]] Marine Biological laboratory Library B Woods Hole, Mass. I I I I I J Presented by II I the estate of II Dr. Herbert W. Rand n B Jan. 9, 1964 II I m THE INTERNAL SECRETIONS OF THE SEX GLANDS LONDON agents: SIMPKtN, MARSHALL, HAMILTON, KENT AND CO., LTD. INTERNAL SECRETIONS OF THE SEX GLANDS The Problem of the "Puberty Gland" ALEXANDER LIPSCHUTZ, M.D. Professor of Physiology in Dorpat University (Estonia), formerly Privatdocent of Physiology in Berne University (Sw^itzerland) With a Preface by F. H. A. MARSHALL, F.R.S. Author of The Physiology of Reproduction With over 140 Illustrations in the text ENGLAND W. HEFFER & SONS LTD., CAMBRIDGE AMERICA WILLIAMS & WILKINS COMPANY, BALTIMORE 1924 PRINTED IN GREAT BRITAIN Preface. It has been known from very early times that castration in both man and animals, besides suppressing the sexual instincts, causes marked differences in the conformation of the body and the secondary characters of sex, and, moreover, that these results are most definite if the operation be performed before maturity has been attained. Numerous references to this subject occur in the works of Aristotle, who comments on the extensive modifications brought about in the general configuration as a consequence of the mutilation of a compara- tively minute organ. The manner in which this influence is exerted, however, has only been ascertained comparatively recently, and although great progress has been made in the last few years there are still wide gaps in our knowledge. According to Berman, the author of a work on The Glands Regulating Personality, the first to put forward the idea that the gonads produce their effect through substances discharged into the^blood was Bordeu, court physician to Louis XV., in the eighteenth century. It would appear, however, that Berthold in 1849 was the first physiologist to base the conception on experimental investigation. Little account was taken at the time of Berthold's work, and it was not until considerably later that the idea of an endocrine organ which elaborated a secretion transmitted through the medium of the blood was revived by Claude Bernard to describe the glycogenic and sugar-producing activities of the liver. The conception of internal secretion received a great stimulus from Brown- Sequard's experiments with the injection of testicular extracts in 1889, and although the vahdity of this particular work soon became discredited, it served a useful purpose in directing attention to the study of the endocrine organs and the possi- bilities of appl57ing it practically in medicine. Brown- Sequard's views, which he extended so as to refer to all the elements of the body, contributed largely to the adoption of organotherapy, the methods of which have been applied to all the organs of internal secretion as well as to others of problematic or unknown function. It was not until much more vi PREFACE recently that Prof. Starling suggested the term "hormone'' for the active principles of those internal secretions which act as chemical messengers and have a definite specific stimulating effect upon other and sometimes distantly situated organs. The result of such a stimulus is usually either growth or, in the case of a glandular organ, secretion, and one of the most obvious effects of the reproductive hormones is to produce growth. This, however, is far from being the only effect, since the influence of the testicular and ovarian hormones is mani- fested in greater or less degree throughout the whole body, and is extended to the psychical activities, as is plainly manifested in the display of sexual feeling and those associated phenomena which play so important a part in the activities of the organism. There is one important respect in which the endocrine functions of the gonads appear to differ from those of other organs of internal secretion, and that is in being cycHcal. For although the ovarian and testicular hormones are probably produced to some extent at all times, especially throughout the period of reproductive Ufe, the secretions change in quantity, and probably also in the female in composition, with certain recurrent seasons. This periodicity is apparently partly inherent in the reproductive organs themselves, but it is also influenced by external or environmental factors such as nutrition and seasonal and climatic conditions. Numerous instances of the cycHcal activity displayed by the gonads and the modes of working of their internal secretions, with many cognate matters, are given by Prof. Lipschiitz in the pages of the present work. The book was first published at Berne in 1919 under the title Die Puhertatsdrilse und ihre Wirkungen. The name "puberty gland" was given by Prof. Steinach, of Vienna, to denote the testicular and ovarian endocrine organs, since these glands, although they are beUeved to exert their influence on the organism from early stages of development onwards, show an especially accentuated activity at the phase of life when the gonads become mature. In the present edition, which contains a considerable amount of new matter, Prof. Lipschiitz has thought it expedient to change the name to The Internal Secretions of the Sex Glands, a title that indicates more accurately and more completely the contents and character of the book. PREFACE vii The reader will find in these pages a comparative and connected account of the endocrine functions of the gonads, so far as these are known, in all groups of multicellular animals. The importance of such knowledge has now become generally recognised, and the subjects treated are of profound interest for zoologists and physiologists alike, as well as for medical men, psychologists and students of eugenics. As a guide to the literature of a branch of endocrinology that has grown rapidly in recent years the work should be of great value. The manuscript has been written by the author in EngUsh, and in my capacity as editor I have confined myself for the most part to making such alterations as seemed to render Prof. Lipschiitz's meaning more clearly. For the views ex- pressed (with which I am not always necessarily in complete agreement) the author is solely responsible, and to him alone the credit is due. F, H. A. MARSHALL. Christ's College, Cambridge. April, 1924. Author's Preface. It is only owing to my esteemed friend, Dr. F. H. A. Marshall, who has contributed so much to our knowledge of the internal secretion of the ovary, that it was possible for me to publish this book. Dr. Marshall has kindly corrected my foreign EngUsh throughout the whole manuscript and afterwards read the proofs. May I be permitted here to express my sincere gratitude to Dr. Marshall, who has done all this hard work in the most unselfish manner. It was originally intended to publish a revised translation only of my book Die Puhertdtsdruse und ihre Wirkungen (Berne, 1919). But when I began translating the book, to- gether with my friend Dr. Karl Kautsky jun. in Vienna, who had undertaken to translate part of it, it became clear to me that the book had to be entirely rewritten. Since 19 18 im- portant experimental work has been done in this special field of physiology. To the foundation laid by Bouin and Ancel, by Steinach and by Tandler, facts have been added which have enriched our knowledge on the internal secretions of the sex glands and on their bearing on morphogenesis in an extra- ordinary manner. I mention only the important work done by Goodale and by Pezard in fowls and the quantitative investi- gations of the latter in the laboratory of Gley; the remark- able work done by Sand in mammals, especially on herma- phroditism; the experiments of Zawadowsky, who confirmed and richly enlarged the statements of Goodale and Pezard; the most interesting observations of Lillie and his pupils and those of Tandler and Keller on the freemartin; the work of Marshall and his co-workers, of Morgan, of Pearl, of Crew, of Athias, Harms and Wilhelm. Bouin and his pupils, and Champy, Guyenot and Kolmer have extended the problem to a great many species. Goldschmidt has given knowledge of unexpected facts on insects. Some of these new investi- gations have been shortly mentioned already in the first edition, but most of them were published only in the last five years. My point of view has been widely influenced also by the result of my own experimental work done during the last five years in this Institute. So a new book originated from the old one. AUTHOR'S PREFACE ix I have taken into consideration all the recent literature without distinction of language. I am indeed aware that some important papers may have been omitted without intention. There were also great intervals between writing the different parts of the English edition, and some very interesting state- ments from more recent literature could be introduced in Chapters II. and III. only very shortly during the reading of the proofs. But, intentionally, I have omitted some papers which, though much quoted in the current literature on the interna! secretion of the testicle, are devoid of scientific value and are contrary to the real spirit of scientific discussion. My personal relations with colleagues working in the same field have been of the greatest use to me. Many of them gave me the opportunity of seeing their patients, their experimental animals and specimens. These colleagues are too numerous to be named here, and I must confine myself to thanking them collectively. Many of them have contributed to the book by kind permission for reproducing their figures. The book as it is now could not have been written without the help of those who have collaborated with me in the Institute of Physiology in Dorpat. To Dr. Karl Wagner, now Professor of Histology at the University of Kovno, I am highly indebted for his histological work. The collabora- tion of Dr. B. Ottow, Dr. H. E. V. Voss, Dr. W. Krause was also of great value to me, and likewise that of Dr. E. Blum- Sapas, Miss E. Kropman, Miss S. Brunnow, Miss A. Ibrus, Mr. F. Bormann, Dr. F. Lange, Mr. H. Fuchs>^, Dr. M. Tiitso and Mr. W. Faure. Most of the figures which were in the first edition have been replaced by new ones from my own experimental observation. Dr. H. Kull and Mr. S. Vesnjakov did the photographic work, whilst Miss L. Lehbert and Mrs. Lipschiitz made the drawings. I have dictated almost the whole EngHsh manuscript to Mrs. Lipschiitz. I thank her here also for the great patience and unselfishness she exhibited and for her linguistic help. To Messrs. W. Heffer & Sons my warm thanks are due for the interest they have taken in the publication of the book and for the great care they have shown. A. LIPSCHIITZ. Institute of Physiology OF THE University of Dorpat (Tartu, Estonia). ist July, 1924. CoiXfglts/^^^iii^ PREFACE X: * K^^ ^ AUTHOR'S PREFACE . . ^^ ^ ^P^ . . viii LIST OF ILLUSTRATIONS xv EXPLANATION OF SIGNS xviii CHAPTER I. SEXUAL DIMORPHISM AND THE SECONDARY SEXUAL CHARACTERS i CHAPTER 11. THE RESULTS OF CASTRATION 5 A. The Results of Castration in Man ... 5 Observations ........ 6 Theoretical . . . . . . . . 15 B. The Results of Castration in Mammals . . 18 1. Morphological Signs of Castration . . , 18 2. The Psycho-sexual Behaviour of the Mammal . 33 C. The Results of Castration in Birds . • , 36 Observations ....... 36 Theoretical ........ 46 D. The Results OF Castration IN THE Frog AND IN Fishes 51 E. The Results of Castration in Arthropoda . . 55 1. Moths 55 2. The Parasitic Castration of Crabs . . . 59 3. The Parasitic Castration of Insects ... 66 F. The Results of Castration in other Invertebrata 67 G. Summary ........ 70 Bibliography ........ 71 CHAPTER III. THE INTERNAL SECRETIONS OF THE SEXUAL GLANDS 79 A. Transplantation . . . . . . .81 B. Feeding with Sexual Gland .... 92 C. Injection ........ 93 D. Internal Secretion of the Sex Glands and Nervous System ........ 97 1. Is there an Accumulation of the Internal Secretion in the Central Nervous System? ... 97 2. Physiology of the Clasp Reflex .... 98 3. The Pyscho-sexual Behaviour of Man . . 102 Bibliography . . . . . . . .105 ^1 .3y/ Xll CONTENTS CHAPTER IV. THE SEAT OF PRODUCTION OF THE SECRETION OF THE TESTICLE . INTERNAL A. Mammals ....... I. The Interstitial Cells of the Testicle The Ligature of the Vas Deferens The Retained Testicle .... The Engrafted Testicle .... The Influence of X-Rays on the Testicle The Relation between the Quantity of Interstitial Tissue and the Hormonic Effect {a) Is there a compensatory hypertrophy in the Testicle? ..... {b) The Law of "All or Nothing " 7. On Cyclic Changes in the Development of the Interstitial Tissue .... 8. The Phases of Puberty in the Male . 9. The "Follicular Theory" of Hormone-Production in the Testicle . . . 10. The Condition of the Interstitial Cells in Intoxica tion and Disease ..... Conclusions ....... B. Interstitial Cells in the Testicle of other Species 1. Invertebrates ...... 2. Fishes ....... 3. Amphibians ...... 4. Birds ....... Bibliography ....... CHAPTER V. THE SEAT OF PRODUCTION OF THE INTERNAL SECRETION OF THE OVARY A. Mammals ....... 1. The Interstitial Cells of the Ovary 2. The Origin of the Interstitial Cells of the Ovary 3. The Influence of X-Rays on the Ovary 4. Transplantation of the Ovary 5. The Condition of the Ovary in Partial Castration 6. The Internal Secretion of the Corpus Luteum {a) Histogenesis of the Corpus Luteum (6) The Functional Relationship between the Corpus Luteum and the Interstitial Tissue {c) Objections to the Theory of the Internal Secre tion of the Corpus Luteum 7. The Phases of Puberty in the Female Conclusions ....... B. Other Vertebrates . . . , Bibliography ....... PAGE 109 no no 127 142 148 153 155 ^55 166 170 175 176 178 185 186 186 186 187 191 200 211 211 211 222 227 235 243 246 248 251 263 267 270 272 276 CONTENTS xiu CHAPTER VI. THE SEX SPECIFIC ACTION OF THE AND OVARIAN HORMONES . A. Experiments on Amphibians . B. Feminization and Masculinization Birds .... 1. Experiments on Mammals . (a) Feminization (6) Masculinization . 2. Experiments on Fowls C. Experiments on Arthropoda Bibliography TESTICULAR IN Mammals and CHAPTER VII. THE QUESTION AS TO THE ISOLATION OF THE SEXUAL HORMONES A. Extracts of the Whole Sex Gland B. Extracts of Different Parts of the Sex Gland. Bibliography ........ CHAPTER VIII. THE SEMINAL VESICLES AND THE PROSTATE GLAND IN RELATION TO THE DEVELOPMENT OF THE SEX CHARACTERS A. Physiology of the Seminal Vesicles 1. Experiments on Frogs 2. Experiments on Mammals . Physiology of the Prostate Gland 1. The Effect of Prostatic Injections 2. Simultaneous Removal of the Seminal Vesicles and of the Prostate 3. Removal of the Prostate The Secretion of the Genital Passages in Relation TO THE Vitality of the Spermatozoa Bibliography ...... B. C. CHAPTER IX. INTERSEXUALITY A. True Hermaphroditism and Pseudo-Hermaphro DITISM ....... B. Experimental Hermaphroditism 1. The Antagonism between Testis and Ovary . 2. Somatic Characters of the Experimental Herma phrodite ...... 3. The Psycho-sexual Behaviour of Experimental Hermaphrodites ..... 4. Histological ...... PAGE 285 285 287 288 288 299 307 312 313 319 319 322 330 335 335 335 336 338 339 340 341 343 346 347 347 351 352 359 364 365 XIV CONTENTS C. Intersexuality in Man, Mammals, Amphibians, and Insects ....... 1. Man {a) Homosexuality ..... {b) Other forms of Intersexuality in Man (c) Is Hypospadia a Symptom of Intersexuality 2. Mammals ..... {a) Different forms of Intersexuality in Mammals (6) The Case of the Freemartin . 3. Birds ..... {a) Different forms of Intersexuality {b) Experimental 4. Amphibians .... 5. Insects. Goldschmidt's Experiments • D. Classification .... Bibliography ..... CHAPTER X. EUNUCHOIDISM AND SEXUAL PRECOCITY A. Eunuchoidism. .... B. Sexual Precocity .... Bibliography ..... CHAPTER XL SEXUAL HORMONES AND MORPHOGENESIS A. The Asexual Embryonic Soma B. Determination of Sex ..... C. Fixation of Sex Characters .... D. Evolved Characters of the Asexual Embryonic Soma ....... E. Terminological ...... F. Asexual Embryonic Soma and Heredity G. Classification of Sex Characters H. The Hormonic Activity of the Sex Glands which is not Sex Specific ..... Bibliography ....... CHAPTER XIi: SOME PRACTICAL ASPECTS. THE PROBLEM OF REJUVENATION Bibliography ........ INDEX OF AUTHORS GENERAL INDEX . PAGE 367 371 378 379 379 383 390 390 394 397 400 403 413 423 424 431 438 441 441 448 449 453 454 456 465 473 479 483 493 495 501 List of Illustrations. Fig. Page 1. Section through the penis of a eunuch 28 years old . 6 2. Section through the middle of the penis of a normal adult 7 3. ScoPEC of 28, castrated at the age of 16 . . . 8 4. Man of Central Europe with well developed body hair 9 5. scopec of 24, castrated at the age of 5 . . . lo 6. Adult European woman . . . . . . . ii 7. Normal male rat, i month old . . . . . 19 8. Normal adult male rat . . . . . . . 19 9. Male rat, 8 months old, castrated at the age of i month . 20 10. The penis and intromittent sac of guinea pig, castrated at different ages . . . . . . . 21 11. Penis of guinea pig castrated at the age of 4|r months, DRAWN 2 months LATER ...... 22 12. Seminal vesicles of a normal guinea pig i^ years old . 22 13. Seminal vesicles of a guinea pig 21 months old castrated AT the age of 2 WEEKS ...... 23 14. Seminal vesicles of guinea pig castrated at the age of 4^ months, drawn ii months later .... 23 15. Influence of castration on the rabbit's penis . . 24 16. Influence of prepuberal castration on the uterus of RABBIT ......... 25 17A, B, c. Histological features of the uterus of normal AND castrated RABBITS ...... 26, 27 18. Profile of normal and castrated cows ... 29 19. Pelvis of a new-born male lamb ..... 30 20. Pelvis of a new-born female lamb ..... 30 21. Pelvis of an adult ram ....... 30 22. Pelvis of an adult sheep . . . . . . 31 23. Pelvis of a ram castrated at an early age . . . 31 24. Pelvis of a sheep castrated at an early age . . 31 25. Growth of comb and spurs in the normal and in the castrated cock ........ 37 26. Comb of normal and castrated animals in Brown Leghorn 38 27. A Brown Leghorn capon, 3 years old .... 39 28. Head apparel in the cock castrated when one year old . 41 29. Ovariotomized Pullet ....... 42 30. Hen castrated four months previously .... 43 31. Normal Rouen duck 32. Normal Rouen drake 33. An ovariotomized duck 34A. Normal Sebright cock 34B. Castrated Sebright cock 35. Pad of male Rana temporaria in July, 36. Pad of male Rana temporaria in April, at time of heat . 53 37-45. Transformation of Inachus by Sacculina ... 60 46. Male rat, 8 months old, with testicular autotransplanta- tion at an age of i month ..... 83 XV 44 45 45 . 48 49 AFTER PERIOD OF HEAT 52 xvi LIST OF ILLUSTRATIONS Fig. Page 47. Section through uterus of a normal rat ... 89 48. Section through the uterus of a castrated rat . . 90 49. Section through the uterus of a rat with ovarian auto- transplantation . . . . . . .91 50. Brain of frog ........ 99 5 1 A. Section through testicle of normal guinea pig, aged about 4^ MONTHS . . . . . . . . .110 5 IB. Section through testicle of normal guinea pig, aged about 41^ MONTHS . . . . . . . . .Ill 52. Section through testicle of normal rabbit, 14 months old 112 53. Group of interstitial cells in testicle of adult cat . 113 54. Section through testicle of man 26 years old . . 114 54A. Section through testicle of human embryo of fifth month 115 55. Section through testicle of ADULT CAT, STAINED WITH Sudan 116 56. Interstitial cells of different animals . . . .117 57A. Development of interstitial tissue in guinea pig . , 118 57B. Development of interstitial tissue in guinea pig . . 119 57c. Development of interstitial tissue in guinea pig . . 120 57D. Development of interstitial tissue in guinea pig . . 121 58. Section through testicle of guinea pig, 2 to 3 weeks old 123 59. Section through testicle of rabbit, 2 months old . . 124 60. Section through testicle of adult guinea pig . . 127 61. Section through testicle of guinea pig 78 days after ligature of vas deferens . . . . . .128 62. Testicle of adult guinea pig . . . . .131 63. Testicle of adult guinea pig, about 18 months old , 132 64. Diagram of different operations performed on the testicle OF mammal ......... 132 65. Section through testicle of rabbit 8 months old, with eunuchoid penis . . . . . . .134 66. Section through testicle of rabbit about 8 months old, with normal sex characters . . . . -135 67. Section through testicle of rabbit 6J months old, with eunuchoid penis . . . . . . . i36 68. Section through testicle of rabbit 6^ months old, with normal sex characters . . . . . .137 69. Interstitial cells of rabbits with normal and eunuchoid penis . . . . . . . . . .138 70. Section through testicle of rabbit 6 months old, with normal penis . . . . . . . .139 71. Section through testicle of rabbit 6 months old with eunuchoid penis ....... 140 72. Another section ........ 141 73. Seminal VESICLES OF GUINEA PIG (4 states) .... 144 74. Retained testicle of pig (bilateral cryptorchism) . . 146 75. Retained testicle of pig (unilateral cryptorchism) . 147 76. Section through testicle which 8 months previously had BEEN subjected TO AUTOTRANSPLANTATION (RAT) . 1 49 77. Section through normal testicle of a rat about 9 months OLD . . . . . . . . . . 149 78. Section through testicle of normal adult guinea pig . 151 79. Upper testicular fragment of a partial " castrate " (guinea pig) ........ 151 LIST OF ILLUSTRATIONS xvu Fig. 80. a similar section ........ 81. Interstitial cells of a normal adult guinea pig , 82. Section through upper testicular fragment of guinea pig subjected to "complex" testicular section 83. Section through testicle of guinea pig subjected to OPERATION V. OF FiG. 64 . . . . , . 84. Section through upper testicular fragment (guinea pig) 85. Diagram to illustrate the hypothesis that the so-called compensatory hypertrophy of the remaining testicle is only an accelerated growth 86. Section through testicle of rabbit 14 months old, uni laterally castrated when i^ months old 87. Section through testicle of rabbit, 8 months old, with eunuchoid penis ...... 88. Section through upper testicular fragment (guinea pig) 89. Diagram: Dependence of hormonic effect upon the quantity of testicular hormones 90. Diagram to illustrate the law of "All or Nothing" 91. Cyclic development of generative and interstitial tissue OF THE testicle OF HIBERNATING MAMMALS . 92. Section through testicle cut horizontally . 93. Diagram: Cyclic development of generative and inter STITIAL TISSUE OF THE TESTICLE OF AMPHIBIANS . 94. Ovary of rabbit 18 months old . . . 95. Section through ovary of rabbit .... 96. Interstitial tissue in the ovary of Phascolomys 97. Lutear and interstitial cells .... 98. Section through ovary of pregnant rabbit 99A. Development of interstitial tissue of the ovary in rabbit 99B. Another section ....... 99c. Another section . . . . . 100. Section through ovary of rabbit 2J weeks old loi. Section through ovary of adult cat 102. Growing primary follicle in rabbit 7 months old 103. Young Graafian follicle in rabbit ii^ months old . 104. Section through ovary of white rat, 62 days old 105. Influence of X-rays on sex characters in virginal female guinea pig ........ 106. Other sections ........ 107. Section through ovary engrafted six months previously into a castrated male ..... 108. Section through ovary engrafted a year previously on a castrated male ...... 109A. Disappearance of primary ova in highly hypertrophied MINUTE ovarian FRAGMENTS .... 109B, Another section, after treatment .... II OA. Decrease of number of oocytes in ovarian fragment HOB. Another section ....... 111. Section through ovary of pregnant cat 112. Section through fresh corpus luteum of rabbit 113. Influence of the corpus luteum on the mammary gland of the rabbit ...... Page 156 157 158 159 160 161 162 164 165 167 168 171 182 189 212 213 214 215 216 217 218 219 220 221 223 224 225 229 232 236 237 240 241 244 245 247 252 254 xvm LIST OF ILLUSTRATIONS Fig 114, 115 116 117 118 119 120, 122 123 124. 125. 126. 127. 128. 129. 130. 131. 132. 133. 134. 135- 136. 137. 138. 139- Influence of ovarian transplantation on the teats of the castrated male guinea pig A. Normal male . . . . . . . B. Feminized male (during lactation) Feminized male guinea pig suckling young Body weight of normal and feminized male rats Body weight of castrated and feminized male rats. Litter of normal guinea pigs, about 7 months old Influence of ovarium transplantation on size of male guinea pig ........ Influence of testicular transplantation on the clitoris of the guinea pig ...... Influence of testicular transplantation on size of female GUINEA pig ........ Feminized cockerel ....... A, B, c. Influence of extracts of corpus luteum on the UTERUS ........ Influence of extracts of corpus luteum on the ovary Artificial ovariotestis in the guinea pig Artificial ovariotestis in the rat .... Experimental hermaphroditism in guinea pigs (6 states) Same drawn from nature. ..... Section of ovariotestis (see text) .... Twins in cattle ....... Twins in sheep ....... Prostate and seminal vesicles of a eunuchoid of 28 and of a normal adult man ..... Testicle and epididymis of eunuchoid of 28 . Diagrams to illustrate how a changed capacity on the part of the central nervous system to respond to sex hormones interferes with erotization, without the hormone production being disturbed pubertas praecox in a boy of three .... x-ray picture of the hand of a girl of 13^ with sexual precocity ......... Diagram: Origin of the different parts of the male and female sex apparatus ...... Unilateral underdevelopment of seminal vesicles in case of unilateral castration in guinea pig 6^ months old ■142. "Rejuvenation" of senile dog, i8 years old Page 290 291 292 294 295 296 296 301 304 308 326-7 328 353 354 360-1 362 374 385 386 . 425 426 429 432 433 457 477 486-9 EXPLANATION OF SIGNS. cJ = male 5 = female j^ = castrated male 00 j^ = partially castrated male ^ = castrated female t(S = male with transplantation m-^ = masculinized female t j^ = castrated male with transplantation t ^ = castrated female with transplantation fj^- = feminized male Chapter I. Sexual Dimorphism and the Secondary Sexual Characters. When we speak of sexual dimorphism we refer to the morpho- logical and physiological differences between the two sexes, differences which relate to other characters besides the dimorphism of the generative cells. In so doing we recognise two different groups of sexual characters : first, the generative cells or the primary sexual characters, and, secondly, the so- called secondary characters. But the term "secondary sexual characters" is not always used in the same sense. By "secon- dary sexual characters" one often means those morphological and physiological characters which are directly connected with the sexual functions (the actual generative cells being the primary sexual characters), all the other differences between the sexes being called "tertiary" characters. On the other hand all the morphological and physiological differences between the sexes, other than the generative cells, are sometimes designated secondary sexual characters. Disputes about the boundary lines between the characters designated primary or secondary sexual characters have bulked largely in scientific literature. These terminological polemics merely show an insufficiency of knowledge of the facts. The standpoints taken up by those who have been engaged in controversy as to the meaning of the terms primary, secondary and tertiary sexual characters reflect individual opinions on the value or importance of the different characters in relation to the sexual and repro- ductive functions. Some authors assess a higher value and some a lower to a particular character according to their opinions as to its precise functions. And as our knowledge is still very incomplete, it is easy to understand that the opinions of various authorities as to what are primary, secondary and tertiary characters differ widely from one another. The distinction between primary and secondary sexual characters might be based also on another wholly different 2 INTERNAL SECRETIONS view. In drawing a definite distinction between primary and secondary sexual characters one might intend to express the idea of an ontogenetic dependence of the second upon the first. One might imply that the formation and full develop- ment of the morphological and physiological sexual characters — and under the latter we have to reckon also the ps\^chical differences between the two sexes — depend upon the sexual gland or the primary sexual characters. One would then understand that the terms in question are not used merely as more or less conventional definitions necessary for mutual understanding, but that they in reality involve a kind of explanation of the ontogenetic origin of certain characters. There is implied in this distinction of primary and secondary characters something of the nature of a genetic system of sexual differences. Certain questions should be answered before one is in a position to group the sexual characters in such a genetic system. These questions may now be formulated. (i) Is it possible to show that certain sexual characters are in a genetic dependence upon the sexual glands, i.e., to show that the ontogenetic development of these sexual characters is influenced by the sexual glands, and that the further per- sistence of these characters depends on the presence of the sexual glands ? (2) Does the formative and preserving influence of the sexual glands concern all the sexual characters, or, in other words, are all or only some of the sexual characters in a genetic dependence upon the sexual glands ? In the latter case only a certain number of the sexual characters could be described as genetically secondary in comparison with the sexual glands. (3) If it be shown that only certain sexual characters are in a genetic dependence upon the sexual glands, there arises the question whether the formative and preserving influence of the sexual glands relates only to characters necessary for the performance of the sexual function, or whether the influence of the sexual glands concerns also other sexual characters which are in a more distant relation to the sexual function, or are in no relation to them at all. (4) How far does this genetic dependence on the sexual glands go, i.e., is a development of sexual characters for the full differentiation of which the sexual glands are necessary. SEXUAL DIMORPHISM 3 also possible to any degree at all in the absence of the sexual glands ? It will be our task in the following chapters of this book to supply answers to all these questions, basing our statements on the known data, and only after this has been done shall we have the material necessary for a genetic system. Until these questions have been answered, there can be no object gained in discussing whether or in what way we should distinguish between "secondary" and ''primary" sexual characters. Nevertheless it is desirable at the outset that we should have a clear idea as to what we mean by a "sexual character." In the present work we propose to use the term so as to include all morphological, physiological and psychological features b}^ which the individuals of one sex of a given species differ from the individuals of the other sex of the same species. It will not matter whether these distinguishing features are related to the sexual function or not. That certain features are different in the two sexes suffices to designate them as sexual characters. For us the generative cells will be sexual characters in the same sense as the penis, the clitoris, the uterus and the prostate, as the hairiness, size and proportions of the body, as voice, temperament and sexual behaviour. The problem we have to solve is the genetic systematization of the sexual characters. From what has just been said it follows that at the base of our attempt to erect a genetic system of the sexual characters we shall put the sexual glands. The justification for doing so will be apparent when we have dealt with the facts described in the following pages. These will show to how great an extent the sexual characters depend upon the sexual glands. But one realizes also at the outset, as has been clearly show^n, that the sexual glands themselves depend in their development and function upon other internal factors. The thyroid gland, the adrenals, the hypophysis, the pineal body, are in functional relation with the sexual glands and consequently with the sexual characters also. These relationships must be taken into consideration, if we are to understand the formation and persistence of the sexual characters. Now, before we are in a position to erect a scientific superstructure we require a relatively fixed point or basis on which we may start to build. This relatively quiescent basis is afforded by the sexual gland. 4 INTERNAL SECRETIONS Not until we have built up a genetic system of sexual characters on this basis will it be possible for us to approach the second great problem, the investigation of the manner in which the other parts of the organism influence the sexual gland and through them the sexual characters. Meanwhile we must also leave the question open as to whether the other endocrine glands and parts of the organism influence the development of the sexual characters directly, and if so, how this is effected. We have so far tacitly assumed that the two sexes are definitely distinguishable by morphological, physiological and psychical characters, that male and female are, as it were, like two opposite poles within the same species. But we know that there are in reality transitions between ''male" and "female," and what is still more important, that "male" and "female" organs are not mutually exclusive even in the same individual. Moreover, these matters must be taken into con- sideration in discussing a genetic system of sexual characters. Chapter 11. The Results of Castration. It is not our purpose in this book to give a full description of the results of castration. We shall describe these only in so far as is necessary for the purpose of discussing and answering the questions formulated above. So far as possible we shall base our position on investigations made in recent years, since the older observations were often ' made at random, and from an unsatisfactory standpoint. We shall include also our own observations in setting out the evidence. A. THE RESULTS OF CASTRATION IN MAN.i It is probable that the castration of bulls was universally practised wherever agriculture was sufficiently developed as to be based on the employment of animal labour. And it is at the same time very probable that the castration of animals was preceded by the castration of man himself. In any case there can be scarcely any doubt that castration of man was done in very ancient times. But what we know about the results of castration in man comes almost exclusively from observations collected in the last few decades. The older observations were made mostly on men who were castrated on account of religious beliefs. On the other hand castration has been per- formed frequently in recent times for therapeutic reasons ; for instance, in cases of tuberculosis of the testes, and for osteomalacia and different affections of the abdominal organs in women. Sometimes cases have been observed where the testes were lost by an accident, as during the late war, or owing to criminal injury. Finally, the senile atrophy of the sexual gland in both sexes may be considered as a sort of physiological castration. On the other hand, the various cases in which the testicles or ovaries are described as being ^ For references see Biedl (1913), pp. 258-279; Hofstdtter, pp. 246-267 ; Kammerev (1912), pp. 62-91; Tandler and Gross (1913); Hirschfeld (1917), Chapter I.; Koch (192 1). 6 INTERNAL SECRETIONS congenitally absent are very problematic, as Tandler and Gross have shown in a critical analysis. But a deficient development of the testicles and ovaries has often been observed; this is a matter which we shall discuss later. C. c. p. C. c. ur. Observations. The morphological and physiological changes which follow castration vary according to the age at which the organism is castrated. (a) After prepuberal castration in man {Tandler and Gross, 1909, 1910), i.e., after castration in the first decade of life, as for instance in the Russian religious sect known as Skopecs, the genital organs do not develop in a normal manner. In the adult prepuberally castrated man we find the penis, the vesiculae seminales and the prostate underdeveloped. They are abnormally small. Tandler and Gross made the interesting statement that the corpus cavernosum urethrae of such a penis attains a normal development, and Fig. 1.— Section through that only the corpora cavernosa penis fs^ye^rs'^o^.^'Tl ^^e underdeveloped (Figs. 1 and 2). The cc.p. = Corp. cav. histological examination of the prostate ?av.* urethrar^'The ^^^^^ ^ Scarcity of glandular tissue. The c. cav. ur. almost vas deferens is relatively thin, with an normally developed; muroc;a c. cav. pen. much ^^^^ mucosa. reduced.— From In the distribution and the develop- Tandie^r^ and^Gross. ^^^^ ^f ^^^ ^13,11 of the body characteristic with Fig. 2.) abnormalities may be observed. The beard does not develop {Fig. 3). Only lanugo is present on the face. But in old age there may be, according to Tandler, a development of the beard like that present in old women. Diagnostically very important is the abnormal distribution of hair in the regio pubis. In the normal man {Fig. 4) the hair in this region is limited by a convex line, and in individuals with much hair there is a triangle of hair, having this convex line as the base and the navel as the apex. On the contrary, in the prepuberally castrated man we find, as in the normal woman, an horizontal, RESULTS OF CASTRATION 7 or even a slightly concave limit of the hair in the regio pubis {Figs. 5 and 6). The rest of the body, the axillae, and the extremities are deprived of the hair normally present in the male. The skin is pale, and often swollen and creased. The subcutaneous fat of the prepuberally castrated man is Fig. 2. — Section through the middle oj the penis of a normal adult. X 3. Corp. cavernosa pen. above; corp. cav. ur. below. — Adaptation from Toldt. more developed than normally. The localisation of the fat is very characteristic, as was stated by Tandler and Gross and Hirschfeld. One finds much fat in the gluteal region, under the breasts, in the trochanters, in the abdominal wall, es- pecially on the mons veneris and on the lateral sides of the upper eyelids (Fig. 3). Hirschfeld speaks of the "characteristic slippery and fatty face of the castrated man."^ But it seems ^ Gorki gives in his memoirs ("With Strange People ") the following descrip- tion of the Skopec: " At Sarapul (on the Volga) a strange passenger came on board ; a fat man with a flabby womanish face ; the long warm kaftan resembUng a dressing gown and the fox fur cap with ear lapels made him still more womanlike. . Before Jacob (the stoker on board) went again to work I asked him what kind of a man that was. But one sees that on the spot, my dear, he answered smiling, he is a Skopec. From far away, from Siberia ! a diligent man, he has a plan of life. . . He has 8 INTERNAL SECRETIONS that there are two different types of "castrates," the fatty and the thin one. It suffices to compare the two figures {3 and 5). The skeleton of the castrated individual shows also some characteristic changes. The zone of proliferation of the epiphyses in the extremities re- mains longer than normally. Tandler and Gross observed by X-rays the persistence of the zone of proliferation in the proximal epiphysis of the humerus in a 35-years-old Skopec, of whom it was said that he had been cas- trated at the age of 8 ; the same observation was made on a 26- years-old Skopec. As the growth of the long bones is continued beyond the usual time, the cas- trated individual attains a greater height, caused by the longer growth of the under extremities. Owing to this there is a dis- proportion, the under part of the body being too long as compared with the upper part. In ten Skopecs who had an average height of 178 cm. Pittard found a length of 1 01. 9 cm. for the leg, whereas the average length of the leg in Frenchmen of the same height was 91.8 cm. {Martin, 1914). The pelvis of the castrated man has a juvenile form. The larynx of the castrated man is in its shape like a sHghtly enlarged infantile larynx, and the voice remains for the whole of life the same as in the normal boy before puberty. It is well known that the Church of Rome formerly made use of castration systematically to obtain ' soprani ' for singing. All examined Skopecs were found to have an extremely small thyroid gland. We have no exact knowledge on this point. In regard to the hypophysis we have direct knowledge only from Fig. 3. — Scopec of 28, castrated at the age of i6. Hair of head thick, but face hairless. Fat deposits in the lateral part of the eyehds. Short neck. The larynx was found to be not prominent. — From Tandler and Gross. taken me as his servant. . . Will you come with me ? He will take you also if I only say a word to him. . . . They will cut away from you what you do not need and will give you money. For them it is a matter of great rejoicing if they can maim a man, they reward him richly. . . . The Skopec stood on board with a white bundle under his arm, awkward and swollen Uke one drowned, staring fixedly at Jacob. . ." RESULTS OF CASTRATION Fig. 4. — Man of Central Europe ivith well developed body hair. Compare the hairiness of the regie pubis with that of the "castrate" (Fig. 5). — From Martin. 10 INTERNAL SECRETIONS Fig. ^. — Scopec of 24, castrated at the <^g^ oj 5- Body length 184 cm. Thin and tall. Insufficient hair on the face ; no prominentia laryngea. Extraordinarily short torso without any hairiness. More developed pubic hair with a concave line above. — From Tandler and Gross. RESULTS OF CASTRATION II Fig. 6. — Adult European woman. Compare the shape of pubic hairiness with that of the castrate. — From Martin. 12 INTERNAL SECRETIONS castrated women in whom the hypophysis was found to be greater and heavier than normally (Kon, 1908, Rossle, 1914). Tandler and Gross state that in the castrated individual the sella turcica of the base of the skull is correspondingly enlarged. It is often said that an hypertrophy of the mammae takes place after castration in man ; but it is very probable that only an accumulation of fat occurs without any hypertrophy of glandular tissue. With reference to the psycho-sexual behaviour of the pre- puberally castrated man one often reads that erection and co- habitation are still sometimes possible. Tandler and Gross observed erection in a prepuberally castrated Skopec during the examination. But on the other hand one cannot take all statements on the potentia coeundi after prepuberal castration very seriously, as every practitioner will understand; thus it is stated by some writers with absolute certainty that even after postpuberal castration erection and cohabitation do not take place as a rule after a certain time. The general intelligence does not seem to be influenced by prepuberal castration, but a certain apathy is a characteristic feature, and sometimes psychical disturbances of a not very serious character occur. Koch (1921) has re-examined the question of the condition of the Scopecs, and he has confirmed the statements of Tandler and Gross. For details the original paper must be referred to. (b) On the results of postpuberal castration we have new observations by Tandler and Gross {19 13), Magnus Hirschfeld (1916), and Lichtenstern (1916) on individuals between 21 and 46 years of age. These cases were carefully observed. An almost complete disappearance of the beard and a great change in the distribution of hair on the body are described. In Lichtenstern' s two cases, which were men of 28 and 29 years of age, these changes were already visible after four months and three weeks respectively. In all the four cases there was superabundance of fat tissue characteristically localized in the hips, in the abdominal wall, on the breasts and on the face. Hirschfeld relates of his two cases, which were men of 21 and 46 years when castrated, and were observed by him ten and three years after the operation, that the larynx was small and the voice high. The sexual libido was completely absent in all the four cases of Hirschfeld and Lichtenstern. In the case where RESULTS OF CASTRATION 13 castration was done at the age of 46, erections still occurred, but they were not accompanied by sexual sensations. On the other hand the man castrated at the age of 21 said that he cohabited every day, but that the erections did not persist for long; the orgasm took place very quickly. Some other authors also relate that erection and cohabitation are still possible after post- puberal castration {Busquet, 1910, p. 250; Oberholzer, 1912, two very careful observations from the standpoint of a psycho- analyst). It seems that in regard to sexual libido and sexual activity after postpuberal castration, great individual variation may occur. But, nevertheless, the desirability of resorting to castration should always be considered in cases of criminal sexual behaviour. I saw myself a case of this kind with good results after castration in Hirschf eld's " Institut fiir Sexual- wissenschaft." In regard to the results of castration in women the available observations almost exclusively concern postpuberal castra- tion. The data are much less uniform than in the case of the male. It is very probable that this lack of precision is due to the fact that castration in women is performed, as a rule, very late, and the external changes are of course less marked. But in all cases an atrophy of the genital organs takes place; an atrophy of the vagina and especially of the uterus. In general, menstruation ceases, although some authors relate having observed menstruation after castration. I think that they were misled by an accidental haemorrhage. A very marked accumulation of fat takes place, and we find there- fore a marked augmentation of weight. The accumula- tion of fat, however, is not present in all cases. The data on the distribution of the hair after castration are also very conflicting. In general it is agreed that the increased hair growth on the face (the beard of old women) is a characteristic feature of the castrated woman. But Tandler and Gross found also in old Skopecs a fair growth of beard on the chin and above the corners of the mouth, whereas the middle of the upper lip, the skin under the chin, the cheek and the upper part of the neck, which in normal men have a rich growth of hair, were hairless. Such an abnormally localized beard corresponds more to the beard so often found in old women (Tandler and Gross, 1910 a, p. 249). So one might suppose that the hair- growth of the aged woman after the climacteric is nothing else 14 INTERNAL SECRETIONS than a phenomenon common to the aged female and male " castrate." Some authors relate having observed an augmented growth and changed locahzation of hair also in other parts of the skin of castrated women, such as near the breasts and over the sternum. According to other observers, in the castrated woman, as in the castrated man, the hair of the body disappears. As regards the breasts, a diminution and also an augmenta- tion after castration have been described by different authors. The statements about the sexual libido are also conflicting, but it seems that it is generally diminished. As in men, a certain psychical disturbance is sometimes observed in women after postpuberal castration, whereas the intelligence, as a rule, remains unchanged. In many cases changes in the general metabolism occur in women after castration. The most remarkable phenomenon is the diminution in the oxygen used, and this results in the accumulation of fat. Sometimes one may observe changes in the calcium and phosphorus metabolism probably correlated with changes in the skeleton ; but the data are very contradic- tory. Only when castration is performed on account of osteomalacia can one state with certainty that the metabolism of calcium and phosphorus depends upon the ovary. In general, the data quoted to show the influence of castration on the different metabolic processes are so contradictory that it is impossible to give a precise description of these influences. As we said above, the cessation of function in the sexual glands in old age can also be regarded as a castration effect. In men commonly about the age of 60 or later one observes nervous troubles of an undecided nature. Much more definite are the phenomena occurring at the climacteric in women; the cessation of menstruation, the accumulation of fat, and sometimes an increase of hair on the face or the appearance of a beard. But it must not be forgotten that we have no direct evidence that these phenomena are caused by the sexual glands ceasing to function, and it is impossible to base definite conclusions as to the influence of the sexual glands in modifying the morphological and physiological characters of the organism upon this kind of observation. RESULTS OF CASTRATION i5 Theoretical. The different observations referred to above on the results of castration in man are discussed here from a more general point of view. There can be no doubt that the formation of the morpho- logical, physiological, and psychical characters of man depends on the sexual glands. There may be di,fferent opinions as to the extent of this dependence, and one cannot deny that the data relating to the results of castration are sometimes very un- certain, but on the other hand we are absolutely certain that this dependence exists. Basing his position on clinical observations, Blair Bell (1920, p. 152), takes the view that "the gonads . . . especially in the absence of active genital cells may be described as more or less indifferent organs in the matter of sex-characterisation." A similar view was recently expressed by Robert Meyer (1921), who declares that "for the development of secondary female characters, both physical and psychical, ovaries are not necessary " ; this statement of Meyer is based on observations on pseudo-hermaphrodite individuals. We shall discuss this question more fully in Chapter IX. Here it may be said that in any discussion experimental evidence must take the first place, because the conditions of experiment are more or less known to us, whereas in clinical cases the conditions are unknown. We have seen that the sexual glands influence not only the genital organs, but also sexual characters which have nothing to do with the sexual function, such as the growth of the hair, the accumulation of fat, and the proportions of the body. If castration is done at a time when sexual characters are already fully developed, the results of castration are not so marked as after prepuberal castration. But the influence of the sexual glands on the sexual characters may be observed even when castration is done very late. We see that the sexual gland does not only influence the development of the sexual characters by initiating and stimulating their growth but also by keeping them in a state of maximal development. Taking into consideration the changes in some of the measure- ments of the skeleton, the accumulation of fat and the high voice in the prepuberally castrated man, and on the other hand the beard as one of the marked signs of the woman after i6 INTERNAL SECRETIONS the climacteric, the possibiUty suggests itself that castration leads not only to the disappearance or partial atrophy of the homologous sexual characters, but also to the appearance of heterologous sexual characters. In support of this view it may be pointed out that in castrated men, even when the operation is done postpuberally, the breasts may develop in a very striking manner. But, as we have said already, modem authors seem to agree that there is only an accumula- tion of fat in the breasts and not a development of glandular tissue. Also certain measurements of the skeleton as observed in castrated men, as for instance, those of the pelvis, which appeared to resemble those of the female, are in reality infan- tile; it is the same with the voice and the sexual libido. More- over, the accumulation of fat is not a female sexual character, because it is not the fact that fat is accumulated, but rather the localization of the fat, which characterizes the castrated man. This is very different in a castrated man from what it is in a normal woman, and one cannot designate it as a female character. The only facts one might make use of in support of the suggestion that heterologous sexual characters appear after castration, are the beard and the low voice of the woman after the climacteric. But as already remarked, Tandler and Gross observed a similar beard in the castrated man. In view of these facts there can be no question of the appearance of heterologous sexual characters after castration. A similar statement may be made about animals. As stated above, the prepuberally castrated man shows a disproportion in the growth of the different parts of the skele- ton, since the growth of the bones does not stop at the normal time. It may be that the influence of the sexual glands on the skeleton is not a direct one. It is very probable that they exert their influence by the intermediation of other internally secreting glands, and this is rendered probable in view of the fact that the sexual glands react upon almost all the other glands which elaborate internal secretions (see especially Bell, 1920), and these in their turn influence the growth of the organism in manifold ways. Koch (1921), when examining the Scopecs, has especially insisted on this question. He postu- lates, hke Tandler, different types of " castrates," the one being "hypophyseal-adipose," the other "acromegaUc." According to Koch it depends upon the age at the time of castration RESULTS OF CASTRATION 17 which type will develop. I think that possibly the individual endocrine condition in general is of great influence on the results of castration. Unfortunately the mutual relations of the organs producing internal secretions are not yet sufficiently known, and at present it is only possible to discuss this question superficially. The complete elucidation of the problems involved in the study of these interrelations implies the solution of all the problems of biochemistry. Taking into consideration the fact that some sexual characters remain after castration ever after in an infantile stage, and especially that the skeleton is longer than normally in that stage, Tandler made the suggestion that some of the phenomena observed in the castrated individual are merely symptoms of a prolonged prepuberal stage ("protrahierte Unreife"), the result being that the sexual divergence is less marked in the castrated than in the normal individual. The castrated man and woman tend more or less towards a common type, that is, to a juvenile form common to both sexes, or to a form in which sexual divergence has not yet taken place (Tandler and Gross, 1913, p. 58). One might object that there are in the castrated man some features, as, for instance, the larger pelvis and the hairless face, the female character of which cannot be denied; but these features are only apparently female. Although it is illegitimate to explain all differences in body shape between man and woman by the woman remain- ing always in an infantile stage, or by the growth of the woman's body stopping earlier than that of the man, it seems certain, as Martin (1914, pp. 33 and 205) points out, that the body shape in the woman is nearer to the infantile form than that of the man. Under these circumstances one can understand that the castrated man must have some characters which seem to be more or less female, but are in reality not necessarily female characters ; they should be regarded rather as infantile, and common to both sexes. The facts recognised by Tandler and related above, compel us to believe that in the ontogenetic development of the soma there is in the beginning an asexual stage, the subsequent differ- entiation of which is caused afterwards by the formative influence of the sexual glands [Steinach, 1912, Lipschutz, 1917 and 1918 a). It is true that the results of castration in man might be interpreted differently. One might point out that i8 INTERNAL SECRETIONS some sexual characters, as for instance, the penis, the beard, and the sexual libido can continue their development to a certain degree after prepuberal castration. And after post- puberal castration the sexual characters, both physical and psychical, persist to some extent. So the sexual characters are in a certain degree independent of the sexual gland, and the influence of the latter on the former may be understood as of the nature merely of a "protection " necessary for the develop- ment of the sexual characters. This view was put forward notably by Halhan (1903). But on the other hand we must not forget that castration, even when done as early as possible, is always performed on an organism with sexual characters already partly developed, and we cannot exclude the possi- biUty that the sexual glands before removal were already able to fix, in a sexual sense, the embryonic soma. Thus the fact that some sexual characters persist after castration is no real evidence against the conception of an asexual stage in the ontogenetic development of the soma. But we must confess that the observations made on the castrated man do not supply the proof we would like to have in dealing with the question whether and how far the "castrate" approaches to a type common to both sexes, although it must be said that our conception that every sexually differentiated soma goes through an asexual stage during ontogenetic develop- ment, is not incompatible with the facts observed in man. Now the experimental investigations made with castration in mammals, and still more those in birds, give a very strong support to this conception. We shall see that for birds the existence of a common type after castration is a well- established fact, at least in regard to external appearance. B. THE RESULTS OF CASTRATION IN MAMMALS. I. Morphological Signs of Castration. Although castration was performed on mammals, such as on the bull and the horse, even in ancient times, our knowledge of the influence of the sexual glands on the development of the sexual characters of this class was not much advanced thereby. Not until lately have systematic scientific observations been made on the bull and the cow. Important data upon the question as to the results of castration have been obtained from experi- ments made on the rat, guinea pig, rabbit, dog, and hedgehog. RESULTS OF CASTRATION 19 If we perform castration on young male rats about four or six weeks old we observe very striking results on the genital organs {Sieinach, 1894, 1910). These organs are very slightly developed {Fig. 7) in the young rat. The vesiculae seminales are very small. Of the pros- tate macroscopically very little is to be seen. The penis is short and thin. The corpora caver- nosa have not yet formed the characteristic proximal part of the penis. In the full grown animal {Fig. 8) the vesiculae are enormous sacs filled by a coagulable secretion ; the pros- tate is a great lobular organ ; the penis is long and wide and can be easily protruded; the corpora cavernosa form the proximal Fig. 7. — -Normal male rat, i month old. T. = testis; Pr. = prostate (macroscopically almost invisible) ; Vd. = vas deferens ; Vs. = seminal vesicles (infantile stage) ; Vu. = bladder. — From Steinach. Fig. 8. — Normal adult male rat. Testis in the scrotal sac. Explan. signs as in Fig. 7; Pr s. = prostatic tissue around the sem. vesicles. — From Lichtenstern. 