 from the value of later generations. Hybrids in which these undesir- 
 able primitive character- come int -ion must be grown for at 
 least two generations before -election can be effectively applied. The 
 characters shown by the first generation do not afford any practical 
 indication regarding the characters of the later generations. 
 
 Approved : 
 
 James Wilson, 
 
 n tary <>i . Vgricultun . 
 
 Washington, D. ('.. October /.'. 1908. 
 
 [Clr. 18] 
 
iMivtKSi i y Oh FLORIDA 
 
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