20 INTERNAL SECRETIONS part of the penis. Wholly different is the copulatory apparatus of a full grown ^'castrate" {Fig. 9). The vesiculae and the prostate are here in the same stage of development as in a four or five weeks old animal, and the penis has grown but little. I observed an underdevelopment of the genital apparatus also in white mice which were castrated by Ottow and myself, when weighing about 4.5 gr. We observed a very marked under- development of the vesiculae and of the penis. Fig. 9.^ — Male rat, 8 months old, castrated at the age oj i month. Yd. = sectioned vasa deferentia. Prostate and seminal vesicles remain at the same infantile stage as I made detailed observations on guinea pigs. The penis of an adult guinea pig, castrated when about two weeks old, is smaller than in the normal animal, but externally it has the characteristic features of the normal penis (Fig. 10). We see that the distal part of the corpora cavernosa penis, not yet formed at the time of prepuberal castration, can develop however to a certain degree (Fig. 10, D and E). This is of great interest, as the development of this part of the penis RESULTS OF CASTRATION 21 really depends on the testicle; it never attains the same size after prepuberal castration as it does during normal postpuberal development, for in the normal animal it continues to grow for more than a year after the attainment of puberty at an age of about 2^ months. The influence exerted by the testicle Aa Ab Ba Bb Ca Cb E P Fig. le- ases. sac. A. B. C. -The penis and intromittent sac of guinea pig, castrated at different Nat. size. Aa, Ba, Ca, D, E = penis. Ab, Bb, Cb= intromittent Normal, 12 months old. Castrated at 6 months, drawn at 12 months (Prot. Nr. 25). Penis shorter. Mucosa of intromittent sac ^smooth; homy styles very shortened. Castrated at i^ months, drawn 7^ months later (Prot. Nr. 15). Penis shorter than in B; homy styles invisible. Castrated at ^ month, drawn 6 J months later (Prot. Nr. 23). Penis very short, but more developed than the juvenile penis (E). Normal penis at age of J month. before castration may suffice in some instances to maintain the growth for a certain time after prepuberal removal of both testicles, contrary to what we see with the vesiculae seminales, or to what Marshall observed with the horns of sheep, which also stop their growth immediately after castration. The D. E. 22 INTERNAL SECRETIONS \ age at the time of castration is of great importance. A series of observations carried out with Bormann (1922) showed this very strikingly. In the corpora cavernosa urethrae of the guinea pig there is a bhnd sac on the bottom of which two horny styles may be seen ; in erection this blind sac is turned back like a finger of a glove {Fig. 10, Ab); the homy styles are protruded and moved rhythmically. I showed that the horny styles may regenerate to a certain degree in the normal animal; if in an animal a year old we cut away a horny style 5 or 6 mm. long, leaving only a Httle stump of less than i mm., we shall observe a regeneration of the latter to a length of about 3 mm. If now we castrate a guinea pig with horny styles of about V Fig. II. — Penis of guinea pig castrated at the age of 4^ months, drawn 2 months later (Phot. Nr. 27). Great quan- tity of preputial secretion. Fig. 12. — Seminal vesicles of a normal guinea pig 1^ years oia (Prot. Nr. 80). Nat. size. Below the vasa deferentia are to be seen. 5 mm. the latter diminish in a fev/ weeks forming finally only thin stumps of about i to 2 mm. (Fig. 10, Bb). If the RESULTS OF CASTRATION 23 castration is performed on a younger animal with horny styles about 2 mm. long, the latter diminish as far as the bottom of the blind sac, and no horny styles can be seen with the naked eye or magnifying glass {Fig. 10, Cb). In how striking a manner the result varies according to the age at which castration was performed, is also shown by our observations on the penis in general (Figs. 10 and 11) and on the vesiculae seminales {Figs. 12, 13, 14). A detailed histological exami- nation of the changes the vesiculae seminales undergo in the guinea pig after castration was made by Gley and Pezard (1921). The epithelium, normally cylindrical, becomes cubical. Fig. 13. — Seminal vesicles oj a guinea pig 21 months old castrated at the age of 2 weeks (Prot. Nr. 23). Nat. size. Fig. 14. — Sei)iuictl cc sides of guinea pig castrated at the age of 4^ months, drawn 11 months later (Prot. Nr. 27). and loses its granulation. By this fact the changes in the secretory activity of the vesiculae seminales after castration can be explained. Similar observations were made by N. F. Fisher (1923) in the rat. As was stated by Gley and Pezard and by myself, the secretion of the vesiculae seminales, which normally coagulates under the influence of the prostatic juice, does not coagulate after castration. A characteristic feature in the castrated guinea pig is the accumulation of preputial secretion on the penis {Fig. 11). The penis remains undeveloped or infantile after ptepuberal castration also in the rabbit, as was stated by Richon and Jeandelize (1903). They castrated rabbits of one to two months old, and observed them during one year. The differ- ence between the penis of a normal adult rabbit and that of a prepuberally castrated animal of the same age is extraordinarily striking {Fig. 15, B and C). The distal part of the corpora cavernosa penis, designated as a glans penis, is absent after 24 INTERNAL SECRETIONS prepuberal castration. Although the penis continues to grow after prepuberal castration, it does not acquire the character- istic shape of the normal penis. A careful investigation of the relations between the testicle and the activity of the prostatic gland in the dog has been made by Amantea (1919). D f ; jgmn^^^ Fig. 15. — Influence of castration on the rabbit's penis. A. Normal, 2 months old. B. Normal, 12 months old. (Prot. Nr. 42). C. 12 months old, castrated when 2 months old (Prot, Nr. 43). D. 12 months old, castrated when 6 months old (Prot. Nr. 56). All these experiments show that normal development of the genital organs is possible only when the sexual glands are present in the organism. But I have mentioned already that there is a diminution of the length of the horny styles also after postpuberal castration in the guinea pig. An even more striking instance of this kind is presented by observations made on the penis of rabbits postpuberally castrated. ^At the time of the operation the penis was fully developed, having attained the characteristic shape of the normal adult animal; RESULTS OF CASTRATION 25 about three months later the degeneration of the penis pro- ceeded so far that it more or less resembled that of a pre- puberally castrated rabbit (Fig. 15, D). It is of great interest to notice that the penis remains sometimes almost unaltered during one or two months after castration to undergo after- wards a more or less rapid and almost complete atrophy of the Fig. 16. — Influence oj prepuberal castration on the uterus oj rabbit, A. Uterus and tubes of normal rabbit (Prot. Nr. 129) 8 months old. B. Uterus of rabbit of the same litter castrated at an age of 2 months and 10 days (Prot. Nr. 127). distal part of the corpora cavernosa penis. We see how different are the reactions of the various parts of the organism to the removal of the testicles. Observations made on female mammals^ also showed that after prepuberal castration the genital organs cease to develop. The difference between the uterus of a normal and that of a prepuberally castrated rabbit is very striking, both macro- scopically and microscopically (Figs. 16 and 17). There is an underdevelopment both of the mucosa and of the muscle *See the books of Biedl, Kammerer, Tandler and Gross, especially Carmichael and Marshall (1907) and Marshall (1910), Ch. IX. 26 INTERNAL SECRETIONS Fig. 17. — Histological features of the uterus of normal and castrated rabbits (Prot. Nr. 129 and Nr. 126, both of same litter). A. Section through uterus; low magnification. All layers of the uterine wall (mucosa, muscularis) are highly reduced in the castrated animal. RESULTS OF CASTRATION C B 27 f ? Fig. 1 7. — Histological features of the uterus of normal and castrated rabbits (Prot. Nr. 129 and Nr. 126, both of same littei). B. The uterine mucosa; high magnification. No folds of mucosa in the castrated animal. C. Muscular wall; high magnification.— Prepar. of Wagner; design of Lehbert. 28 INTERNAL SECRETIONS layers. Glands are absent in the mucosa and the epithelium is flattened. The muscle layers are several times thinner than in a normal uterus. The vascularization of the uterus is also diminished. Similar observations have been made on guinea pigs, on rats, and on the cow. Athias (1919) has shown in experiments on the isolated uterus of guinea pigs that the uterus after castration is functionally different from the normal one; the intensity of the spontaneous contractions of the uterus decreases after castration or they ma}' even disappear. What is stated about the features of the mammary glands of animals after castration is just as contradictory as in the case of man. Sellheim (1901) described in calves castrated at six or eight weeks of age an augmented growth of the mammary glands, both nipple and glandular tissue. The older the ox is the more striking is the difference between it and the bull, the nipples of the ox being longer and broader, the glandular tissue showing microscopically a richer development in the ox than in the bull. Even milk secretion after castration is reported. In male guinea pigs and rabbits prepuberally castrated, I never could observe an increased growth of the nipples; but the question is worth further investigation in regard to the microscopical character of the glandular tissue. Very con- tradictory, also, are the statements made on the mammary gland after castration in the female mammal. Halban and Steinach found that the mammary gland of prepuberally castrated guinea pigs remained undeveloped. But some authors seem to have observed that after postpuberal castra- tion the mammary gland not only persists, but can even increase and secrete colostrum (Kammerer, 1912, pp. 108 and 109). I think that a mistake may have occurred here, as small particles of ovarian tissue left unintentionally in the body can replace functionally the whole ovary, and they can grow and even undergo a very marked hypertrophy, as w^as stated by Car- michael and Marshall (1908) and confirmed by myself (1922). In prepuberally castrated animals heat never occurs; the genital organs not being fully developed cannot undergo the characteristic cychcal changes. With postpuberally castrated animals the data are contradictory, as they are with those on menstruation in women. But in general it seems that investigators have not directed their attention in a suffi- cient manner to this question in mammals. Marshall affirmed RESULTS OF CASTRATION 29 definitely that heat does not occur in the hedgehog when postpuberally castrated. A great number of observations have been made on the growth of the skeleton in the castrated mammal. These observations have shown that different parts of the skeleton react to castration in a different manner. This explains why the skeleton as a whole has other proportions than normally, and even each single bone. As in man, so also in certain mammals the bones of the extremities are longer, this having been shown by measurements on guinea pigs and rabbits. Fig. 18. — Profile of normal and castrated cows. Normal, average of 100 animals; castrated, average of eleven animals. — From Tandler and Keller. though the differences may not be very significant, as in the experiments of Moore (1922) on guinea pigs. As in man this phenomenon is presumably caused by the more prolonged persistence of the zone of proliferation. Observations on the skeleton after castration have been made also on the dog, sheep and ox. The observations of Tandler and Keller, who measured a great number of normal and castrated cows and bulls, are very important. They found striking differences in the height of the normal and of the castrated cow. Out 01 eleven castrated cows ten attained a height of 140 cm. or more; out of 250 normal animals only four attained this height (Fig. 18). The greater height is due to the longer extremities. Very careful investigations have been made also on the skull of the castrated mammal. Tandler and Keller (1910) stated that the very striking sexual divergences in the size INTERNAL SECRETIONS Fig. 19. — Pelvis of a new-horn Fig. 20. — Pelvis of a new-born male lamb. female lamb. Great similarity between male and female. The female pelvis somewhat bigger, but relative proportions identical. — From Franz. Fig. 23. — Pelvis of a ram castrated at an early age. RESULTS OF CASTRATION Pelvis of an adult ram. Fig. 2 2. — Pelvis of an adult sheep. Very pronounced differences between both sexes. — From Franz. Fig. 24. — Pelvis of a sheep castrated at an early age. The castrated animals were of the same age (2 years) as the normal ones in Figs. 21 and 22. Great similarity between the male and female castrate. — From Franz. D 32 INTERNAL SECRETIONS and shape of the skull in horned cattle are much less marked after prepuberal castration, there being a great resemblance in the size and shape of the skull in the castrated cow and the ox. The ox and the castrated cow are very similar also in the proportions of the body. Castration leads, according to Tandler and Keller, to a convergence of both sexes. The skeletons of the castrated cow and bull represent something like an asexual type. These statements of Tandler and Keller are in accordance with those made previously by Franz (1909) on the pelvis of the sheep. Franz examined the pelves of new-born lambs and of fully grown male and female sheep ; he found no striking sexual differences in new-born lambs, whereas the pelvis in fully grown sheep was very different in both sexes {Figs. 19-22). These differences are due to variation in the size and shape of the bones which compose it. But in male and female sheep which were castrated soon after birth, Franz found the pelvis two years after the operation, i.e., at a time when the growth of the animal is completed, very similar in castrated animals of both sexes (Figs. 23 and 24). The figures leave no doubt about the tendency of the pelvis of the castrated male and female to approach a common form or an asexual type. If a small particle of the ovary remained in the body the pelvis developed normally. There can be no doubt that in mammals there is no develop- ment of characters characteristic of the other sex after castration. On the contrary, what we see in mammals gives us new and important evidence that castration, performed at an age when sexual characters are not yet very marked, leads the organism to a form common to both sexes. The obser- vations of Franz on the pelvis, and of Tandler and Keller on the skull, are very important in this connection. ^ It may be also that the observations made on the mammary gland of the ox where an increased growth was recorded, and those on the mammary gland of the cow where an underdevelopment occurs, can be taken as further evidence for the conclusion of Tandler and Gross. But for the mammary gland the question would appear to be not yet decided. (For the castrated deer see Tandler and Gross, 1913, pp. 31-40). *New important data as to this were given by Zawadowsky (1922). RESULTS OF CASTRATION 33 As in man changes in the hypophysis after castration have T^een found in the rat, guinea pig, rabbit, horned cattle and buffalo. An increased volume and weight and characteristic histological changes have been recorded. (See especially Schoenberg and Sakaguchi, 19 17). For the changes occurring after castration in the other glands of internal secretion, such as the thyroid, the pineal, the suprarenals, the thymus, BelVs book (1920, pp. 38-46) may be referred to. According to Ocaranza (1921, 1922) a diminu- tion of the number of the red corpuscles occurs after castra- tion. Transplantation of testicle induces an increase in the number of red corpuscles. But these changes are transitory. As already said, the changes in the skeleton as observed after prepuberal castration, and characterized by Tandler and Gross as a prolonged infantile stage, are probably caused through the intermediation of the internally secreting glands. The question of the mutual relations between the sexual and other endocrine glands is of great importance in relation to the physiology of growth. A great many observations have been made on the meta- bolism of the castrated animal, but little definite knowledge -exists on this subject. The accumulation of fat, however, may be mentioned. In prepuberally and postpuberally castrated male rabbits I found six to sixteen months later enormous quantities of fat in the abdominal cavity such as I never saw in normal males ; the quantity of the fat in the ab- dominal cavity represented as much as 10 % of the body weight, whereas in the control animal of the same litter less than 3 % of fat was found. The greater weight of the ''castrate" seems to be due according to my weighing, especially, if not "exclusively, to the accumulation of fat. Moore's papers (1919, 1922) may be referred to, but further data are needed on this point. 2. The Psycho-sexual Behaviour of the Mammal. Besides the morphological changes a series of changes in the psycho-sexual behaviour also has been recorded in the castrated mammal.^ As far as I know the first systematic ^ To simplify matters we will call all morphological and physiological charac- ters alike physical or somatic. By "psycho-sexual behaviour" we mean all the reactions brought about by the intermediation of the nervous system. 34 INTERNAL SECRETIONS observations on the psycho-sexual behaviour of the castrated mammal were made by Steinach (1894; see also Exner, 1903, p. 221). He records that male rats castrated at an age of 45 days first showed signs of sexual activity at the ninetieth day, i.e., at the same time as a normal control animal. They recognised a female "on heat," followed her in the same manner as a normal male would, and even made some attempts at coitus. But erection was only rarely to be observed. With a normal strange male the "castrates" fought less vigorousl3\ After a space of a year even these traces of a diminished sexual activity disappeared. I have made some observations, but not very systematically, on prepuberally castrated guinea pigs. If a female is put into a cage with a normal male, the latter recognises her b\^ smelling her body in the neighbourhood of the vulva ; a similar behaviour on the part of the normal male may be observed even when the other animal is also a male. If the strange animal is recognised as a female, she will be followed by the male, who makes attempts at coitus. The normal male shows great tenacity in following the female guinea pig and making these attempts. The prepuberally castrated male, on the other hand, shows no such tendency. Sometimes the "castrate" will fight with the female, but often he \vill display no excitement whatever. I once witnessed the following scene. A female, probably on heat, was followed by a normal male with great tenacity. When the normal male was taken away, and replaced by a castrated male, the latter remained quietly in a corner. The female approached him, and even bit his fur, but without any result ; the "castrate" remained as quiet as before. A "castrate," if put with a female together with a normal male, will be recog- nised sooner or later by his want of sexual interest. If attempts are made by the castrated male to follow the female, the normal male will interfere, and the "castrate" will soon become quiet. He will only fight if attacked. Nevertheless, castrated animals sometimes fight together in the presence of a female. There can be no doubt that postpuberally castrated males may show sexual behaviour for a considerable time. Steinach records normal sexual libido in rats four, or even six, months after csLStrsition; IJchtenstern (1916a) confirmed these observa- tions. Faure in our Institute observed sexual activity in RESULTS OF CASTRATION 35 postpuberally castrated rabbits about two months after the operation. But eventually the postpuberally castrated animal also will lose its sexual activity; about three months after the operation adult castrated male rabbits can be distinguished from normal males. All these experimental observations are in accordance with those upon male domestic animals, in which after prepuberal castration sexual activity disappears after a certain time. Horses postpuberally castrated lose sexual activity after about two or three years. According to French military veterinarians about 2 or 3 % of castrated horses continue to show sexual activity, and even undergo coitus with sterile ejaculations. Busquet (19 10) whom I quote, thinks that possibly another organ replaces the sexual glands in these cases; but this suggestion is not supported by evidence. The psycho-sexual behaviour of man and mammals is very different according to the age at which castration was performed and according to the period of time after castration. The older the animal at the time of castration and the shorter the period after the operation, the greater the probability that some signs of sexual activity may continue. There can, however, be little doubt that castration generally leads to disappearance of sexual activity in the horse as in other mammals. It now seems certain that the sexual glands not only are responsible for the development of the psycho-sexual be- haviour, but also for its continuance after full puberty is attained. Prepuberal castration admits of the existence of a rudimentary sexual behaviour; when castration is done after the psycho-sexual behaviour has been fully developed, the influence of the sexual glands exerted hitherto evidently suffices for its continuance for some time; possibly because certain reflex actions which lay at the root of the sexual behaviour are more or less fixed under the influence of the sexual glands. But, as already said, sexual activity eventually ceases soon after postpuberal castration. There seems to be some difference between man and animals in this respect, sexual activity continuing longer and being more frequently displayed in the former than in the latter. I think that this is to be explained by the reflex actions responsible for erection and coitus being fixed and brought into play in the normal man by more manifold external factors than in the lower 36 INTERNAL SECRETIONS mammal. These external factors seem to be very uniform in the latter, and olfactory stimuli play an important part. Steinach records an experiment in which he smeared the labia of a female rat with a mixture of cod liver oil and paraffin, with the result that this female was not followed, and coitus was not attempted with her by a bhnd male until the labia were cleaned with soap, when the male once more showed sexual excitement in her presence. On the other hand the sexual reflexes in man are put in action by many different stimuli. It seems that in man any external stimulus may excite the sexual reflexes. This is due to the high psychical de- velopment of man. Sexual fetishism finds its roots therein, being some kind of a "conditional reflex" in the sense of Pavlov. So it is not difficult to understand that sexual activity may persist some time in man after postpuberal castration, and a priori one would expect to find sexual activity even in the postpuberally castrated man more often and more markedly than actually is the case. Persistence of some signs of the sexual activity which diminish very slowly after postpuberal castration is by no means incompatible with the contention that the erotization of the nervous system (Steinach, 1910) depends upon the sexual glands. What we said about the influence of the sexual glands on the development and the maintenance of the sexual reflexes in animals and in man is also true for the heat of mammals so far as it concerns changes in the psycho-sexual behaviour during this period. In experiments with female hares Bucura (1913, p. 22) show^ed that after castration heat never occurred. In experiments made with normal male rabbits and females castrated prepuberally Lacassagne (1913, p. 218) never saw signs of heat. As already mentioned, Marshall could prevent heat in the male hedgehog by removal of the testicles. C. THE RESULTS OF CASTRATION IN BIRDS. Observations. Castration has been performed for a long while on the cock for economic reasons. Systematic experiments on the cock have been made by Sellheim, Foges, Poll and others. But nevertheless there has never been complete unanimity con- cerning the results of castration. As Goodale (1916, p. 27) RESULTS OF CASTRATION 37 pointed out, this is probably due to the fact that the various authors have not always taken into consideration the differ- ences between the races and the variation present among normal birds of the same race. It is also very probable that in the older experiments the sexual glands were not always removed completely. In recent years Pezard (1911, ^ 6 / y / / ^ / 1 30 / / / / 1 1 0 J / J / \ y / / r—" — - / / 70 / 60 X / ,/ y 1 50 40 ^ / ) 20 ^ ^ ^ ^ ^ 0 Oper ation ^ ^ ^ ^" VF comb sex inst. months 3 + 56789 10 11 12 1 23 5 6 7 8 9 10 11 12 Fig. 25. — Growth of comb and spurs in the normal and in the castrated cock. No difference in body growth expressed in increase of 3 of the body weight P. The gro-wi:h of the comb in the normal cock does not accord with the body growth, but it does so in the capon. No influence of castration on the growth of spurs. Crow and sexual instincts absent in the capon. — From Pezard (changed). 1918) and Goodale (1913, 1916) have recorded successful ex- periments in which cocks were completely castrated. The interest of those who made the experiments on birds was directed especially to the external sexual characters. Pezard castrated cocks at the age of three months, when the external sexual characters, the comb, wattle and barbies, spurs and male plumage are not fully developed (Leghorn and 38 INTERNAL SECRETIONS Orpington). Pezard showed that the comb grows after pre- puberal castration, but that the curve of growth is very different from that of the normal animal. He compared the curve of comb-length at different ages with the curve of the cubic root of the body weight, so as to have a linear measure for comparison, and stated that these two curves are different. On the contrary, the growth of the comb of the castrated animal accords with that of the body as a whole {Fig. 25). This being so, the relation of the length of the comb / to the cubic / root of the body weight P, or -3-7: will remain unchanged ^ P during the whole development in the "castrate," whereas in the normal animal it wall increase very markedly. The Fig. 26. — Comb of normal and castrated animaJs in Brown Leghorn, a = adult cock; b and c = adult hens; d = adult capon. — From Goodale. characteristic divergence begins at the time when the sexual differentiation in the normal bird commences. This apphes also to wattles and barbies. Comb, w^attles and barbies are not only smaller in the capon, but also bloodless and thin. Very detailed observations on the head apparel of the castrated cock were made by Goodale, especially on Brown Leghorns castrated at an age of about three or four weeks. Goodale also found that the comb increases in length in the same pro- portion as the head as a whole ; he points out that the growing comb of the capon is not feminine but infantile, and does not attain the measurements of the comb of the female of this race (Fig. 26). However, by comparing the comb of a Brown Leghorn capon with that of a Plymouth Rock female, which RESULTS OF CASTRATION 39 has a comb much smaller than that of a Leghorn female, one might erroneously suppose that the capon had a "female" comb. Unlike the head apparel, the spurs of the cock are not influenced by castration. All the animals castrated by Pezard and Goodale had spurs of the same length as those of a normal animal. Some authors report having observed an under- development of spurs in the capon. But, as Goodale points Fig. 27. — A Brown Leghorn capon, 3 years old. He is known to be completely castrated. Undeveloped head apparel, but normal spurs, and brilliant male plumage. — -After Castle (photo kindly lent by Goodale). out, this has nothing to do with castration, as underdevelop- ment of spurs sometimes occurs in uncastrated cocks, especially in the Brahma and related breeds. The plumage of the castrated cock is in its general appearance unchanged, or it may be even more richly developed than in the normal cock. This fact has been recorded more or less definitely by Sellheim (1898) and Foges (1903, p. 42 and 19 14, p. 378). Pezard and Goodale showed that the castrated cock 40 INTERNAL SECRETIONS always keeps the male plumage. Pezard found the taiJ feathers of the capon to be sometimes better developed, shinier, and brighter in colour than in the normal male. Similar observations were made on the other feathers of the capon by Goodale. From his own observations Goodale says that if it were not for the narrow comb and barbies the capon would have the appearance of a normal cock {Fig. 27). Pezard records a further observation illustrating in a striking manner the absence of dependence of the male plumage upon the sexual glands ; his capons moulted a year after castration, and again acquired a male plumage. As regards the growth of the skeleton, Sellheim found that it is influenced by castration in many ways. Pezard found the neck and the body of the capon to be longer than in the normal cock. Goodale also records that the capon is larger than the normal animal. Sellheim states that the body weight of the full grown capon is about 25 % more than that of the cock. But the greater weight of the capon is due mainly to the greater accumulation of fat, which explains the fact that in relation to the weight of the body as a whole that of the internal organs, such as brain and heart, is smaller than normally. The accumulation of fat is recorded also by Foges, and especially by Pezard, who stated that the quantity of fat is very great. Whereas the fat in the abdominal wall, i.e., the fat remaining after the abdominal organs have been taken away, in a normal animal weighs about 10 to 60 gr., the capon's fat weighs about 90 to 250 gr. The hypophysis of the castrated cock was found by Fichera to be twice as large as in the normal animal. The vas deferens seems to undergo a marked atrophy. As a rule Goodale could not find it in the capon; sometimes it is represented by a thin streak of tissue. The changes in the psycho-sexual behaviour caused by prepuberal castration of the cock are evidently more marked than in mammals, although the statements of different authors are sometimes conflicting. As a rule the capon does not crow, and he does not fight with cocks; he shows no interest in the hens and does not tread them. So one may say that the capon in a general way loses the psycho- sexual behaviour of the cock. But Sellheim says that the crow of the capon is hoarser, and shorter than that of the RESULTS OF CASTRATION 41 cock, but that he fights hke the cock. Pezard's records are more definite; according to him the capon does not even crow Hke a cockerel at the time of the sexual metamorphosis ; the cry of the capon is rather like the monosyllabic clucking of the hen ; the capon is tame, peaceful and apathetic. Pezard never observed a cock fighting with a capon, as the latter retreated when the cock approached. The behaviour of the capon is, in a general way, a neutral one, as Pezard says. He does not seek the hen, and never shows sexual interest. Pezard also found no evidence for the statement that the capon some- times shows female instincts. In view of all these observations of Pezard we may conclude that in the prepuberally castrated cock a male psycno-sexual behaviour does not develop. It is a b c d s- Fig. 28. — Head apparel in the cock castrated when one year old. a = at time of operation; b = 26 da3"s after operation; 0 = 36 days after operation; d = 3i months after operation.- — From Pezard. probable that the differences in the statements of the various authors as to the psycho-sexual behaviour of the capon are to be explained by castration not always being complete. Some experiments of Foges, Pezard, and Goodale support this sugges- tion; consequently the results of castration may be partly counteracted. But Foges points out that the amount of testicular substance must not be too small if they are to produce a visible effect ; his observations in regard to quantity, however, are not very definite. Similar observations have been made by Shattock and Seligmann (1904), and lately by Pezard; we shall deal with this question of the relation existing between the quantity of the sexual gland and its effect in another chapter, where we shall describe also our own observations on mammals. 42 INTERNAL SECRETIONS As concerns postpuberal castration of cocks, Poll (1909) described an atrophy of the comb and wattles, but no change in plumage. Pezard (1912, 1918, pp. 57-82) made similar statements (Fig. 28) and studied the atrophy of the comb in the piostpuberally castrated cock from an exact quantitative point of view. If the castration is a complete one, the results of the operation may be observed after a few days. For details the original papers of Pezard may be referred to (1919, 1920, 1921). Besides the atrophy of the erectile organs, the capon ceases to crow and loses its sexual instincts. i\s with the plumage, there are also no changes in the spurs. If the castration was an incomplete one, atrophy of the sexual characters does not occur. ? Fig. 29. — Ovariotomized pullet. Male plumage and spurs. Compare with Fig. 27; great similarity between castrated cock and castrated hen. — Reproduced from a coloured plate of Goodale's. In view of the intimate relation between the sexual characters and the sexual glands in mammals it may seem difficult to explain why some of the sexual characters such as the plumage and the spurs develop independently of the sexual glands. But this can be understood if we compare the castrated cock with the castrated hen. Goodale (1913, 1916) castrated Brown Leghorn hens at an age of four weeks to four months. These hens acquired a male plumage. The plumage was more like that of a capon than that of a normal cock, the feathers being longer. Spurs were developed. So the castrated hen is in her external appearance RESULTS OF CASTRATION 43 mistakably similar to a castrated cock {Fig. 29). A more or less marked change to apparent maleness was observed by Goodale in 25 castrated hens. Similar results were obtained by Pezard (1914, 19 15, 19 18) in hens castrated when a few months old. The spurs of these birds about a year after the operations were 2.3 cm. long, i.e., they grew with the same rapidity as in a normal cock. At the time of moulting a change in plumage occurred, the castrated hen acquiring the plumage of a cock (Fig. 30). The characteristic feathers of the neck, the back and the tail were present. And as Goodale and ^ Fig. 30. — Hen castrated four months previously. Male plumage (feathers of neck, back and tail) and spurs. — From a photo of Pezard 's. Pezard point out, a castrated hen differs externally from a normal cock only in the smaller comb and in the wattles and barbies. If one does not know the history of such a bird, one cannot decide upon its external appearance whether it is a castrated hen or a castrated cock. Goodale quotes also ex- periments of Guthrie (1910), in which the castrated hen likewise acquired a male plumage. The oviduct was always found by Goodale in the castrated hen. He stated that the oviduct was larger than in the young chick, corresponding in its dimen- sions to the increased size of the bird, but was otherwise 44 INTERNAL SECRETIONS entirely infantile. As regards sexual instincts Goodale and Pezard agree that they are absent in the castrated hen. After partial resection of the ovary no castration results occur if the remaining particle is not too small. It seems that small particles of ovarian tissue left in the abdominal cavity can hypertrophy and counteract the results of castration. Similar observations to those on domestic fowls were made on other birds with very marked sexual differences. Pezard (1911, 1918, ch. V.) castrated golden and silver pheasants at an age at which male sexual characters were not yet developed. Fig. 31. — Normal Rouen duck. — From a coloured plate of Goodale's. The growth of the spurs was not inhibited by castration; after moulting the animals acquired a male plumage. The erectile head apparel did not develop in the silver pheasant, and sexual instincts were absent. Fitzsimons (1912) has described an ostrich hen with male plumage after castration. Somewhat more complicated is the case of the duck, on which Goodale (1910, 1916) made very extensive experiments. Female Rouen ducks castrated when a few weeks old acquired a male plumage (Figs. .31-33), and after moulting invariably assumed a fresh male plumage. In one experiment the female duck acquired even a voice that was more or less like that of a male. On the other hand the drake keeps his male plumage after RESULTS OF CASTRATION 45 it^-^ ^pp. 230-231) {Figs. 35 and 36). Also the muscles of the fore arm hypertrophy {Nussbaum, 1912). Amongst the changes in the sexual organs the increase of the vesiculae seminales must be mentioned. Functional signs of the oestrus are the <:haracteristic sound of the male and the clasping movement or reflex. This reflex of the male in heat is highly developed; in the breeding season males may be often found embracing dead fishes or pieces of wood. The clasping movement can be evoked at once when the skin of the chest is touched by the finger. The male presses the tuberculate pads on to the chest of the female, and the skin of the latter will be often found rubbed through to the muscles. All the above-mentioned characteristic signs of the oestrus fail to develop if the animal has been castrated some time or other after the last oestrus. The vesiculae seminales remain -small, the pad does not develop to the normal size, and the clasping reflex does not develop to the normal degree {Nussbaum, 1909, pp. 530, 532, 534; M eisenheimer , 1912). Steinach (1894, pp. 313, 314) castrated a number of specimens 52 INTERNAL SECRETIONS of Rana temporaria in the first days of January, whereas the control animals were dealt with by a simple laparotomy, the testicles remaining intact. Early in March the control animals began to embrace spontaneousl3\ On the other hand, not one of the castrated frogs embraced spontaneously. Harms (1914, pp. 175, 176) stated that the castrated male makes the oestral sound only alter artificial irritation of the skin ; then a dull, hoarse noise can be heard. V-^ . '/•' % Fig. 35. — Pad of male Rana temporaria in July, after period of heat, x 80. — Prepar. of Wagner; photo, of KuU. A dependence of the oestral characteristics on the sexual glands has been observed also in other Amphibia. Bresca (1910) has shown that the atroph}^ of the nuptial apparel of the triton can be accelerated if both testicles are removed. Recently Avon (1921, a, b) has investigated this question in a more detailed manner. He performed bilateral castration just at the beginning of the breeding season; the development of the nuptial apparel was stopped, and it atrophied rapidly. If castration is done when the nuptial apparel is alread}^ fully RESULTS OF CASTRATION 53 developed, the atrophy is completed in about three weeks. There can be no doubt that here cyclical oestral changes are caused by the testicle. We have seen that man and mammal can be deprived of certain sexual characters by means of castration, but that other sexual characters may be preserved after castration, at least to a certain degree. It is the same with the frog, as shown by observations of Goltz, Nussbaum, Steinach and Harms. Goltz (1869) mentions that copulation does not cease Fig. 36. — Pad of male Rana temporaria in April, at time oj heat, x 80. Epidermis thickened, glands increased. — Prepar. of Wagner; photo, of Kull. after castration. Nussbaum (1912, p. 47) stated that males castrated during the breeding season embrace immediately if placed on top of the female. Steinach (1910) found that the clasping reflex disappears in the course of days or weeks, but returns later, though to a decreased extent; spontaneous embracing in the "castrate" seems no longer to occur at all. Also the pads of the "castrate," according to Harms (1910, p. 35) and Steinach, show an enlargement, which reappears periodi- cally in the breeding season. But this enlargement of the 54 INTERNAL SECRETIONS pads, though microscopically easily visible, is not to be com- pared to that observed in the normal animal during oestrus. Speaking generally then, we see that in amphibians the development and the maintenance of oestrus depend on the sexual gland. Though the cyclical changes take place to a certain degree after castration, whether carried out before or during the oestrus, a normal oestrus will never recur. According to Kammerer (19 19, p. 341) it is not the same with the male of Alytes, in which a pad on the fore limb was produced under conditions of experimental breeding. When Kammerer forced the frog to spawn in the water, the males of the next genera- tion got pads. If male Alytes bred in that way are castrated, the oestral pad reappears nevertheless at every oestral season. Kammerer concludes from his experiments that in Alytes the regeneration of the pad does not depend on the sexual gland. But I think that the question of the inheritance of acquired characters is such a complicated one that it would be unwise to draw from Kammerer' s experiments any definite conclusions concerning the dependence or independence of oestral changes in relation to the sexual glands in amphibians. If we compare these data upon the dependence of the oestral phenomena on the sexual glands in Amphibia with what we learned as to the significance of the sexual glands in relation to the development and the preservation of the sexual characters in man, mammals and birds, we find a parallelism in the behaviour of the different species. In some cases the sexual characters are dependent on the sexual glands, but in others the sexual characters may continue to exist or even develop further after castration. Also one might suppose that these apparently independent sexual characters — the c^^clicaUy reappearing weakened embracing-reflex, the formation of the pad — were already established by the formative function of the sexual glands at the time when the castration was done. Observations on fishes have been made by Koped (19 18). He castrated the common fish Phoxinus laevis, which exhibits in the spring a red nuptial colouring in the back, both in the male and female. The animals survived the operation only for three weeks, but results of castration were obvious. In two series of experiments out of 30 animals castrated in April and March only 7 exhibited the nuptial colour, whereas out of 18 partially castrated animals (half a testicle on each side RESULTS OF CASTRATION 55 having been removed) 16 developed normal colouring. Like- wise out of 18 normal control animals kept under the same external conditions, 16 developed normal colouring. In a series operated upon in March, there was no nuptial colouring either in the castrated, or in the partially castrated and control animals; Kopec explains the failure of this series by the assumption that in these animals caught so early, the gonads did not attain maturity in confinement. That some castrated animals of the April and March series exhibited nuptial colour, may be due according to Kopec to the fact that at time of catching there was already a beginning of nuptial colouring, or, in other words, that at that time the gonads were already more or less developed physiologically. There can be scarcely any doubt that nuptial colouring in fishes depends upon the sex glands. E. THE RESULTS OF CASTRATION IN ARTHROPODA. I. Moths. ^ Castration experiments in moths have been made by Oudemans, Kellogg, Meisenheimer and Kopec on Lymantria dispaVf the silk-moth (Bombyx mori) and other species in which the sexual dimorphism is well marked. Both cater- pillars and moths were castrated; the sexual glands were removed with scissors or burned out with a hot needle or a galvanocautery such as is used for medical purposes. All the investigators agree that the formation and persist- ence of the sexual characters in moths are quite independent of the sexual glands. The internal and external copulatory organs developed normally in "castrates," although the differ- entiation of the copulatory apparatus and of the excretory ducts occurred long after the operation {Meisenheimer). The colour, size and form of the wings were normal, even when the caterpillars were castrated immediately after the first desquamation. If together with the sexual glands the wing rudiments on one side are removed, as was done by Meisen- heimer, a more or less complete regeneration of the wings occurs. The regenerated wings are of the normal appearance, ^ Kope6y 1912; Meisenheimer^ 1909; Harms, 1914, pp. 139-155; Kammerer^ 1912, pp. 109-115. 56 INTERNAL SECRETIONS characteristic of the sex, although they develop in an organism deprived of the sexual gland. Also the antennae and the shape of the abdomen are normal in the "castrate." It is the same with the sexual instinct and the instinct for progeny rearing. Copulation is performed by the male in a normal manner, and both normal and castrated males copulate also with castrated females. The castrated female of Lymantria dispar prepares for the reception of the eggs in the usual manner after copula- tion, although no eggs can be laid. From these results the authors unanimously concluded, as already mentioned, that the sexual characters in butterflies do not depend upon the sexual glands, and from these results they drew conclusions also upon the Vertebrata. We have seen that some sexual characters in man and mammals re- main more or less unaltered after castration, and this fact suggests the possibility that the sexual characters may be to some extent independent of the sexual glands, as was suggested more particularly by Halban. It is possible, how- ever, to raise objections to the conclusions reached about insects, and these we may now consider. Firstly, one might object that the castration was done too late, at a time when the sexual characters were already fixed by the influence of the sexual glands; further, such a fixation might be a latent one. We know from the experiments with man and mammals that the sexual characters show more independence of the sexual glands both in regard to their formation and their preservation, the later the castration is performed. Herhst (1901, p. 80) has raised this objection against the experiments of Oudemans. Meisenheimer and Kopec, however, castrated their caterpillars at a very early stage of development. Furthermore, the objection is weakened also by the experiments of Meisenheimer mentioned above, in which together with the sexual glands the wing rudiments were removed. The regenerating wdngs were not subjected at all to the influence of the sexual glands during their develop- ment; nevertheless they showed the characteristic features of normal male and female wings. A second objection has been discussed by Kammerer. He argues that the castration was possibly not a complete one. We shall see later on how important such an objection might be when considering the question of the formative action of the RESULTS OF CASTRATION 57 sexual gland from a quantitative point of view. But this objection is scarcely valid against the conclusions of Meisen- heimer and Kopec, as they carefully examined the internal organs of their experimental animals . The same ob j ec tion was made by Kammerer to the experiments of Regen on crickets.' The grubs developed into animals with fully developed sexual characters. Still a third objection remains to be considered, and this is one which was pointed out by Kammerer, and which might be much more weighty than the previous ones if it were based on definite facts. The zoologists who experimented on moths have described certain somatic changes after castration. One might be tempted to explain these changes which do occur as due to a lack of a specific influence on the part of the sexual glands. In Lymantria dispar castrated by Meisenheimer, there were changes in different parts of the internal sexual apparatus such as the oviduct, the receptaculum seminis, and the vas deferens. It is, however, impossible to conclude from these changes that the formation of the respective organs is influenced in a specific manner by the sexual glands. These changes do not occur constantly. Kopec found further that the}^ are present after unilateral castration only on the operated side. Kopec explains all these changes as due to the modified mechanical relations after castration. According to Kopec this is particularly clear in the female, in which a good deal of space is set free in the abdomen by the removal of the ovaries. Lesions of the internal sex-apparatus, made during the opera- tion, may also be of importance. Meisenheimer found further changes in the colouring of the wings after castration. A darkening of the wings which are normally white could often be observed in castrated females of Lymantria dispar. In the castrated males the wings, which are normally dark, became lighter. Meisenheimer, however, could bring about this change in the wings of the male by starving the normal caterpillar. These pecuharities of the wing colouring, therefore, are to be explained as due to external factors. Kopec came to the same conclusion. After all there can be no doubt that in moths the sexual characters are by no means dependent upon the sexual glands. The external appearance, the internal and external sex-apparatus, the regenerating wings and antennae, and the psycho-sexual behaviour are not influenced in their formation by the sexual glands. 58 INTERNAL SECRETIONS We have seen that in many species the sexual characters are fixed during ontogenetic development by the action of the sexual glands, so as to acquire finally a relative independence of the sexual glands. One might suppose that such a fixation of sexual characters takes place also during phylogenesis; the sex characters in such cases would be wholly independent of the sexual glands. This hypothesis has been put forward by Oudemans, in order to explain why the various species differ from one another in the degree to which the formation of the sex characters depends on the sexual glands. But Herbst has pointed out, for good reasons, that in this conception one is making the old mistake into which investigators who are insufficiently influenced by evolutionist ideas so often fall . For if the formation of the somatic and psychical sex characters in the butterflies does not depend on the sexual glands, it follows that we must look for other regulating factors. There- fore, from the standpoint of the physiology of evolution, nothing is explained by supposing a fixation by heredit}^ There are two groups of new facts which show how justifiable Herbst's argument was. We know that in mammals the sexual gland is by no means a homogeneous formation, and we shall see later that the formative influence which the sexual glands exert on other parts of the body is possibly not a direct function of the generative part of the glands. And it may be that the two parts, although endowed with such different functions, are welded together in the mammahan sexual gland into one organ, but are separated in some groups, such as the Arthropoda. In the latter case a removal of the testicles or of the ovaries, containing only the generative cells, will naturally be without any influence upon the sexual characters. Caullery (1913, pp. 128, 129), Harms (1914, p. 147), and lately Courrier (1921) have also considered this possibility. Secondly, the facts discovered by Goldschmidt (1917, 1920 a, 1920 b) in moths are of great importance in this connection. In crossing different species of the gipsy moth Goldschmidt obtained different degrees of "intersexuality." The intersexuahty con- cerned all external and internal sexual characters, and even the sexual gland. Further, Goldschmidt stated that all the in- dividuals which became intersexual turn from maleness or femaleness into the other sex at a time which is constant for a given combination of races. It follows from his experiments RESULTS OF CASTRATION 59 that the sexual characters of insects are of great lability. Evidently there are in insects other factors besides the sexual glands which control the sexual characters, and even the gonads themselves. We do not know where these factors are localised in the gipsy moth; Goldschmidt is oithe opinion that the male and female factors are present in every cell of the body in given quantities. According to Goldschmidt (1920 a, p. 18) all the characters by which one sex differs from the other are derived from an identical anlage, influenced by a given quantity of the male or female factor. We see that Goldschmidt finds himself forced to make an assumption similar to that which was previously p>ostulated for mammals and birds, i.e., that a neutral soma (asexual or bisexual) becomes monosexual under the influence of a certain internal factor or combination of internal factors at a given time for each species. We shall deal with this most important work of Goldschmidt again in a later chapter (Chapter IX.). In the following section it is shown that in crabs as well as in some insects there are certain external factors which may produce an inversion of the sexual characters from one sex to the other. 2. The Parasitic Castration of Crabs. It has been known for more than thirty years that in certain species of crabs the sexual glands may be destroyed by parasites. This phenomenon has been called "parasitic castration." Giard (1886, 1887) discovered it, and Geoffrey Smith (1906) and Potis studied it exhaustively in Inachus, and in the hermit crab and other species. The sexual characters are distinctly pronounced in the Inachus. The male {Figs. 37 and 38) has a longer and a larger claw, and the abdomen, which is relatively small, has only two pairs of appendages, the longer serving for copulation, and the shorter being rudimentary appendages. The claw of the female (Figs. 39 and 40) is shorter and smaller, and on her broad abdomen there are four pairs of fissipedes. The infection of Inachus which results in castration is caused by the Cirrhipedian Sacculina. The parasite causes in the male Inachus a reduction of the copulatory appendages which are a very pronounced male sexual character, and the assumption of female characteristics 6o INTERNAL SECRETIONS Figs. ^-j-^s.—Tvansfoymation oj Inachus by SaccuHna.—Fiom Geoffrey Smith. Fig. 37. — Normal male. Dorsal. Nat. size. Big pincer, small abdomen. 3 Fig. 38. — Abdomen of normal male. Ventral, x 2 enl. Big copulatory appendices and reduced extremities. ^\ ]? vr •ncfopm-' rM>j\ ? Fig. 39. — Normal female. Dorsal. Nat. size. Small pincer, big abdomen. Fig. 40. — Abdomen of normal female. Ventral, x 2 enl. Four pairs of extremities. RESULTS OF CASTRATION 6i w-=^:-: A 1 Fig. 41.^ — Infected male. Dorsal. Nat. size. Reduced pincer and enlarged abdomen. Compare with Fig. 39; similarity between infected male and normal female. I \ .-.^'-PX Fig. 42. — Abdomen 0/ infected male. Ventral, x 2 enl. Reduced copulatory appen- dices and development of extremities. Compare with Fig. 40. r} '> Fig. 43. — Infected male. Dorsal. Nat. size. Reduced pincer and enlarged abdomen. ^J-^X^ / ^ ^--^ y Fig. 44. — Abdomen of infected male. Ventral, x 2 enl. Reduced copulatory appendices and four pairs of well developed extremities. $r ■? Fig. 45. — Abdomen of infected female. Ventral. 2x enl. Reduced extremities. At s scar from Sacculina. 62 INTERNAL SECRETIONS like the fissipedes. The claw of the male becomes smaller, the abdomen broader. In this way the infected males become more or less female in their external appearance {Figs. 41 and 42). They sometimes resemble normal females so closely (Figs. 43 and 44) that they can be recognised as modified males only by the reduced copulatory organ and the sHghtly smaller abdomen. On the contrary, the infected females are only slightly altered {Fig. 45). They differ from normal females only by the shorter fissipedes, and they never assume male characters. In 70 % of the male and female Inachus in which changes in the external sex characters were present. Smith found also changes in the sexual glands. In the female-like males Smith found the sexual glands destroyed to such a degree that even by serial sections no remains of a sexual gland could be found. A further instance of parasitic castration in crabs is afforded by Pachygrapsiis marmoratus likewise investigated by Smith in Naples. Here also the castrated male approaches the female in its appearance. The results of castration, however, are not all equally marked in the different species of crabs, the change towards the opposite sex being much more pronounced in some than in others. In some the male sexual characters remain unaltered notwithstanding castration. The results of the observations made on Inachus could be conceived at first sight as similar to those with birds, which after castration change more or less to the male type. But in Inachus the change takes place from male to female, and not from female to male as in birds. Like the castrated cock, the castrated female Inachus shows only slight changes in the external sexual characters. We have interpreted the assump- tion of male sexual characters by the castrated hen as of the nature of an approach to an " asexual " or neutral form common to both sexes, and not as an inversion to the other sex. We may in the same way interpret what we observe in Inachus, supposing that the common neutral form in this animal resembles the female rather than the male. The absence of fissipedes in the normal male of Inachus and their appearance after castration might be explained in the following manner : there is normally an inhibition exerted by the male sexual gland upon other parts of the body, and this inhibition is removed by castration. A similar explanation may be adopted. RESULTS OF CASTRATION 63 as we have seen, for birds. From the experiments of Steinach on rats, and those of Pezard and Goodale on cocks, it seems probable that such an inhibitory action on the part of the sexual glands exists. We shall discuss these experiments more fully in Chapter VI. Smith explains his observations in a wholly different manner. He begins by pointing out that in the female, as in the male, there is sometimes an hermaphrodite sexual gland with almost fully developed ova and spermatozoa. Smith thinks that these were males which were first castrated by parasites, and that afterwards an hermaphrodite gland devel- oped. We have seen that female sexual characters may be present in the castrated male also when no hermaphrodite gland is present; it follows from this that the female somatic characters in the modified male are not caused by the newly formed ovary. Smith suggested that there is another factor, a sexual formative substance which causes the development both of the somatic sexual characters and the sexual glands. According to him this formative substance may be thought of as a product of the general metaboHsm ; under the influence of the parasite the formative substance is changed, and in this way an atrophy of the sexual glands and a change in the sexual characters are caused. Further, Smith assumes that there is in every male a potential formative substance in relation to both sexes, the female one being latent; in the female sex the female substance only would be present. Now he assumes that in the male castrated by the parasite the male substance only is destroyed, and so the female substance inverts the animal to the female sex. I do not think that Smith's hypothesis is justified in all its details, and I do not think that it is sufficiently supported by what Smith observed. But it is interesting to note that in this hypothesis we have a clear foreshadowing as long ago as 1906 of a later and somewhat similar theory based on a remarkable body of evidence, and already tentatively accepted by many. For the experiments of Goldschmidt on moths make it probable that there is indeed a sex specific formative substance controlling both somatic sexual characters and generative cells, and that in the same individual the male and female sex-specific substance may be present, one of them being latent, and that a turning over to the other sex may be caused 64 INTERNAL SECRETIONS by changes in the quantitative relations between the two substances. A third explanation of the sexual inversion of the male Inachus was attempted by Biedl (1913, p. 225). According to him the Sacculina parasitic on the crab is always female, and he thinks that there is in reality an influence exerted by the female sexual gland of the parasite on its host. There is, according to Biedl, not only parasitic castration, but also a kind of transplantation of a heterosexual gland, a feminization in the sense of Steinach. But Biedl' s suggestion is not justified since Sacculina is hermaphrodite {Smith, 1906, pp. 19-33). In the first edition of this book I intimated that parasitic castration in crabs involved something wholly different from what has been observed in experimental castration in Arthro- poda. I thought that the persistence of the sexual characters in the moth after castration was an exception even in the group of Arthropoda, and that no general conclusions could be drawn from these experiments in regard to the relation between the sexual characters and the gonads. But I see now that this con- clusion is not justified, and I am inclined to accept in principle the explanation of Smith. We have already mentioned that only in 70 per cent, of the male and female Inachus in which the external sexual characters changed, were the sexual glands affected. Evidently the destruction of the sexual gland is not a conditio sine qua non for the changes in the sexual characters. Similar observations have been made by Potts on male shore crabs infected by Sacculina; here certain female characters appeared even when the castration was not a complete one. The question has been recently studied also by Coiirrier (1921). He examined 66 male Carcinus maenas infected by Sacculina. In 46 cases the abdomen was female in appearance, but only in four were the testicles absent. In most of the animals the testicles were in full activity, athough they were a little smaller than in normal crabs. It would be a mistake to think that the changes in the sexual characters could be changed by the testicular mass being diminished ; we know that minute particles of a sexual gland can quantitatively replace the normal testicular mass. On the other hand one might object to Smith's explanation on the ground that female characters, as already mentioned, often appear in the infected male without an ovary or an RESULTS OF CASTRATION 65 hermaphrodite gland being found. But it may be that this is caused by the different organs reacting in a different manner under the conditions created by the parasite in the general meta- bolism of the host. Discussing in the first edition of this book the results of castration and heterosexual transplantation in mammals (see especially Chapters IX. and XI.) I pointed out that the differences one observes in these experimental conditions in regard to the behaviour of the different parts of the body can only be understood if we take into consideration their different growth intensity, which seems to be a function of time. In his remarkable investigation on the gipsy moth Goldschmidt (1917, 1920) has shown that the different organs change over to the opposite sex in different degrees ; he showed further that those organs or parts of organs which normally become differentiated very late turn to the opposite sex also in slight degrees of intersexuality, as for instance the colouring of the wings. On the contrary, organs which are normally differentiated very early, change to the opposite sex only in crossings with a very pronounced degree of intersexuality ; this is especially true for the sexual glands which differentiate cmbryologically very early, and which are found in different stages of intersexuality only when all the somatic organs are inverted. According to Goldschmidt time is a factor in the degree of intersexualit}^ the latter being the more pronounced the sooner the inversion to the opposite sex begins. We find here in the crossing experiments of Goldschmidt an explanation of the facts observed by Smith, Potts, and Courrier in parasitic castration of crabs where many male somatic organs become female without the testicle being destroyed or transformed into an ovary or an hermaphrodite gland. Here again, as in the case of the moth, the possibility must be taken into consideration that there is in the body of the crab a special organ which controls the sexual characters besides the sexual glands. No knowledge exists on this point, but such a conception would not be in any way opposed to Smith's hypothesis. It may also be mentioned that there are many other examples of Crustacea in which one or more of the sexual characters are sexually inverted to a greater or less extent without interference by a parasite. For details Morgan s paper (1920 b) may be referred to 66 INTERNAL SECRETIONS 3. The Parasitic Castration of Insects. Giard (1889 a, 1889 b) about 35 ^^ears ago described very pro- found alterations in insects caused by parasitic castration con- sequent upon an infection taking place very early in the life his- tory of the insect, possibly in the larval stage. Signs of castration are more pronounced in some species than in others. It must be taken into consideration that the dimorphism of the two sexes is developed to a different degree even in related species. When there is a pronounced dimorphism, destruction of the sexual glands was found to cause an alteration of the sex characters. The penis of the male Typhlocyba hippocastani is visibly changed b}- parasitic castration. '' Le caractdre specilique est ainsi profondement atteint," as Giard said. But on the other hand Kopec's objection that all these phenomena observed in insects could also be explained by the unfavourable conditions amid which the animals are placed in regard to nutrition when infected by a parasite, may be valid. Further observations on the parasitic castration of insects were made by Perez (1886) on the earth-bee Andrena, infected by another little insect, Sty lops. The sexual dimorphism is very pronounced in Andrena, and the sexual characters are altered by the parasitic castration. The brighter design on the head of the nonnal male tends to become subdued, whereas the design of the infected female becomes brighter. Also the hind legs of the male and female are altered, and the female loses the apparatus necessary for the collection of pollen, normally attached to the hind legs. Recently Kornhauser (1919, quoted from Morgan, 1920 b) has made observations on the parasitic castration of the tree hopper, Thelia bimacidata, infected by another insect, Aniphe- lopus. The infected male exhibits many of the characteristics of the female; the degree of the change is mainly dependent on the stage at which the infection has taken place. On the contrary, infected females do not assume any of the charac- teristics of the male. The sexual glands in both sexes are usually degenerate. But Kornhauser observed also that an infected male, which showed considerable sexual change in the direction of the female, contained nevertheless full sized normal testes with many spermatozoa. This observation of Kornhauser's fully bears out those of Courrier on the crab. RESULTS OF CASTRATION 67 It seems after all unjustifiable to explain the changes caused by the parasite by destruction of the sexual glands. The inversion of the male towards the female type in the infected Arthropoda must be caused directly by the parasite, and does not necessarily bear any relation to the influence which the parasite has on the sexual gland. This is further evidence of the fact that the sexual characters are independent of the sexual glands in the Arthropoda. F. THE RESULTS OF CASTRATION IN OTHER INVERTEBRATA. We may begin by referring to the parasitic castration of the earthworm. This animal has normally an hermaphrodite gonad and somatic sexual characters of both sexes. Now Sottas (1911) observed in Lumhricus herctdeus a destruction of the male part of the gonad caused by bacterial parasites; the pouches in which the testicles are normally to be found are empty in many infected animals, whereas the ovaries remain normal. The clitellum disappears in such infected animals. The €litellum is an organ consisting of thickened skin near the sexual pores with glands secreting a sticky substance facili- tating adherence during copulation; the clitellum increases in size during the breeding season and decreases afterwards. In animals in which the male part of the gonad was destroyed the vesiculae seminales were sometimes found to be smaller. In those animals in which the degeneration of the vesiculae was most pronounced, alterations of the vas deferens and of the genital bristles were also present. In some places where infected w^orms were found, about half of the individuals were without a chtellum. We see that in the earthworm many of the male sexual characters are controlled by the male gonad. But the question arises whether we have here a dependence of seasonal changes only upon the gonad as in amphibians or also a dependence of the sexual characters in general as in mammals and birds. This question cannot yet be answered. Another peculiarity is of the greatest interest. The observa- tions of Sollas show that the ovary which remains intact in the 68 INTERNAL SECRETIONS infected earthworm cannot replace the testicle or control the male sexual characters. The influence which the ovary and the testicle in the earthworm exert on its somatic characters are different from one another; the action of the gonads on the body is evidently a sex specific one. We shall discuss the question of sex speciiity more fully later on. The observations of Sollas have been extended experimentally by Harms (1914). Experimental castration can be performed in Lumbricidae without great difficulty, the male and female gonads being localised in different segments; male or female castration can be performed by cutting away male or female segments and sewing together the remaining segments. Harms showed that the clitellum disappears after male castration, but remains intact after female castration. Some of the animals operated on by Harms lived for nine months after the operation. In opposition to the observations related above is a statement recently made by Dvagoiu and Faure-Fremiet (1920) about a female of Ascaris megalocephala} They found an individual in which no generative cells were present in the ovary, the wall only being visible. Nevertheless, the oviducts and the uterus were normal. Observations on Planaria have been made by Vandel (1920). In certain species of Planaria the gonads are situated princi- pally in the front or in the prepharyngeal part of the body, whereas the copulatory organs are to be found in the posterior or postpharyngeal region. Vandel cut off an anterior frag- ment of the body in order to make observations on regenera- tion phenomena. He found that an anterior fragment could undergo regeneration and develop very rapidly in about 15 to 25 days a new posterior part with copulatory organs. Now, in one case regeneration took place, but no trace of copulatory organs could be found in the newly-formed posterior part even five weeks after the operation. This was confirmed by histological examination, which revealed only the presence of intestinal branches. But the most interesting result of the histological examination was that the germinative cells in the gonads of the anterior part were degenerated and destroyed, evidently by parasites, as Vandel thinks. He concludes from this observation that the castration did not prevent the process of regeneration or the formation of a new posterior ^A Nematode or thread-worm parasitic in the horse. RESULTS OF CASTRATION 69 part, but that castration hindered the development of the copulatory organs. Vandel considers this as a proof that the gonads play an important part in the regeneration and development of the copulatory apparatus in Planaria. Another experiment of Vandel (1922) is also of great interest. As a rule the regenerating posterior fragment, containing in the beginning the copulatory apparatus but no gonad, loses the former by some process of remodelHng. In one case the posterior fragment kept the copulatory apparatus and re- generated to a perfect sexual individual. The histological examination showed that a part of the testicle was left with the posterior fragment. In some experiments Vandel destroyed the gonads in the anterior fragments by exposing the latter to a temperature of about 20° to 2i°C. Under these circum- stances regeneration takes place, but no copulatory apparatus, or an underdeveloped one, is to be found in the regenerated animal. The objection might be made that both gonads and the regenerating copulatory organs were simultaneously inhibited by the action of the temperature. As the Planaria are hermaphrodite, the question arises as to whether regeneration or persistence of the copulatory apparatus is controlled by the testicle or by the ovary. To decide the question, Vandel performed the following experiment. He sectioned the animals in such a manner that from the anterior fragment which contains the ovaries and the testicle, the cephalic region with both ovaries was cut away. The frag- ment regenerated in both directions; in the posterior part the copulatory apparatus regenerated, as likewise happened in the above-mentioned anterior fragments. Evidently the ovaries are not necessary for the regeneration of the copulatory apparatus. There seems to be some evidence as to the control of the sexual apparatus by the gonad also in Mollusca. According to Gould (1917; quoted from Vandel, 1922), there is in Crepidula plana a very pronounced hermaphroditism. First the testes and the male copulatory apparatus develop; after- wards the testes and simultaneously the male copulatory ap- paratus degenerate; and the ovaries and the female copula- tory apparatus develop. Vandel thinks that there is evidence that the development of the copulatory organs depends upon the sexual glands. This is not true of all the organs, since the 70 INTERNAL SECRETIONS uterus develops independently of the gonad. I do not think that Vandel's suggestion is justified; the development of the gonad and that of the copulatory apparatus of the respective sex may both be contoUed by some other factor. Contradictory as they are, the observations made on different Invertebrata show that here also somatic sexual characters depend in some cases upon the sexual glands ; this dependence concerns, as we have seen, those parts which are intimately involved in the sexual function. G. SUMMARY. The facts recorded permit us to answer the questions put in the first chapter: 1. It is shown with absolute certainty that the formation and the persistence of sexual characters in mammals, birds, amphibians, and some invertebrates depend upon the sexual glands. These sexual characters may be designated as "secondary," in a genetic sense of the word> in relation to the sexual glands. 2. The formative and conservative influence of the sexual glands does not relate to all the sexual characters. Only some of the sexual characters therefore can be designated as geneti- cally secondary in relation to the sexual glands. 3. The formative and conservative influence of the sexual glands concerns not only those sexual characters which are involved in the sexual function, such as the genital organs, the characteristics of heat and the psycho-sexual behaviour, but it concerns also sexual characters which seem to be in no special relation to the sexual function, such as the plumage, body proportions, and so on. This formative and conservative influence may even relate to other characters which are not necessarily different in the two sexes, e.g., some of the other organs of internal secretion. 4. (a) By castration the sexually differentiated type, i.e., the male or the female, loses more or less its sexual characters, and shows a tendency to become a sexually indifferent form common to both sexes. The later castration is performed the greater the number of the sexual characters which remain in the *' castrate." RESULTS ^OF^ CASTRATION 7 1 (b) It is probable that the somatic basis of mammals and birds is sexually undifferentiated, i.e., it is asexual or bisexual at the beginning, being changed during embryonic Hfe in the male or female direction by the differentiating sexual gland. In other words, we suggest that those sexual differences which develop under the action of the sexual glands are really caused by this action only. On the contrary, those sexual differences which develop and exist independently of a formative or preserv- ing action on the part of the sexual glands might be explained as the result of the independent development of asexual charac- ters common at the beginning to both sexes. These characters merely become sexual owing to their being changed in one of the sexes by the sexual glands, as, for instance, the bright plumage and the spurs in the cock on the one hand, and the dull plumage, and the lack of spurs in the hen on the other. The sexual characters which are independent of the sexual glands must not be mistaken for those which are only apparently inde- pendent and which remain after castration, merely because the formative action of the sexual glands has already taken place and because the duration of this action was long enough to fix these sexual characters in the asexual embryonic soma. The first three theses and the first part of the fourth are really statements of ascertained facts on which it is only possible to raise doubt in regard to details, whereas the second part of the fourth thesis is a matter of hypothesis. It will be our purpose in the latter part of this book to present further evidence in support of this hypothesis. BIBLIOGRAPHY FOR CHAPTER 11, [* Not seen in the original.] Amantea. 1919. Sulla secrezione spermatica. VIII. Alcune os- servazioni su cani castrati e su cani sottoposti a escissione parziale dei deferenti. Atti della B. Acad, dei Linceif 28, ser. 6a. Aron. 1921a. Sur le conditionnement des caracteres sexuels second- aires chez les Batraciens Urodeles. C. R. de VAcad. d. Sc, 173, p. 482. — - 1921b. Sur r existence et le r61e d'un tissu endocrinien dans le testicule des Urodeles. G. B. de VAcad. d. Sc.y 173, p. 57. 72 INTERNAL SECRETIONS Athias. 1919. Effets de la castration sur les mouvement auto- matiques de I'uterus chez le cobaye. Jl. de Phys. et Path. Gener., 18. 1920. Action d'extraits et produits derives d'organes a secretion interne sur I'uterus isole, particulierement apres la castration totale. Arch, internal, de Pharmacodynamie et de Therapies 25, p. 423. Bell (W. Blair). 1920. The Sex-Complex. London. BiEDL. 1913. Inner e Sekretion. 2 Aufl. Berlin- Wien. BoRMANN. 1922. tjber die Folgen der Kastration in ihren zeitlichen Beziehungen. Skand. Arch, fiir Physiol., 42, p. 270. Bresca. 1910. Experim. Untersuch. iiber die sek. Sexualcharaktere der Tritonen. Arch. f. Entw.-Mech., 29, p. 403. Brehm. 1911 and 1913. Tierleben, VII. and IX., 4 Aufl. Leipzig. BucuRA. 1913. Geschlechtsunterschiede heim Menschen. Wien u. Leipzig. Busquet. 1910. La fonction sexuelle. Paris. Carmichael and Marshall. 1908. The correlation of the ovarian and uterine functions. Proc. Boy. Soc, 79. 1908. On the occurrence of compensatory hypertrophy in the ovary. Jl. of Physiol., 36. Caullery. 1913. Les probUmes de la sexualite. Paris. CouRRiER. 1921. Sur le determinisme des caracteres sexuels second- aires. C. R. de VAccad. d. Sc, 173, p. 668. Dragoiou et Faure-Fremiet. 1920. Sur une anomalie du develop- pement de I'ovaire chez I'ascaris megalocephala. C. R. de la Soc. de Biol, 83, p. 123. ExNER. 1903. Physiologic der mannlichen Geschlechtsfunktionen. Handb. d. Urologie von Frisch und Zuckerkayidl, I. Wien. Fisher. 1923. The influence of the gonad hormones on the seminal vesicles. Amer. Jl. of Physiol., 64, p. 244. ♦FiTZSiMONS. 1912. A hen ostrich with the plumage of a cock. Agr. Jl. Univ. South Africa, 4, quot. Goodale, 1916. FoGES. 1903. Zur Lehre von den sekundaren Geschlechtscharakteren. PflUgers Archiv, 93. 1914. Keimdriisen. In Jauregg und Baj^er, Le/ir6wc7i c?er Or^ano- therapic. Leipzig. 1920. Zentralhlatt f. Gyndkol. Franz. 1909. Zur Entwicklung des knochernen Beckens nach der Geburt. Beitrdge zu Geburtsh. u. Gyndk., 13. GiARD. 1886. De I'influence de certains parasites rhizocephales sur les caracteres sexuals exteriein-s de leur hote. C. R. de VAcad, d. Sc, 103, p. 84. 1887. Sur la castration parasitaire chez TEupagimis Bernhardus L. et chez la Gebia stellata Mont. Ibidem, 104, p. 1113. I RESULTS OF CASTRATION 73 GiARD. 1889a. Sur une galle produite chez les Typhlocyba rosae L., par une larve d'Hymenoptere. C. R. de VAcad. d. Sc, 109, p. 79. 1889b. Sur la castration parasitaire des Typhocyba par une larve d'Hymenoptere et par une larve de Diptere. G. R. de VAcad. d. Sc, 109, p. 708. Gley et Pezard. 1921. Modifications des glandes genitales acces- soires du cobaye apres la castration. Arch, internation. de Physiol., 16, p. 363. GoLDSCHMiDT. 1917. Intcrsexualitv and the endocrine aspect of sex. Endocrinology, 1, p. 433. 1920a. Die quantitative Grundlage von Vererbung und Art- bildung. Vortr. und Aufs..uber. Entw.-Mech. d. Org., Heft 24. Berlin. English edition, London, 1923. 1920b. Mechanismus und Physiologic der Geschlechtshestimmung, Berlin. *GoLTZ. 1869. Beitrdge zur Lehre von den Funktionen der Nerven- zentren des Frosches. Berlin. Good ALE. 1910. Some results of castration in ducks. Biol. Bull., 20. 1913. Castration in relation to the secondary sexual characters of brown leghorns, American Naturalist. 1916. Gonadectomy in relation to the secondary sexual characters of some domestic birds. Carnegie Institution Publications. Washington. *GouLD. 1917. Studies on sex in the hermaphrodite mollusc Crepidula Plana. Jl. Exper. Zool., 23, quot. Vandel, 1922. ♦Guthrie. 1910. Survival of engi'afted tissue. Jl. Exp. Med., 12, quot. Goodale, 1916. Halban. 1903. Die Entstehung der Geschlechtscharaktere. Eine Studie iiber den formativen Einfluss der Keimdriise. Arch. f. Gyndk., 70. Harms. 1910. Hoden- und Ovarialinjektionen bei Rana fusca- Kastraten. PfliXgers Archiv, 133. 1914. Exper imentelle Untersuchungen uher die innere Secretion der Keimdrilsen und deren Beziehung zum Gesamtorganismus. Jena. Herbst. 1901. Formative Reize in der tierischen Ontogenese. Leipzig. Hesse-Doflein. 1910. Tierbau U7id Tierleben, 1. Leipzig. HiRSCHFELD. 1916. Ubcr Geschlechtsdriisenausfall. Neurologisches Zentralblatt. 1917. Sexualpathologie, I. Teil. Bonn. Hofstatter. ? Unser Wissen iiber die sekimdaren Geschlechts- merkmale. Zentralbl. /. d. Grenzgeb. d. Med. u. Chir., 16, p. 246-267. 74 INTERNAL SECRETIONS Kammerer. 1912. Ursprung der Gesclilechtsunterscliiede. Fort- schr. d. naturwiss. Forsch., 5, p. 62-91. 1919. Vererbung erzwungener Formveranderungen. I. Mitt. Die Brunstschwiele des Alytes-Mannchen aus Wassereiern. Arch. f. Entiv.-Mech., 44. Koch (Walter). 1921. tjber die russisch-rumdnisch Kastratensekte der Skopzen. Jena. *KoN. 1908. Hypophysenstudien. Zieglers Beitrdge, 44. Kopec. 1912. Untersuchungen iiber Kastration iind Transplantation bei Schmetterlingen. Arch. f. Entw.-Mech.y 33, p. 1. 1914. Nochmals lib. d. Abhangigkeit der Aiisbildung sek. Geschlechtschar. von den Gonaden bei Lepidopteren (Fiihler- regenerationsversuche mit Kastration und Keimdriisentrans- plantation kombiniert). Zoolog. Anz., 43. — 1918. Contribution to the study of the development of the nuptial colour of fishes. C. E. de la Soc. d. Sc. de Varsovie, 9, p. 108. ♦KoRisrHAUSER. 1919. The sexual characteristics of the Membracid Thalia bimaculata (Fabr.). I. External changes induced by Aphelopus theliae (Gahan). Jl. Morph., 32, p. 531. Lacassagne. 1913. Etude histologique et physiologique des effets produits sur I'ovaire par les rayons X. TMse med. de Lyon. LiCHTENSTERN. 1916a. Untcrsuchungen iiber die Funktion der Prostata. Zeitschr. f. Urologie, 10. 1916b. Mit Erfolg ausgefiihrte Hodentransplantation am Men- schen. Munch, mediz. Wochenschr. No. 19. LiPSCHUTZ. 1917. Die Gestaltung der Geschlechtsmerkmale durch die Pubertatsdriisen. Anz. d. Akad. d. Wiss., Wien, No. 10. 1918a. Archiv f. Entw.-Mech., 44. 1918b. Prinzipielles zur Lehre von der Pubertatsdruese. Arch, f. Entw.-Mech., 44. - Wagner et Tamm. 1922. Sur I'hypertrophie des fragments ovariens dans la castration partielle. C. R. de la Soc. de BioL, 86, p. 240. Marsblall. 1922. The physiology of reproduction, 2nd edition. London. Ch. IX. Martin. 1914. Lehrhuch der Anthropologic. Jena. Meyer (Robert). 1921. Ein Mahnwort zum Kapitel "Interstitielle Driise." Zentralhl. f. Gyndk.^ No. 17. Meisenheimer. 1909. Experimenielle Studien zur Soma.- und Ge- schlechtsdifferenzierungy I. Jena. " 1912. Experimentelle Studien zur Soma- und Geschlechtsdif- ferenzierung, II. Jena. RESULTS OF CASTRATION 75 Moore. 1919. On the physiolog. properties of the gonads as con- trollers of somatic and psychical characteristics. II. Growth of gonadectomized male and female rats. Jl. of Exper. Zool., 28, p. 459. 1922. On the physiolog. properties of the gonads as controllers of somatic and psychical characteristics. V. The effects of gonadectomy in the guinea pig, on growth, bone lengths, and weight of organs of internal secretion. Biological Bulletin, 43, p. 285. Morgan. 1915. *Demonstration of the appearance after castration of cock-feathering in a hen-feathered cockerel. Proc. Sac, Exp. Biol, and Med., 13. 1919. The genetic and the operative evidence relating to secondary sexual characters. Cam. Inst. Puhl, Washington. — — 1920a. The effects of castration of hen-feathered Campines. Biol. Bull., 39. 1920b. Variations in the secondary sexual characters of the fiddler crab. American Naturalist. NussBAUM. 1909. Hoden und Brunstorgane des braunen Landfro- sches (Rana fusca). Pfliigers Arch., 126. 1912. Uber den Bau \md die Tatigkeit der Driisen, VI. Mittl. Arch. f. mikr. Anat., 80, II. Abt. Oberholzer. 1912. Uber die Wirkung der Kastration auf die Libido sexualis. Sexual-Prohleme. Zeitschr. Sexualwiss. und Sozialpolitik, 8. OcARANZA. 1921, 1922. Contribucion experim. para el estudio de la fisiol. del testiculo. Revista Mexic. de Biol., I, No. 6; 2, No. 5. Van Oordt. 1921. Ornithological Notes from Spitzbergen and Northern Scandinavia. 1921. "Ardea," Tijdschr. d. NederL Ornitholog. Vereen. ♦Perez. 1886. Des effets du parasitisme des Stylops sur les apiaires du genre Andrena. Soc. Linn. Bordeaux, 12, p. 21. Pezard. 1911. Sm* la determination des caracteres sexuels second- aires chez les Gallinaces. C. R. de VAcad. d. Sc, 153, p. 1027. 1912. C. R. de VAcad. d. Sc, 154, p. 1183. 1914. Developpement experimental des ergots et croissance de la Crete chez les femelles des Gallinaces. G. R. d. VAcad. d. Sc, 158, p. 513. 1915. Transformation experimentale des caracteres sexuels secondaire chez les Gallinaces. C. R. de VAcad. d. Sc, 160^ p. 260. 1918. Le conditionnement physiologique des caracteres sexuels secondaires chez les oiseaux. Edition du Bulletin Biologique de la France et de la Belgique. Paris. ^6 INTERNAL SECRETIONS Pezard. 1919. Facteur modificateiir de la croissance normale et loi de compensation. C R. de VAcad. d. Sc, 169, p. 997. 1920. Secondary sexual characteristics and endocrinology. Endocrinology, 4, p. 527. 1920. Castration intrapuberale chez les coqs et generalisation de la loi parabolique de regression. G. R. de VAcad. d. Sc, 171, p. 1081. 1921. Numerical law of regression of certain secondary sex characters. Jl. of Gener. Physiol., 3, p. 271. PoiiL. 1909. Ziu* Lehre von den sekundaren Sexualcharakteren. Sitzungsber. d. Gesellsch. naturforsch. Freunde. Berlin. *PoTTS. 1906. The modification of the sexual characters of the hermit crab caused by the parasite Peltogaster. Quart. Jl. Micr. Sc, N. S., 50, p. 599. RiCHON et Jeandelize. 1903. Influence de la castration et de I'ovariotomie totales sur le developpement des organes genitaux externes chez le jeune lapin. C. R. de la Soc. de Biol, 55, p. 1684. RoESSLE. 1914. Das Verhalten der menschlichen Hypophyse nach Kastration. Virchows Archiv, 216. ScHONBERG und Sakaguchi. 1917. Der Einfluss der Kastration auf die Hypophyse des Rindes. Frankf. Zeitschr. f. Pathol., 20. Sellheim. 1908. Zru" Lehre von den sekundaren Geschlechts- charakteren. Beitr. z. Geb. u. Gyndk., 1. Shattock and Seligmann. 1904. Observations upon the acquire- ment of the sec. sex. characters, indicating the formation of an internal secretion. Proc. Roy. Soc, 73. Smith. 1906. Rhizocephala, Fauna und Flora d. Golfes v. Neapel, 29 Monographic. Berlin. SoLLAS. 1911. Note on parasitic castration in the earthworm Liun- bricus herculeus. An7i. and Magaz. of Natur. History, 7, 8th Ser. Steinach. 1894. Untersuchungen z. vergleich. Physiologie der mannl. Geschlechtsorgane, insbes. der akzessor. Gesch- lechtsdriisen. PfliXgers Archiv, 56. • 1910. Geschlechtstrieb und echt sekundare Geschlechtsmerkmale als Folge der innersekretorischen Funktion der Keimdriisen. Zentralbl. f. Physiol., 24. • 1912. Willkiirliche Umwandlung von Saugetier-Mannchen in Tiere mit ausgepragt weiblichen Geschlechtscharakteren und weiblicher Psyche. Eine Untersuchung uber die Funktion und Bedeutung der Pubertatsdriisen. PfliXgers Archiv, 144. RESULTS OF CASTRATION 77 Tandleb, und Gross. 1909. Uber den Einfluss der Kastration auf den Organismus. I. Beschreibung eines Eiinuchenskelets. Archiv f. Entw.-Mech., 27, p. 35. 1910a. II. Die Skopzen. Arch. /. Entw.-Mech., 30, Part 2, p. 236. 1910b. Uber den Einfluss der Kastration auf den Organismus. III. Die Eunuchoide. Arch. /. Entw.-Mech., 29, p. 290. ■ und Keller. 1910. IV. Die Korperform der weiblichen. Friihkastraten des Rindes. Arch. f. Entw.-Mech., 31, p. 289. und Grosz. 1913. Die biologischen Grundlagen der sekunddren Geschlechtscharaktere. Berlin. Vandel. 1920. Le developpement de I'appareil copulateur des Planaires est sous la dependance des glandes genitales. C. R. de VAcad. d. Sc, 170, p. 249. 1922. Recherches experimentales sur les modes de reproduction des Planaires Triclades Paludicoles. Bull. Biol, de la France et de la Belgique, 55, p. 343. WiTSCHi. 1921. Der Hermaphroditismus der Frosche und seine Bedeutimig fiir das Geschlechtsproblem und die Lehre von der inneren Sekretion der Keimdriisen. Arch. /. Entw.- Mech., 49, p. 316. Zawadowsky, M. M. 1922. Das Geschlecht und die Entwicklung der Geschlechts?7ierkmale, (Russian, with German summary.) Moscow. Chapter III. The Internal Secretions of the Sexual Glands. The question now arises as to the nature of the mechanism whereby the sexual glands exert their influence on the sexual characters in different species. Two possibilities present themselves; an influence may be by the intermediation of the nervous system (as by some kind of a reflex), or directly through internal secretions which pass into the circulation. Experiments with transplantation and injection of sexual glands have been made on mammals, birds and amphibians with the purpose of solving this question. It is to-day generally agreed that the sexual glands act by means of internal secretions. Before entering into a discussion of the experimental proofs of this contention we shall state in a few words what we mean by "internal secretion. "^ It is really a more or less arbitrary matter to distinguish between the special internally secretory organs and the other parts of the body. All organs and cells in a multicellular organism are connected with and dependent upon each other by the intermediation of products of metabolism secreted into the body fluids. These substances may be specific or otherwise for the respective organs by which they are secreted. We know that the secretions produced by one set of organs influence all the other cells and organs of the body. Take, for instance, carbonic acid, a katabolic product secreted by every cell and thus without any specifity. The action of the respiratory centre in the medulla oblongata depends upon the quantity of carbonic acid present in the blood. Thus every cell in the multicellular organism acts by some kind of "internal secretion" on the respiratory centre. This action of the carbonic acid or of the hydrogen ion is a specific one. The specifity of the action which different secretions have on * Besides the literature quoted in the text see Gley, (1914); Caullery (1913. p. 115); LipschUtz (191 7). 79 ^ 8o INTERNAL SECRETIONS other organs or on the metaboHsm in general by the inter- mediation of the body fluids is often taken as the only character- istic feature of what we call an internal secretion par excellence. But I think that such a conception, which seems now to be very widespread, cannot be of much use in physiology. If any kind of specific action by intermediation of a katabolic substance entering into the body fluids is alone sufficient for designating this substance an internal secretion, there is in the multicellular organisms of animals and plants, no organ or no cell which could not be designated an organ of internal secretion. If one takes this standpoint, it is possible to speak of an internal secretion of the lungs, of the skin, or any other organ. But an organ of internal secretion should not be simply characterised by the fact that it is connected with other organs by the intermediation of chemical messengers or hor- mones (Bayliss and Starling, 1906). It must also be an organ which has no other function than to secrete chemical messengers or hormones of a special chemical composition and such as are never produced in other organs. Organs such as the thyroid gland, the hypophysis, the adrenals, and so on, are only characterized functionally by these specific substances which have a specific action. So I think that it would be best to restrict the term '* endocrine organ " in the first instance to glands which, as far as we know, have no other function than the secretion of specific substances which enter into the blood and influence the other organs in a specific manner, i.e., organs secreting chemically specific hormones. Such a definition of an endocrine organ is not an ideal one. But, unfortunately, as so often happens in physiology, we cannot hope for an ideal definition on account of the numerous transitional conditions which exist. There are organs pro- ducing chemically specific hormones, i.e., performing an endocrine function besides their other well-known functions; this is the case with the pancreas, with the mucosa of the duodenum or small intestine, and with the sexual glands; the same may be true also for other organs, as for the skin. We must never forget that knowledge of the secretion of chemically specific hormones is merely additional biochemical knowledge of the mutual relations between the organs in the body; endocrinology in the larger sense would be only another name for biochemistry. INTERNAL SECRETIONS OF SEXUAL GLANDS 8i It is of great interest to ascertain whether in those organs, which have an endocrine function besides their other special function, such as the pancreas and the sexual glands, the internal secretion is really produced by the same cellular elements as the external secretion. This question will be discussed in the case of the sexual gland in Chapters IV. and V. A. TRANSPLANTATION.! The first experiment upon the transplantation of the sexual glands was performed by John Hunter in 1762 on fowl. Berthold (1849) i^ade a similar experiment on cocks two or three months old. He removed the testicles of several birds; in one of them he replaced the testicles into the abdomen (auto- transplantation); in the abdomen of a second castrated bird the testicles of another cock were placed (homoiotransplanta- tion). The engrafted testicles " took " in different places, normal or abnormal, especially on the intestine. The appearance of the birds was like that of normal cocks. Two months later Berthold removed the engrafted testicles in one of these; the bird became a capon. Some other experiments of a similar kind were also performed by Berthold on cocks. He found the engrafted testicle five months after the transplantation adhering to the large intestine and containing spermatozoa. Berthold concluded from his experiments that the character- istic features of sexual maturity are caused by the testicle producing some kind of substance, and through this changing the composition of the blood which reacts on the organism in general, especially on the nervous system. We thus see that the fundamental principles underlying our knowledge of the internal secretions of the sexual glands had been already laid down by Berthold seventy-five years ago. But in those days nobody seems to have taken any interest in this matter and Berthold's experiments were forgotten; they remained too isolated to have any immediate bearing on physiology and ^ Manifold terms are in common use to describe the different forms of transplantation. We shall confine ourselves to the following: yi w/otransplantation — or transplantation in the body of the same individual. Howoiotransplantation — or transplantation into the body of another individual of the same species. i/e/erotransplantation — or transplantation into the body of an animal of another species. 82 INTERNAL SECRETIONS medicine, they were not brought into relation with other similar phenomena, and so they had no influence on scientific thought, and temporary oblivion was their inevitable fate. New experiments with transplantation were made about fifty years later by Foges (1902) on cocks. He succeeded in completely removing the testicles in two cases and trans- planting them into another position in the abdominal cavity. Foges relates that these animals appeared to stand midway between a normal cock and a capon, the head apparel being smaU and pale, while there was an increase of fat, but the spurs and plumage of the cock were well developed. Foges concluded from this experiment that there is an internal secretion produced by the testicle, but that the sexual characters were only partly developed in his birds because the engrafted testicular mass was smaller than that of the normal testicles. But from what we know today of the results of castration in the cock it is clear that in reality the two birds became capons and that autotransplantation had not succeeded. Homoiotransplantation was also attempted by Foges without success. New and careful experiments have been made on cocks by Pezard (1911, 1918, pp. 91-98). After having completely removed the testicles of birds five months of age, the organs were cut into small pieces and replaced in the abdomen. At first there were signs of castration; a regression of the comb began, sexual instincts and crowing did not develop, though already manifested in the control animal. But about a month after the operation the experimental birds were normal in regard to head apparel and sexual behaviour. Pezard con- tinued his observations for two months longer without observing any abnormality in his animals. Whereas it is very difficult to remove completely the testicle in the cock, castration in mammals can be done without any difficulty. But on the other hand it seems that in the mammal the testicle does not "take" so well as in the cock. Many experiments have been made by different investigators on the dog, rabbit and rat (Biedl, pp. 282-284). These experiments were not always successful, even when an autotransplantation was made. Positive experiments, however, with autotrans- plantation have been described by Steinach (1910). He operated on 40 rats from three to six weeks old; in 36 cases INTERNAL SECRETIONS OF SEXUAL GLANDS 83 the graft took and remained and was observed functioning for more than nine months. The operation was made by Steinach (1916, p. 312) in such a way as to guarantee a good vascularization of the graft. Both testicles were fixed on to the peritoneum or the abdominal muscles, the funiculus spermaticus remaining intact ; a few days later the connection with the funiculus was cut. Similar grafts may remain even for the whole life of the animal. Auto- and homoiotransplanta- tions on guinea pigs and rats were made by Sand (1918), who Fig. 46. — Male vat, 8 months old, with testicular autotvans- plantation at an age of i month. Compare with Figs. 7 to 9. Prostate, seminal vesicles and penis developed as in normal animal of same age. Explan. signs as in Fig. 7. — From Steinach. succeeded especially when puncturing the graft with a needle; evidently this method assures a better vascularization. In view of the experiments performed there can be no doubt that an animal in which the testicles were removed at an early age and to which simultaneously its own testicles or those from another animal were engrafted and took in the new place, can develop in a normal way in regard to somatic and func- tional sexual characters. The prostatic gland, the vesiculae seminales and the penis in such animals are found to be as large as in normal ones (Fig. 46). 84 INTERNAL SECRETIONS Steinach relates having observed in some of his experi- ments an underdevelopment of the sexual characters ; in these cases the testicular grafts were small. He concluded from these observations that there is a correspondence between the degree of maleness and the quantity of testicular mass in the animal. But I think that this conclusion is not justified, since complete maleness is possible even when the testicular fragment is extremely small, as in partial castration (Pezard, 1918 ; Lipschutz and co-workers, 1920 and 1921). I am inclined to beheve rather that the underdevelopment of the sex characters in some of these experiments was caused by the underdevelop- ment of the testicles. In Chapter IV. we shall discuss more fully our own experiments, in which we were able to show that, by manipulating the testicle of a young animal, develop- ment of the organ and of the sex characters can be retarded, although finally normal maleness may be attained. As to the psycho-sexual behaviour Steinach relates that some animals Avith a transplanted testicle showed an abnorm- ally intense libido. But I am rather sceptical as to detailed data concerning the intensity of the psycho-sexual behaviour in small experimental animals. If the graft does not take the animal will show all the usual signs of castration. In general one is inclined to consider such experiments as sufficient proof for the contention that the influence the testicle has on the sex characters is produced not by intermediation of some kind of nervous reflex beginning in the sexual gland, but by the action of internal secretions. We shall see later on that these experiments taken by themselves are open ta criticism, that is to say, they do not afford sufficient proof for the assumption that the testicle acts really by an internal secretion. The medical practitioner must know that successful trans- plantation of testicles is practicable also in man (for literature see especially Mauclaire, 1923). As far as I am aware, the American surgeon Lespinasse was the first to perform a successful testicular transplantation in man. Pieces of testicle were implanted on the musculi recti of a man who lost both testicles in an accident. Sexual capacity was regained and persisted for many months when the patient was under medical observation. J INTERNAL SECRETIONS OF SEXUAL GLANDS 85 The question of testicular transplantation in man has been advanced by the experiments of Steinach, and since 1916 testicular transplantation has been accomplished a number of times. It is impossible here to give a full account of this matter which is more especially of a surgical interest. Some of the successful cases which have so far been recorded may be taken as examples. Lichtenstern (1916) operated on the man mentioned already in Chapter 11. (p. 12), where examples were given of the results of castration in man. The individual in question lost both testicles when 29 years old, owing to being wounded in the war. When he came under medical observation, pronounced signs of castration were already present; these were the accumulation of fat, the hairless face, and the con- figuration of the hair in the regio pubis characteristic of the eunuch. Sexual libido and sexual abihty were absent for the whole of the six weeks the man spent in the hospital before transplantation was attempted. Then a testicle was taken from a man of 40 who suffered from a congenital hernia which caused a painful pressure on the retained testicle. A thorough clinical examination and an examination of the blood of the man from whom the testicle was to be taken were made previously. The extirpated testicle was cleared from the epididymis, cut in two, and inserted in the obhquus externus muscle, at a spot previously scarified with the cut surface underneath. Thin catgut stitches were made to fix the al- buginea to the muscle; one stitch going through the muscle from both sides and through the top of the graft was tied above the top to make the contact between the cut surface of the graft and scarified muscle closer. The fascia of the muscle previously split was not tied so as to avoid any pressure on the graft. The first day after the operation hot cloths were put over the bandage to promote hyperaemia and favour vasculari- zation. Lichtenstern relates that about the second week after the operation signs of regained sexual desire and capacity (erotic dreams and erections) were experienced. The first normal sexual act was performed about six weeks after the operation. The accumulation of fat decreased and the beard began to grow. When examined nine months after the operation all the somatic and physical signs of castration were absent, the sexual life of the man was normal and he intended to marry; fifteen months after the operation he did marry; according to a 86 INTERNAL SECRETIONS communication made by the patient two and a half years after transplantation the marriage is a happy one. The last state- ment of Lichtenstern concerning this patient which I have read, was made four years after the operation ; at this time the man was still sexually normal. Lichtenstern (1918) describes also a transplantation performed on a man castrated ten years ago on account of tuberculosis. All the signs of castration were present. Testicular trans- plantation was successful Hkewise in this case ; signs of sexual ability appeared within three weeks. In a series of subsequent communications Lichtenstern has described several other cases in which successful testicular transplantations were made on castrated and eunuchoid men. Also autotransplantations were made with men which are of a still greater practical interest. All these cases relate to tuberculosis of the testes. The Swiss practitioner Stacker (1916) of Lucerne seems to be the first to have adopted the method of engrafting healthy parts of the removed tuberculous testes into the scrotum. A year after the operation, when Stocker made his communication, the man was still sexually normal. Successful autotransplantations in cases of tuberculosis of the testes were made also by Els (1920) in the same manner as Stocker. He stated that two years after the operation the engrafted testicular fragment was of the same size as in the beginning. Els engrafted healthy fragments of the testes also in those cases where only a unilateral tuberculosis was present. In five out of seven cases Els engrafted into the scrotum, whereas in two cases, on account of a scrotal fistula, trans- plantation was made on to the abdominal w^all. Out of these seven cases five were successful and Els is of the opinion that in all cases of tuberculosis where a resectio epididymidis is no longer advisable, castration with transplantation of healthy fragments should be performed. It is not our purpose to give a full description of all the testicular transplantations made in man with a view to counter- acting the symptoms or effects of castration or eunochoidism or homosexuality. But papers by Wildholz (1917), Lichtenstern (1916-20), Miihsani (1920-21), Forster (1920), and Mauclaire (1923) may be mentioned in this connection. Abstracts of the English papers concerning testicular transplantation will be found in the American Journal, Endocrinology. A paper by INTERNAL SECRETIONS OF SEXUAL GLANDS 87 Stanley and Kelker (1920) may be referred to. These surgeons transplanted on to men suffering from testicular atrophy or abnormal sexuaUty testicles taken from executed individuals. The graft was simply placed in the scrotum or sewn together with the freshly cut atrophying testicle. The last method (already used in 1902 by Mauclaire for testicular autotrans- plantation) gave better results. The effect on the sexual behaviour was extraordinarily striking; a man of 72, having received a double testicular graft from an Indian of 19, had an erection on the third night after operation, although he had experienced none for many years. Changes of voice and vision (in a man of 54) were also observed. Moreover, the authors record a general improvement in condition, the operated men being livelier, moving more rapidly and feeling in better condition generally. Many of the testicular transplantations performed during recent years have been successful, whereas others have had no effect, the graft degenerating and disappearing sooner or later. Probably the number of unsuccessful transplantations is much greater than those which were successful, since surgeons are naturally more inclined to make public a therapeutical success than a result which is negative or unsuccessful. But in discussing the practical side of the question it is obvious that the unsuccessful cases must be taken into consideration. The techni- cal side of the transplantation operation is undoubtedly of great importance. And failure when it occurs should not be allowed to cause discouragement in the use of the method. It is also of practical interest that even very minute testicular fragments may suffice for the full development of the sexual characters {Pezard, 1918; Lipschiitz, Ottow and Wagner, 1920, 1921). That failure should often be met with ought to be only an incentive to discover better methods for increasing the chance of survival of the autoplastic or homoioplastic graft. This is the only practical conclusion to be drawn from what we actually know about testicular transplantation. It is of importance also to obtain more certain knowledge as to the cases in which testicular transplantation is indicated. There are indeed many conditions of eunuchoidism in which testicular transplantation must necessarily be unsuccessful; in eunu- choidism testicular transplantation is indicated only when it is caused primarily by testicular dystrophia and not by a 88 INTERNAL SECRETIONS disturbance of some other endocrine gland. From what Stahel communicated at the meeting of the Society for Sexual Reform held in Berlin in 192 1 it seems clear that in homosexuality- good results are very rare. We shall discuss this side of the question in another chapter. Heterotransplantations have also been attempted several times in man. Stanley and Kelker (1920, 192 1) have reported on an experiment with implantation of rams' testicles; the glands were laid in the pampiniform plexus or imbedded in the fascia overlying the rectus muscle of the abdomen. But the grafts always became necrotic and were gradually absorbed. Falcone (1920) transplanted rams' testicles in the abdominal wall of three men, 53 to 74 years of age, all of them sexually impotent. All the patients showed remarkable improvement in regard to sexual behaviour and general health ; in two cases an increased sexual excitability was observed. The men did not know what effect was to be expected from the graft, so suggestion was excluded. Their own testicles increased in size. I observed during several months a patient into whom the testicle of a goat had been engrafted by Krause in our Institute; the graft was made on the scarified surface of the m. rect. abdom. There was a definite erotising influence, which began a few days after the operation, and lasted for several months. The graft disappeared some weeks after the operation. A great number of very successful testicular grafts were made from ape to man by Voronoff (1923, 1924) and by Thorek (1923). The observations of these authors leave no doubt that a testicular graft from certain anthropoids can survive in the human body for several months, and possibly even for years, exhibiting a normal hormonic activity. A great number of ovarian transplantations have been made during the last twenty-five years in the lower mammals as well as in women. There is no need to give a detailed account of the question as it has already been discussed by various authors [see especially Biedl, pp. 280-2; Stacker (1916); Unterberger (1918)]. It may be mentioned that the atrophy of the uterus and of the tubes does not take place when an auto- or homoio- transplantation of the ovary is made {Figs. 47-49). Athias (19 19) has stated that the functional alterations undergone by the uterus of the guinea pig after castration, are prevented by subcutaneous transplantation of ovaries. It seems very INTERNAL SECRETIONS OF SEXUAL GLANDS 89 likely that the ovarian graft has a better chance of survival than the testicular one ; even successful ovarian heterotransplanta- tion has been described by Bucura, who engrafted the ovaries of rabbits and guinea pigs into female hares. He relates that these animals behaved like normal females, and admitted CO . Fig. 47. — Section through uteyus oj a normal rat. To be compared with Fig. 48. — From Marshall and Jolly. the males, a process which never occurs with castrated females; but I am doubtful whether a castrated female is really so easily distinguishable in her behaviour from a normal one. As regards ovarian transplantation in women there can be no doubt that the atrophy of the uterus can be prevented by transplantation ; menstruation occurs and even returns when it had formerly disappeared in consequence of the removal of 90 INTERNAL SECRETIONS both ovaries. For a discussion of the practical side of the ques- tion the reader may be referred to Blair Bell's book (1920, pp. 180-1) where some of the chnical hterature is quoted, and to the paper by Unterberger mentioned above, and to the paper by Sippel (1923) from the chnic of Bumm. It would seem that, wherever possible, any healthy portion of a removed ovary should be engrafted. The question may also be discussed as to whether an ovarian graft can "take" when the normal healthy ovaries are pre- sent in the body. Bell relates that in his expsriments on rabbits the graft grew as well when one ovary was left in situ as when both were removed. I made homoiotransplantations on rabbits with both ovaries in situ; 15 ovaries of animals of the same litters were im- planted into five rabbits one to about three months of age. The ovaries were placed on one of the abdominal muscles. Two months later grafts could be felt in two or three animals; in one of these animals the graft seemed to be in a state of cystic degeneration. When killed five to six months after the operation no remains of the grafts could be found. Similar experiments were recently made with success by Haherlandt (1921) on adult rabbits; we shall return to these experiments in Chapter V. There can be no doubt that a testicular or ovarian graft not only can "take" in mammals and man, but that the ovary, as we shall see in Chapter V., can undergo after transplantation the cyclical changes of the organ in situ. |\' Testicular transplantations in the frog were made by Nuss- haum (1909, p. 546) who went carefully into the whole question. He points out that one can improve the chances of the graft Fig. 48. — Section through the uterus of a castrated rat. Much reduced muscle layers. Uterine glands absent. ■ — From Marshall and Jolly. INTERNAL SECRETIONS OF SEXUAL GLANDS ,. to the air; ^ golTv^SZiz'ZT T '^""''' '^"P°^"-"^ -.0. The a.op., o^^ S:-;- ^ ^^^r^ ^ - r:'^;^w<^^ J!?V'<->:t- »!'! /*^C ■;■'/ <:''' ^r-/;L*^'?--^-i--V-irV.' ■ Vj^'/;"4^; »ent of the uterus.-From'lg^.ffiatfjolf;""^' "^^^'"P" signs of castfation mini est them.", "°' ^' ''''' ^" *^^ "-^' cessful transplantations ftoaiTJ^r'- ; "" ■^''^' "^""^ ^'^^- is m toads (5«/b TO/g«„s) have recently 92 INTERNAL SECRETIONS been made by Guyenot and his co-workers, Ponse (1922) and Welti (1923). But do all these experiments really afford sufficient proof that the sexual glands act on the sexual characters by internal secretions ? I mentioned above that we are confronted with an objection here. We cannot exclude the possibility that centri- petal nervous fibres have grown into the graft and that a nervous path was re-established between the sexual gland and the central nervous system. Nussbaum seems to have been the first to have called attention to this. He pointed out that by testicular or ovarian transplantation a new logical position is not thereby created, and that there is nothing to decide the question whether the graft is acting on the sexual characters by the intermediation of a nervous path or by some chemical substances. As far as I know the question whether nerves also enter into the graft along with blood vessels has not yet been studied anatomically. But observations certainly show that a nervous connection between the engrafted sexual gland and the central nervous system is established. A man on whom a testicular transplantation was made by Lichtenstern (1916) said, about five weeks after the operation, that bending low (and pressing on the graft placed on the obliquus externus) gave him the same pain as formerly when his own testicles were pressed upon. The same thing was told me by another patient also operated on by Lichtenstern. Els (1920) also describes a case. where the sensitiveness of the testicular graft was like that of a normal testicle. In view of these observations it seems certain that the graft really becomes connected by nerves to the central nervous system and that transplantation experi- ments cannot absolutely decide the question whether the sexual glands act by nervous reflexes or by internal secretions discharged into the circulating blood. B. FEEDING WITH SEXUAL GLAND. Unlike the experiments with transplantation, those upon feeding with testes or ovary should supply satisfactory proof of an endocrine action on the part of the sexual glands if proved to be successful in preventing the symptoms of castration. The important part played by feeding experiments with thjnroid gland or its extracts in contributing to our know- ledge of internal secretion in general may be mentioned here INTERNAL SECRETIONS OF SEXUAL GLANDS 93 But what is stated about the results of feeding with sexual glands is very contradictory, especially in therapeutical ex- periments where different pharmaceutical preparations were administered. We shall restrict ourselves here to giving an example of one successful and one unsuccessful experiment . The first was made by ^. Loewy (1903, pp. 138-40) on capons which were fed with testes. Loewy relates that the head apparel developed better than in control capons. He mentions also an effect on the skeleton in which all the changes characteristic of the "castrate" were prevented when young capons were fed with testes. Steinach (1910) fed rats castrated at an age of four weeks with fresh testes of adult rats, guinea pigs and rabbits. Although the feeding experiment lasted more than three months the animals remained typical "castrates," and not the smallest effect could be observed. The negative result does not however imply that feeding with testis or with ovary must necessarily always be negative in its results with mammals. On the other hand there can scarcely be any doubt that the metabolism of mammals may be changed in one or other direction by feeding with ovary or its preparations. This is in accordance with Loewy' s ex- periment mentioned above and with numerous experiments performed lately by many investigators on tadpoles for different purposes. In my Institute Wagner (1922) found that the metamorphosis of tadpoles, retarded by late artificial fecun- dation, can be accelerated by feeding with ovary. But no specific influence through feeding with testis or ovary has ever been observed, i.e., the formative influence which the testicle or the ovary exerts on the sex characters in the body could not be replaced by feeding upon these organs. C. INJECTION. As with the feeding experiments injection experiments with testis or ovary on mammals have given very contradictory re- sults. It suffices to mention the experiments of Brown-Sequard (1889) ^^^<^ others upon man. New experiments of this kind have been recently performed by Stanley (1921), who made numerous injections in over 300 cases. He used aseptically prepared material from ram, goat or boar a year to eighteen months old, i.e., from animals which had reached sexual maturity. The injections were made subcutaneously on the 94 INTERNAL SECRETIONS abdomen. Sometimes material kept frozen at — i8°F. for as long as 30 days after the death of the animal was used without the potency seeming to be affected. The cases treated were of a very different order, and included neurasthenia, senility, asthma, different chronic nervous diseases, testicular atrophy, rheumatism and diabetes. Some of the treated men stated that their eyesight was improved, that they experienced a renewed joy in living and an increased energy, besides other beneficial effects. Stanley concluded from his experiments that animal testicular substance injected into the human body really produces definite effects. One can scarcely say that these experiments on men provide proof of a specific testicular internal secretion. But positive results in replacing the specific influence of the sexual glands on the sex characters by means of injection were obtained by Bouin and Ancel in experiments on guinea pigs and in the experiments of Pezard on cocks. Bouin and Ancel (1906) gave to three guinea pigs castrated when two to four weeks old, sub- cutaneous injections of an extract from retained testicles of mammals. The extract was prepared with glycerine and water, and injections were made every two days. The experiment lasted nine months. It was found that the penis and the vesiculae seminales were much more developed than in ordinary "castrates." The striking way in which the penis and the vesiculae seminales of the guinea pig react to castration may be recalled, as well as the marked difference between, for in- stance, the length of the vesiculae seminales of a normal and a prepuberally castrated adult guinea pig {Figs. 12 and 13). Now Bouin and Ancel found that the length of the vesiculae seminales of the injected animals was not only greater than in " castrates," but that in one case the length shown by a control normal animal was nearly attained. Moreover, they measured various bones, and claim to have found differences between normal and castrated animals, whereas the proportions in the injected animals were like those in the normal; but in my judgment the differences are very small. It is the same with another experiment performed by Bouin and Ancel with the purpose of studying the body weight of injected guinea pigs. (1906 b). They found that the injected animals had about the same weight as normal ones, whereas the "castrates" weighed less. But the question as to the body weight after castration INTERNAL SECRETIONS OF SEXUAL GLANDS 95 is a very complicated one, since it is influenced by many factors such as the skeleton, muscles, internal organs and fat deposit. In male rabbits I found no difference between the weight of normal and castrated animals in the first six months after birth, or about four months after castration, whereas later on I found a striking difference, the "castrate" attaining a greater weight. This seems to be due especially, as already said, to the accumu- lation of fat. Pezard's experiment (1911) was performed on a cockerel castrated two months before and showing signs of castration. Intraperitoneal injections of an extract of retained pig testicle were made twice a week for about five months. The comb of the injected bird got longer than in the control which was an ordinary "castrate." The entire head apparel underwent development, became rich in blood, and capable of erection. When the injections were stopped the comb decreased in length, and about 2^ months later was of the same length as in the uninjected control "castrate." The whole of the head apparel also became pale. Pezard relates also that sexual instincts were shown by the injected bird which crowed and fought with other birds. The sexual instincts disappeared and the crowing ceased when the injections were stopped. The body weight of the castrated bird was not changed by the injections. Experiments have been made on the frog by several in- vestigators. Nussbmim (1909, p. 554) inserted the testicles into the Ijmiphatic sacs in a number of castrated frogs ; the pads and the vesiculae seminaJes grew, although the testicles gradu- ally degenerated. In order to bring about a successful result it is necessary to place a new portion of testicle into the lym- phatic sac before the previous portion has entirely degenerated. Castration effects can be prevented also by repeated injections into the lymphatic sac with a pulp made of testicle. A great number of similar experiments were made by Steinach (1910), who studied the dependence of the clasp reflex upon the testicle. Having castrated the frogs and found by repeated testings that the reflex could no longer be evoked, he injected into the dorsal Ijmiph sac a pulp of testicular substance taken from frogs "in heat." About 12 to 24 hours later the clasp reflex appeared; in some cases it began gradually. In about two days the maximum was reached and the reflex disappeared 96 INTERNAL SECRETIONS gradually in from three to four days. The reflex could be evoked again when new injections were made. Such striking results were not, indeed, obtained in all the experiments performed, but in the greater number the reflex could be evoked after injection. The disappearance of the clasp reflex evoked by injections could be accelerated by washing out the dorsal lymph sac with isotonic salt solution. According to Steinach, among frogs caught at the time of heat some are found in which the clasp reflex is naturally absent; in these animals also, however, the reflex could be evoked after injection. Control experiments were made with pulp of muscle and hver of frogs in heat, but no effect could be obtained. Simultaneously with Steinach' s work a paper was published by Harms (1910) containing an account of similar observations on the clasp reflex. The above-mentioned observations of Nussbaum on the influence produced by testicular injections on the thumb pads were confirmed by Steinach, Harms, Mcisenheimer (1912), and Takahashi (1919). All these experiments performed on mammals, birds and amphibians show that the formative and preserving effects possessed by the sexual glands in relation to the sex characters are caused not by nervous impulses from these glands, but by chemical substances secreted by the latter into the circulation. We know practically nothing about the chemical nature of these substances. But they are in any case specific, as the same effect cannot be evoked by the injection of any other gland or tissue. The active substances present in the sexual gland are therefore specific hormones. The question as to the chemical nature of these hormones will be discussed more fully in Chapter VII. According to Steinach the clasp reflex can be evoked only by testicular injection from a frog in heat. When heat is over, the testicle has no effect when injected into a " castrate." From this one would conclude that the specific hormone evoking the clasp reflex is produced only at the time of heat. INTERNAL SECRETIONS OF SEXUAL GLANDS 97 D. INTERNAL SECRETION OF THE SEX GLANDS AND NERVOUS SYSTEM. I. Is THERE AN ACCUMULATION OF THE INTERNAL SECRETION IN THE Central Nervous System ? We have seen that the nervous system is erotized by an internal secretion of the sexual glands in such a manner that the psycho-sexual reflexes are rendered possible, and further that this erotizing action is caused by hormones The question next arises as to whether this action is an elective one similar to that of certain well known chemical poisons. Such an elective action could be proved, if one could demonstrate that erotizing substances secreted by the sex gland are accumulated in the central nervous system. Steinach relates having observed such an accumulation. He injected into a series of castrated frogs extract of brain and spinal cord from frogs on heat, and into a second series of castrated frogs brain and spinal cord of "castrates" were injected. In the first series a good clasp reflex appeared, in the second series no changes were visible. On the other hand Steinach claims to have shown, as already mentioned, that injections of other organs of frogs in heat are unable to evoke the clasp reflex in a "castrate." These ex- periments seem to show that there is an elective action of substances secreted by the testicle upon the central nervous system, due to an accumulation like that of strychnine; but the subject requires a more detailed experimental investigation. It has also been claimed that the central nervous system acts as a mediator between the sex glands and the organs influenced by the internal secretion during heat. This question was investigated by Nussbaum (quoted from Pfluger, 1907) ex- perimentally. He severed the nerve of the forearm of the frog on one side just at the time when the pads begin to hypertrophy. The development of the pad did not take place on the operated side. Nussbaum concluded from this obser- vation that the internal secretion of the testicle acts in a specific manner only on certain nervous centres from which impulses are sent to certain organs, and the metabolism of the latter is changed in a given direction. A similar view was held by Steinach, who pointed out that the primary action of the internal secretion would be that on the central nervous system. 98 INTERNAL SECRETIONS by which, possibly through local changes of blood supply, the development of certain sex characters during the state of heat would be promoted. But Pfluger (1907) raised the objection that by sectioning the nerve of the forearm disturbances may be caused which are sufficient to explain the underdevelop- ment or degeneration of the pad. The question as to the role played by the nervous system in regard to the effect of the sex glands on the somatic sexual characters is a very important one. It would be useful to investigate this question more fully than has so far been done experimentally. 2. Physiology of the Clasp Reflex. The clasp reflex is a relatively simple and very pronounced physiological phenomenon characteristic of heat, and it may be conveniently considered here in preference to the more com- plicated psycho-sexual reactions observable in mammals. There are no special difficulties in experimenting on the physiology of the clasp reflex, whereas enormous difficulties arise when the psycho-sexual reflexes of mammals and man are studied. On the other hand the slight results obtained by experimental investigation of the clasp reflex of the frog may show us that we must not expect too much from research work on the psycho- sexual reactions in mammals and man. We see that the question as to the physiology of the clasp reflex, and the role played by the internal secretion of the sex gland in connection with it, is of a greater importance than one might at first think. The clasp reflex has been studied by many investigators and over a long period. Spallanzani (1786, pp. 93 and 319) showed experimentally that for the reflex to occur, only the spinal cord and no higher parts are necessary. He decapitated male frogs when clasping the females, and they continued to clasp. We shall see below that by decapitation the clasp reflex can be evoked even outside of the time of heat. Further detailed experiments on the clasp reflex were made by Goltz (1869, quoted from Tarchanoff, 1887), who stated that the clasp reflex can be evoked when the skin of the breast or the ventral side of the arm is stimulated. After excising these parts of the skin or cutting through the corresponding posterior roots of the spinal cord the clasp reflex can no longer be evoked. According to Goltz there are influences emanating from the INTERNAL SECRETIONS OF SEXUAL GLANDS 99 female by which the male is attracted, and the clasp reflex is kept up by the continuous stimulation of the above-mentioned parts of the skin. According to Goltz there is also a reflex dilatation of the seminal ducts and a reflex ejaculation. Goltz supposed that the spinal cord and the sensory organs in the skin are, during heat, in a state of increased irritability. Since Goltz' time many experiments have been performed to determine the role played by different parts of the central nervous system on the clasp reflex. All these experiments have shown that the mechanism of this reflex is a much more complicated one than Spallanzani and Goltz supposed. Alhertoni (1887, 1889) and Tarchanoff (1887) showed that the clasp reflex in toads and frogs can be inhibited by stimulation of the corpora bigemina {Fig. 50). Schrader (1887) concluded from experi- ments on the frog that centres inhibiting the clasp reflex are to be found also in lower parts of the brain, such as the cerebellum and the upper portion of the medulla oblongata. The later experiments of Busquet (19 10), Steinach (19 10), and Baglioni (1912) afforded a more detailed knowledge of this question. Busquet separated the spinal cord from the brain in the frog by an incision just below the medulla oblongata, outside the time of heat. By touching the skin of the breast, or by laying the operated animal Brain of frog on another frog, the clasp reflex may be evoked, and may persist for several hours. This experiment may be successful at any time of the year. Busquet performed 200 of these experiments with success. The reflex can be evoked for about a week after the operation, i.e., as long as the animal survives. Similar results may be obtained after decapitation or a strong blow on the head. Evidently outside the time of heat certain impulses from above the spinal cord inhibit the clasp reflex, and we must suppose that the hormones produced by the sex gland during heat lower the irritability of these inhibiting centres. According to Busquet, this nervous mechanism is present only in the adult male; in 200 females Busquet never could evoke the clasp reflex after the operation mentioned above. Further, Busquet tried to show that this nervous mechanism develops Corp. bi^. med. obi. Fig. 50. loo INTERNAL SECRETIONS gradually in the male ; in young males of about 15 to 25 gr. the experiment was unsuccessful, as in females, whereas in males of 35 to 40 gr. the clasp reflex, although evoked, was weaker than in males of 50 to 60 gr. Similar experiments were performed by Steinach and Langhans (Steinach, 1910). They made incisions just below the medulla oblongata or between the cerebellum and the medulla oblongata, and evoked the clasp reflex in some cases for as long as two days. Like Schrader, they take the view that inhibitory centres are to be found, not only in the corpora bigemina, but also in the cerebellum and in the medulla oblongata. Busquet, on the contrary, holds that inhibitory centres are locahsed in the cerebellum only; the clasp reflex cannot be evoked after removal of the lobi olfactorii or of the corpora bigemina. When he destroyed the cerebellum only, which consists in the frog of a small transverse border above the medulla oblongata, the reflex could be evoked. The same result was obtained when the middle part of the cerebellum was destroyed with the point of a pin. Besides the inhibitory centres there must be a centre for the clasp reflex in the spinal cord ; it is the cervical part by which the muscles of the fore legs are innervated. By destro3dng the spinal cord 2 to 3 mm. below the medulla oblongata, Busquet caused the reflex to disappear. But the reflex persists when incisions are made just below the medulla oblongata and between the third and fourth cervical vertebrae. It is possible that the clasp reflex is caused not only by the weakening or absence of the inhibition from the upper parts, but also by an increased irritability of the spinal cord during heat; the question is worth further investigation as to whether the irritability of the spinal cord may be altered by the internal secretion of the testicle. The results obtained in experiments on toads and frogs by Baglioni are contrary to those of the earlier investigators. He confirmed the statement of Albertoni and Tarchanoff, however, that the clasp reflex in the frog can be inhibited by mechanical stimulation of the corpora bigemina. But, on the other hand, Baghoni stated that the clasp reflex is not in- hibited when the corpora bigemina are stimulated electrically, since under these conditions the reflex became even stronger. Another observation of Baghoni corroborates this; by placing INTERNAL SECRETIONS OF SEXUAL GLANDS loi a cotton wool pad soaked with stovaine on the corpora bigemina the clasp reflex could be inhibited. Contrary to the former authors, Baglioni concludes that in the corpora bigemina there are no inhibiting centres ; Baglioni suggests that centres evoking the clasp reflex are to be found in the corpora bigemina. The contradictory results obtained by Baglioni are possibly to be explained by the assumption that the electric stimulation or the influence of the poison affected in reality not only the corpora bigemina, but also the spinal cord. Baglioni con- firmed the statement that by sectioning the spinal cord just below the medulla oblongata the clasp reflex can be evoked also outside the time of heat. In toads Baghoni obtained the clasp reflex by this operation, even in females. But as Baglioni points out, the reflex obtained in male and female in such a way is in reality not the true clasp reflex, but a climb reflex. Some further observations of Baglioni show also that certain in- hibitory effects, due normally to the cerebral centres, are not displayed during heat. He found that the clasping male frog makes a prolonged extensory movement with the hind legs when touched on the soles of the feet. Outside the time of heat the same tonic movement can be observed only in frogs in which a section had been made between the medulla and the spinal cord. As regards the sensitive parts in the skin from which the clasp reflex can be evoked, Steinach and Langhans made observations showing that probably the pads are a special sensitive organ. According to them the clasp reflex can be inhibited by painting the pads with a 5 per cent, solution of cocaine. Steinach thinks that the clasp reflex can be evoked by stimulation of the skin itself, owing to the fact that by stimu- lation of the skin the pads are in reahty simultaneously mechanically stimulated. According to Schrader the clasp reflex lasts very long only in cases where it is evoked by the female itself, although, as we know, anything touching the skin of the breast can evoke the reflex. Evidently there are certain special influences coming from the female and acting on the male which cause the prolonged reflex. In view of these considerations one sees that the clasp reflex of the frog in heat, which at first sight seems to be so simple, is in reality a very complicated nervous mechanism, in which both stimulating and inhibitory impulses play a part. The I02 INTERNAL SECRETIONS irritability of the nervous centres involved in this mechanism seems to be regulated by the hormones of the testicle. How much more complicated must be the physiological mechanism underlying the psycho-sexual behaviour of the mammal or man! One realises how manifold must be the variations in psycho- sexual behaviour which have arisen on so complex a physiological basis, especially when one takes into consideration that the inter-play of irritation and inhibition may be changed by variation in the activity of the hormone- producing sexual gland. 3. The Psycho-sexual Behaviour of Man. The observations which have been made on castrated men leave no doubt that the internal secretion of the sex gland is one of the physiological conditions of the characteristic psycho- sexual behaviour in the human species. After seeing how complicated the mechanism of the clasp reflex is, we come to understand how hopeless it is at present to attempt to build up a comprehensive account of human sexual behaviour on purely physiological lines. What we know about these physiological conditions is very little, and theories in this field are usually elaborated rather on analogies than on real knowledge of facts. It must not be forgotten also that the influence of external factors on the sexual behaviour attains in man the highest degree observed in the animal kingdom. There is in the psycho-sexual behaviour of man almost unlimited variation. Every epoch, every social class, every profession, and even every individual has a characteristic sexuality very different from that of others. The conditions determining the psycho- sexual behaviour of man relate not only to a certain type of structure of the nervous system and to the hormones of the sex gland, but at the same time to the whole complex designated under the terms "culture" or "civilisation." We must admit that the psycho-sexual behaviour may be very different even when the physiological basis is the same (Lipschutz, 1922). It is absolutely necessary to emphasize this, because it would be dangerous for human society to overlook the external conditions on which sexuality in man depends. This is true not only within the limits of normal sexuality, but also for all the numerous pathological INTERNAL SECRETIONS OF SEXUAL GLANDS 103 deviations which the medical man and the educationahst have to cope with. It is merely an abstraction that we are dealing with when we consider the relations existing between the internal secretion of the sex gland and the psycho-sexual behaviour of man. But even within the limits of this problem our knowledge relates only to some general points. We shall see in the following chapters how little we know about the pathological changes in the sex glands or in the other glands of internal secretion in cases of quantitative and qualitative variation in human psycho-sexual behaviour. But, on the other hand, anyone who has learnt something about the physiology and pathology of the organs of internal secretion, and especially of the hormone-producing sex gland, will agree that in a scientific analysis of the psycho-sexual behaviour of man the endo- crinological aspects cannot be left unconsidered. * * * Another question may be shortly discussed here. Many authors in recent years have adopted the view that the sex characters depend in reality not only upon the sex glands, but upon the vv^hole internal secretoiy system. We have already touched on this question in Chapters I. and II. There can surely be no development of sex characters without all the other organs of internal secretion par- ticipating; all of these glands are influenced by the internal secretion of the sexual glands, and the latter are influenced by the former, and no doubt these interrelations between the endocrine glands are of the greatest importance in relation to the development of the sex characters. But this does not mean that the determination of somatic and ps^^chical sex characters is in no special relation with the sexual glands, or that there is no special link between the sex gland and somatic and psychical sexuality. I think that in belittling the influence of the gonads one is making two great mistakes. The first mistake is a logical one, whereas the second is due to not taking into consideration the facts concerned. Let us discuss these two points. When we speak in science of the " cause " of a thing we mean by this a factor which is able to change a certain thing into the given thing. We always leave on one side the whole complex of other factors involved in this given thing; scientific research. 104 INTERNAL SECRETIONS and even practical understanding, would be wholly impossible if such a proceeding were not adopted. What we mean when we state that an internal secretion of the sex glands causes male or female characters, is, in the first instance, merely that male or female sex characters can develop only when in an otherwise healthy organism and ceteris paribus the internal secretion of the testicle or the ovary is produced. It is the same with all the other functions attributed to the different structures or organs. Take, for instance, the cortex of the cerebral hemi- spheres considered as an organ of intelligence. Nobody presumably will doubt that the cortex really has this function. But the accomplishment of this function depends upon manifold factors: upon the heart, the blood vessels, and the stimuli acting on the organs of sense. Nevertheless, everyone will agree that great confusion would aiise in physiology if a man of science put forward the view that the cerebral cortex was not responsible for the intelligence merely because the other living organs and tissues were involved in giving effect to intelligent action. And similarly with the sexual gland. Complete maleness or femaleness does not occur without the hypophysis, the adrenals, the thyroid, and so on. In such an objection the second error manifests itself. Extirpation or destruction by disease of any one of these endocrine glands wiU cause a pathological condition which is incurable except by the transplantation of the gland or by feeding or injecting its extract. The position after castration (or in cases of true genital eunuchoidism) is different; no pathological condition arises. It is true that the organism becomes altered function- ally and structurally, but there are no disturbances of a patho- logical order if the other endocrine glands or organs were in a healthy state before. The ovary and the testicle have a specific sexual effect; ceteris paribus femaleness depends upon the ovary, maleness upon the testicle. This sex specific action of the gonads through their internal secretions is a characteristic feature of these glands. It will be dealt with later in this book. i INTERNAL SECRETIONS OF SEXUAL GLANDS 105 BIBLIOGRAPHY FOR CHAPTER HI. [* Not seen in the original.] Albertoni. 1887. Sui centri d'arresto nel rospo. Arch. ital. de Biol., 9. (Reprinted in Ricerche sperimentali eseguite nel laboratorio diretto dal Albertoni. Bologna, 1889, p. 14.) Baglioni. 1912. Zur Kenntnis der Zentrentatigkeit bei der sexuellen Umklammerung der Amphibien. Zentrlbl. f. Physiol., 25. 1913. Physiologie des Nervensystems. Handb. d. vergleiel. Physiologie von Winterstein, 4. Jena. (See the section: "Die die sexuelle Umklammerung vermittelnden Nerven- vorgange," p. 401.) Bayliss und Starling. 1906. Die chemische Koordination der Funktionen des Korpers. Erg. d. Physiol., 5. Bell (W. Blair). 1920. The Sex-Complex. London. Berthold. 1849. Transplantation der Hoden. Arch. f. Anat. u. Physiol., Physiol. Abt., p. 42. BiEDL. 1913. Innere Sekretion, 2 Aufl. Berlin- Wien. BouiN et Ajstcel. 1906a. Action de I'extrait de glande interstitielle du testicule sur le developpement du squelette et des organes genitaux. G. R. de VAcad. d. Sc, 142, p. 232. 1906b. Sur I'effet des injections d'extrait de glande interstitielle du testicule sur la croissance. C. R. de VAcad. d. Sc, 142, p. 298. *Brown-Sequard. 1889. Experiences demonstrant la puissance dynamogenique chez Fhomme d'un liquide extrait de testicules d'animaux. Arch, de Physiol., I, p. 651. * 1889b. Du role physiologique et terapeutique d'un sue extrait de testicules d'animaux d'apres nombre de faits observes chez Fhomme. Ibidem, 1, p. 738. * 1890. Nouveaux faits relatifs a I'injection souscoutanee chez I'homme d'un liquide extrait de testicules mammiferes. Ibidem, 2, p. 204. Bucura. 1913. Geschlechtsunterschiede beim Menschen. Wien u. Leipzig. Busquet. 1910. La fonction sexuelle. Paris. 1910a. Existence chez la grenouille male d'un centre medullaire permanent presidant a la copulation. C. R. de la Soc. de Biol., 68, p. 880. 1910b. Action inhibitrice du cervelet sur le centre de la copula- tion chez la grenouille. Independance fonctionnelle du centre vis-a-vis du testicule. C. R. de la Soc. de Biol., 68, p. 911. io6 INTERNAL SECRETIONS CahlIjERY. 1913. Les prohlemes de la sexvxiUte. Paris. Els. 1920. Neuere Gesichtspunkte bei der Behandlung der Hoden- tuberkulose. Dtsche med. Wochenschr., No. 17. ♦Falcone. 1920. Sugli innesti della ghiandola interstiziale. Riforma med., 36, p. 1177. FoERSTER (W.) 1921. Ein Fall von Hodentransplantation mit Kontrolle nach einem Vierteljahr. Dtsche med. Wochenschr. FoGES. 1902. Zur Lehre von den sekundaren Geschlechtscharakteren. Pfliigers Archiv, 93. • 1914. Keimdriisen. In Jauregg und Bayer, Lehrbuch der Orga- notherapie. Leipzig. Gley. 1914. Les secretio?is internes. Paris. 1921. Quatre legons sur les secretions internes, 2 ed. Paris. ♦GoLTZ. 1869. Beitrdge zur Lehre von den Funktionen der Nerven- zentren des Frosches. Berlin. Haberlandt. 1921. Uber hormonale Sterilisirung des weiblichen Tierkorpers. (Vorl. Mitt.) Miinch. med. Wochenschr., No. 49, p. 1577. Harms. 1910. Hoden- und Ovarialinjektionen bei Rana fusca Kastraten. Pfliigers Archiv, 133. Lichtenstern. 1916a. Untersuchungen iiber die Funktion der Prostata. Zeitschr. f. Urologie, 10. 1916b. Mit Erfolg ausgefiihrte Hodentransplantation am Men- schen. Miinch. mediz. Wochenschr., No. 19. 1918. Offiz. Protokoll d. Gesellsch. d. Aerzte in Wien. Wiener klin. Wochenschr., No. 45, p. 1217. * 1920. Bisherige Erfolge der Hodentransplantation beim Men- schen. Jahresk. f. drztl. Forthild., 11, p. 8. LipschHtz. 1917. Zur allgemeinen Physiologie des Wachstums. Zeitschr. f. allgem. Physiol., 17. (See espec. Part VIII.) et Ottow. 1920. Sur les consequences de la castration partielle. C. R. de la Soc. de Biol, 83, p. 1340. , Ottow et Wagner. 1921. Nouvelles observations sur la castration partielle. Ibidem,, 85, p. 42. 1921. Quantitative Untersuch. iiber die innersekretorische Funktion der Testikel. Dtsche med. Wochenschr., No. 13. 1922. Die innere Sekretion der Geschlechtsdriisen und ihre Bedeutung fiir die Sexualitat des Menschen. Referat I., Internat. Tagung f. Sexualreform in Berlin. Sexualreform und Sexualwissenschaft. Stuttgart. Loewy (A.) 1903. Neuere Untersuchungen zur Physiologie der Geschlechtsorgane. Ergebn. d. Physiol., 2, 1 Abt. Mauclaire (P.) 1923. Les greffes testiculaires chez les animaux et chez rhomme. Arch, des maladies des reins et des organest genito-urin., 1, p. 513. INTERNAL SECRETIONS OF SEXUAL GLANDS 107 Meisenheimer. 1912. Experimentelle Studien zur Soma- und Ge- schlechtsdifferenzierung, II. Jena. MiJHSAM. 1920. Tiber die Beeinflussung des Geschlechtslebens durch freie Hodeniiberpflanzung. Dtsche med. Wochenschr., No. 30. 1921a. Der Einfluss der Kastration auf Sexualneurotiker. Ibidem, No. 6. 1921b. Weitere Mitteilungen iiber Hodeniiberpflanzung. Ibidem>, No. 13. 1921c. Influencia de la transplantacion del testiculo y de la castracion sobre el sentido sexual. Revista medica de Hamhurgo, 2, No. 7. *NussBAUM. 1906. Innere Sekretion und Nerveneinfluss. AnaL Anz., 29, p. 431. * 1906. Innere Sekretion und Nerveneinfluss. Erg. Anat. u. Entw.-Gesch., 15, p. 39 (both quoted Pfliiger, 1907). 1909. Hoden und Brunstorgane des braunen Landfrosches (Rana fusca). Pflugers Arch., 126. 1912. tjber den Bau und die Tatigkeit der Drusen, VI. Mittl. Arch. f. mikr. Anat., 80, II. Abt. Pezard. 1911. Sur la determination des caracteres sexuels secon- daires chez les Gallinaces. C. R. de VAcad. d. Sc, 154, p. 1183. 1918. Le conditionnement physiologique des caracteres sexuels secondaires chez les oiseaux. Edition du Bulletin Biologique de la France et de la Belgique. Paris. PrLtJGER. 1907. Ob die Entwicklung der sekundaren Geschlechts- charaktere vom Nervensystenie abhangt ? Pfliigers Archiv 116. PoNSE. 1922. Disparition et recuperation des caracteres sexuels secondaires males par castration et greffe chez Bufo vulgaris. C. R. de la Soc. de phys. et d'hist. nat. de Geneve, 39, p. 144. Sand. 1918. Experimentelle Stvdier over K^nskarakterer hos Pattedyr. Copenhagen. ScHRADER. 1887. Zur Physiologie des Froschgehirns. (Vorl. Mitt.) Pflugers Arch., 41, p. 75. SiPPEL. 1923. Die Ovarientransplantation bei herabgesetzter und fehlender Genitalfunktion. Arch. f. Gyndkol, 118, p. 445. Spallanzani. 1786. Versuche ilher die Erzeugung der Tiere und Pflanzen. Deutsche Ubersetzung. Leipzig. ♦Stanley. 1920. Experiences in testicle transplantation. Calif. State J. M., 18, p. 251; quoted Ber. ges. Phijsiol, 3, 1921, p. 514. * and Kelker. 1920b. Testicle transplantation. Jl. Am. M. Ass., 75, p. 1501; quoted Ber. ges. Physiol., 2, 1920, p. 575. 1921. Testicular substance implantation. Endocrinology, 5, p. 708. lo8 INTERNAL SECRETIONS Stocker. 1916. tJber die Reimplantation der Keimdriisen beim Menschen. Korresp.-Blatt f. Schweizer Aerzte, No. 7. Steinach. 1910. Geschlechtstrieb und echt sekundare Geschlechts- merkmale als Folge der innersekretorischen Funktion der Keimdriisen. Zetitralbl. f. Physiol., 24. 1916. Pubertatsdriisen und Zwitterbildung. Arch. f. Entw.- Mech., 42, p. 307. ♦Takahashi. 1919. tJber die Geschlechtsdriisen der Wirbeltiere. Mitt. Med. Fak. Univ. Tokyo, 22 (quoted from Witschi, 1923, Zeitschr. f. ind. Ahst. und Vererb.-Lehre, 31, p. 307). Tarchanov. 1887. Zur Physiologie des Geschlechtsapparates des Frosches. Pfliigers Arch., 40. Thorek. 1922. The present position of testicle transplantation in surgical practice; a preliminary report of a new method. Endocrinology, 6, p. 771. 1923. Tiber eine neue Methode der Hodenverpflanzung u. verwandte Probleme. Wien. Med. Wochenschr., No. 60. Unterberger. 1918a. Hat die Ovarientransplantation praktische Bedeutung? Dtsche med. Wochenschr., No. 33. 1918b. Die Transplantation der Ovarien. Arch. /. Gyndkol., 110, p. 1. VoRONOFF. 1923. Grebes testiculaires. Paris. 1924. Quarante-trois greffes du singe a Vhomme, Paris. Wagner. 1922. Experiment elle Untersuchungen iiber die Um- wandlung des Geschlechts beim Frosch. Arch. f. Entw.-Mech., 52, p. 386. Welti. 1923a. Le sort des autogreffes chez le Crapaud. G. R. de la Soc. de phys. et d'hist. nat. de Geneve, 40, p. 152. 1923b. Les homogreffes sont-elles capables de persister chez le Crapaud? C. R. de la Soc. de phys. et d'hist. nat. de Geneve, 40, p. 156. WiLDBOLZ. 1917. Ein Fall von kongenitaler Anorchie. Korr.-Bl. f. Schweizer Aerzte, No. 39. Witschi. 1921. Der Hermaphroditismus der Frosche und seine Bedeutung fiir das Geschlechtsproblem und die Lehre von der inneren Sekretion der Keimdriisen. Arch. f. Entw. Mech., 49, p. 316. Chapter IV. The Seat of Production of the Internal Secretion of the Testicle. From the facts communicated in Chapter III. it follows that in all vertebrates and in some invertebrates the sexual glands influence by an internal secretion the sexual characters both in forming and also in conserving them. There are different tissues in the sexual glands, and the question now arises which of these tissues represent the organ of internal secretion in the sexual gland. The question is, indeed, as Gley (1922) has rightly pointed out, histological rather than physiological. But it is one which can be decided only b}^ the help of experimental physiology. At first sight one might suppose that the internal secretion of the testicle is produced by the generative part. This sugges- tion has been contested in recent years by several authors. A long series of investigations has encouraged the belief that the internal secretion ascribed to the sexual glands is elaborated by the so-called cells of Leydig, the "interstitial substance," or "interstitial cells," situated in the connective tissue between the seminiferous tubules. It was shown by these investiga- tions that the formation and the preservation of the sexual characters in the organism of mammals occur also when the generative part of the testicle is in a state of degeneration. Bouin and Ancel (1903) were the first to identify the cells of Leydig with the organ of internal secretion in the mammalian testicle. They called these cells Glande inter stitielle, or inter- stitial gland, whereas Steinach (1912) described them later under the name Puberty gland. As regards other vertebrates and invertebrates no sufficient knowledge of the interstitial cells in the testicle yet existed for locating the internally secreting elements. Not until lately has a systematic investigation in this direction been under- taken for amphibians and birds and fishes, but this has now been done by Bouin and his co-workers. 109 no INTERNAL SECRETIONS A. MAMMALS. I. The Interstitial Cells of the Testicle. In his first account of the interstitial cells, Ley dig (1850, p. 47) described them as follows: — "One sees in studying the ^l.'^ i m m 1^4/^®' IP'" t^' ; &-.\.r***v^ ■iC* .'^f v% ..'*5' t: .. >• ^'. Fig. 51A, — Section tJiroii^Ji tcbtich "/ nnnnn/ guinea pig, aged about 4|- months. (Prot. Nr. 27). x 280. Quadrangle between four tubules. Interstitial cells surrounding a capillary. Granulated interstitial mass. comparative histology of the testicle that besides the semin- iferous tubules,, blood vessels and nerves, there is present in the testicle of mammals another constant part, a cellular mass which surrounds the blood vessels when present only in small quantity, and in which the seminiferous tubules are INTERNAL SECRETION OF TESTICLE iii wholly embedded when the quantity of this cellular mass is greater. The principal part of this mass consists of corpuscles of fatty appearance which do not .change in acetic acid and in caustic soda, and which are colourless or yellowish." (See also Leydig, 1857, p. 495.) Since Leydig a great number of papers Fig '^iB— Section through testicle of normal guinea pig, a ^ed about ,h months. (Prot. Nr. 27). ^ ^^.-' .^^'Z^^^f, cells, capillaries and granulated mass m mtertubular space.-^Prepar. of Wagner; photo of Kuli. have been pubhshed on the histology of the interstitial cells. The most important paper of this kind dealing with the history of this question is that of Bouin and Ancel (1903 a). i^e papers of Bonng and Pearl (1917). Waldeyer (1921), and Benda (1921) may also be referred to. ^ 112 INTERNAL SECRETIONS I shall give in this section a description of the interstitial cells, based on observations made by myself and Dr. Wagner on different species, especially on the rabbit, the guinea pig, the mouse and the cat. The interstitial cells in the testicle of mammals can be well recognised under normal circumstances m «* 9 i 4. G - Pf'^v e^ ? Fig. 52. — Section through testicle of normal rabbit, 14 months old (Prot. Nr. 82). x 280. — Prepar. of Wagner; photo of Kull. by staining with haematoxylin and eosin ; the solution of Bouin for fixation gives very good results; that of Helly (solution of Miiller with subhmate and 5 per cent, formalin) is also very useful. In the testicle of an adult rabbit or guinea pig Vv^e see between the tubules triangular or quadrangular masses or cords of cells very well stained by eosin {Figs. 51, 52). The spherical nucleus is large and light coloured, the quantity of chromatin INTERNAL SECRETION OF TESTICLE 113 The being small; two or three nucleoli are generally present, protoplasm surrounding the nucleus is very large. The dimen- sions of these cells are very variable, but by their characteristic appearance they are as a rule easy to distinguish from common connective tissue cells which are present in the testicle of an adult rabbit or guinea pig only in small quantity. In the testicle of the mouse the number of the interstitial cells is less, Fig. 53. — Group of interstitial cells in testicle of adult cat (Prot. Nr. 277, weight 3-2 kgr.). Weight of testicle, 1-2 gr. The big inter- stitial cells with spherical nucleus and vacuolated protoplasm can easily be dis- tinguished from connective tissue cells. — Prepar. Wagner; design, Lehbert. whereas, as stated by different authors, it may be enormous in other species as, for instance, in the wild boar. In the cat {Fig. 53) the interstitial cells are also very well developed. In man the interstitial cells are embedded in connective tissue con- sisting of fine filaments {Fig. 54). Very often one finds between the tubules and the interstitial cells empty spaces about which there has been much discussion {Figs. 51, 52); some authors consider these spaces to be artificial, whereas others regard them as something in the nature of l37mphatic spaces. Lately 114 INTERNAL SECRETIONS Wagner showed that these spaces are often filled with a homo- geneous or granular mass, and as this phenomenon could be observed after fixation Hkewise in formaHn and in the solutions of Flemming, Bouin and Helly, it seems very probable that these spaces are not artificial, but have something to do with the function of certain parts of the testicle. ^% '<^I% .#*? '#»1 ■1 *^a^9 ^iS^ Til ly^?.-* '» ^ Fig. 54. — Section through testicle of man 26 years old (executed). Haematox.-eosin. Complete sperma- togenesis; well developed interstitial cells. — From a preparation kindly lent by Aunap; design, Lehbert. By differential stains inclusions may be observed in the protoplasm of the interstitial cells. There has been much discussion about the fatty granules in these cells ; such granules are, indeed, to be found generally in the interstitial cells. Some authors are inclined to consider them as the most characteristic feature. But on staining preparations of an adult rabbit or mouse with "Sudan," one can see that the INTERNAL SECRETION OF TESTICLE 115 quantity of fat in the interstitial cells is very inconstant, and that fat may even be absent. On the other hand, the inter- stitial cells are sometimes completely filled up with fatty inclusions; a " Sudan" preparation from the testicle of an adult cat shows this in a very striking manner {Fig. 55). It seems Fig. 54a. — Section through testicle of hitman embryo of fifth month. Same augmentation as 54. The greater part of the testicle consists of interstitial cells. Note the great quantity of capillaries in the interst. tissue. — From a preparation kindly lent by Aunap; design, Lehbert. to us improbable that the fatty inclusions are to be considered as the characteristic feature of the interstitial cells, and it is not possible to deduce therefrom conclusions as to the function of these cells. This is clear if we take into consideration the fact that numerous other inclusions are detected in the inter- stitial cells by other differential stains. I mention only the crystaloids detected by Reinke in the testicle of man, and the ii6 INTERNAL SECRETIONS different granules of protein nature detected afterwards by other investigators (see e.g. Whitehead, 1912 b). The secreting granules characteristic of glandular cells and chondriosoma can be seen in the interstitial cells {Wagner, 1923) {Fig. 56). Dr. Wagner finds that, when a common connective tissue cell is in process of transformation into an interstitial cell, the protoplasm Fig. 55. — Section through testicle of adult cat, stained with Sudan. — Complete spermatogenesis; great quantity of interstitial cells full of fat. — Prepar. Wagner; design, Lehbert. is characterised by an increase in size of the secreting granules and the chondriosoma which augments the size of the whole cell. Wagner has also made some observations which tend to show that, so far as fat appears in an interstitial cell, this fat is very specially localised (see Fig. 56). If it is permissible to draw conclusions as to function from histological appearance, one must presume that the interstitial cells are glandular. INTERNAL SECRETION OF TESTICLE 117 1-^ \ J\ >v % % ^ s ^^ ^ *~i, .'••> o ^'*5:r Fig 56. — Interstitial cells of different anitnals. Differential staining, (A, B, C, E, F, Sudan and haematoxylin ; D, osmic acid and saffranin). High magnification, A, adult mouse; B, adult guinea pig; C. adult rabbit; D and E, adult cat in March; F' human embryo, 6 months old. In A, B, C, E, F vacuoles with or without lipoid sickle-shaped bodies are visible ; in D the vacuoles are com- — pletely covered by fat. G, adult mouse. Vital staining of Goldmann ; the animal was treated during six weeks with " Pyrrholblau." The smaller, rather spindle-shaped cells became blue, whereas the big epithelioid cells remained uncoloured. Possibly the smaller " pyrrholic " mterstitial cells are in a different functional state from the big interstitial cells.— From Wagner. ii8 INTERNAL SECRETIONS As to the origin of the interstitial cells there are two different opinions. According to Bouin and Ancel (1903 c), who made observations on the embryo of the pig, the interstitial cells belonged to the mesenchyme, but grew into the primitive generative epithelium, separating the latter into solid cords. On the other hand, Rubaschkin (1912), who published very Fig. 5 7 a. — Development of interstitial tissue in guinea pig. Abortus, not very far from normal birth (Prot. Nr. loi). detailed observations on the guinea pig, showed that it is probable that the interstitial cells originate from mesodermal epithelium, i.e., from the generative cords; it maybe mentioned that from the mesoderm arise also some other glandular cells, for instance, those of the renal tubules. It seems to me that the views are not so contradictory as one might at first think. The observations of a number of workers whom Wagner has confirmed {Figs. 57A, B, c, d), for guinea pigs, before and after birth, leave no doubt that real interstitial cells INTERNAL SECRETION OF TESTICLE 119 can arise from connective tissue cells. The same conclusion seems to follow from new observations by Guilera and Kronfeld (1921). Sometimes all transitions between the spindle-shaped nucleus of the connective tissue cell to the spherical nucleus of the inter- stitial cell can be observed ; but Rubaschkin suggested that the connective tissue cells, from which after birth interstitial cells K-^ ^9 m £> o® * ^/ * v^ ^ '^> 1s^ s x^'^:* ^^» t 0 Fig. 67. — Section through testicle of rabbit 6| months old, with eunuchoid penis (Prot. Nr. 95, unilaterally castrated at age of 6 weeks; of same litter as Fig. 68.) Complete spermatogenesis; spermatozoa present in the epididymis. Interstitial cells with little protoplasm; nucleus smaller than in Fig. 68; cells with spindle-shaped nuclei prevail. — Prepar. and design of Wagner. INTERNAL SECRETION OF TESTICLE 137 • ft 1^ i#^ ^ ^«B5 %^, « ft s ..^v-^ ^*V» '^^ %^. 10 ' ® *© «:3 ^A ©" w. l«^ «Sfc •v*^> ^^ ♦' *^[c?] j, t , . ^>"t*«fc 'iff >.'. . ** ^» «*■ ■■:^ ^^' Fig. 68. — Section through testicle of rabbit 6^ months old, with normal sex characters (Prot. Nr. 94; unilaterally castrated at age of 6 weeks). Complete spermatogenesis; spermatozoa present in epididymis. Well developed interstitial cells (big spherical nucleus, big area of propotoplasm). — ^Prepar. and design of Wagner. 138 INTERNAL SECRETIONS I 'f)<^ 4 No. 95. l^^U'] No. 94. \ S^ V$\ Fig. 69. — Interstitial cells of rabbits with normal and eunuchoid penis (Prot. Nr. 94 and 95). Stained with Heidenhain. Compare with Figs. 67 and 68. — Prepar. design of Wagner. _ A. Triangular groups wath about equal quantity of interstitial cells. B. Quadrangular groups with about equal quantity of interstitial cells. C. Two interstitial cells. Greater magnification. INTERNAL SECRETION OF TESTICLE 139 r .'-ip^SRf .' '^^ *- ^ '^* W^v r.. • Fig. 70. — Section through testicle of rabbit 6 months old, with normal penis. Same litter as Figs. 71 and 72. Seminal tubules with one stratum only. Well developed interstitial cells. — Photo of Kull; from Wagner and Loeper. 140 INTERNAL SECRETIONS '#'-v* ^tfl* * # If '/ .-^ if f> ^,i^ *'/-- .#-•; ' -. ^ > ' * I'' * ;■ '^' 1 ^ % i -V^. ♦«^ Fig. 71. — -Section through testicle of rabbit 6 months old with eunuchoid penis. Complete spermatogenesis. Few small interstitial cells ; connective tissue prevails. To be compared with Fig. 70. Photo of Kull. — From Wagner and Loeper. INTERNAL SECRETION OF TESTICLE 141 '-^ /"* vV -1^-*' #^ -^^ifciSft*^ "" ^- ' , > •x;.^-l "-y^S^ Fig. 72. — Section through testicle of rabbit 6 months old with eunuchoid penis. Complete spermatogenesis. Few small interstitial cells; connective tissue prevails. To be com- pared with Fig. 70. Design of Wagner.^ — From Wagner and Loeper. 142 INTERNAL SECRETIONS caused degeneration of the tubules by operative interference with the nervous system; Ceni (19 14) observed degeneration of the tubules after an experimentally produced cerebral commotion; Houssay and Hug (1923) found that a lesion of the infundibulum and of the hypothalamic region in the dog does not interfere with the development of the testicle and of the sex characters ; there was only one out of a great number of operated animals which exhibited testicular atrophy; Takahashi (1922) claims to have caused testicular atrophy by extirpating the lumbosacral part of the sympathetic nerve in guinea pigs. But it may be mentioned that the testicle of the guinea pig is very sensitive to all abdominal operations. I am not aware whether the experiments of Takahashi, which gave contra- dictory results, justify the conclusion that the sympathetic nerve has some kind of trophic influence on the testicle. In cats I removed the fifth and sixth lumbar ganglia on one side without any disturbance of spermatogenesis being caused by the operation. The papers of Bolognesi (1921 a, 192 1 b) also may be referred to here. 3. The Retained Testicle. It has long been known that with men having both testicles retained in the abdominal cavity a condition of sterility may be present whereas the somatic sexual characters and the sexual libido are normal. Similar observations have been made on animals, especially on the horse. A stallion with a unilaterally retained testicle preserves the behaviour of a stallion when only the normal testicle is removed, becoming a gelding when the retained testicle also is extirpated. Numerous investigations have shown that the seminiferous tubules in the retained testicle of men and animals are often in a state of degeneration. The retained testicle consists in some cases only of interstitials cells and cells of Sertoli, whereas in other cases generative cells in different stages may be observed (Michon and Porte, 1920). Sometimes a condition of eunuch- oidism exists when both testicles are retained. In these cases there is a complete sclerotization of the testicles, in which the interstitial cells are absent. Retention of testicle has been produced also experimentally in rats, guinea pigs and dogs by different workers ; all record the atrophic state of the testicle or INTERNAL SECRETION OF TESTICLE 143 of the tubules (quoted from Sand, 1921 c). Some investigators especially Kyrle, mention also an hypertrophy of the inter- stitial cells. Very detailed investigations on this question have been made by Sand (1918, p. 109; 1921 c), who caused in rabbits, guinea pigs and rats retention of both testicles by loosening the testicle from the gubernaculum and closing the processus vaginalis. He observed a degeneration of the semini- ferous tubules and an hypertrophy of the interstitial cells; there were no signs of castration. Crew (1922), suggested that the degenerative changes occurring in the undescended testicle are due to the differ- ence of temperature in the scrotum and the abdominal cavity. The testis is adapted to the lower temperature of the scrotal sac ; the temperature of the abdominal cavity (the difference is of several degrees) is not that at which the final stages of spermatogenesis normally develop. The observations made on men and animals with retained testicles show with complete certainty that full development of sexual characters is possible without spermatogenesis proceeding to production of spermatozoa. Ancel and Bouin (1904 b) further record an observation made on a pig killed at an age of six months with normally developed sexual characters, in which animal in the retained testicles even the cells of SertoH were absent. So one may suppose that the internal secretion of the retained testicle is produced only by the interstitial cells. This was already suggested in 190 1 by Regaud and Policard (1901). Detailed investigations on this question were made by Bouin and Ancel on pigs, in which retention of testicles is very frequent. The degree of develop- ment of the genital organs in pigs with retained testicles is very variable. According to Ancel and Bouin (1904 g) the interstitial tissue in the retained testicle of the pig is the better developed the greater the weight of the testicle, and there is, as already mentioned, a proportional relation between the quantity of the interstitial cells and the degree of develop- ment of the genital apparatus. It is clear that such a quantita- tive statement is of the greatest importance in relation to the question of the endocrine function of the interstitial cells, and it was these most important observations of Bouin and Ancel which first led me to plan out quantitative investigations on the internal secretion of the testicle. As a result of our 144 INTERNAL SECRETIONS z'. oo^ co^ ^ Fig. 73. A. B. Seminal vesicles oj guinea pig with testicular fragment of about 60 cmm. (instead of normal testicular weight of about 2 -0-2 -5 gr). Nat, size. Prot. Nr. 34. Operation at age of about 2-3 weeks; drawn 11 months later. Highly developed seminal vesicles; to be compared with C. Seminal vesicles of guinea pig, with testicular fragment of about 35 cmm. (instead of about 2 -0-2 -5 gr.). Nat. size. Prot. Nx. 35. Operation at age of 4^ months; drawn 7 months later. Highly developed seminal vesicles; to be compared with D. Seminal vesicles of guinea pig, 2 1 months old, castrated at the age of 2 weeks (Prot. Nr. 23). Nat. size. Seminal vesicles of guinea pig castrated at the age of 4 J months (Prot, Nr. 27). Drawn 1 1 months later. Nat. size. INTERNAL SECRETION OF TESTICLE 145 experiments, we met with the following objections to the con- clusions of Bouin and Ancel. In experiments (Lipschiitz and co- workers, 1922-23) where only very small testicular fragments were left in the body (young guinea pigs), and where sometimes a very small quantity of interstitial cells was present, an almost or quite normal development of the sexual characters occurred (Fig. 73). In some cases where we left small testicular fragments, we observed a retardation in the development of the sexual characters. First, I supposed (1920, 1921 c) that this retardation was due to the quantity of the hormone being diminished, and that the velocity of the reaction of the somatic substratum was diminished somewhat after the manner of enz5mie reactions. But as we have already seen, an under- development of the testicular fragment occurs sometimes {Fig. 65), and the underdevelopment of the sexual characters, or the eunuchoidism, can be explained as due to the under- development of the testicle (1921 f). In another case (Lipschutz, Wagner and Bormann, 1922 e) we found that a retardation in the development of the testicle can really be determined experimentally. I made horizontal incisions of the testicles (Fig. 64, III.) of a young rabbit, the penis of which remained infantile till about the seventh month, when a rapid puberal development began. The microscopical observation showed that spermatogenesis was stopped by desquamation occurring, whereas the interstitial cells were well developed (Fig. 66). In view of these observations I am incHned to explain the quanti- tative statements of Bouin and Ancel on pigs with retained testicles in a different way from them. I think that the differ- ences they observed in the sexual characters were caused by a different degree of retardation in the development of the retained testicle in individual cases. (See also Section 4 of this chapter.) Bouin and Ancel (1904 d) made also quantitative experi- ments on pigs with retained testicles. On pigs with one retained testicle they removed the normal testicle at an age of six weeks. They stated that in the retained testicle a marked h3rpertrophy of the interstitial cells took place, whereas the number of cells of Sertoli remained unaltered (Figs. 74, 75). The weight of such a retained testicle was about twice as great as that of a retained testicle in the presence of a second normal testicle. These statements of Ancel and Bouin were confirmed 146 INTERNAL SECRETIONS by Sand (1918, pp. 117, 118, 212). Sand caused retention of the testicle in rabbits and guinea pigs on one side, and removed the other testicle. In these experiments the retained testicle weighed two and a half times as much as a retained testicle in the presence of a second normal testicle. Like Bouin and Ancel, ^ . :^^ 4 Fig. 74. — Retained testicle of pig (bilateral cryptorchism). X 200. No spermatogenesis; seemingly only cells of Sertoli present. Normal quantity of interstitial cells. - — From Ancel and Bouin. Sand found the interstitial tissue in a state of hypertrophy, whereas the cells of Sertoli in the degenerated tubules were not increased in number. But these statements of Bouin and Ancel, and of Sand are., in view of our own experiments, insufficient to prove that a compensatory hypertrophy of interstitial cells for endocrine purposes occurs (see below). All the observations made on man and animals with retained INTERNAL SECRETION OF TESTICLE 147 testicles and recorded here supply evidence that the sperma- tozoa or other cells in late stages of spermatogenesis are not necessarily involved in the internal secretion of the testicle. But they do not afford conclusive evidence for the suggestion that the interstitial cells only represent the endocrine apparatus Fig. 75. — Retained testicle of pig with unilateral cryptorchism ; the normal testicle has been removed, x 200. Increased number of interstitial cells; no change of number of cells of Sertoli. — From Bouin and Ancel. in the testicle. The observations of Bouin and Ancel alone, where the sexual characters were normally developed, although there was a complete disappearance of cellular elements of the tubules, can be regarded as a proof of the theory that the interstitial cells are the only testicular internal secretory organs. But here, also, we are confronted by an objection. It takes some time for the effects of castration to become visible after the disappearance of the endocrine testicular elements. It is 148 INTERNAL SECRETIONS not impossible, therefore, that in the animals mentioned testicular secretory products were no longer present, though the effects of castration were not yet visible. The knowledge of the fact that the absence of the higher stages of spermatogenesis or of spermatozoa in the retained testicle does not hinder the normal endocrine function of this organ, has found practical application in human pathology. We learned in Chapter III. that the results of castration can be counteracted by the implantation of a retained testicle. In a case reported by Lichtenstern, the microscopical examination of a particle of the engrafted testicle showed that the semini- ferous tubules were atrophic, and that no spermatozoa were present. Thorek (1923) succeeded in restoring potency in an ape previously castrated a year ago by engrafting a human crypt orchic testicle. 4. The Engrafted Testicle. We referred above (p. 82) to the experiments of Steinach on rats where testicles were transplanted; in many cases the transplantation was successful, and the animals reached full maturity. But the histological examination (Steinach, 1916) of the engrafted testicle showed that the generative part was not normally developed. If there are originally fully developed seminiferous tubules, or if these develop, they degenerate afterwards. This is shown by the histological examination of grafts at different intervals after transplantation. The greater the interval after transplantation the greater the atrophy of the generative part. The diameter of the atrophying seminiferous tubules decreases. According to Steinach the ceUs of Sertoli are finally the only part of the cellular elements of the semin- iferous tubules which persists (Fig. 76). It may be, as Benda (1921) has pointed out, that the cells forming the wall of the degenerate tubules are really not cells of Sertoli, but primitive cells of a generative character, which can enter into a new phase of spermatogenesis. I sometimes found degenerate tubules in a condition identical \nth that of young tubules. This is why I suggested that degeneration of semi- niferous tubules implies really something which might be characterised as "backward development" (1921 d, 1922 c), to use an expression of the Russian zoologist, Eugen Schultz (1908) The changes observable in a degenerating tubule are, indeed. INTERNAL SECRETION OF TESTICLE ^i---i^'i:y? W ".;-. I?«^^V.. -y '■■''}■'' ■; • . ^ 1. /** v: J*': '•! 'a;' .•' V : : '•' .'•."",. •';**.* ■•.**•-.. 'm-:;> ^H Fig, 76. — Section through testicle which 8 months previously had been subjected to autotransplantation [rat). ;x 100. From the same litter as Fig. 77. No spermatogenesis. Hypertrophy of interstitial tissue. — From Steinach. 149 ^ ';••. - ^"S" '^^V.^'*-^' J< 6- , §t-^-. • ,.^i ^i;- - \:;> .V# ■■-sj ■■ --s;.:. ,. "'\i\''^' -•••• •", »!•.••*•'".**:%•,"••. ■;•. " Sr^^^' ^: 'V m- - . ; '•*.%'- ; ■ ' -:. .V ' ' '~ '. . . - Fig. jy.— Section through normal testicle of a rat about g months old. x 100. Complete spermatogenesis ; small quantity of interstitial cells. — From Steinach. 150 INTERNAL SECRETIONS very different in each case. But the differences seen are possibly caused by other factors interfering with the backward development (1921 c). Wholly different from the behaviour of the tubules is that of the interstitial tissue. In the normal testicle of the mouse or the rat (Fig. yy) we find between the seminiferous tubules a fine net of connective tissue, and between the fibres of the^latter here and there single cells of Leydig or httle nests of these cells. In the transplanted testicle the number of the cells of Leydig is enormously increased (Figs. 76 and yy). The cells of Leydig now form a compact mass of thick cords situated between the degenerate seminiferous tubules. The network of connective tissue fibres between the proliferated interstitial cells is very insignificant. It seems that the number of the interstitial cells in the transplanted testicle is several times greater than in the normal one. It was objected that there is no real increase of interstitial tissue between degenerating tubules, the increase being only an apparent one. This may be true in some cases. But various observations certainly show that this objection is not always justified. From our own experi- ments I reaHsed that it is not difiicult to determine whether the hj^ertrophy of the interstitial tissue is real or only apparent. And in our experiments with partial castration there was often an enormous hypertrophy of the interstitial cells in small fragments of the upper pole of the testicle (Figs. yS and 79). It would be out of place to discuss this question more fully here. My paper (1923) may be referred to. As the animals with an engrafted testicle reached full maturity, although the seminiferous part of the graft ceased to develop further, or else degenerated, we must conclude that the internal secretion of the sexual gland does not depend on the accomplishment of spermatogenesis or upon the presence of spermatozoa. Full sexual maturity is possible without any spermatoza in the graft. According to Steinach, the graft does not remain always in the same condition. A few months after the transplantation the cells of Sertoli also undergo a degenera- tion, and according to Sand this may occur very early. The seminiferous tubules lose their structure and disappear; the testicle now consists almost entirely of interstitial cells repre- senting, according to Steinach, an "isolated puberty gland." I made a similar observation in our experiments with partial INTERNAL SECRETION OF TESTICLE 151 castration. But after a short time further changes take place in the graft. There is an increase of connective tissue. Although the interstitial cells surrounded by connective tissue persist for months, they, nevertheless, finally undergo degeneration. Fig. 78. — Section through testicle of normal adult guinea pig (Prot. Nr. 228, 600 gr.). X 70. Full sperma- togenesis. Normal quantity of interstitial cells; the latter often surrounded by granulated mass (especially at the *). To be com- pared with Fig. 79, — Prepar. of Wagner ; design of Lehbert. '•r / 4 ■-- ' s. Fig. 79. — Upper testicular fragment of a partial *' castrate " (guinea pig. Prot. Nr. 30). X 70. Operation at age of 10 days; fragment removed at age of ^^ months. Fragment represents about i per cent, of total normal testicular mass. Seminal tubules with one stratum only; diameter of some tubules remains normal. Number of interstitial cells in general increased; besides this, very pronounced local increase. Sex characters normal. — Prepar. of Wagner; design of Lehbert. We have already mentioned that the number of interstitial cells in the graft can be sometimes greatly increased. Steinach argues that if the interstitial cells are the endocrine apparatus of the testicle, one might expect that where there is an increased number of interstitial cells there would also be signs of an 152 INTERNAL SECRETIONS increased action on the part of the puberty gland. As we have already seen above, Ancel and Bouin have argued in the same manner, when dealing with the proportion between the number of the interstitial cells in the retained testicle and the develop- ment of the sexual characters. Observations of Steinach seemed to corroborate this. He records that several rats, in which both transplanted testicles had "taken," showed an abnormally great sexual activity. In other cases where the engrafted testicle was diminished in size the sexual characters were midway between those of a castrated and those of a normal animal; the genital organs had continued their development to a certain degree, but there was no sexual activity. Thus, according to Steinach, the experiments with transplanted testicles corroborate the view that the degree of development of the sexual characters depends upon the degree of development attained by the interstitial tissue. A series of experiments with transplantation performed by Sand (1918, pp. 74-95) on rats seemed to give further evidence for a proportionality existing between the number of interstitial cells and the degree of development of the sexual characters. When in the transplanted testicle only a few interstitial cells were present, the animals developed into "castrates"; the spermatogonia and cells of Sertoli, which were present in great quantities, were unable to prevent eunuchoidism. When more interstitial cells were present, the animals showed almost normal genital organs, although in the tubules only cells of Sertoli were to be found. When the interstitial tissue was well developed or hypertrophied, the sexual characters were normal, or even in some respects hypertrophied. Steinach concluded from his experiments on rats that in the higher animals the individual differences in the develop- ment of the somatic sexual characters and in the sexual activity are caused by differences in the quantity of inter- stitial cells. This suggestion cannot, I think, be accepted without reserve. Kyrle (1911), amongst others, has pointed out that the increase in the interstitial cells is of the nature of a local reaction to the tubules degenerating. INTERNAL SECRETION OF TESTICLE 153 5. The Influence of X-rays on the Testicle. Since X-rays have been used in medicine it is known that steriUty can be caused by them without any visible changes in the somatic and psychical sexual characters. A number of authors have experimented on this question with animals also and there is general agreement among them that X-rays can cause sterility without interfering with sexual activity (Albers- Schonberg, 1903). Later it was shown by Bergonie and Trihondeaii (1904, 1905) that X-rays cause a degeneration of the seminiferous tubules, whereas the interstitial cells and the cells of Sertoli are not altered. Even a single irradiation could produce this effect provided the irradiation was strong and long enough. The authors also called attention to the fact that simultaneously with the atrophy of the tubules there is a proliferation of the interstitial cells, their number being sometimes two or three times greater than normally. Also a proliferation of the ceUs of Sertoli was reported. Villemin (1906 a) confirmed the statements of Bergonie and Tribondeau, An investigation upon this question was made also by Tandler (1913) on the roedeer. Several months after irradiation the seminiferous tubules were in a state of degeneration, whereas the interstitial cells were normal. The roedeer treated with X-rays cast and regrew their antlers like normal animals. Objections may be made to the assumption that in these experiments a complete suppression of the activity of the seminiferous tubules had taken place. Bergonie and Tri- bondeau (1904) and Villemin (1906 b) found that a regeneration of the degenerated tubules can occur if the irradiation was not too strong. Villemin showed that this result takes place only when besides the cells of Sertoli the spermatogonia also are resistant to X-rays. The question of regeneration was studied further by Simmonds (1909), who records that some tubules may persist unaltered even after radiation of long duration; in regenerated tubules he found spermatozoa. Simultaneously with the regeneration of the tubules the interstitial tissue decreases. This latter observation might be taken as further evidence that the increase of interstitial tissue after degenera- tion of tubules is often only apparent, the extension of this tissue being only greater in comparison with the diminished 154 INTERNAL SECRETIONS extension of the seminiferous part of the testicle. As was shown by Simmonds, mesothorium acts Hke X-rays. In view of these phenomena of regeneration, Simmonds concluded that the internal secretion is produced by the sper- matozoa, and that the interstitial cells take up this function only when the seminiferous tubules of the testicle are partially destroyed. I do not deny that these experiments with X-rays are insufficient for demonstrating that the occurrence of different stages of developing spermatic ceUs is not correlated with the production of the internal secretion of the testicle ; irradiation seems to be a very uncertain means of destroying the semini- ferous tubules, depending greatly upon strength and duration. We have no guarantee that in all the experiments with X-rays recorded hitherto a more or less extended regeneration has been avoided. But in 19 16 a Russian author, Nemenov, published a paper which has not yet been taken into considera- tion in the criticism directed by different authors against the theory of the "interstitial'* or "puberty" gland. Nemenov irradiated dogs repeatedly and examined the testicles and the prostate a long time after the last irradiation. Nemenov stated that even more than eight months after the last irradia- tion only cells of Sertoli were present in the seminiferous tubules. Nevertheless, the prostate was very well developed, many mitoses were present and the tubules of the prostate were full of secretion. The paper of Nemenov is of great importance in its bearing upon the question, and taken in conjunction with the experiments with ligation and trans- plantation recorded above, together with our experiments with partial castration, the observations of Nemenov supply further evidence that seminal cells are not directly involved in the internal secretion of the testicle. Further, Ancel and Bouin (1923) irradiated young guinea pigs and kept them till nine months after irradiation. Though the seminal tubules were in an infantile stage and generative cells were totally absent, the sex characters were normal; the fluid of the seminal vesicles coagulated as in a normal animal. The objection may, how- ever, be made that spermatogonia were still present in the tubules, or that the cells of Sertoli represent some kind of primitive generative cells. But if it is so, it nevertheless remains true that these generative cells alone would be unable to produce the internal secretion of the testicle; we have seen INTERNAL SECRETION OF TESTICLE 155 in a preceding section that in the experiments where cells of Sertoli and spermatogonia were present in the tubules eunu- choidism occurred when interstitial cells were underdeveloped. In view of these considerations the criticism directed against the evidence provided by the X-ray experiments in support of the theory of the interstitial cells is deprived of its importance. Thorek (1923) has made testicular homoiotransplantation in apes (Cynocephalus and Macacus) one to two years after castra- tion ; immediately following this implantation, the animals were subjected to the action of X-rays. Removal of specimens proved that generative tissue was absent. Nevertheless, out of five animals four revealed a return of sexual potency. 6. The Relation between the Quantity of Interstitial Tissue and the Hormonic Effect. (a) Is there a compensatory hypertrophy in the testicle ? We have seen that the number of interstitial cells may be greatly increased under certain conditions. It may be, as already pointed out, that in some cases with retained testicles, ligature or irradiation, this increase is only an apparent one. But no doubt in certain of Steinach's transplantation experi- ments, and in many of our own with partial castration, the hypertrophy of the interstitial tissue was very great {Figs. y^ to 81). We do not know the real cause of this hypertrophy. It seems that it always occurs when a degeneration or a retrograde development of the tubules takes place. My observations agree with Kyrles (1911) in regard to the hypertrophy of the interstitial cells which often occurs in the same testicle or testicular fragment in the neighbourhood of the degenerated tubules only, and not in that of the normal ones. This is an indication that the cause of this hypertrophy is often local rather than general. Further, I observed an enormous hypertrophy of the interstitial cells in a small testicular fragment {Fig. 82) in a guinea pig, notwithstanding that the second testicle was present (1922 c, f). There was an hypertrophy of interstitial cells also in those experiments in which both testicles were transformed into upper fragments without reducing the total testicular mass {Fig. 83). From these observations one must conclude that the hypertrophy of the interstitial cells occurring in small 156 INTERNAL SECRETIONS testicular fragments is not a compensatory one, i.e., that this hypertrophy has nothing to do with the function of the testicle in relation to the organism as a whole. In a number of cases with partial castration we observed full development of sexual 3 .r> Fig. 80. — Same age as Fig. 79. High magnification. X 300. At the top the waUs of two tubules visible. To be compared with Fig. 81. — Prepar. of Wagner; design of Lehbert. characters without any increase of interstitial cells, or only an insignificant one having taken place in the small testicular fragment {Fig. 84). Further, we found in numerous experiments that the behaviour of a testicular fragment is different according to the pole of the testicle to which it belongs (see Fig. 64, I. or II.) INTERNAL SECRETION OF TESTICLE ^S7 (Lipschiitz, Ottow and Wagner, 1921 d, e). In an upper pole we often found a great hypertrophy of the interstitial cells, whereas in the under pole hypertrophy was rather the exception. The blood is supplied to an upper fragment by the arteria sper- matica interna, to an under fragment by the arteria defer- entialis ; the blood supply of an upper pole is better than that of an under pole. It seems likely, therefore, that the hypertrophy depends upon the greater blood supply. V. . o 'JL ' ^^ Fig. 81. — Interstitial cells of a normal adult guinea pig (Prot. Nr. 27). Same age as Fig. 80. Same magnification. The interstitial cells are disposed between five seminal tubules and surround various small and one bigger blood vessel. To be compared with Fig. 80; there is in the latter an increase also of the size of the int. cells.^ — Prepar. of Wagner; design of Lehbert. In view of these considerations I think that the hypertrophy of the interstitial cells as observed under different experimental conditions is not a compensatory one. At first sight this con- clusion may seem to weaken our theory concerning the endocrine function of the interstitial cells, in view especially of other observations which one might consider as evidence of a compensatory hypertrophy of the seminiferous part of the testicle. Since the experiments of Ribberi (1890) it has been known that unilateral castration leads to an hypertrophy of the remaining testicle, the seminiferous tubules attaining a greater 15^ INTERNAL SECRETIONS diameter than in a normal testicle. The hypertrophy of the remaining testicle was observed later by Sand and by myself. Similar observations have been made in studying human Fig. 82. — Section through upper testicular fragment of giiinea pig subjected to "complex" testicular section (Prot. Nr. 76; operation IV., Fig. 64). x 280. Stained with Heidenhain. Operated at weight of 400 gr. ; fragment removed about 4 months later. Increased number of interstitial cells. Seminiferous tubules with only one stratum of cells (cells of Sertoli). — Prepar. of Wagner; photo of Kull. pathology. But. is this hypertrophy really a compensatory one, i.e., is this hypertrophy related to an increased endocrine function of the testicle necessary for the organism as a whole ? That this is not the case is shown by our experiments, in which INTERNAL SECRETION OF TESTICLE 159 very small testicular fragments were sufficient for a normal development of the sexual characters. One might, indeed, object that the seminiferous tubules are as a rule degenerate, r* ^'^ -w 'P ^.%' **<-* 'j»' *'i ■■■»_.'„■ .5'p' Fig. 83. — Section through testicle of guinea pig subjected to operation V. of Fig. 64 (Prot. Nr. 72). x 280. Operated at weight of 516 gr. ; testicle removed about 4 months later. Backward development of seminiferous tubules. Increased number of interstitial cells. — Prepar, of Wagner; photo of Kull. and the result is that the fragment is diminished in size; in reality the size estimated by weighing or by microscopical observation indicates a far greater "potential" volume of the fragment. But we observed a case where in the testicular fragment (of the under pole — a guinea pig) almost all the tubules were fully developed, and nevertheless the volume of i6o INTERNAL SECRETIONS this fragment was calculated to be only about 20-25 nigr., or about i per cent, of the weight of two normal testicles (1921a, b, c; 1922 d). The sexual characters were fully developed. Together with Miss Kropman, I made a similar observation on the mouse (1922 k). This showed that the '^l'*¥^^w^^\l. _.\ ^. r- V: , « ' ■\ V, / •:' "n '^l ■ "-• ~ »0 ^''^ 1: '«> 10^ -Of -^ l\- •' / '^ 1 '^'■^'^s^^'^ ' ^ • '**r -^V>%^' L - i ^ ^ " ' -" *^ V ^ co^ Fig. 84. — Section through upper testuitl ay fragment (guinea pig. Prot. Nr. 39). Same magniftcation as Figs. 80 and 81. Operated at age of 3 weeks; died at age of 3 J months. Fragment of about the same volume as Figs. 79 and 80. Backwardly developed (or infantile?) seminal tubules. No increase of number or size of interstitial cells. No signs of castration, but development somewhat retarded. — Prepar. of Wagner; design of Lehbert. hypertrophy of the testicle or of the seminiferous tubules after unilateral castration is not a compensatory one. This view is supported by the fact that in adult animals only a sHght hj^er- trophy or no hypertrophy at all occurs after unilateral castra- tion (Nothnagel, see Exner, 1903; Kyrle, 1911, p. 13; Lipschutz, INTERNAL SECRETION OF TESTICLE i6i 1922 a, 1923 e). From the results of a detailed study made on the hypertrophy of the testicle after unilateral castration it seems further very likely that the increase of weight observed in young animals in this experimental condition is not an hyper- trophy at all but a phenomenon of a very different kind (1922 c). (Fig. 85). Further, Lipschiitz and Ibrus (1923 c, d) have shown that no change in the quantity of the interstitial cells takes place after unilateral castration. The remaining testicle 4.0 3.5 3.0 in I t.O 0.5 /^ 0 500 1000 Body we'iojht or 1500 2000 2500 3000 Fig. 85. — Diagram to illustrate the hypothesis that the so-called com- pensatory hypertrophy of the remaining testicle is on'y an acceler- ated growth. The thick hne indicates the real curve of growth of testicle in the normal rabbit ; the thin line shows the supposed curve of growth of the remaining testicle after prepuberal uni- lateral castration; this curve is the normal one removed to the left. The difference between a normal and a remaining testicle is supposed to increase gradually and after a maximal differ- ence is attained at time of puberty, to decrease again gradu- ally. Different points of the supposed curve have been verified by experiments. reveals" a structure (Fig. 86) quite identical with that of a normal one. It may be mentioned that in the frog the testicle or the testicular fragment seems to react differently from the way it does in the mammal (Lauche, 1915); in the frog the testicular fragment undergoes hypertrophy. No matter where the seat of the endocrine function of the testicle is situated, no compensation seems necessary in the mammal for the performance of the normal internal secretory i62 INTERNAL SECRETIONS function even when the testicular mass is greatly reduced (Lipschutz, 1922 d, 1923 b). Yet the fact remains that in many animals at any rate an hypertrophy of the interstitial cells takes place, and that the number and the size of the interstitial cells are really increased «»>^&|. •'^^ ^t ■7^%*t *:^:V 1 ti' ' •i--.' Fig. 86. — Section through testicle oj rabbit 14 months old, unilaterally castrated when i|- months old (Prot. Nr. 86). X 280. The biggest testicle we observed in rabbits ; the weight was 3 -8 gr. Normal quantity of interstitial cells. To be compared with Fig. 52. — Prepar. of Wagner; photo of Kull. under different conditions affecting the testicle. If now the interstitial cells are an endocrine apparatus, one might suppose that under conditions of hypertrophy there should be also an increased hormonic action. As already mentioned above, Steinach records having observed an abnormally great sexual INTERNAL SECRETION OF TESTICLE 163 activity in animals with highly hypertrophied interstitial tissue in transplanted testicles. Similar observations have been recorded by Lacassagne and Sand in animals with ligature of the vasa deferentia. On the contrary Alfred Kohn (19 14 a) points out that in cases of retained testicles there are no such results, notwithstanding the hypertrophy of the interstitial cells. There is a disproportion between virility and inter- stitial tissue. But against all these contradictory statements manifold objections may be made. First of all, in view of my own observations, I cannot but repeat that I have httle con- fidence in quantitative statements concerning sexual activity in rats, guinea pigs and rabbits; secondly, it is still an open question whether there is always in a retained testicle a real hypertrophy of the interstitial cells (the hypertrophy being possibly in many cases only an apparent one); thirdly, the functional state of the interstitial tissue must also be taken into consideration. Fig. 8y {Lipschutz, 1923 a) may serve as an example. Horizontal sections through the testis and the ductus epididyraidis were made on both sides at an age of two months. The animal was observed for about six months. It remained eunuchoid as shown by the observation of the penis. Spermatogenesis had ceased at a somewhat earher stage than in Fig. 66. No differential stain for fat was employed, but the large vacuoles occupying the enormous interstitial cells and separated only by very small threads of protoplasm are most probably remains of droplets of fat. In some places interstitial cells of the usual appearance were present. Were the interstitial cells normal or not, and is the eunuchoidism in this case to be explained by an abnormality of the interstitial cells ? Another case is also of high interest (Lipschutz, 1921c; 1922 d). There was an underdevelopment of sex characters in a guinea pig with a very small upper testicular fragment (Fig. S8) in which quite normal interstitial cells were to be found. It is most probable that there was in this case a retarded development of the testicle and of sex characters, due to the operative interference in the former, and that the animal would have attained some time later full sexual development. But quite apart from all this, the ques- tion remains whether it is justifiable to expect an increased hormonic effect when the interstitial tissue is hypertrophied. By taking into account certain general physiological and 1 64 INTERNAL SECRETIONS pharmacological observations a negative answer is arrived at. We know that if an excess of certain compounds which play a part in the metabolism is introduced into the organism, this excess will be oxidized or excreted, as, for instance, pro- teins and salts of which only small quantities can be stored. Fig. 87. — Section through testicle of rabbit, 8 months old, with eunuchoid penis (Prot. Nr. 41, same litter as Fig. 66; horizontal incisions on the testicle at age of 2 months). Seminal tubules in a state of degeneration; they seem to be less developed than in Fig. 66. Interstitial cells of extraordin- ary dimensions packed, full evidently with fat. — Prepar of Wagner; design of Lehbert. Although these substances, such as amino-acids or some ions, have definite biochemical properties, their introduction in increased quantity does not necessarily augment these functions or affect the metabolism in general, provided that certain limits are not surpassed; all we observe is that in such cases INTERNAL SECRETION OF TESTICLE 165 there is an increased demand on the organs of digestion, absorption, circulation and excretion, and that eventually there is an increase of oxidation in general. We know further that some toxic substances such as morphine can be introduced in relatively great quantities without any specific effect in cases -.>st^y^^ "^m...^ mim -'^^c ^r^^S^^" .,«>^ Fig. 88. — Section through upper testicular fragment (guinea pig. Prot. Nr. 29). Operation at age of i week; frag- ment removed at age of 4^ months. The smallest fragment ever observed. Some tubules of normal diameter; one stratum only. Highly increased number of interstitial cells. Sex characters underdeveloped, but no signs of castration. — Prepar. of Wagner; design of Lehbert. of abuse. I do not intend to deny that flooding the organism with a particular hormone may have an increased specific effect, and cause some disturbance or trouble, such a result being known to occur in the case of certain internal secretions. And in the same manner it is probable that a sudden temporary flooding of the organism with sexual hormones may have an i66 INTERNAL SECRETIONS increased specific effect, as, for instance, a greater sexual activity during heat. It may also be that this increased effect will last a considerable time, as in Steinach's transplantation experiments, and those of Lacassagne and Sand with ligature of the vas, referred to above. But this is very different from supposing that with an increased quantity of hormone there will be always and necessarily an increased specific hormonic effect. On the other hand, it must not be forgotten that the result of an increased hormonic influence depends, not only upon the actual hormones and the quantity present, but also upon the substratum affected thereby. Take for instance the psycho-sexual behaviour or certain somatic sexual characters such as the uterus and the mammary gland, on the one hand, and the prostate, the vesiculae seminales and the penis on the other. The former are probably in a very labile state, easily influenced, as it seems, by the quantity of erotizing hormones temporarily present; whereas the latter organs are more stable, and in their case, it may be, the quantitative laws which hold are of a different kind. (b) The Law of "All or Nothing^' We mentioned in a preceding chapter that it had been already suggested by Foges that small particles of gonad suffice to produce a normal development of the sexual characters, but that these fragments must not be too small. Further we discussed above the suggestion of Bouin and Ancel that there is a proportionality between the quantity of interstitial tissue and the stage of development of the genital organs in pigs with retained testicles. Steinach reported a similar pro- portionality in his experiments with testicular transplantation. The observations of Sand seemed to corroborate those of Steinach. I showed in preceding sections of this chapter that our own new experiments make it possible to explain all these observations without assuming a proportionality between the quantity of the hormone and the degree of the hormonic effect. In the first edition of this book I attempted to formulate quantitative laws on the basis of all the different data, not- withstanding that these data were at first sight contradictory. I suggested that the hormonic effect is in a certain measure proportional to the quantity of the hormone, but that beyond this measure the proportionality does not exist. I tried to INTERNAL SECRETION OF TESTICLE 167 illustrate these quantitative relations by the following diagram {Fig. 89). The quantities of the hormone secreted in the blood are given on the abscissa; the intensity of the effects on the ordinate. The normal development of the somatic sexual characters, A^, seems to be brought about by a quantity of hormone, q^, the threshold quantity which is smaller than that normally secreted and entering the blood; the latter assumption is supported by the fact that castration results do not appear when small particles of the testicle are present. When the quantity of the hormone is greater than q^, the hor- monic effect is not increased, and an excess of the quantity, for instance, q2, will cause only a temporarily increased effect such as at the "heat." Within the limits of 0 and q^, the intensity of the hormonic effect might be proportional to the quantity of the hor- mone, beyond qi this pro- portionality will not exist excepting under certain special conditions (heat, pregnancy). Further, I sug- gested that an excess in the quantity of the hormone of the sexual glands prior to puberty might have an accelerating effect on the development of the somatic sexual characters and the psycho-sexual behaviour, i.e., that this excess might cause a pubertas praecox. Basing himself on his own experiments and on observations of Houssay (1907) on fowls, Pezard (1918, 1919) suggested that the relations between the hormonic quantity and the hormonic effect may be somewhat different. Pezard stated that not only did small quantities of testicular tissue cause development of sexual characters, but that this develop- ment was always a complete one, when a certain minimal quantity of testicular tissue was present. When this minimal quantity is Fig. 89. — Diagram : Dependence of hor- monic effect upon the quantity of tes- ticular hormones. Abscissa: quantity of hormone ; ordinates : hormonic effect as expressed by somatic sex characters e.g , length of comb). ^1 — quantity of hormone sufficient for normal hormonic effect {N). q^ — quantity of hormone normally present. It is assumed that there is between o and q^ proportionality between the quantity of hormone and the hormonic effect, whereas no such proportionaUty exists beyond 9i and q^. Further increase of the quantity of hormone may tempo- rarily cause an increase of the hor- monic effect as during heat (as indi- cated by dotted line) ; but this increased hormonic effect does not last. i68 INTERNAL SECRETIONS present, there are no intermediate stages in regard to develop- ment of sexual characters; they are either fully developed or else they are in the same state as in the "castrate." Pezard suggested that the hormonic action of the sex gland is regulated by the law of "All or Nothing," applied already in the case of the heart (Marey) and nerve (Lucas and Adrian, Verworn, Veszi), and probably true also for skeletal muscle (Lucas, Adrian). This law afhrms that when the strength of the stimulus is increased beyond that of the liminal or threshold stimulus the effect is not varied {Fig. 90). The difference between the suggestion of Pezard and that developed by myself in the first edition of this book and represented in the above diagram {Fig. 89) is, that according to Pezard only the horizontal part of this curve is correct and, further, that this horizontal part must be much 2% 100 % thr. 11. Fig. go.^Diagram to illustrate the law of "All or Nothing." The maximal hormonic effect (ordinates) is brought out when the threshold quantity (thr) of sex hormones is produced. The threshold quantity is supposed to be very small as compared with the average normal quantity {n), displaced to the left. Our own experiments with partial castra- tion justify us in discussing this quantitative problem more fully. In confirmation of Pezard's statements on fowl we have showoi in mammals that the testicular particles which can admit of full development of somatic sexual characters may be so small that it is impossible to lay down any practical Hmit to the minimal quantity sufficient for the growth of the sexual char- acters. In other words, the horizontal part of the curve will begin not far from o, in our experiments near one per cent, or even less. But this does not necessarily imply that no pro- portionality between hormonic quantity and hormonic effect exists in the limits between o and one per cent. In our INTERNAL SECRETION OF TESTICLE 169 experiments with partial castration, as already mentioned, we did observe intermediate stages between castration effects and normally developed somatic sexual characters. In one of these experiments we found that the weight of the fragment was much less than one per cent, of the normal testicular mass. At first sight one might take these observations as being contrary to the law of "All or Nothing/' But on the other hand we have shown from our own experiments that by in- juring the testicle it is possible to retard its development. In view of these observations it seems justifiable to assume that the intermediate stage is in reality due to retarded de- velopment of the testicle or the testicular fragment, and that any animal representing an intermediate stage in the develop- ment of sexual characters may attain to full puberty provided no detrimental changes occur in the operated fragment. These observations of our own confirm Pezard's view, as represented in the law of "All or Nothing." Pezard (1922 a) gave full experimental evidence of his suggestion in remarkable experi- ments on fowls. The objection that in small fragments the interstitial cells are often really in a state of hypertrophy, is not justified, as it was shown above that this hypertrophy has no relation to functional compensation in regard to internal secretion. Another objection might, however, be made; it might be said that a small testicular fragment is possibly producing as much hormone as both the normal testicles, without there being any visible histological or cytological changes in the fragment. We are not in a position to discuss such an objection, since there is no indication of the functional state of the testicle other than that provided by microscopically visible changes. There is yet another objection. One might suppose that retardation of development of sexual characters as observed in some cases with partial castration is caused by the time normally necessary for the development to puberty being lengthened on account of a diminished quantity of sexual hormone. This assumption would, as already said, be in ac- cordance with what we know about ferment action. Such a dependence of the development of the sexual characters upon a time factor would not be contrary to the law of "All or Nothing," although, at first sight, one might suppose it. Whatever the truth about these questions may be, we are now 170 INTERNAL SECRETIONS far removed from the original quantitative standpoint adopted by Bouin, Ancel, Steinach and Sand as a result of their experi- ments, and which I had adopted in the first edition of this book No doubt the view taken by Pezard and myself in regard to the quantitative law in the action of the sexual hormones will undergo further development as a consequence of sub- sequent experimental research. Future experiments must, I think, relate especially to the question as to whether by di- minishing the quantity of the hormone the time necessary for puberal development is lengthened. 7. On Cyclic Changes in the development of the Interstitial Tissue. Cyclic changes in sexual activity occur in some species in the male as well as the female. It is of interest to enquire whether, corresponding to the transitory increase in the sexual activity during rut, there is any augmentation of the inter- stitial tissue in the testicle. It is clear that this question is of great importance in relation to the function of the male "puberty" gland. It has long been known that the interstitial tissue of the testicle in some animals undergoes seasonal changes. Hanse- mann (1895, 1896) stated that in the woodchuck the interstitial cells are hardly represented at all during hibernation, whereas in the spring after awakening the interstitial tissue is as highly developed as in the wild boar, the cat, the mole, etc. This question has been studied also by several other investigators on mammals and on amphibians (see Rasmussen, 1917, 1918). We shall deal in this paragraph with mammals only. Ganfini found, like Hansemann, that the interstitial tissue in the testicle of the woodchuck was apparently reduced during hibernation; but he points out that in reality there is no decrease in the number of interstitial cells, the latter being only reduced in size. Detailed investigations on the hedgehog were made by Marshall (1911); he found a simultaneous de- velopment of the interstitial cells and seminiferous tubules in the period of heat, and a simultaneous diminution of both during the time of sexual inactivity. The statements of the different observers on the hedgehog and the woodchuck are represented in the follo\ving diagram taken from the paper of Rasmussen (Fig. 91). The curve of spermatogenesis and the INTERNAL SECRETION OF TESTICLE 171 curve of development of the interstitial tissue are more or less parallel. Similar results have been obtained lately by Ras- mussen in the woodchuck. Rasmussen emphasized the dis- crepancies between the older observations and his own, but I think that no serious discrepancy exists. Rasmussen finds that spermatogenesis attains its maximum about a month sooner than the interstitial tissue, and further that the inter- stitial tissue remains several months at its maximal state of hedgehog Marshall 1911 //" ' » ^V^ rrt. 1 3 5 7 0 11 tnarm. niarm. Hansemann 1S95 Ganfini 1903 m. 1 3 5 7 9 11 martn. monax Rasmussen 1907 ^<7^ ______ X ^\ mole Regaud 1907 Lecaillon 1909 Tandler-Gross 1911 m. . ^__ — Reg. ^r::: 1 3 5 7 9 11 ^ — -- ^^^" x Fig. 91. — Cyclic development of generative and interstitial tissue of the testicle of hibernating mammals. Plain lines indicate generative tissue ; dotted lines, interstitial tissue. Climax of spermatogenesis during heat, hibernation from November till ^Nlarch; birth of young indicated by x. — Parallel develop ■ ment of generative and interstitial tissue in the hedgehog and in Marmota marmota (for marm. marm. data available only for some months). Some deviations between both tissues in Marm. monax; no parallelism in the mole. — From Rasmussen (with changes). development, whereas the curve of spermatogenesis is lowered long before. But I think that it is impossible to draw from such observations detailed conclusions in regard to time and quantity of interstitial tissue or tubules, especially as all these con- clusions are naturally derived from different individuals which may show much variation. On the other hand all these observations are a sufficient basis for the general conclusion that in the woodchuck and in the hedgehog the interstitial 172 INTERNAL SECRETIONS tissue attains its minimum during hibernation or in the time of sexual inactivity, and that it attains its maximum during heat. Marshall concluded from his experiments that the characteristic features during heat are caused in the hedgehog by an increased internal secretion of the interstitial cells. In disagreement with the statements concerning the wood- chuck and the hedgehog are those relating to the mole. The mole experiences heat once in the year about the beginning of March, and at this time the generative part of the testicle attains its maximum. Regaud found the interstitial tissue well developed in June and July, when the generative part is already at its minimum. In December only a few interstitial cells are to be found ; at the same time the tubules enter upon new spermatogenesis. The statements of Lecaillon on the mole are somewhat different from those of Regaud, as seen in the diagram. Finally a detailed investigation on the cyclic changes in the testicle of the mole was made by Tandler and Gross (1912, 1913, p. 117)- Their results were again somewhat different from those of Regaud and Lecaillon as concerns the time of development of the interstitial tissue. They stated that the maximum of the generative part corresponds to the minimum of the interstitial tissue, this being reduced at the period of heat. In the time of sexual inactivity, in the autumn, when the generative part is at its minimum, the interstitial tissue attains its maximal development. Tandler and Gross never found mitoses in the interstitial cells when at their maximal number,- and they suggested that the connective tissue cells in the testicle are mostly inactive interstitial cells, which can be activated at a given moment and assume the morphological character and the function of interstitial cells. Evidently the cyclic increase of the number of interstitial cells does not imply a cyclic proliferation of cells. Courrier (1923 a) made an investigation on the cyclic changes in the bat. He insists on the very important fact that the generative part of the testicle is inactive during the autumn and winter, and, nevertheless, the accessory genital glands (the epididymis, the vas deferens, the seminal vesicles and the prostate) are in full secretory activity; likewise sexual inter- course can take place during that time. The interstitial cells have at that time the appearance of highly active glandular cells. The interstitial cells undergo a pigmentation at the end INTERNAL SECRETION OF TESTICLE 173 of May and concomitantly the secretion of the epidi(i5miis ceases. From all these observations, and likewise from those on other mammals with a periodic spermatogenesis (1923 b), Courrier concludes that the cyclic changes of the interstitial gland are in a striking correspondence with the cyclic changes of the sex characters. The cells of Sertoli, however, also under- go concomitant changes. On the contrary, the accessory genital glands may be in a state of rest when the seminal tubules are active. The statements of Regaud, Tandler and Gross on the mole disagree with those made about the hedgehog, the woodchuck and the bat. They are also opposed to the view that heat is caused by an increased activity of the interstitial tissue. But, as already mentioned, the statements of Lecaillon about the mole are somewhat different from those of the other authors. It is also possible that the decrease of the interstitial tissue in the mole during heat is only an apparent one. The nearer the time of heat, the greater the room occupied by the seminiferous tubules in the testicle and the greater also the space in which the interstitial cells are distributed. If the total volume of the interstitial tissue is not increased in the same measure as the total volume of the seminiferous tubules, a microscopical preparation will give the impression that the interstitial tissue is reduced, even though in reality there is a very marked increase of the latter. One will understand the weight of such an objection, if one takes into consideration how enormously the volume of the testicle is increased in heat owing to the augmentation of the tubules. As said already in the first edition of this book, it is absolutely necessary to know the real number of interstitial cells, or the real volume of the interstitial tissue in the testicle during heat and during sexual inactivity; we learn nothing about this question when we merely count the cells in one or another preparation. We shall meet with the same difficulties in dealing with amphibians as we here encounter in mammals (see below in this chapter). Tandler and Gross concluded from their observations that the interstitial cells play a leading role in causing the condition of heat. They suggested that the interstitial cells are a factor in the spermatogenesis of the next heat, influencing the generative part of the testicle as they influence the somatic characters. If this were true, it would follow that the generative 174 INTERNAL SECRETIONS cells are a "secondary" sexual character genetically dependent upon the interstitial cells. This may seem at first sight wholly inacceptable. But there are some facts which support this view. Ancel and Bouin stated that the interstitial cells in the embryo of the pig are present before spermatogenesis begins. The interstitial cells in the embryo of 30 mm. can be recognised with certainty. Bouin records having observed signs of secretory activity in the interstitial cells during embryonic development (1903 c). In view of these facts Bouin and Ancel (1903 d) suggested that the interstitial cells determine in some measure the sex of the generative cells. In accordance with Bouin and Ancel one might suppose that the cyclic spermato- genesis under the influence of the increased or hypertrophied interstitial cells occurring before heat is nothing else than the recapitulation of what happens during embryonic life. The suggestion of Bouin and Ancel has lately been supported by Witschi (1921), who made observations on the frog. There has been much discussion about a so-called "trophic" function, the suggestion being that the interstitial cells prepare some kind of material necessary for the nutrition of the spermatic cells. This view is supported by many histologists, especially by Plato, Kyvle (1911), Winiwarter, and recently by Kohn (1914 a, 1920). Kyrle expressed the belief that the increase of the interstitial cells in the neighbourhood of degenerated tubules (or backwardly developed tubules, as I should prefer to say) indicates that the interstitial cells have something to do with the regeneration process which occurs in these tubules. Such an assumption is in reality not very different from what Bouin and x\ncel suggested. But no sufficient proofs exist for this assumption, although some histologists claim that it is definitely proved that the interstitial cells are no more than a trophic organ in relation to the seminiferous tubules. It may be useful to compare what such a critical histologist as Alfred Kohn pointed out about this question. He claimed in 1914 that there is " absolutely no proof " and that it is very "improbable " that the interstitial cells of the testicle should be necessary for the development of the seminiferous tubules. Later (1920), without any new fact having been added, the same author declared that the interstitial cells are probabfy a "trophic" apparatus for the generative part of the testicle. Quoting these two contradictory passages from Kohn, I should like to INTERNAL SECRETION OF TESTICLE 175 make it clear that, in my judgment, all the statements based on "definite" proofs that the interstitial cells have nothing to do with the internal secretion of the testicle, and that they are nothing else than a nutritive organ for the seminal tubules, are without any foundation. 8. The Phases of Puberty in the Male. It is generally assumed that " puberty" marks the time when a developmental process takes place in the organism of a different kind from that going on previously. But in reality it is not so. At the time of puberty we have only an acceleration of processes culminating in the full development of the sexual characters. Such a suggestion will be especially acceptable if one takes into consideration the fact that the development of the sexual characters, as we must now assume, has begun already during embryonic life. The first steps towards sexual maturity are made in the embryo; maturity is consummated at the time known as puberty in the ordinary sense of the word. In man and other mammals there is from birth to puberty a relatively long period when the development towards sexual maturity proceeds very slowly, or even for a time ceases altogether. I showed experimentally with rabbits that in all probabihty no internal secretion of the testicle is produced at all for about three months after birth, the development of the penis in the rabbit prepuberally castrated at an age of one to two months being, until the commencement of the time when puberty would otherwise occur, exactly like that in the normal animal. So one may suppose that there are in reality two great phases of puberty; the first at a certain time of embryonic development, the second one several months (rabbit) or years (man) after birth, and that these two great phases or climaxes of puberty are separated b}/ an intermediate phase. Such an assumption is necessary to the theory of the existence of an asexual or indifferent state of the somatic substratum of the sexual characters before the internal secretion of the gonads enters into activity. We must now ask ourselves whether we have any knowledge of the condition of the testicle at the indicated phases, so as to explain the true correlation of the latter with corresponding changes in the endocrine function of the testicle. As we have seen at the beginning of this chapter, the interstitial cells seem 176 INTERNAL SECRETIONS to show a first climax of development during embryonic life and a second climax at sexual maturity. So it should be possible to explain the sequence of the phases of puberty by a sequence of phases in the development of the interstitial tissue. One might, indeed, object that synchronously with the development of the interstitial tissue, at the time of sexual maturity, we have also a rapid development of the generative part in the seminiferous tubules, and more or less synchronously with the first appearance of interstitial cells we have the formation of the generative part. But if we take into consideration the fact that a testicle with cells of Sertoli and spermatogonia, but without fully developed interstitial cells, is not capable of producing the internal secretion, we shall understand that, if there is any internal secretion of the testicle during embryonic life, it cannot be due to the primitive generative cells. This will be especially clear if we consider how in the rabbit, for instance, as already mentioned, there is in the first three months no internal secretion of the testicle, although numerous spermatogonia, and even spermatocytes, may be present in the seminiferous tubules. After all it cannot be denied that there is a correspondence between the sequence of changes in the interstitial tissue and the phases of puberty, whereas no such correspondence exists in relation to the phases of sper- matogenesis. In the time between the two great phases ol puberty the interstitial tissue is possibly in an "intermediate" stage, the cells being quiescent. The further question arises as to whether also the changes which take place in sexual activity with advancing age are related to changes in the interstitial tissue. 9. The "Follicular Theory" of Hormone-Production IN THE Testicle. If we compare figures 65 and 66, figures 70, 71 and 79, and if we take into consideration only the actual state of the interstitial tissue and of the seminiferous part in all the above-mentioned cases, it is impossible to avoid the conclusion that well developed interstitial cells represent the organ of internal secretion in the testicle of mammals, and that the generative part is not involved in this function. A condition of eunuchoidism may occur in the presence of full spermato- genesis and a normal development of sexual characters may be INTERNAL SECRETION OF TESTICLE 177 brought about by testicular tissue where the tubules are in an infantile stage, but where the interstitial cells are of the adult type. But if we consider the state of the testicle or of the testicular fragment in these cases from a dynamical point of view, together with all the resulting processes, it is difficult to avoid the conclusion that spermatogenesis is possibly in- volved in the puberal development of the interstitial cells, and so is indirectly involved in the internal secretion of the testicle. Spermatogenesis proceeding to a certain degree may be neces- sary for the transformation of the quiescent form of the interstitial cells into the puberal form. Our knowledge, however, of the time relations between spermatogenesis and puberal development of the interstitial cells is at present incomplete. There is a further consideration of a more general character which supports such a theory. As we shall see in Chapter V., it is almost unanimously agreed that the follicle is an endocrine apparatus in the ovary. Folhcular development is connected with development of the ovum. But the ovum itself is not necessary for the production of the internal secretion of the follicle, as is shown by the fact that the follicle or the corpus luteum which persists after the death or the exodus of the ovum, continues to elaborate internal secretions. Cells (of epithelial or connective tissue origin) hitherto not involved in internal secretion are transformed into endocrine cells during the process of ripening of the germinative cells of the ovary. The same is possibly true for the testicle. So the theory suggested above has its analogy in what is known in regard to the ovary. The term "follicular theory" may be conveniently used in this connection. Such a follicular theory of the endocrine function of the testicle cannot be based on proof, at any rate at present. Nevertheless it may serve as a convenient working hypothesis. The assumption of Berblinger (1921), that the interstitial cells serve for the storing of hormones produced by spermatic cells, seems to me unjustified by the facts described in this chapter. 178 INTERNAL SECRETIONS 10. The Condition of the Interstitial Cells in Intoxication and Disease. It is known that degeneration ol the seminiferous tubules can also be caused by certain poisons. The influence of chronic alcoholic intoxication on the tubules, as noted by various observers on alcohoHc subjects, is of great practical interest. Simmonds (1898, quoted from Kostitch) showed that 60 per cent, of cases of azoospermia are caused by chronic alcoholic intoxication. The histological investigations of Bertholet (1909, Kost.) and Weichselhaum (1910, Kost.) revealed that in the testicle of alcoholic subjects spermatogenesis may decrease or even disappear, whereas the interstitial cells are increased in number. The same was demonstrated experi- mentally on animals under conditions of chronic alcoholic intoxication by Bouin and Gamier (1900, Kost.), Kyrle and Schopper (1914, Kost.). Lately, Kostitch (1921), a pupil of Bouin, has performed new experiments and published a detailed paper on this question. Adley (19 14) has shown that similar degenerative processes in the testicle can be caused by subcu- taneous application of different compounds of iodine ; Hofstdttev (1923) has demonstrated the same for nicotine. The changes which the interstitial cells undergo in different diseases may also be considered as due to toxic substances. As far as I know, Hansemann (1895, p. 544) was the first to draw attention to this question. He found the interstitial cells in a state of hypertrophy in chronic diseases, such as tuberculosis of the lungs and cachexia caused by cancerjor syphilis. Thaler (quoted from Kasai, 1908) records having observed in many cases of acute diseases that the interstitial cells were rather numerous, whereas in some cases the inter- stitial tissue was not well developed. The increase of the interstitial cells in cachectic diseases, according to Thaler, is not a constant one. A marked increase of the interstitial cells was observed by Cordes (quoted from Kasai, 1908) in seven out of twelve cases of tuberculosis. The question was studied also by Bouin and Ancel (1905 a). They record an hypertrophy of the interstitial tissue in acute diseases such as pneumonia and tuberculosis, which progress rapidly. But this hyper- trophy is not always of the same degree, neither does it always take place. They observed also the hypertrophy of the INTERNAL SECRETION OF TESTICLE 179 interstitial cells in chronic diseases such as in tuberculosis of the lungs. They record that this hypertrophy may be very marked, the bands of cells of Leydig between the tubules being twice as large as normally ; there are signs of an intense secretory activity in the cells. But, on the other hand, a degeneration or a complete atrophy of the interstitial cells may take place in diseases, especially in cachexia of long duration. The interstitial cells are decreased in number and size, they are filled with pigment, and their edges are serrated. Bouin and Ancel (1905 b) observed also an hypertrophy of the interstitial tissue in cases of experimental infection or great loss of blood experimentally produced, where the hypertrophy occurs after a few days ; in the final stage of a chronic infection or intoxica- tion (general experimental tuberculosis or alcoholic intoxication during several months) an atrophy of the interstitial cells may occur. The same point was observed in the final stage of an acute mortal infection. In opposition to these statements are those of Kasai, who found no changes in the interstitial tissue in pneumonia and acute tuberculosis; in septicaemia and in purulent peritonitis the interstitial cells were sometimes visibly increased in number, whereas in other cases the interstitial tissue showed no abnormality. In chronic diseases of the organs of circulation or bronchi an increase of interstitial cells was observed only exceptionally. In cancer no increase of the interstitial cells was found by Kasai even when the tubules were atrophied. But a marked increase of the interstitial cells was observed by Kasai in seventeen out of twenty-two indi- viduals who died of tuberculosis. The tubules were mostly more or less atrophied. In some cases also the interstitial tissue was in a state of degeneration, the cells having only a little protoplasm ("quiescent interstitial cells," according to Kasai). The question of the behaviour of the human testicle under different pathological conditions has been very carefully studied by Kyrle (1911, 1920), who examined for this purpose more than a thousand testicles. As Kyrle points out, the testicle in man is sensitive to such a degree that it is hardly ever possible to find a normal testicle in adults who died of acute infectious diseases, such as pneumonia, or acute septic infection. But sometimes the number of tubules affected by degeneration is very restricted. More pronounced are the degenerative changes in chronic diseases. Kyrle says that out i8o INTERNAL SECRETIONS of 1000 testicles examined by him he found none which could serve as an example of the wholly normal testicle. Kyrle is of the opinion that most of the new-born have underdeveloped testicles. This is surely an exaggeration. If most of the new- born who die from accidents during birth have testicles of a certain structure, it is most likely that this is the normal state. As to the degenerative changes in the adult testicle which Kyrle so often met, the}^ relate to a very restricted number of tubules. I found the same several times in our "normal'* laboratory rabbits and guinea pigs. It may be that this backward development of seminal tubules, occasionally occurring in normal men and animals, has some Idnd of genetic relation with the cyclic changes which occur regularly in other species. Notwithstanding all the contradictory reports related above, it seems that in general there is an atrophy of the seminal tubules, and an increase of the interstitial cells, in serious acute and chronic diseases, and, further, that an atrophy of the interstitial cells may occur when the organism is very much injured by the disease. Two objections must be taken into consideration; first, that the increase is only an apparent one, caused by the degeneration of the tubules, and, secondly, that the increase, if really present, is not caused by a direct influence of toxic substance, but represents only a reaction to the degeneration of the tubules. The first objection, which we have already met with several times in other connections, could be advantageously studied in microscopic detail, and by taking into consideration the total volume of the interstitial cells. Kasai's statement is of importance here ; he sometimes observed mitotic figures, which shows that the increase in the number of cells is not always merely an apparent one. The second objection is of a rather different order. There is no doubt that the increase of the interstitial tissue is in many cases merely a local reaction to changes occurring in the tubules, and may be a process related to the regeneration of the seminal tubules, as was pointed out hy Kyrle (1911). But, on the other hand, certain observations have been made showing that the increase of the interstitial cells can take place inde- pendently of changes in the tubules. An observation of Hedinger (1920) must be mentioned here. He observed a man of 29 with a chorion-epithelioma of the right testicle. The INTERNAL SECRETION OF TESTICLE i8i tumour occupied almost the whole testicle, only a few atrophic tubules and isolated interstitial cells being visible in some sections. The man died some time after the extirpation of the right testicle on account of multiple metastases. The micro- scopic examination of the left testicle was of great interest ; the seminiferous tubules were well developed and in a state of full spermatogenesis, and^ nevertheless, any microscopical prepara- tion, whatever place it was taken from, showed an increase of interstitial cells disposed in large groups or nodules of i to 1-5 mm. in diameter between loose connective tissue. To control this statement Hedinger examined the testicles of about 100 men, mostly robust and healthy individuals of 25 to 35 years of age, who died of Spanish influenza ; he never found groups of interstitial cells which could in any way be compared with those in the left testicle in the case described above. This shows that an increase of interstitial cells cannot be considered merely as a reaction to local changes in the tubules ; hypertrophy of the interstitial tissue can occur independently of any change in the tubules. That hypertrophy of the interstitial cells, although very often only a local reaction to the degeneration of tubules, is not always so, is rendered probable also by some experiments of our own. Horizontal incisions were made on the testicle of adult guinea pigs without touching the ductus epididymidis ("incomplete testicular section" [Fig. 64, III.]). We observed in most of these cases a degenera- tion of tubules only near the level of the incision ; but I have the impression that some hypertrophy of the interstitial cells occurred, nevertheless, throughout the whole testicle between normal tubules in a state of active spermatogenesis (Fig. 92). We have not yet made a detailed examination of the total volume of the interstitial tissue in these cases . Our experiments with partial castration, as reported above, showed further that not only the tubules, but other local conditions also, such as a rich blood supply, are to be taken into consideration in studying the hypertrophy of the interstitial cells. In view of the hypertrophy of the interstitial cells in disease, Alfred Kohn objected that no relation has been observed between virihty and the interstitial cells, as one might expect on our theory. I have already tried to show that an increased quantity of hormone in the blood need not necessarily have an increased hormonic effect. On the other hand, it must not be l82 INTERNAL SECRETIONS forgotten, that the hormonic effect depends not only upon the quantity of hormone, but also upon the sensitiveness of the substratum; in this case upon that of the central nervous Fig, 92. — Section through testicle cut horizontally. (Opera- tion III., Prot. Nr. 76, left testicle) x 280. The testicle was adherent to the abdominal wall. Spermatozoa were not to be found in the epididymis, but there was spermatogenesis in many tubules. Great quantity of hypertrophic interstitial cells between four tubules in complete spermatogenesis. — Prepar. of Wagner; photo of Kull. system. No doubt the sensitiveness of certain parts of the latter is much diminished in acute and chronic diseases. It is easy to understand that in such conditions even an in- creased quantity of the hormone will not lead to a normal INTERNAL SECRETION OF TESTICLE 183 erotization. Moreover, as has been shown, especially by Kasai, there is sometimes a degeneration of the whole testicle, as, for instance, in tuberculosis; the interstitial cells are often of the so-called quiescent type, with a little protoplasm and with an elliptic nucleus. Bouin and Ancel suggested that the hypertrophy of the interstitial cells in diseases represents a means of defence for the organism. As a result of various experiments, Voinov (1905) put forward the theory that the interstitial cells produce certain chemical substances for the protection of the generative part of the testicle. A similar view is held b}^ Kit ah ar a (1923J, being based upon embryological evidence. Kitahara and Cejka (1923) consider it possible that the interstitial cells act also as a kind of chemical transformer of substances produced in the generative part. Although it cannot be denied that there is, perhaps, some truth in all these hypotheses, they are none of them based on sufficient evidence. The papers of Goette (1921), Jaffe (1922), and Berherich and Jaffe {ig22),who deal with a great number of pathological observations, and of Brack (1922), may also be referred to here. In any case there can be no justification for urging the dis- proportion between the number of the interstitial cells and the very low level of erotization in certain diseases as evidence against the theory that the interstitial cells elaborate an internal secretion. According to Stcinach and Kammerer (1920) the quantity of interstitial cells is increased when animals are kept for a long time under a higher temperature. They claim that there was in these animals an hypertrophy of sex characters such as the seminal vesicles and the prostate. As was shown recently by Tsuji (1920) a degeneration of the seminiferous tubules may occur when rats are fed on a diet poor in vitamines, such as a mixture of casein, starch, cane sugar, lard and salts; the degeneration of the tubules can be prevented when small quantities of milk are added to the standard diet. No changes were found in the interstitial cells surrounding the degenerated tubules. As Tsuji points out, the changes in the testicle are evidently due to a diminished activity on the part of the thyroid gland, which showed con- siderable changes in the experimental animals, the weight of the thyroid per 100 gr. body weight not reaching even half of i84 INTERNAL SECRETIONS that of the control animals. It has been ascertained from former experiments (for references see Tsuji's paper) that thjnroidectomy causes degeneration of the generative part of the testicle. No data are given by Tsuji as to the sexual characters of his experimental animals. In fully grown white mice, fed for a long time without any experimental object in view with a uniform diet of oats and bread, we observed great changes in the seminiferous tubules, many of them being in different stages of degeneration; the penis was normally developed. According to Mattill and Carman (1923), even a uniform milk diet can cause in rats degenerative changes in the testicle; desiccated preparations of kidney, spleen, thymus, etc., were unable to prevent these changes. The theoretical value of all these observations concerning the behaviour of the testicle under different conditions (disease, intoxication, diet and operative interference), seems to be very small. But every practitioner will agree that these observa- tions are of the greatest practical interest. It is very probable that intoxications are much more commonly the cause of sterihty in man than admitted hitherto. Since degeneration of the seminiferous tubules does not lead to signs of castration, many cases of sterility in man remain undetected without special examination. The practitioner is as a rule disposed to explain the existence of sterility in the wife as due to an abnormality when he hears that the sexual behaviour of the husband is normal. I am of opinion that one of the greatest mistakes a gynsecologist can make is to refrain from repeated examination of the semen of the husband when a woman is supposed to be sterile. Every practitioner will agree that the difficulties in this field of practical medicine are much greater than is publicly admitted. There are cases where intellectual people suffer for many years from not having progeny, and yet are unable to decide upon consulting a doctor. I regard it as absolutely necessary that the general practitioner should be well trained in this matter both in theory and in practice. In many cases of sterility a properly trained medical man is better able to assist his patients by sound advice and simple explanation than, by having recourse to a severe operation on the uterus. And he may be sure that the success and the gratitude he will obtain will often be incomparably greater. INTERNAL SECRETION OF TESTICLE 185 Conclusions. The experiments recorded in the preceding sections supply evidence that in mammals (i) Underdevelopment of interstitial cells is connected with eunuchoidism. (2) Signs of castration are absent when the seminiferous tubules undergo manifold changes, and even when the tubules undergo retrograde development to the infantile stage, provided that the interstitial cells are fully developed. (3) Complete sexual maturity is possible even when spermatozoa were never present in the testicle. (4) On the other hand, eunuchoidism is not excluded in the presence of spermatozoa. It follows that in mammals (a) the interstitial cells are a necessary part of the endocrine apparatus of the testicle; {b) no proof exists of a direct hormonic action by the cells of Sertoli or by other constituents of the wall of the tubules independently of the interstitial cells. It might be assumed as a working hypothesis that the transformation of the interstitial cells after birth into an endocrine apparatus is connected with spermatogenesis ("follicular theory") or with some stages of this process. It is probable that the hormonic apparatus of the testicle in man and other mammals during ontogenetic development reaches a culminating point .twice; the first in embryonic development, the second at the time of puberty. It is certain that in the rabbit the endocrine apparatus does not function in the first three months after birth, and it is possible that in man also the hormonic apparatus of the testicle is, until puberty, in such an "intermediate" state, when the secretory activity of the interstitial cells is much reduced or even ceases completely; the latter is the more probable. What we generally call the "age of puberty'' is on this view really the second great phase of puberty. The first great phase of puberty should be placed at the time of embryonic development when the embryonic asexual or indifferent soma turns over to the male side. An intermediate phase of puberty may be said to occur between the first and the second great phases ; it is the i86 INTERNAL SECRETIONS time when the sexual characters cease to develop further, or continue to develop in so far only as they do so " concordantly " with the general growth of the body and independently of the hormonic apparatus of the testicle, or when they continue their ** discordant" growth at a very low level. * * * These conclusions are founded mostly on experimental evidence taken in conjunction with clinical evidence such as that derived from the study of cryptorchism. Further clinical evidence, as, for instance, that afforded by some cases of eunuchoidism in man, and especially cases of hermaphrodit- ism, seem to militate against the theory elaborated above. This evidence will be discussed later on. B. INTERSTITIAL CELLS IN THE TESTICLE OF OTHER SPECIES. We have so far confined our discussion of the question as to the seat of the endocrine testicular function to the mammals. It is, however, a matter of great interest to go deeper into the problem from the standpoint of comparative physiology, as we have indicated when comparing the rabbit and the guinea pig (Section Ai). We shall now consider the question as to whether there are other animals besides mammals, in which the genera- tive cells of the testicle can be considered as having no direct connection with the internal secretion of the testicle, and in which certain other elements of the latter can be regarded as endocrine organs. As we said above, systematic investigations on this question have been made only recently upon fishes, amphibians and birds. I. Invertebrates. We know that in the earthworm the development of the male sexual characters depends upon the sexual gland. As in the testicle of the earthworm, besides the generative cells, only connective tissue can be found, Harms (1914, pp. 117, 158) has concluded that in this animal the generative cells alone produce the sexual hormones. 2. Fishes. Observations on interstitial cells in fishes have recently been made by Coiirrier (1921, 1922) and by Kolmer and Scheminzky (1922), who state that they are present in numerous species. INTERNAL SECRETION OF TESTICLE 187 It has been shown by different observers that the interstitial tissue in vertebrates other than mammals undergoes cychc changes. Among fishes observations have been made by Courrier (1921, 1922) on Gasterosteus aculeatus. According to this observer the connective tissue cells of the interstitial tissue in April begin to assume the appearance of glandular cells surrounding the blood vessels. This transformation of connective tissue cells into true interstitial cells takes place only after spermato- genesis is accomplished. Spermatogenesis begins long before, and as early as the end of March spermatozoa are to be found in great number in the seminiferous tubules. In May and June Gasterosteus assumes the features characteristic of heat, i.e., long after spermatogenesis has been accomplished, and when the testicle contains a well developed tissue of glandular cells. From these observations Courrier concludes that the inter- stitial cells produce the internal secretion upon which the nuptial transformations depend. It is also of great interest that in cases where spermatogonia and spermatocytes only were found in the testicle, and no interstitial cells, the nuptial transformations fail to take place. Further, Courrier concluded that the interstitial tissue cannot be considered as a trophic organ in relation to the seminiferous tubules, as the former does not develop until after the latter. Van Oordt {ig2^) and Champy (1923), however, consider that these statements are insufficient to prove the dependence of the nuptial changes upon the interstitial cells. It may be pointed out that Courrier's observations can be explained also in the light of the "follicular theory" developed in the foregoing section of the chapter. 3. Amphibians. For amphibians the statements are very contradictory. The question has been studied both histologically and experi- mentally. Harms (19 14, p. 117) claimed to have demon- strated that in Bufo vulgaris the Bidder's organ is a factor in the development of the finger callosities. As this organ can be considered as a rudimentary female sexual gland, in which, according to Harms, interstitial cells do not occur, one might conclude that in this case the degenerating female generative cells present in Bidder's organ produce male sexual hormones. i88 INTERNAL SECRETIONS But Guyenot and Ponse (1923) have made a detailed experi- mental study of this question and they have come to a con- clusion definitely opposite to that of Harms. According to Guyenot and Ponse the Bidder's organ has no influence at all on the sex characters, the testicle alone being responsible for hormone production in the male toad. According to Champy (1921), who has studied the changes in the testicle of Triton alpestris for two years, real interstitial cells are absent. But Champy found in the testicle connective tissue cells which can store lecithin ; they are regarded as homologous with the interstitial cells of other amphibians and vertebrates. The lecithin is not stored until after the spermatozoa are formed, and after the external signs of heat have already appeared. Champy inhibited in Triton alpestris the completion of sper- matogenesis experimentally by inanition during the summer. In this case the external signs of heat also were absent. Champy concluded from his observations that in the triton the inter- stitial cells have not the endocrine function such as was demon- strated by Ancel and Bouin in other vertebrates, but that in the animal in question this function is performed by the generative part of the testicle only. The same conclusions were drawn by Champy (1908) for Rana esculenta. He found that the interstitial tissue in the testicle of this animal attains its climax in autumn when spermatogenesis ceases. The interstitial cells assume at that time the appearance of glandular cells, which they lose more or less suddenly in the following July when spermatogenesis begins again. The statement made by Champy about Rana esculenta does not agree with those of various authors about other frogs and Biifo vulgaris, where the curve of growth of the interstitial tissue is more or less parallel to the curve of the generative part {Fig. 93). The difficulties in the way of our theory arising from observations like those of Champy, which diverge so much from those on other amphibians, are the same as those already dealt with in discussing the seasonal changes in the testicle of mammals. The objection may also be made that the decrease of interstitial tissue during heat in Rana esculenta is only an apparent one. Champy's observation that the interstitial cells assume the character of glandular cells only after the completion of spermatogenesis does not justify this objection. Similar observations were made by Humphrey (1921) on INTERNAL SECRETION OF TESTICLE 189 the Urodele testis. He stated that hpoid inclusions appear in the interstitial cells only after the spermatozoa have left the testicle; after the degeneration of the seminiferous part the interstitial cells disappear. Like Champy, Humphrey con- cluded that the interstitial cells in the Urodele testis have no bearing either on the spermatogenesis or on the nuptial changes. Perez considers the interstitial cells of the triton as phagocytes without any relation to the internal secretion. A statement which is in complete contradiction to that of Champy and Humphrey was lately made by Aron (1921), a Rana fusca Rnna viridis Friedmann 1898 Mazzetti 1911 .--<:^^^''''^-. . ^_, ->'' ^ ^^~'><^ m. 13 5 7 9 1] Hyla arbor. Friedmann 1898 , ^/^:^^''^\ in. 13 5 7 9 11 Rana e%ctil. Champy 1908 ZIxl" m. 13 5 7 9 11 . Bufo vulgaris Friedmann 1898 ^^.^---^^^^^^ ^^^-r^^^^^^^''''^^ Fig. 93. — Diagram : Cyclic development of generative and interstitial tissue of the testicle of amphibians. — Plain lines indicate generative tissue; dotted lines interstitial tissue. Parallelism in Rana fusca and viridis, in Hyla arborea and Bufo vulgaris. No parallelism in Rana esculenta (as in the mole, see Fig. 91.) — From Rasmussen. pupil of Bouin, on another triton, Molge cristata. Here the male assumes in spring a nuptial apparel, consisting of a comb on the back, and other characteristics concerning the colouring of the skin ; the nuptial characters disappear in May or June. No interstitial cells of a glandular nature are to be found in the testicle. But at the time of heat there is near the hilus of the testicle a tissue with rich fatty inclusions, which can be easily recognised by its reddish-yellow colour.^ This tissue is formed of spermatic cysts in which the cells of Sertoli had undergone a peculiar transformation. These cells proliferate, ^I am indebted to Dr. Wagner for having demonstrated this fatty body to me both in situ and microscopically. 190 INTERNAL SECRETIONS and their protoplasm becomes filled with big granulations staining with osmic acid. Finally the whole cyst is charged with these cells. As was previously observed by Champy, "corpora lutea" of some kind are formed in the testicle. As Aron points out, this glandular paratesticular tissue develops and persists during the whole time of heat, and its regression begins at the same time as regression of the nuptial features sets in. Experiments performed by Aron on this species are of great interest. It has already been shown in the triton that castration leads to rapid disappearance of the nuptial characters. Now Aron succeeded in destroying the glandular paratesticular tissue by galvanocauterization at the beginning of heat. This operation was successful in several cases ; a rapid and complete regression of the nuptial characters followed. The histological examination showed that the spermatic part of the testicle was intact. We see that the latter alone is not sufficient to prevent castration effects from occurring. If only an incomplete destruction of the paratesticular tissue was made, there were no changes in the nuptial characters. Objections have been made by Champy to the experiments of Aron. The various papers of Champy (1922) and Aron (1922) may be consulted. Lately Kolmer and Koppdnyi (1923 a, 1923 b) have demon- strated that in Pleurodeks Waltli there is a special organ near the testicle consisting almost exclusively of interstitial cells, though islets of generative tissue can be found also in this special organ. It is scarcely possible to sa}^ anything about the physiological bearing of this organ. The results obtained by Lauche (1915) in experiments with partial castration on the frog must also be mentioned. A small testicular fragment left in the body hypertrophied and attained the volume of two normal testicles; in reality there was an hypertrophy up to about the volume of one testicle, as the tubules of the regenerated organ were very distended. In other experiments only one testicle was removed; the remaining testicle showed no hypertrophy. Also no signs of hypertrophy occurred when one whole testicle and a fragment of the second testicle were left in the body. We thus see that the case of the frog is very different from that of the mammal, in which there is no hypertrophy of a testicular fragment, but in which an apparent hypertrophy of the remaining testicle after unilateral INTERNAL SECRETION OF TESTICLE 191 castration may be observed. As Lauche points out, the hypertrophy of the testicular fragment in the frog is caused especially by a proHferation of the generative cells within the seminiferous tubules. He concludes from his experiments that this hypertrophy of the generative elements is to be con- sidered as compensatory in regard to the endocrine function of the testicle. But I think that the great difference in the be- haviour of the remaining testicle, or of the testicular fragment in mammals and in the frog, is sufficient to show that the factor here involved is not simply the need of hormones, but something else which is not yet known to us ; it seems very hkely that a variety of factors come into play. Patzelt (1923) has observed a frog with testicular atrophy and far-going degenerative changes in the seminiferous tubules. The interstitial cells were well developed and likewise the sex characters such as the pads and the vasa deferentia with their enlargements. The fatty bodies were abnormally voluminous. 4. Birds. For the purpose of a comparative physiological study of the problem before us, investigations on birds should be of special interest, since in this class the dependence of the sexual characters upon the sexual glands is particularly striking. There is, moreover, in many species of birds a cyclic change in the appearance of the external sexual characters. Those who have described the histology of the testicle in birds do not agree upon the question as to the quantity in which interstitial cells are present, or indeed as to whether they occur at all. They disagree also in regard to the data concerning time relations. Detailed investigations on all these questions have been made in the last few years by Boring and Pearl, by Pezard, Morgan, Nonidez, Massagha, Punnett and Pease, and still more recently by Courrier and Benoit in Bouin's laboratory. One of the first studies on the interstitial cells in the testicle of the cock was made by des Cilleuls (1912). He found the interstitial tissue in the first weeks to be not very well de- veloped; this is the time when the sexual characters which depend upon the sexual glands have not yet manifested them- selves. Des Cilleuls reports that at about the forty-fifth day the connective tissue cells begin en juasse to transform 192 INTERNAL SECRETIONS themselves into polyhedric interstitial cells disposed around the blood vessels. At this time the development of such sexual char- acters as the head apparel also begins. Des Cilleuls concluded from his observations that there is in the cock a parallelism in the development of the interstitial tissue and that of the sexual characters. The detailed investigations made by Boring and Pearl (1917) are opposed to these observations of des Cilleuls. Boring and Pearl examined more than 60 birds from chickens just hatched to eighteen-months-old cocks. In the former they found a small number of interstitial cells, whereas in older birds interstitial cells were never detected. According to Boring and Pearl the interstitial cells in the testicle of the cock dis- appear at the age of about six months. They think that the observers who found interstitial cells in the testicle of the cock (des Cilleuls, Mazzetti and Reeves) were misled by small pieces of tubules surrounded by connective tissue. Boring and Pearl observed in their preparations several places which resemble the illustrations of groups of interstitial cells. They point out "that the only way to be sure of interstitial cells is to use a differential stain." Boring and Pearl claim to have used such a stain, since they employed osmic acid for blackening the fat and several differential stains for secretion granules of a protein nature, and they say that there is "no possibility of missing secreting cells when these stains are used, if there are any present." Boring and Pearl conclude from their obser- vations that true interstitial cells are not a necessary or a constant element in the testicle of the cock. Basing their position on these histological and other observations made by them on the gonads of hermaphrodite birds (1918) they con- cluded that the interstitial cells have probably no influence on the development of the sexual characters in the fowl. The question was examined dlsohyPezard^i^iS, pp. 109-117) who confirmed the statement of des Cilleuls, Reeves, Boring and Pearl as to the presence of interstitial cells in the testicle of the young chicken. But like Boring and Pearl, Pezard states that at the end of the second and at the beginning of the third month the interstitial tissue decreases; as he points out, this decrease is possibly only an apparent one, as by this time the generative part is more markedly increased than the interstitial tissue. The interstitial tissue continues to decrease, INTERNAL SECRETION OF TESTICLE 193 whereas the seminiferous tubules increase further and enter upon spermatogenesis. At the age of eight months the inter- stitial cells have almost disappeared. Pezard supposes that the development of the sexual characters in the cock is not parallel to the development of the interstitial tissue: the discordant growth of the comb and the development of the sexual in- stincts take place at a time when the interstitial tissue is already nearly at the minimum. As the discordant growth of the comb and the development of the sexual instincts can take place only when the hormones of the testicle enter without interruption into the blood, Pezard concluded from his ob- servations that the sexual characters in the cock are formed and preserved by hormones arising not in the interstitial cells but in the generative part of the testicle. Against the conclusions of Boring, Pearl and Pezard the same objection can be made as in the cases of the mole and Rana esculenta, i.e., that the decrease of the interstitial tissue in the testicle of the growing cock is only an apparent one. The testicle increases enormously owing to the development of the seminiferous tubules, and if the volume of the interstitial tissue remains unaltered or even markedly increases, a single microscopical preparation will always give the impression that the insterstitial tissue decreases as compared with what is found in the just hatched or young chicken, whereas there may be in reality only a distribution of the interstitial tissue in an enlarged space. A detailed study of the interstitial tissue in the cock as made by Benoit (1922) showed that this objection is justified. Benoit claims that the investigators drew erroneous conclusions about the interstitial cells in the cock, owing to an insufficiency in their methods. According to Benoit the interstitial cells of the cock acquire the appearance of glandular cells at an age of about three months. A quantitative study of the question reveals that the total mass of interstitial tissue increases enormously, though there is seemingly a decrease when judged from a single microscopical preparation. Benoit (1922 d) stated that at an age of two and a half months when, according to Pezard, the interstitial tissue decreases, there is in reality an increase of about three times compared to that at an age of two weeks. At about seven months the total mass of glandular interstitial cells is about 24 times greater, and in the fully-grown cock the 194 INTERNAL SECRETIONS increase may be one of 86 times. But there seems to be less interstitial tissue as the generative tissue has increased more than 1000 times. The result is contrary to what was sup- posed by Pezard; the discordant growth of the sex characters is concomitant with the development not only of the generative tissue but also with that of the interstitial cells. Lately Massaglia (1921) repeated the experiments of Bouin and Ancel on the rooster. He performed ligation and resection of the vas deferens in birds of different ages. Contrary to the authors mentioned above, he stated that interstitial cells are present also in the testicle of the adult normal cock. He found in the interstitial cells numerous small fatty granules and mitochondria well stained by acid fuchsiri. After ligation and resection of the vas deferens a marked atrophy of the semini- ferous tubules occurred, whereas the interstitial cells remained normal or increased in number. Nevertheless the sexual characters of the animals remained normal, or in the case of young birds developed normally. In some experiments Mas- saglia removed the degenerated testicle; after this signs of castration became visible. ^lassaglia considers the elaboration of the fatty granules and of mitochondria as a proof of the conception that the interstitial cells have the character of secretory cells, and he concluded from his experiments that the endocrine function of the testicle in the cock is performed by the interstitial cells. Further Massagha points out that no fact exists which supports the conception that the endocrine function is carried out by the spermatogenetic cells. Against the experiments of Massaglia the objection might be made that the seminiferous tubules still contained sper- matogenetic cells after ligation, and that these produced the hormones; it is the same objection as that which we have dealt with in describing the experiments on mammals. But I should like to repeat here that it is very improbable that such deep-seated changes as those occurring in the seminiferous tubules after ligation could have no effect on the organism, if the seminiferous tubules were really endocrine in function. This is why I consider the conclusions of Massaglia to be justified, although I think it is still necessary to continue the experiments further. A degeneration of the seminiferous tubules associated with an enormous increase of the interstitial tissue was observed INTERNAL SECRETION OF TESTICLE 195 also by Guyer (1912) in hybrids between the guinea and the common fowl, and by Poll (1920 a, 1920 b) in hybrids between pea and guinea fowl. It would be difficult to say whether the hybrids showed a "normal" plumage or a "normal" sexual behaviour, both having been different from those of any other race ; only a detailed analysis and experimental investi- gation could give evidence on this point. But it seems that in the cases of both Guyer and Poll the sexual behaviour of the hybrids was different from that of the ordinary "castrate," and that there was consequently an internal secretion of the testicle. We have no detailed knowledge of the changes the testicle of the cock undergoes after transplantation. According to Foges and Pezard the seminiferous tubules in the engrafted testicle of the cock do not degenerate. Also Massaglia found in one case numerous spermatozoa in the seminiferous tubules in small fragments transplanted on to the peritoneum; the interstitial cells were normal. The bird showed diminished sexual instincts; Massaglia is disposed to explain this by the small number of interstitial cells which were present in the body. It may be that the quantity was so small that the effect produced was beneath the threshold, and that the bird was on the way to become a capon. As to the function of the interstitial cells in birds the ex- periments of Cent (1909) on drakes should also be recorded here. Cent (quoted from Boring and Pearl, 19 17) removed the cere- bral hemispheres from drakes ; the interstitial tissue increased, whereas the seminal tubules underwent a decrease. The sex characters remained undeveloped. He does not state whether this hypertrophied interstitial tissue consisted of connective tissue or of epithelioid interstitial cells. The "interstitial tissue " is a very complex formation, in which cells of Leydig are intermingled with simple connective tissue cells. More "interstitial tissue" does not imply more active epithelioid glandular cells of the type of Leydig, and by ignoring this fundamental consideration the discussion of the problem be- comes impossible. We have some further knowledge of the interstitial cells derived from the study of other birds such as the sparrow, canary, pheasant and jackdaw. The data accumulated concern the cyclic changes in the testicle occurring during heat, when 196 INTERNAL SECRETIONS the testicle in many birds increases to a very considerable degree. (For details see Marshall, 1922, p. 22). Loisel (1902 b) recorded that in the house sparrow and in another species of sparrow from Madagascar the spermatogenetic cells and the cells of Sertoli, when heat is approaching, are full of fatty granules, whereas no signs of secretory activity are to be seen in the interstitial cells. From these and similar observations on other species of birds Loisel concluded that the endocrine function of the testicle must be ascribed to the spermato- genetic cells and to the cells of Sertoli, and that heat is brought about by the endocrine function of these cells only, not by that of the interstitial cells. But, on the other hand, Loisel himself mentioned that in the canary fatty granules occur also in the interstitial cells, which are present in small numbers. Further, Loisel observed signs of secretory activity in the interstitial cells of the sparrow during embryonic development. Long before the formation of seminiferous tubules, long before the sexual differentiation of the sexual gland, he found interstitial cells packed full with fatty granules besides the cells of the germ epithelium. But he records that these cells eventually decrease in number and disappear finally in the testicle of the adult (1902 a). Observations on the interstitial cells in the testicle of the silver and the golden pheasant have been made by Pezard. Before puberty the interstitial cells are very numerous, but as in the cock they disappear almost completely when the first spermatogenesis is completed, i.e., when puberty is at- tained; this takes place during the first great moult in spring and summer. Observations on the interstitial cells of the pheasant are all the more interesting as the sexual behaviour of this bird undergoes cycHc changes from the time of rest to that of heat. Pezard stated that in the golden pheasant the inter- stitial cells again increase in number during sexual inactivity when the generative part of the testicle assumes an almost embryonic appearance. But I think that here we have to do with an apparent change in the number of the interstitial cells. This is why I do not agree with Pezard, who thinks that in birds the interstitial cells are merely a factor in spermato- genesis, whereas the other sexual characters of birds are formed and preserved, according to Pezard, by an hormonic action of the spermatogenetic cells or of the cells of Sertoli. INTERNAL SECRETION OF TESTICLE 197 Lately Benoit (1922 a), a pupil of Bouin, has made observations on different species of birds, and concluded that there is a close correlation between the nuptial plumage and the interstitial cells, whereas no such correlation exists between the sex character and the generative part of the testicle. Different objections have been made by Pezard (1923 a). Investigations on the cyclic changes of the interstitial tissue in birds have been made by Watson (1919). The histo- logical observations of Watson on the greenfinch are of interest in this connection. As in the mole, the greenfinch shows a rela- tive decrease in the number of interstitial cells during oestrus. But it seems that marked cyclical changes of a cytological nature take place also in the interstitial tissue. This question must be investigated in greater detail and by special cytological methods ; but what Watson stated, indicates that the fibrous tissue cells gradually disappear in the interstitial tissue, and are replaced by another type of cell. These seem to be the true interstitial cells massed together in the angles formed by the greatly increased tubules. Similar statements were made by Benoit (1923 a). Certainly more detailed histological investigations are neces- sary. First, it is essential to define in a stricter sense what kind of cells precisely are understood under the name "interstitial cells," and in every case. Differential histological methods should be applied more closely. Secondly, further criticism is necessary in regard to all questions concerning the quantity of the interstitial cells. On the other hand it is unjustifiable and arbitrary to declare that some tissue cannot be considered as having an endocrine function because it is "connective tissue." The notion of connective tissue. is very indefinite, and where such tissue is present it may undergo cyclic changes like the interstitial cells in mammals. It suffices to glance at Fig. 57 where a tissue which seems to be simply connective step by step becomes transformed into an agglomeration of interstitial cells. There is no fundamental reason why cells which are connective tissue cells by origin should not form an organ of internal secretion, and if further embryological investigation should show that, contrary to Rubaschkin's view, the interstitial cells are really mesenchjnne cells, as supposed by Bouin and Ancel, this need not modify our conclusions as to the endocrine 198 INTERNAL SECRETIONS function of the interstitial cells of mammals, based especially on the experimental observations which are above recorded. A new point has lately been made by Goodale. As the interstitial cells containing granules are eosinophile cells, Goodale (1919) is disposed to consider them as leucocytes. He remarks that similar cells are to be found also in other organs, such as the thymus of the moulting drake, where they are abundant, and in the thyroid, pineal and pituitary glands, where they have been found, though they are not common. The question has been taken up by Nonidez (1920). He studied the gonads of embryos and young chicks by differential staining methods ; he concluded from his observations that the granule- laden interstitial cells are derived from primitive blood cells or haemocytoblasts, or in other words from mesenchyme cells. The granule-laden interstitial cells are connected with typical eosinophile granulocytes (or leucocytes) by a graded series of stages. Besides these interstitial cells primitive undifferentiated mesenchyme cells and small lymphocytes are also present in the intertubular space of the testicle of the adult bird. These may become transformed, according to Nonidez, in the adult bird into several types of cells, also into cells closely resembling the interstitial cells in the testicle of mammals; these cells have a finely granular acidophile cytoplasm; they are vacuo- lated and contain fat; the nucleus is round. They are not, however, a constant element in the testes of the adult bird, and may be absent. Nonidez considers them to be wandering cells. As to the function of all these different types of cells Nonidez thinks that neither the granular cells, nor the inter- stitial cells derived from the small lymphocytes, can have a specific endocrine function. The granulocytes and the modified small lymphocytes are not restricted to the gonads occurring elsewhere in the general mesenchyme; Nonidez says that the small lymphocytes may perhaps have some bearing on the development of the sex characters in the young bird, but their inconstancy in the testis of the adult bird shows that they are not necessary for the maintenance of these characters. It seems hkely to Nonidez that the fat stored in the interstitial cells derived from the small lymphocytes may be used by the cells within the seminal tubules, or even transformed into a specific hormone which exerts its influence on the sex characters. It may be remembered that Bouin and Ancel (1905 c) consider INTERNAL SECRETION OF TESTICLE 199 the interstitial cells of the mammal to be derivatives of the cells of lymphoid nodules disposed between the seminal tubules. A similar view was held by Champy (1913) for the frog, and by Courrier (1922 b) for the Gasterosteus. I should like to point out certain objections of a general order to Goodale and Nonidez's conception. I have myself no experience of birds, but what we learned in our laboratory for mammals conforms with some of Nonidez's observations. First, the interstitial cells in the testicle of the mammal seem to be of very different types; a glance at Fig. 56 (especially g) conveys this idea. The size, shape and inclusions of the interstitial cells are manifold. Further, a detailed research on the inclusions of the interstitial cells of the mammals, which Wagner has undertaken in our laboratory, also gave some cytological results very similar to those of this author. But we may still ask whether there is sufficient evidence for the claim that the different types of interstitial cells are merely elements common to all other organs. What is proved by Nonidez is only the fact that the different types of interstitial cells may be derived, like the blood cells, from mesenchyme cells, and further that the interstitial cells are cytologically very similar to cells common to other organs. This does not mean that the interstitial cells can be identified with certain types of blood cells or with similar cells in other organs in regard to their function. I agree that the question as to the function of the interstitial cells in birds and their bearing on the internal secretion of the testicle is a very complex one, more complicated than it might seem at first. The cytologist will play an im- portant part in the elucidation of this question. But it would be a great mistake to build up a theory as to the seat of hormone production in the testicle on the basis of morphological observations only. It may be also mentioned that according to Nonidez (1922) certain interstitial cells in birds are formed from young seminiferous tubules which undergo degeneration. Benoit (1923 b) is even of the opinion that possibly all inter- stitial cells arise in the cock during embryonic development and during youth in a similar manner, i.e., that they are all of an epithelial origin. A new paper of Ceni (1922) may be mentioned here. He claims to have given new proofs of the endocrine function of the generative part of the testicle in the cock. 200 INTERNAL SECRETIONS BIBLIOGRAPHY FOR CHAPTER IV. [* Not seen in the original.'] Adler (Leo) 1914. Uber Jodschadigungen der Hoden. Arch. f. Pathol, u. Pharmakol., 75, p. 362. Albers-Schonberg. 1903. Uber eine bisher unbekannte Wirkung der Rontgenstrahlen auf den Organisiniis der Tiere. Miinch. tnediz. Wochenschr., p. 1859. Ancel et BoxnN {or Bouin et Ancel). 1903a. Recherches stir les cellules interstitielles du testicule des mammiferes. 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Zeitschr. /. wissenschftl. Zool, 2, 1. 1857. Lehrbuch der Histologic des Menschen u. der Tiere. Frankfurt a. M., p. 495. LiPSCHiJTZ et Ottow, 1920. Sur les consequences de la castration partielle. G. R. de la Soc. de Biol, 83, p. 1340. LipschUtz. 1921a. Quantitat. Untersuch. iiber die innersekretor. Funktion der Testikel. Deutsche med. Wochenschr., No. 13. Ottow et Wagner. 1921b. Nouvelles observations sur la castration partielle. C. R. de la Soc. de Biol., 85, p. 42. Ottow u. Wagner. 1921c. tJber das Minimum der Hoden- substanz, das fiir die normale Gestaltung der Geschlechts- merkmale ausreichend ist. Pfliigers Arch., 188, p. 76. Ottow u. Wagner. 192 Id. Sur des modifications histolo- giques subies par des restes du pole inferieur du testicule dans la castration partielle. G. R. de la Soc. de Biol., 85, p. 86. Ottow u. Wagner. 1921e. Sur des modifications histolo- giques subies par des restes du pole superieur du testicule dans la castration partielle. G. R. de la Soc. de Biol,, 85, p. 88. Ottow u. Wagner. 192 If. Sur le ralentissement de la mas- culinisation das la castration partielle. G. R. de la Soc. de Biol, 85, p. 630. 2o6 INTERNAL SECRETIONS LiPSCHUTZ 1922a. Sur I'hypertrophie du testicule clans la castration imilaterale. C. R. de la Soc. de Biol, 87, p. 60. 1922b. The so-called compensatory hypertrophy of the testicle after unilateral castration. Jl. of Physiol., 56. {in collaboration with Ottow, Wagner and Bormann). 1922c. On the hypertrophy of the interstitial cells in the testicle of the guinea-pig under different experimental conditions. Proceed. Roy. Soc, 93, p. 132. {in collaboration with Wagner, Tamm and Bormann). 1922d. Further experimental investigations on the hypertrophy of the sexual glands. Proc. Roy. Soc, 94, p. 83. Wagner et Bormann. 1922e. Ralentissement experimental de la masculinisation. C. R. de la Soc de Biol., 86, p. 238. et Wagner. 1922f. L'hypertrophie des cellules interstitielles, est-elle une reaction compensatrice endocrine ? C. R. de la Soc de Biol., 87, p. 15.. et Wagner. 1922g. Nouvelles observations sur la fonction endo- crine des cellules interstitielles du testicule chez les mammi- feres. C. R. de la Soc. de Biol, 85, p. 306. Bormann und Wagner. 1922h. Uber Eunuchoidismus beim Kaninchen in Gegenwart von Spermatozoen in den Hoden- kanalchen u. unterentwickelten Zwischenzellen. Dtsch. medizin. Wochenschr., No. 10. Ottow und W^agner. 1922i. tJber Eunuchoidismus beim Kaninchen, bedingt durch Unterentwicklung des Hodens. Arch.f. Entw.-Mech., 51, p. 66. Wagner et Kropman. 1922k. Nouvelles observations sur la quant it e minimale de masse testiculaire suffisante pour une masculinisation complete. C. R. de la Soc de Biol, 87, p. 122. ■ und Wagner. 19221. Uber die Hypertrophie der Zwischen- zellen. Ihr Vorkommen und ihre Bedingungen. Pflilgers Archiv, 197, p. 348. 1923a. New experimental data to the question of the seat of the endocrine function of the testicle. Endocrinology, 7, p. 1. 1923b. Uber die kompensatorischen Reaktionen der Gesch- lechtsdrlisen. Skandin. Arch. f. Physiol, 43, p. 45. et Ibrus. 1923c. Sur la quantite de tissu interstitial dans le testicule du lapin apres la castration unilaterale. C. R. de la Soc de Biol, 88, p. 1259. und Ibrus. 1923d. Uber die Menge des Zwischengewebes im Hoden des Kaninchens nach einseitiger Kastration. Skand. Arch. f. Physiol, 44, p. 237. 1923e. Castration luiilaterale chez la Souris blanche. C. R. de la Soc. de Biol, 89, p. 1137. See also Ivropman a)id Wagner. INTERNAL SECRETION OF TESTICLE 207 LoiSEL. 1902a. Sui' I'origine embryonnaire et revolution de la secretion interne du testicule. C. R. de la Soc. de Biol., 54, p. 952» 1902b. Sur le lieu d'origine, la nature et le role de la secretion interne du testicule. C. R. de la Soc. de Biol., 54, p. 1034. LuDWiG und Thomsa. 1863. Die Lymphwege des Hodens u. ihr Verhaltnis zu den Blut- und Samengefassen. Sitz-Ber. Akad^ Wissensch. Wien, Matheni.-Naturwissensch. Kl., 46, p. 221. Marshall. 1922. The physiology of reproduction. 2nd Edition* London. Ch. IX. Massaglla.. 1921. The Internal Secretion of the testis. Endocriri' ology, 4, p. 547. *Mattill and Carman. 1923. The degeneration of the testis of rats on a milk diet. Proc. of the soc. /. exp. biol. a. med., 20, Nr. 7, p. 420. MiCHON et Porte. 1920a. Etude histologique de six cas de testicules ectopiques. Lyon Chirurgical. 1920b. Quelques faits concernant I'histologie du testicule ecto- pique. C. R. de la Soc. de Biol., 83, j). 1438. *Myers. 1915. Histological changes in testes following vasectomy. Anat. Rec, 10, p. 228. Nemenov. 1916. Sur 1' influence de la roentgenisation des testicules sur la prostate. Arch, des Sc. Biologiques, 19. Nonidez. 1920. Studies on the gonads of the fowl. I. Hemato- poetic processes in the gonads of embryos and mature birds. American Jl. of Anat., 28, p. 81. 1922. Studies on the gonads of the fowl. III. Americ. Jl. of Anatomy, 31, No. 2. Van Oordt. 1923. Secondary sex -characters and testis of the ten- spined Stickleback (Gasterosteus pungitius L.). Kon. Akad. v, Wetensch. te Amsterdam, 26, p. 309. Patzelt. 1923. Hypoplasie der Keimdriisen und das Verhalten der Zwischenzellen bei Rana esculenta. Arch. f. Mikrosk. Anat. und Entw.-Mech., 100, H. 1, 2. Pezard. 1918. Le conditionnement physiologique des caracthres sexuels secondaires chez les oiseaux. Edition du Bulletin Biologique de la France et de la Belgique. These. Paris. 1919. Castration alimentaire chez les coqs soumis au regime carne exclusif. C. R. de VAcad. d. Sc, 169, p. 1177. 1922. La Loi du "Tout ou rien" et le gynandromorphisme chez les oiseaux. Jl. de Physiol, et de Pathol. Gener., p. 200 and p. 495. 1923a. Tissu interstitiel et caracteres sexuels secondaires des Oiseaux (Reponse a Benoit). C. R. de la Soc. de Biol., 88, p. 245. 1923b. Critique de la theorie de Bouin et Ancel. C. R. de la Soc. de Biol, 88, p. 333. p 2o8 INTERNAL SECRETIONS Poll. 1920a. Pfaumischlinge (Mischlingsstudien VIII.). Arch. /. mikr. Anat., Festschrift Hertwig, p. 365. 1920b. Zwischenzellengeschwulste des Hodens bei Vogel- mischlingen. Beitr. z. path. Anat. u. z. allgem. Pathol., 67, p. 40. Rasmtjssen. 1917. Seasonal changes in the interstitial cells of the testis in the woodchuck (Marmota monax). Amer. Jl. of Anatomy, 21. 1918. Cyclic changes in the interstitial cells of the ovary and testis in the woodchuck (Marmota monax). Endocrinology, 2. Regaud et Folic ARD. 1901. Etude comparative du testicule du pore normal, impubere et ectopique au point de \aie des cellules interstitielles. C. R. de la Soc. de Biol., 53, p. 450. Rettereb et VoRONOFF. 1923. Structure des testicules d'un chim- panze et resultats physiologiques de leur greffe. Journal d'Urologie, 15, p. 417. RiBBERT. 1890. tJber die kompensatorische Hypertrophic der Geschlechtsdriisen. Virchows Archiv, 120. RuBASCHKiN. 1912. Zur Lehre von der Keimbalin bei Saugetieren. tJber die Eiitwicklung der Keimdriisen. Anatoin. Hefte, 46, p. 345. Sand. 1918. Experimentelle Studier over Kcf)nskarakterer hos Pat- tedyr. Kopenhagen. 1921a. Etudes experimentales sur les glandes sexuelles chez les mammiferes. Jl. de Physiol, et Pathol. Gener., I. mem., 19, p. 305. 1921b. II. mem.: Exper. sur la resection du "vas deferens." Ibidem, p. 494. 1921c. III. mem. : Cryptorchidie experimentale. Ibidem, p. 515. ScHULTZ (Eugen). 1908. Uber imikehrbare Entwicklungsprozesse und ihre Bedeutung fiir eine Theorie des Vererbung. Vortr. u. Aufs. yJb. Entw.-Mech., Heft IV. Leipzig. *SiMMONDS. 1909. tJber die Einwirkung von Rontgenstrahlung auf die Hoden. Fortschr. auf d. Gehiet d. Rontgenstrahlen, 14 (quoted from Steinach, 1912, PfliXgers Archiv, 144). 1913. Uber Mesothoriumschadigung des Hodens. Deutsche mediz. Wochenschr. Steinach. 1912. Wilkiirliche Umwandlung von Saugetier-Mannchen in Tiere mit ausgepragt weiblichen Geschlechtscharakteren und weiblicher Psyche. Eine XJntersuchung iiber die Funk- tion und Bedeutung der Pubertatsdriisen. PfliXgers Archiv, 144. 1916. Pubertatsdriisen und Zwitterbildung. Arch. f. Entw.- Mech., 42, p. 307. 1920. Verjiingung durch experimentelle Neubelebung der alternden Pubertatsdriise. Arch. f. Entw.-Mech., 46, p. 553. und Kammerer. 1920. Klima und Mannbarkeit. Arch. f. Entw.-Mech., 46, p. 391. INTERNAL SECRETION OF TESTICLE 209 Takahashi. 1922. Untersuchungen iiber die tonisierenden und trophischen Funktionen des Sympathicus. Pflugers Arch,, 193, p. 322. Tandler und Gross. 1912. tJber den Saisondimorphismus des Maulwurfhodens. Arch. f. Entw.-Mech., 33, p. 297. 1913. Die biologischen Grundlagen der sekunddren Geschlechts- charaktere. Berlin. Thorek. 1923. Experimental investigations of the role of the Leydig, seminiferous and Sertoli cells. (Quoted from manuscript.) TiEDJE. 1921a. Unterbindungsbefunde am Hoden unter besonderer Beriicksichtigung der Pubertatsdriisenfrage. Deutsche mediz Wochenschr., 1921, No. 13. 1921b. Die Unterhindung am Hoden und die '' Puhertdtsdriisen lehre."" Jena. TsuJi. 1920. On the function of thyroid gland with special reference to the effect of variations of diet upon it. Acta Scholae Med Univers. imper. Kioto, 3, p. 713. ViLLEMiN. 1906a. Rayons X et activite genitale. C. R. de VAcad Sc, 142, p. 723. 1906b. Sur la regeneration de la glande seminale apres destruction par les rayons X. C. R. de la Soc. de Biol., 60, 1-er sem., p. 1076 VoiNOV. 1905a. Sur le role probable de la glande interstitielle, C. R. de la Soc. de Biol., 58, 1-er sem., p. 414. 1905b. Les spermatotoxines et la glande interstitielle. C. R de la Soc. de Biol., 58, I-er sem., p. 688. Wagner. 1922. Uber die Zwischenzellen und das spermatogone Gewebe in einem Fall von Eunuchoidismus beim Kaninchen, Arch. f. Entw.-Mech., 52, p. 386. 1923. Zur Zytologie der Zwischenzellen des Hodens. Anat Anz., 56, p. 559. Wagner und Loeper. 1923. Uber einen weiteren Fall von Eimu choidismus beim Kaninchen bei normaler Spermatogenese, PfiiXgers Archiv, 198, p. 252. Waldeyer. 1921. Anatomie der endokrinen Driisen. Arch. /, Frauenkunde, 7, p. 1. Watson. 1919. A study of the seasonal changes in avian testes Jl. of Physiol, 53, p. 86. ♦Weichselbaum. 1910. tJber Veranderungen der Hoden bei chroni schem Alkoholismus. Verhandl. der Deutsch. Path. Gesellsch Whitehead. 1912a. A microchemical study of the fatty bodies in the interstitial cells of the testis. Anatom. Record, 6, p. 65. 1912b. On the chemical nature of certain granules in the in terstitial cells of the testis. Amer. Jl. of Anatomy, 14, p. 63 1914. Vital staining of the interstitial cells of the testis. Anatom Record, 8. {Proceed. Amer. Assoc, of Anatomists, 1913.) WiTSCHi. 1921. Der Hermaphroditismus der Frosche imd seine Bedeutung fiir das Geschlechtsproblem und die Lehre von der inneren Sekretion der Keimdriisen. Arch. f. Entiu.- Mech., 49, p. 316. Chapter V. The Seat of Production of the Internal Secretion of the Ovary. A. MAMMALS. Before entering into the question as to the parts of the ovary which elaborate the internal secretions, and before proceeding to a discussion of the different experiments made to elucidate this problem, we propose to give a short account of the histology and histogenesis of the ovary in so far as this concerns our problem. We do not intend however to discuss in detail questions which are purely histological. I. The Interstitial Cells of the Ovary. The histological appearances of the ovary are much more complex than those of the testicle. The subject has been examined by many authors, of whom Sainmont, Aime, Wini- warter, Fraenkel and Schaeffer, Limon, Seitz, Wallart and Aschner may be especially mentioned. There have been many controversies about the interstitial cells in the ovary. But there can be scarcely any doubt that interstitial cells homo- logous with those in the testicle are to be found in the ovary of all the species of mammals which have been investigated. The number of these cells is, indeed, very different according to the species, to the age, and to the special condition of the individual. The interstitial cells [Fig. 94) are described as epithelioid and polyhedric, and as cells of a glandular nature grouped around the capillaries {Fig. 95). The cells may form nests or cords separated by thin threads of connective tissue {Fig. 96). The latter contains blood vessels from which capillaries enter into the nests. These cells are in no way similar to connective tissue cells ; they resemble rather the cells of the liver or of the cortical substance of the adrenals. The protoplasm of these cells is granulated or vacuolated, and ■contains small droplets of fat. As to the presence of the yellow 212 INTERNAL SECRETIONS lutein pigment in these cells the different authors disagree. The cells are smaller than those of the corpus luteum {Figs. 94, 97). According to Limon (1901) these cells occupy in the bat and in the mole almost the whole ovary forming a paren- chyma traversed only by blood vessels. The same is true for the rabbit, as seen in Fig. 98. Interstitial cells may be found in the ovary already during embryonic life. As mentioned above, most authors, especially Winiwarter, insisted that interstitial cells are present in the ovaries of all species. Fraenkel (1905) and Schaeffer (1911), who studied , -^'^r.,^-^ ^. ■» . < _ jf 0 \ 'i * > ,' I ' if '^^V r 4 A ^ Fig. 94. — Ovary of rabbit 18 months old (Prot. Nr. 44). Fix. in the solution of Helly. A, Cells of Corpus luteum; B, Interstitial cells. The cells of the C.l. are bigger; the protoplasm of both is highly vacuolated. The cells are associated with closed capillaries. — Prepar. of Wagner; design of Lehbert. a great number of different species, concluded, on the contrary, that these cells are not always present in the ovary. But their material was very incomplete for many species, only one or a few ovaries having been investigated. Since the interstitial cells are not to be found always in different indi- viduals of the same species, the absence of interstitial cells in one or some individuals of a given species is not sufficient evidence for concluding that these cells are really absent in that species. The interstitial cells in the ovary vary, indeed, very greatly in number and size, according to age. Anyone who examines a sufhcient number of ovaries of the rabbit will confirm this {Fig, 99 A, B, C). The interstitial cells which are always present in the adult rabbit do not acquire the size characteristic of the adult animal until about the age of six months. Up INTERNAL SECRETION OF OVARY 213 to this age the stroma consists mostly of connective tissue cells {Figs. 99 A, 100; see also Figs. 102-103) and later of cells, having a spherical nucleus and a small quantity of protoplasm. Afterwards the ovary becomes transformed, long before corpora lutea appear, into an organ consisting almost entirely of interstitial cells, surrounded on the surface by a layer of follicles in different stages of development. That the number and the condition of the interstitial cells depend on the age of the animal was emphasized especially by Aschner Int. c. — -^— - r* -' "■ ^^^""^^1^-'^ Cap. % ^^^3^" ^~'^- ^ ^ Fig. 95. — Section through ovary of rabbit, x i8o. Injection of blood vessels by 1-300 nitrate silver. Impregnated endo- thelial cells of capillariesjwhich are surrounded by interstitial cells. — From Lim.on. (1914 c). Employing "Sudan" as a stain for fat, he was able to find interstitial cells in the ovaries of species in which they had not been detected by Fraenkel and Schaeffer, for instance, in the dog and in the cat. Aschner found the interstitial cells well developed before puberty in Rodentia, in the hedgehog, in the bat and in different species of Carnivora. He found that these cells increase in quantity till puberty. When puberty is attained and the first corpus luteum is formed, the space occupied by the interstitial cells is relatively smaller than before, as the corpora lutea now occupy the greater part of the ovary. According to Aschner, the quantity of the interstitial 214 INTERNAL SECRETIONS cells may even in some species decrease after the first corpora lutea have appeared; this he stated to be the case for the dog and for the cat (Fig. loi); he says that whereas the interstitial tissue in the ovary of the dog when stained with "Sudan" becomes gradually more accentuated till puberty, so that the ovary is full of cells with red granules of fat, these cells cannot be Fig. 96. — Interstitial tissue in the ovary 0} Phascolomys [Marsupialia). Photo, low magnif. The epithehoid cells of the stroma are disposed in the form of lobules. On the left a degenerated ovum is to be seen in the middle of a lobule, the lobules being nothing else than follicles undergoing atresia. — From L. Fraenkel. detected any longer by the usual methods at the time of the first heat. In the cow, sheep, goat, horse, ape and man there is, according to Aschner, only a rudiment 6i an interstitial tissue, if compared with that of the ovary in the species mentioned above. As Aschner points out, there seems to be a parallelism between fertility and quantity of interstitial cells in the ovary. Those species in which, as in the rabbit, hedge- hog, bat and others, the number of the young in each htter is INTERNAL SECRETION OF OVARY 215 large, have a well developed interstitial tissue. In these species the well developed interstitial cells are present not only up to puberty, but also afterwards, although the interstitial tissue is much reduced when corpora lutea appear. On the other hand, the interstitial tissue is rather rudimentary in the ovary •of the cow, ape and man, where only one or two young are born Fig. 97. — L'Utear and interstitial cells (Prot, Nr. 104). x 250. Outer limit of the Corp. lut. illustrated in Fig. 112. Big lutear cells; between them and the theca externa consisting of connective tissue, remains of the theca interna are to be seen. Then come the interstitial cells, which are of smaller size than the cells of the corp. lut. — ^Prepar. of Wagner; photo of Kull. simultaneously; in these species it hardly ever forms a parenchyma hkethe interstitial tissue in the ovary of the rabbit. Among Ungulata the pig is an exception, several young being present in a Utter. Aschner stated that in the pig the inter- stitial tissue of the ovary is much more developed before puberty than in other Ungulata, although the nests of interstitial cells do not form an uninterrupted parenchyma as in the rabbit. Interstitial tissue in the ovary of the pig is transitional between 2l6 INTERNAL SECRETIONS Fig. 98. — Section through ovary of pregnant rabbit (Prot. Nr. 280). Weight without embryos 2-7 kg. Ten embryos found in the uterus; total weight of embryos 230 gr. There were 1 1 corpora lutea in both ovaries and great quantity of Graafian folUcles. Three corpora lutea surrounded by inter- stitial tissue occupying almost whole ovary. — Prepar. of Wagner; design of Lehbert. INTERNAL SECRETION OF OVARY 217 that of the rabbit and that of the cow, ape and man. From his observations made on the ovaries of 250 females of very different species, Aschner concludes that the corpus luteum becomes more and more dominant over the interstitial tissue, the higher the position of the species in the class Mammalia. Fig. 99. — Development of interstitial tissue of the ovary in rabbit., x 280. A. 2.^; weeks old (Prot. Nr. 54). No epithelioid cells between the oocytes, the stroma consisting entirely of cells of connective tissue. — ^Prepar. of Wagner; photo of Kull. Aschner's suggestion as to the parallehsm between fertihty and quantity of interstitial tissue does not conform with what Athias (1919, 1921) states about the Cheiroptera, in which there is generally only one young produced yearly, and in which there is, nevertheless, an abundant development of interstitial tissue. 2l8 INTERNAL SECRETIONS According to Winiwarter, the interstitial tissue is present in all mammals, which differ only in regard to the quantity of this tissue. "As far as I know there is no species," he says (quoted from Athias, 1921) "where it (this tissue) is wholly absent." The contradictory data, so noticeable in the papers V-rli Fig. 99. — Development of interstitial tissue of the ovary in rabbit. X 280. B. 7 months old (Prot. Nr. 1 18). The stroma consists of small epithehoid cells. Two corpora albicantia are to be seen surrounded by interstitial cells. — ^Prepar. of Wagner; photo of Kull. on the subject, and even in recent ones, he explains as due to the researches being very incomplete. Sainmont and Wini- warter consider the interstitial cells as nutritive organs. It may be emphasized again that interstitial cells have been stated by the different authors to be present in the ovary of the INTERNAL SECRETION OF OVARY 219 cat, guinea pig, rat, mouse, bat, mole, hedgehog, horse, sheep and goat. Lately, Athias (1919) investigated in a very detailed way the question of the interstitial tissue in the ovary of the bat, where this tissue occupies a large space in the ovary. Athias gave also a very thorough description of the cytological !<•; - . TV' J~ f 'T Fig. 99. — Development of interstitial tissue oj the ovary in rabbit, x 280. C. 18 months old (Prot. Nr. 44). The epithelioid cells with very rich protoplasm and big spherical nucleus. — Prepar. of Wagner; photo of Kull. character of this tissue, the structure of which he declares to be that of an endocrine gland. The interstitial cells show the attributes of glandular elements. Athias considers the fatty inclusions of the protoplasm as secretory products. But he thinks that the secretion undergoes some chemical change before leaving the cells, since no substance of a Hpoid character 220 INTERNAL"! SECRETIONS is revealed in the intercellular or lymphatic spaces. Athias (1921) also is of the opinion that the interstitial tissue is always present in the ovaries of mammals. There is not as yet unanimity in regard to the interstitial tissue in the ovary of man. According to Seitz (1906) and Wallart (1907), who examined a great number of human ovaries, beginning with one in a five months old embryo and ending with an ovary of a woman of 91, interstitial cells exist hke those described by Limon and others for different mammals as interstitial tissue. They point out that the epithelioid cells with fatty inclusions are alreadv present during embryonic ':£i f>: U_- i'», ^» .'^ ■*.■-'.•- ,'.. . ■ -■•'^■■'.■v"'A'-■ Fig. 100. — Section through ovary of rabbit 2^ weeks old (Prot. Nr. 54). Stroma consisting of cells of con- nective tissue. — Prepar. of Wagner; design of Lehbert. life. Wallart mentions that the number of the cells increases up to puberty. At the time of puberty the interstitial tissue decreases; the greatest development of the interstitial tissue is attained during gravidity. At the climacteric only remains of the interstitial tissue are to be found. Wallart states that the fatty inclusions, always present in the interstitial cells, are often yellow like the fatty granules in the cells of the corpus luteum; they probably contain lutein (Wallart, 1907, p. 327). Winiwarter (1908) also stated that interstitial cells are to be found in the human ovary. Fraenkel (1905, p. 508) and Schaeffer (1911, p. 531), on the contrary, claim that not even rudiments of a similar tissue are present in the ovary of the INTERNAL SECRETION OF OVARY 221 adult woman. The question has been re-examined by Aschner. He states that the epithehoid interstitial cells are already present in the new-born child. The interstitial tissue is also well developed during early youth, but the quantity of lipoids in the ovary varies very much. Contrary to Wallart, Aschner finds that the interstitial cells in the ovary of man diminish as puberty is approached. The statement of Aschner, that Fig. 10 1. — Section through ovary of adult cat (Prot. Nr. 276). x 150. Epithelioid interstitial cells are visible in the connective tissue of the stroma. — Prepar, of Wagner; photo of KuU. during gravidity the interstitial tissue, after being reduced to its minimum upon the development of the first corpus luteum, increases again, is in accordance with the above-mentioned statement of Wallart. The increase of the interstitial tissue takes place especially in the second half of gravidity. During menstruation no increase in the number of cells could be found by Aschner. Lately the question of the interstitial tissue in the human ovary has been very much discussed by German authors. Most of them deny the presence of such cells in the 222 INTERNAL SECRETIONS stroma of the ovary. Robert Meyer (1921) declared that there are never nests of interstitial cells in the ovary of the non- pregnant woman independently of the follicular tissue, and that the "interstitial gland" is only a "phantasy" of some authors. On the contrary, Seitz (1921) claims that it would be "nonsense" to deny that the gland exists in the guinea pig or in the rabbit, and that the interstitial gland is present also in the woman. This tissue is absent or rudim.entary in the woman only after she has attained maturity; it is then replaced by the corpus luteum. The want of agreement between the statements of various observers may be explained partly by the fact that whereas some restrict the term interstitial "tissue" to cells which exist outside the walls of the follicles, as in the rabbit, others denote the mass of the atretic folHcles undergoing degeneration in the ovaries of man and mammals as interstitial tissue, and identify it with the parenchymatous tissue in the ovary of the rabbit. It will be shown in the following section that the interstitial tissue of the ovary, even when really present, as, for instance, in the rabbit, is derived in general /row the follicle; the inter- stitial cells originating from the cells of the stroma play quan- titatively a very minor role. Further, interstitial tissue is not necessarily the same as interstitial gland. There is no justifica- tion for confounding a purely histological question with a physiological one. The confusion which has arisen in regard to this question is unfortunate. 2. The Origin of the Interstitial Cells of the Ovary. Limon (1901) was the first to undertake a full investigation of this question. He stated in accordance with a suggestion of former authors that the development of interstitial cells is related to follicular obliteration, as seen especially in the rat and in the rabbit (Figs. 102, 103). The formation of the inter- stitial tissue begins in the rat soon after birth, whereas in the rabbit it does not begin until an age of four months, or, as we foimd, sometimes even later. The whole process begins with the transformation of the irregular or spindle-shaped connective cells of the theca interna, which become spherical and increase in volume. Fat droplets appear in the protoplasm of the cells. At the same time, a degeneration occurs in other cells of the follicle, in the cells of the granulosa and in the ovum itself. INTERNAL SECRETION OF OVARY 223 The degenerating cells finally are resorbed. A vascularisation arising from the stroma takes place in the mass of cells which up till now formed the theca interna. Such an atresia goes on in a very, great number of follicles (Fig. 104). Similar observations were made also by Limon on the guinea pig, on the mouse, and on the bat. We see that the interstitial tissue Fig. 102. — Growing primary follicle with memhr. granulosa and theca in rabbit 7 months old (Prot, Nr. 119). x 200. It can also be seen that threads of interstitial cells arise from atretic follicles; compare the atretic folUcle on the left (with corpus albicans) which has still conserved the round shape, with the atretic follicle on the right which has lost its original shape evidently owing to the growth of the primary folhcle at its left border. — Prepar. of Wagner; photo of Kull. of the stroma of the ovary is, according to Limon, nothing else than the result of a transformation of atretic foUicles. As the epithelioid interstitial cells are derived from the theca interna, it follows, according to Limon, that they are of connective tissue origin. Follicular atresia takes place in the ovaries of all mammals. So one would expect also that interstitial cells would be present Q ^24 INTERNAL SECRETIONS in the ovaries of all mammals. Since the interstitial tissue in some species is certainly due to folHcular atresia, it seems justifiable to identify also as an essentially similar tissue that which is derived from atretic follicles in the ovary of man and Fig. 103. — Young Graafian follicle in rabbit 11^ months old (Prot. Nr. 47). X 200. The granulosa, theca interna and theca externa are to be seen. Compare also the size of the interstitial cells in Fig. 102 and Fig. 103. — Prepar. of Wagner; photo of KuU. other mammals, in which, according to some authors, an interstitial tissue is absent. The only difference is that, in the first, the cells originating from the theca interna of the atretic folHcles form a compact parenchymatous tissue, the so-called "interstitial gland" of Bouin and Limon, whereas, in the INTERNAL SECRETION OF OVARY ^25 second, these cells remain to a great extent as they were origin- ally formed (Fig. 96), without tendency to such a confluence as occurs in the rat or rabbit. It is of considerable interest tp note that according to Salazar (1922) there are even in the; ovary of the rabbit some follicles which do not lose their in- dividual existence when becoming atretic, and which do not form directly part of the interstitial tissue. These atretic norm. cord of Atret. conn. norm, foil. interstit. cells foil. tissue foil. Fig. 104. — Section through ovary oj white rat, 62 days old. x 90. Fix. by Flemming, treated by osmic acid, not stained. Atretic follicles surrounded by connective tissue ; theca cells filled with fat. At different places follicles transformed into cords of interstitial cells.^ — From Limon. folhcles remain for a certain time surrounded by a connective tissue capsule even thicker than that of a true corpus luteum ; afterwards they undergo fatty degeneration and sclerotization. The state of the ovary in man is different from that in the rat or rabbit, since in the former the greater number of the cells of the theca interna, after having been transformed into epitheUoid cells, undergo degeneration and disappear. It may be that some of these cells are transformed again into spindle- shaped connective cells. 226 INTERNAL SECRETIONS The atresia and fatty transformation of the folHcles begin in the human ovary in the fifth month of intrauterine hfe. According to Winiwarter {1908), interstitial cells are present in the human ovary long before. But typical interstitial cells are derived also from the connective tissue cells of the stroma. There is no cytological difference between the interstitial cells originating from the stroma and those originating from follicular atresia. Once follicular atresia begins, formation of interstitial cells from cells of the stroma ceases, indeed, to play a quantitatively important role. Observers differ as to the extension of follicular atresia and of the interstitial tissue during childhood, but all agree that an increase of the interstitial cells takes place in man during gravidity. A very great number of follicles undergo atresia in the second half of gravidity. An enormous quantity of interstitial cells is, so to speak, poured out into the ovarian stroma. According to Seitz (1906, p. 263), these cells assume the character of lutein cells; they increase in size and become epithehoid, so that their appearance is very like that of the cells of the corpus luteum. Seitz called these cells "theca- lutein-cells." This transformation of cells of the theca interna into theca-lutein-cells becomes all the more intensified, the further gravidity has proceeded. As Seitz points out, all the larger follicles present undergo atresia during gravidity; as the cells of the theca interna increase also in number, a great quantity of new theca-lutein-cells full of fatty and lutein inclusions arise by follicular atresia during the second half of gravidity. Like Seitz, other authors hold that the epithelioid cells of the ovarian stroma containing fat and lutein are derived from the cells of the theca interna. In the fifth section of this chapter we shall learn the physiological bearing of such a transformation of the cells of the theca interna into cells some- what similar to those of the corpus luteum. It is, indeed, not impossible that cells of epithehal origin also take part in the formation of the interstitial tissue. The membrana granulosa of the follicle undergoing atresia is possibly such a source of the epithelioid cells of the interstitial tissue. Ra^mussen (19 18) finds it probable that in the wood- chuck new interstitial cells can originate from the germinal epithelium. A similar view is held by Ochoterena and Ramirez (1920) as a result of observations on the rat and on the rabbit. INTERNAL SECRETION OF OVARY 227 According to Goormaghtigh (1921), the interstitial cells of the ovary and of the testicle are formed from the mesothelium like the cortical substance of the adrenals. Being of epithelial origin, these cells are transformed into connective tissue cells, to become later, at the time of sexual activity, epithelioid. Bell (1920) pp. 27, 28) inclines to the view that interstitial cells can be formed even from corpora lutea. So we see that the origin of the cells of the interstitial tissue of the ovary may be a very manifold one; the cells of the stroma, the cells of the theca interna, the cells of the granulosa and possibly the cells of the corpus luteum may take part. We are now, indeed, far from the original point of view of Limon (1901) and of Sainmont (1906), who assumed that the interstitial cells originate exclusively from connective tissue. When speaking about "interstitial tissue" or "interstitial cells,'* we always understand c£lls derived from follicles without presum- ing whether they originate from connective tissue or from epithelial cells. In general there seems to be, indeed, great difficulty in •stating in terms of histology what the origin of the cells of the atretic follicle or of the interstitial tissue has been, since so many contradictory statements are to be found. An increase of the interstitial cells in the above-mentioned sense as observed during gravidity can be obtained also experi- mentally by the application of the X-rays or by transplantation. Now the question arises whether such an hypertrophy of the interstitial tissue in the ovarian stroma causes an increased endocrine activity on the part of the ovary. It seems clear that the answer to this question might furnish important knowledge as to the function of the interstitial cells. 3. The Influence of X-rays on the Ovary. The statements made by different authors on the reaction of the ovary to X-rays are very contradictory. According to some authors, the follicles and the interstitial cfeUs (or cells of the stroma) are injured by X-rays; according to others, there is only a degeneration of follicles, whereas the interstitial cells may even increase in number. But it seems that in discussing this question it is not always borne in mind that the ovary may react in a different manner according to the mode of irra- diation, according to the species, and to the age and condition -of the animal. As Lacassagne (1913, p. 41) points out, the 2^8 ^ Internal SECRETIONS ' want of agreement between the statements of the different authors could be explained by the following factors :. (a) Differences in the technique of irradiation. (h) Differences in the species, age and size of the animal. (c) Differences in the time between irradiation and histo- logical examination; if the latter is done too early the changes which irradiation induces will not have been completed. (d) Incomplete histological examination. The third factor is of an especial importance. It is impossible to discuss properly the results af irradiation without taking into consideration what may be called the histological dynamics of the ovary. Two fundamental facts must be the starting point in every discussion of this kind; first, that the interstitial cells are less sensitive to X-rays than the follicles, i.e., the ova and the cells of the membrana granulosa (see below, p. 230), and secondly, that the interstitial tissue, if persist- ing, has to be provided from time to time with new cells from the folhcles undergoing atresia. Realising this one will be able to understand that by decreasing the strength of irradiation the following three separate results will be brought about, without the sensitiveness of the ovary having been different. First case. Degeneration of both ova and follicles and inter- stitial tissue, which will be replaced by common connective tissue. Second case. Degeneration of all ova and follicles, while the interstitial tissue is injured only slightly or not at all; but as the interstitial tissue can persist only when provided with new cells by follicles, degeneration of follicles will result after a certain time in a reduction and disappearance of the interstitial tissue. Third case. Injury of the follicles without full degeneration of ova but increased atresia; by this a great number of inter- stitial cells will be provided by the obliterating follicles, and an increase in the interstitial tissue will occur. As Lacassagne stated, the sensitiveness of the follicle seems to be different according to the degree of its development; in view of this factor the reaction of the ovary to X-rays will become still more manifold. Further, it seems clear that there will be also transitions between the cases mentioned above; INTERNAL SECRETION OF OVARY 229 " Case 2" and "Case 3 " could end both with atrophy of the inter- stitial tissue and re-estabhshment of the normal condition of the ovary. Chnical observations make it probable that by :.»iS»iS*i!it"»'& „.ij ^m r*. -t^t^n-S-^iV-tW**^- • %. -T^ B Fig. 105. — Influence of X-rays on sex characters in virginal female guinea pig. — From Steinach and Holzknecht. Normal virginal guinea pig, 4I months old. A. Uterus (before bifurcation), x 9. B. Ovary, x 18. Follicles at different stages of development. therapeutical irradiation some kind of a transition between "Case 2" and "Case 3" is generally brought about ; there is an injury of the folhcles, but evidently not so great and not permanent, as in "Case 2." Paul Werner (1918), who has 230 INTERNAL SECRETIONS examined 376 radiated women, concludes that in young individuals the activity of the ovary is stopped only temporarily, that a complete return to a normal state is possible; this is shown by the fact that, after amenorrhoea, caused by irradia- tion, menstruation almost always reappears after a certain time ; women treated by irradiation can conceive subsequently, and give birth to entirely normal children. In view of these considerations, it is easy to understand that the reaction of the ovary to irradiation is an extraordinarily manifold one. The influence of the strength of irradiation on the mode of reaction of the ovary has been investigated by different authors, and most recently by Steinach and Holzknecht (1916). They stated that by an unique irradiation of a certain strength (about 12 "Holzknecht-units") an obhteration of the follicles and an increase of interstitial cells can be obtained in guinea pigs {Figs. 105 B and 106 B). By an unique irradiation of a greater strength both folhcles and interstitial tissue can be destroyed. Even by merely changing the position of the animal, for instance, by irradiating the ventral instead of the dorsal side, the same strength will cause destruction of interstitial tissue instead of hypertrophy. We see that only those experiments can be compared with one another where exact doses of X-rays have been given, and where all the other conditions of the experiment have been the same. As long as quantitative relations are not duly considered, there can be no possibihty of any agreement between different authors con- cerning the influence of X-rays on the ovary; the position is the same here as with any other stimulus known to the physiologist. Bouin, Ancel and Villemin (1906-1907), working on the rabbit, were the first to show that an obhteration of the follicles can be caused by X-rays, the interstitial cells remaining intact. Houssy and Wallart (1915) showed that an increase of the interstitial tissue may take place in the ovary of man when irradiated on account of uterine myoma. Similar observations were made by Hewer (1915, P- 444) on white rats, and by Aschner (1918, p. 45) on the dog. In view of these observations there can be no doubt that by the employment of regulated doses an atresia of a very large number of folhcles and a great increase of interstitial cells can be obtained. INTERNAL SECRETION OF OVARY 231 What will be now the condition of the organism in such circumstances ? This question was examined by Bouin, Ancel and Villemin. They irradiated rabbits several times; two to four weeks after the last irradiation the animals were killed. They describe a marked atrophy on the part of the uterus and the tubes, the vagina, and the clitoris, as well as the mammary glands. No corpora lutea were present in the ovaries, an almost complete atresia of the follicles took place, whereas the interstitial tissue persisted. The authors concluded from these experiments that an atrophy of the genital organs can be checked only by the corpus luteum, and that there was no participation of the interstitial tissue in the endocrine function of the ovary.^ [Later on the authors came to another con- clusion; seep. 259.] We shall show in the following sections of this chapter that this conclusion was erroneous, and it may be pointed out here that puberal development of the uterus in the rabbit can take place before any corpus luteum has developed in the ovary. Indeed, Bouin seems to have been one of the first to call attention to the fact that, before sexual intercourse, there is often no development of a corpus luteum in the ovary. In a virgin rabbit of about 18 months old we found no corpus luteum in the ovary; nevertheless, the uterus was normal. That the conclusion of the French authors in regard to the exclusive dependence of the sexual characters on the corpus luteum is not justified, is shown especially by the experiments of Steinach and Holzknecht. They irradiated guinea pigs two to four weeks old, exposing the back once to about 12 " Holz- knecht-units." As already mentioned, by exposing the ventral side to X-rays, a complete destruction of both follicles and interstitial tissue took place ; the animals showed signs of castration effects. On the contrary, the animals irradiated on the back showed about eight weeks after the irradiation a marked increase in the nipples. The area surrounding the nipple was rounded and shiny; mammary glands could be felt. Even milk secretion was observed for two or three weeks. The microscopical examination of the mammary gland of such an irradiated virgin animal revealed a condition similar to that ^An atrophy of the cHtoris after castration is not very probable. In castrated rabbits I never could find macroscopically any changes in the region of the clitoris. 232 INTERNAL SECRETIONS A B ^'''' jTmk;'^SZT4 ^^Z^V" 't''^'^'' - '"Sinai A. Uterus, x 9. Highly developed. ^- Ovary, x 25. Atresia of most of the folHcles. INTERNAL SECRETION OF OVARY 233 of a pregnant female ; there was a compact gland, rich in blood vessels; the epithelium was full of fat droplets. Also the uterus was in a condition characteristic of pregnancy {Figs. 105 A and 106 A). The ovaries were found about three months after irradiation to be smaller than normally; a great many folHcles were atretic, and the number of the interstitial cells was extraordinarily increased. Steinach and Holzknecht mention that the whole stroma of the ovary was transformed into a mass of lutein cells. It seems justifiable to conclude from these experiments that the marked development of the mammary gland and of the uterus was caused by an increase of the interstitial tissue derived from the follicles. Such a conclusion seems especially true when comparing these results with those observed in animals where irradiation caused destruction and sclerotization of the whole ovary and at the same time signs of castration. A similar observation was made before by Biedl (2nd ed., p. 337) on the uterus of the rabbit. He stated that sclerotization of the ovary after irradiation is accompanied by an atrophy of the uterus. There is no room for the objection that the highest degree of development which can be attained by the mammary gland and the uterus after irradiation is caused by a direct action of X-rays on these organs, since Steinach and Holzknecht made another experiment in which the ovaries were removed after a great development of the mammary gland had occurred after irradiation; they then observed an atrophy of the mammary gland. From all these experiments it is possible to conclude that from the foUicles endocrine cells are, so to speak, poured into the stroma in an increased number, and that consequently the influence of the ovary upon the mammary gland and uterus becomes greater. Steinach speaks of such an irradiated ovary as an isolated endocrine gland; there is in reality no isolation, as ova are still to be found in such an ovary. But this objection does not matter; for in order to reach the above conclusion it is not necessary to suppose that all the ova or folhcles throughout the whole ovary must have disappeared. The conclusion is justified, as it was shown that greater folhcular atresia, and consequently an increased number of interstitial cells, bring about a greater development of the mammary gland and of the uterus, and that this development 234 INTERNAL SECRETIONS does not take place if an atrophy of the epithelioid cells of the stroma was also caused by irradiation. The experiments of Steinach and Holzknecht have not yet been repeated\ but it is desirable that they should be, in view of the theoretical and practical interest involved in the questions. Above all, it is desirable that we should be in a position to explain the different results in the experiments of the French and Viennese authors. It may be also that in the experiments of the former the possibihty of "Case 3" of our scheme was reahsed, but that the French authors interrupted their ex- periments before an hypertrophy of the interstitial tissue could take place. Furthermore, it is possible that at the beginning an injury to the interstitial tissue took place (transi- tion from "Case 2" to "Case 3" in our scheme). As Steinach and Holzknecht pointed out, the first external results of the irradiation became visible about three to four weeks later, and the highest degree in the development of the nipples was observed only eight weeks after irradiation. Steinach and Holzknecht possibly would have arrived at a negative result hke Bouin, Ancel and Villemin, if they had interrupted their experiments sooner ; and possibly the French authors would have attained a positive result if they had con- tinued their experiments longer. Moreover, the technical points we discussed above must be taken into consideration. New experiments with X-rays were recently made by Guggisberg (1922) with the special purpose of elucidating the question as to which part of the ovary performs the endocrine function. Guggisberg's criticism directed against our view is, in reality, in opposition to suggestions which neither Steinach nor myself ever made. He concludes from his experiments that the follicles act as an endocrine organ, a supposition the possibility of which we have never denied. Guggisberg first stated that with rabbits castration leads to an increased sensibility to adrenaline; about a month after ^ Since this was written Rahel Plant (1923) communicated similar experi- ments. The statements of Steinach and Holzknecht were fully confirmed as to the changes in the uterus and the mammary gland occurring after irra- diation. There was no hypertrophy of the uterus and of the mammary gland when castration was previously performed. But according to Plaut the hypertrophy of the mammary gland failed to occur also in the case when only the uterus was previously removed. She assumes that the ovary acts on the mammary glands through the intermediation of the uterine mucosa. But this conclusion is in contradiction to what we know from the feminized male guinea pig. See Chapter VI. INTERNAL SECRETION OF OVARY 235 castration he found a transitory giycaemia to take place when quantities of adrenaline, which were too small to cause giycaemia in normal rabbits, w^ere injected. Then Guggisberg examined rabbits treated by X-rays to ascertain their sensibility to adrenaline, and found a similar increase to that after castration. There was also an accumulation of fat, whereas there was no atrophy of the uterus. The histological examination revealed, about two months after irradiation, a pronounced injury to the follicles, but no change in the interstitial tissue. On considering the increased sensibility to adrenaline as a sign of castration caused by a lack of an internal ovarian secretion, Guggisberg concluded that the interstitial tissue does not participate in the endocrine function of the ovary, only the follicles being the true endocrine organ. This conclusion is without justification. The fact that no signs of castration were visible in the uterus, which is so sensitive to the ovarian hormone, makes it highly probable that the irradiated ovaries in the experiments of Guggisberg were still performing their endocrine function. It may be that the quantitative level of the endocrine activity was lowered, and by this circumstance the disturbance could be explained. But it is by no means certain that the increased sensibility to adrenaline or the accumulation of fat should be considered as caused by a dis- turbed production of sexual hormones. On the contrary, it is possible to regard the accumulation of fat as correlated with reduced activity in the generative part of the gonad. (See the statements of Hey mans, Chapter II.). 4. Transplantation of the Ovary. Like the testicle, the ovary undergoes profound changes after transplantation. Ribbert (i8g8) was the first to make detailed observations concerning these changes in the ovarian graft. After autotransplantation in the rabbit the greater follicles and the corpora lutea undergo degeneration; "repara- tion" takes place by follicular development of the smaller follicles which remained hitherto intact. Similar observations were made by many other authors. The experiments of Marshall and Jolly may be especiall}^ mentioned. According to them {Marshall and Jolly, 1910, p. 324) all the follicles may finally undergo atresia in the ovarian graft in the rat (auto- transplantation and homoiotransplantation). In some cases 236 INTERNAL SECRETIONS the graft consisted almost entirely of lutein cells. They stated also (1907) that in the rat the transplanted ovary can undergo cychcal changes hke the normal ovary. They found in the graft at the commencement of the breeding season large follicles, afterwards also corpora lutea. Evidently ovulation can take place in the transplanted ovary. According to all authors who have made histological observations on the ovarian graft, the difference between a normal ovary and an ovarian i Fig. 107. — Section through ovary engrafted six months previously into a castrated male, x 25. Increased follicular atresia. — From Steinach. graft seems to be merely that there is an accelerated atresia of those follicles which have already attained a certain size at the time when transplantation was performed. There is possibly also an accelerated atresia afterwards. By this a predominance or an hypertrophy of interstitial tissue consisting of epithelioid, or lutein cells, is caused. Several authors have made histological observations also on the condition of the ovarian graft in a normal or castrated male. W. Schultz (1900) was the first to show that an ovarian graft can "take" in a male organism, even when the latter has INTERNAL SECRETION OF OVARY 237 not been previously castrated. According to him the con- dition of an ovarian graft in the male is not different from that in the female (19 10). A large number of observations on ovarian grafts have been made with the special purpose of investigating the bearing of the ovar}^ on the production of sexual hormones. Steinach (1912) transplanted into young castrated male rats and guinea pigs immature ovaries without ripened follicles, and observed all the changes characteristic of the normal ovary up to forma- tion of corpora lutea. This condition lasted only a few months ; Fig. 108. — Section through ovary engrafted a year previously on a castrated male, x 25. Mostly follicles undergoing atresia. — From Steinach. the older the graft, the smaller was the number of the follicles attaining ripeness. There is finally, according to Steinach, an atresia of almost all follicles in the ovarian graft (Figs. 107, 108.) By this a marked hypertrophy of the interstitial tissue is caused, the cells of the granulosa being transformed into cells from which all transitions to lutein cells are to be seen. vSimilar experiments were made hy Athias (1915, 1916 a, 1916 b). He found even eight and a half months after trans- plantation, besides atretic follicles, a great number of primary follicles. The ovaries transplanted by Athias were taken from adult animals, whereas those of Steinach were, from young ones ; it may be that the condition of the ovarian graft depends 238 INTERNAL SECRETIONS also upon the age of the ovary at the time of transplantation. In accordance with Steinach, Athias points out that the number of the atretic follicles is very great in the ovarian graft, and that the theca interna is highly hypertrophied. The richly vascularized stroma is full of nests of interstitial cells. Lately Athias (1922) has given a full account of his histological work on ovarian grafts; he insists especially on the tendency of the graft to undergo cystic degeneration. According to Moore (1921 a) corpora lutea do not develop when the ovary is en- grafted into a male which has not been previously castrated. It seems evident that the time at which the more or less complete transformation of follicles into interstitial tissue will have occurred, must differ from case to case. For instance Marshall and Jolly found once in autotransplantation a normal condition of the ovary fourteen months after the operation; in a case of homoiotransplantation the ovary was still normal six months after the the operation. (In both cases the ovary was implanted into the kidney). If now we compare these statements, which are only instances of what was seen by several other observers after autotransplantation and homoio- transplantation of the ovary, with the statements of Steinach and Athias concerning the condition of the ovary engrafted into the male, it seems that the results are different according to the sex of the animal into which the ovary was engrafted. The difference is indeed mainly a quantitative one. The follicles of an ovarian graft in a castrated male are possibly less able to attain ripeness and to form corpora lutea; follicular atresia is probably augmented in such grafts, and conse- quently an hypertrophy of the interstitial tissue must finally take place. A detailed study of this special question was made by Sand (1918, pp. 121 -51) in a very great number of experiments on rats and guinea pigs. On examining the grafts about six months or less after the operation he confirmed the fact that the follicles can ripen in the ovarian graft; in the majority of his experiments Sand also found corpora lutea. In regard to the comparative condition of the graft in castrated females and castrated males, Sand states that there is in the latter a tendency to an intensified follicular atresia, and to an increase of interstitial cells derived from the theca intema; he concludes that the follicles are in the male really less able to ripen and to form corpora lutea. We do not yet understand INTERNAL SECRETION OF OVARY 239 the precise factors whereby the variation in the ovarian graft according to the sex of the host into which it is transplanted can be explained. The above statements in regard to the condition of the ovarian graft have an especial bearing upon the question as to the cells involved in the endocrine functions of the ovary. We have already learned that signs of castration are absent if the implanted ovary " takes." Now Marshall and Jolly stated that signs of castration are absent also, if an atresia of all the follicles has taken place. Bell (1920, p. 47) implanted in the rabbit only the central part of the ovary, which contains no follicles, and is composed entirely of interstitial cells (as shown in serial sections of the graft); twenty-four days afterwards there was no atrophy of the uterus. From all these observations one must conclude that the epithelial and epithelioid interstitial cells of which such a graft is composed are able to perform the internal secretory functions ascribed to the ovary. But the objection may be made that not- withstanding the highly augmented follicular atresia and notwithstanding the transformation of a very great number of follicles into interstitial cells, ova were still present in the grafts, and that these elements might have produced the internal secretion. This is the same objection that we had to deal with before, when discussing in the preceding section the experiments in which a more or less complete atresia of the folHcles was obtained by means of X-rays. Such an objection was made b^^ Bucura (1913, p. 1839). But it was shown experimentally that this objection is not justified, although the fact remains true that ova and young follicles may be present in the transplanted ovary. We have referred to the experiments of Steinach (19 16) where the ovarian grafts were made into castrated males. These grafts were able to feminize the male, in which an hypertrophy of the mammary gland and milk secretion were observed. Steinach's statements were confirmed by Athias (1915, 1916 a, 1916 b), Sand (1918), and Moore (1921 b) and by myself and my co-workers. We must conclude that the great development of the mammary gland was caused by the fact that in the ovarian graft an intensified follicular atresia and an intensified formation of interstitial cells took place. The hypertrophied tissue then gave rise to an increase of 240 INTERNAL SECRETIONS female sex hormones. In view of these considerations, it seems justifiable to assume that the folhcles undergoing atresia, and the cells derived from the latter, represent in the ovary a gland with an internal secretion. One might object that this may be true only for the species on which Fig. 109. — Disappearance oj primary ova in highly hyper- trophied minute ovarian fragments. x 200. A. Normal ovary of rabbit 18 months old (Prot. Nr. 50). the above-mentioned experiments were made, and for those species where there is an interstitial tissue in the ovary like that in the rabbit: But we have seen that no essential differ- ence exists between the follicle undergoing atresia and the interstitial tissue like that of the ovary of the rabbit. INTERNAL SECRETION OF OVARY 241 Severe criticism has been directed against the conckisions of Steinach and Holzknecht, and it has been pointed out that in the ovarian graft oocytes and small normal follicles are present. But as I desire to emphasize again, this does not matter. •..-•t * >:•» .s' .""f- • v^-' '■•■-J-/-- '■■ ' ^♦•f». ..,^.V!J« CX) -? Fig. log.^Disappearance of primary ova m highly hyper- trophied minute ovarian fragments, x 200. ^ . B Ovarian fragment of animal of same Utter (Prot. JNr. 52). Thick capsule of connective tissue. No primary ova to be seen in the section. For details see the text. The point is, that there is in the ovarian graft an acceleratep folhcular development and, as a result of this, an hypertrophy of the interstitial tissue ; there is at the same time an intensified hormonic effect (development of the mammary gland). Then 242 INTERNAL SECRETIONS we must assume that the ovarian change referred to, the intensified production of lutein cells or of interstitial cells, is the cause of the greater hormonic effect, or the cause of an intensified production of sexual hormones. We have seen above that it is very likely that an hyper- trophy of the interstitial cells takes place both in auto- and homoiotransplantation. If this is true, one might expect to find evidence of an intensified internal secretion also after engrafting an ovary into a castrated female. In the first edition of this book I pointed out that the microscopical figures published by Marshall and Jolly (1907) suggest that the uterus was more developed in the animal with auto- transplantation than in the normal animal; the original coloured figures 5 and 7 on Plate II. of their paper may be referred to here ; but the black and white reproduction shows this clearly enough (Fig. 49). I observed a rabbit on which in- voluntarily an autotransplantation was made, and which gave further support to my suggestion (1922 b). I castrated this animal at an age of about two months. When killed sixteen months later the uterus was found to be even more developed than in one of the normal controls of the same litter. On making a thorough examination of the abdominal cavity, we found two pieces attached to the dorsal peritoneum and resembling ovarian tissue although no Graafian follicles were visible. The microscopical examination showed that the pieces were really ovarian fragments which evidently under- went an enormous hypertrophy and very profound alterations. Although the weight of the tw^o pieces together was about that of one normal ovary of the normal control, only a few young ova were present in these fragments (Fig. 109 B) ; their number may be estimated at a small percentage of the normal number of ova (Fig. 109 A.) FoUicles at different stages of ripeness were present, but hardly any distended Graafian follicles; this indicates that there was an accelerated follicular atresia in the ovarian fragments. The follicles were embedded in the mass of interstitial cells in such a manner that they repre- sented more or less the central part and the interstitial tissue the cortical part of the fragment. The whole fragment was covered by a thick capsule of connective tissue. The lack of young ova in these ovarian fragments is to be explained by the fact that most of them had entered upon folhcular INTERNAL SECRETION OF OVARY 243 development, the hypertrophy of an ovarian fragment being nothing else than the follicular development of a relatively greater but absolutely normal number of ova (Lipschutz, 1922 a, b, c). My observation gives strong support to the assumption that the cells derived from the follicle at different stages of development form part of the endocrine apparatus of the ovary whereas the oocytes themselves are not involved in the endocrine function. Recently Haberlandt (1921, 1922) has performed experiments which give further evidence of the intensified endocrine function of the transplanted ovary. We shall discuss these in another section of this chapter. We still have to deal with the fact that the endocrine function of the ovary is regulated by quantitative laws very different from those valid for the testicle. Whereas it seemed possible to us to accept in accordance with Pezard the validity of the law of "All or Nothing" for the testicle, we see that, for the ovary, increase of endocrine cells causes increase of endocrine function. The cUmax of the latter is attained when the corpus luteum graviditatis is formed. 5. The Condition of the Ovary in Partial Castration. We saw that testicular fragments never hypertrophy in the mammal, but nevertheless are sufficient for performing a normal endocrine function, even when they are extremely small. On the other hand, ovarian fragments hypertrophy to a very considerable extent, as was demonstrated by Bond and Horsley, and Carmichael and Marshall (1908), and confirmed by ourselves (1922). Very small ovarian fragments can attain the volume of a normal ovary. In this respect there is no difference between ovarian fragments in partial castration and the whole ovary after unilateral castration; various authors, and lately Arai and myself, have demon- strated that the remaining ovary doubles its weight. Arai (1920 a, b) has shown that the number of ripening follicles in the remaining ovary is twice as large as in the normal one. This means that the number of ripening follicles present in the body of a given species is constant at a given age. Arai has counted also the total number of ova in the normal and the remaining ovary, and has come to the conclusion that the total number of ova in the latter is the same as in the former. Evidently the hypertrophy of the ovary is to be explained 244 INTERNAL SECRETIONS by the fact that a relatively larger number of ova enters upon follicular development. In our experiments with partial castration of rabbits we were able to demonstrate that this suggestion is justified. In fragments which represented originally a quarter and a half of an ovary (the second ovary having been removed), and which attained the volume of about a normal ovary, we found that the number of young ova was very reduced (Fig. no). Fig. iio.^ — Decrease of number of oocytes in ovarian fragment, x 200. A. Section through ovary of rabbit 7 months old (Prot. Nr. 136). Prepar. of Wagner; photo of KulL In another case which we described in the foregoing section, the number of young ova in the hypertrophied frag- ments was extraordinarily small, representing only about two or four per cent, of the normal On the contrary, the number of ripening follicles and the quantity of interstitial tissue were as large as in a normal ovary. Evidently the majority of young ova had been used up in follicular development. In view of all these observations it seems clear that hyper- trophy of ovarian tissue implies that a relatively larger INTERNAL SECRETION OF OVARY 245 number of ova present in the remaining ovary, or in the ovarian fragment, enters into folhcular development, and that there is no increase in the number of ova. New formation of ova in post-natal hfe may indeed be possible under certain circumstances. Athias (1920) relates having observed such a phenomenon in an engrafted ovary in the guinea pig. Fig. 1 10. — Decrease of number of oocytes in ovarian fragment, x 200. B. Section through ovarian fragment of rabbit of same age as A (Prot. Nr. 134). The fragment represented originally about J to ^ of an ovary, but six months later it had almost the same weight as a normal ovary at this age. A place extremely "rich" in oocytes was chosen in B. The number of oocytes in B is much reduced as compared with A. Prepar. of Wagner; photo of Kull. When comparing the condition of a testicular and an ovarian fragment, two questions arise: — first, how the differ- ence between them can be explained, and secondly, whether the hypertrophy of the ovarian fragment is really a com- pensatory one for endocrine purposes. The first question can be settled, I think, without special difficulty. Since the number of young ova in readiness, so to 246 INTERNAL SECRETIONS speak, for follicular development is very great, there is in an ovarian fragment an almost endless supply available for follicular development or "hypertrophy," unless indeed the fragment is extremely small, as in our last experiment, related above. The case of a testicular fragment seems to be a wholly different one; what takes place in a testicular fragment is only development up to a normal volume corre- sponding to the given fragment of a testicle, since, after completion of spermatogenesis in all the tubules of a fragment, there seems to be no anatomical substratum for further growth. In other words, every cubic millimetre of testicle has a constant maximal potential mass, which is attained when spermatogenesis is completed. On the contrary, a cubic millimetre of ovary has no constant or limited potential mass, the latter depending upon the relative number of ova which enter upon follicular development. It would appear, therefore, that the dynamics of testicular and ovarian growth provide an explanation for the differences as observed in these respects between an ovarian and a testicular fragment. The second question is of a more difficult order. There is normally in the female greater variation in the condition of the sex characters, and no doubt exists that this variation is connected with follicular development in the ovary. The relatively larger number of ova entering in an ovarian frag- ment upon follicular development may be considered as participating in a process of reparation or regeneration. There may be some general factors in the female organism regulating the number of follicles in the ovarian tissue, like the factor regulating in the male organism the speed of testicular growth (Lipschutz, 1923 and 1924 a; Lipschiitz and Voss, 1924 c). We have no knowledge of the special localiza- tion of such hypothetical factors. 6. The Internal Secretion of the Corpus Luteum.^ We have seen that genetically the interstitial cells of the ovary belong mostly to the follicular apparatus, and that these cells are, so to speak, discharged from the atretic follicles into the ovarian stroma. Further, we saw it was very probable that these cells represent an endocrine organ, which can hyper- ^ The new papers of Marshall (1923) and of Corner (1923) and the new edition of Marshall's book (1922) may be referred to here. INTERNAL SECRETION OF OVARY 247 Fig. III. — Section through ovary of pregnant cat (Prot. Nr. 285). Two embryos were found in the left uterus; ovary from the same side. Two corpora lutea and great quantity of Graafian folUcles. The corpora lutea occupy almost the whole ovary. — Prepar. of Wagner; design of Lehbert. 248 INTERNAL SECRETIONS trophy under experimental conditions, and cause an hormonic effect, as normally observed only in gravidity. In view of these results two new questions arise: are there, first, genetical and, secondly, physiological relations between the cells of atretic folHcles or the interstitial cells on the one hand, and the corpus luteum, which characterizes the ovary during gravidity, on the other? (a) Histogenesis of the corpus luteum. The origin of the cells of the corpus luteum graviditatis (Fig. Ill, see also Fig. 98) has been a matter of much dis- cussion. According to most authorities these cells are derived only from the membrana granulosa; others are of the opinion that cells of the theca interna also give rise to cells of the corpus luteum. The first theory implies that the cells of the corpus luteum are of epithehal origin only, whereas, according to the second, cells originating from connective tissue can also become luteal cells. Great importance has been attributed to this question by various authors. If the corpus luteum is formed only from cells of the membrana granulosa, and if the cells of the inter- stitial tissue (to which atretic follicles belong) originate only from the theca interna or from stroma cells, the two formations are genetically different. But, on the other hand, if the cells of the corpus luteum are of a mixed origin, the whole apparatus of epithelioid cells of the ovary might be regarded as genetically one. It seems clear that this conclusion might supply evidence of a functional similarity between the two parts of the ovary. I myself have no experience of this field of enquiry, and it is for the histologist to settle the question as to the origin of the cells of the corpus luteum. Comparative observations on different species play a great role in these discussions. Most observers agree that in lower vertebrates, as in fishes, am- phibians and reptiles, the corpus luteum, when present, is built up out of the epithelial cells of the granulosa (Marshall, 1905). On the contrary, Aschner (1914 a, 1918) pointed out that in some species the ovum is surrounded only by a simple layer of cells belonging to the granulosa, and that cells of the theca take an important part in the building up of the corpus luteum. But this is not true for all lower vertebrates, an hypertrophy of the cells of the granulosa having been observed by INTERNAL SECRETION OF OVARY 249 Mingazzini in reptiles, and by Giacomini in birds, amphibians and fishes. The condition also seems to vary in the different species of fishes (Wallace), some presenting hypertrophy of the foUicular epithelium and others not. Van der Stricht made observations on the bat and concluded that here the corpus luteum is of a mixed origin. Bell (1920) holds that the corpus luteum is formed entirely of cells of the theca interna. On the contrary Fraenkel (1914, p. 20) defends the view that the corpus luteum is formed only by cells of the membrana granulosa, in accordance with Sobotta for the rabbit and mouse, with Franz Cohn for the rabbit, and with Rob. Meyer and others for man. Marshall (1901 and 1903, quoted from Marshall, 1905) has demonstrated this for the sheep, and Zietschmann (1921) for the cow. As regards birds, amphibians, reptiles and fishes, Fraenkel declares that no corpus luteum exists in these species at all, and that even in the monotremes and marsupials the corpus luteum is only rudimentary. According to Hill and O'Donoghue the corpus luteum is present in the monotremes, and certainly in the marsupials. The contradictory statements of the above-mentioned authors as to this question are evidently caused by the fact that there is in reality no sharp line of demarcation between the atretic follicle and the corpus luteum, just as there is no sharp distinction to be drawn between the atretic follicle and the interstitial tissue. Aschner insists that there is something approaching an identity between the atretic follicle and the corpus luteum in lower vertebrates. The former is often spoken of as the so-called "corpus luteum atreticum" in some mam- mals, i.e., in the case of atretic follicles closely resembling real corpora lutea. Even Fraenkel admits that sometimes the atretic follicle is formed by cells both of the membrana granu- losa and theca interna intermingled with each other, although in general, according to him, only the cells of the theca interna form the atretic folHcle. Various authors (Volker, Winiwarter Sainmont and recently Gerlinger, 1923 a) have called atten- tion to the so-called "partial" corpus luteum, being a follicle which has not ruptured, but is undergoing atresia and producing lutein cells derived from the granulosa only in a Hmited zone of the wall. Many authors have insisted on the great resemblance be- tween the cells of the atretic foUicle (the theca-lutein cells 250 INTERNAL SECRETIONS of Seitz) and the lutein cells of the real corpus luteum. On the other hand, some authors, as Winiwarter and Sainmont, hold that the atretic follicle, like the corpus luteum is com- posed only of cells of the granulosa. But if the assumption of Lane-Claypon quoted from Marshall, 1905), of Ochoterena and Ramirez (1920) and of Goormaghtigh (1921) as to the origin of the interstitial cells and of the cells of the folHcular wall from the germinal epithelium is true, all these controversies lose their importance. Speaking generally, the process of formation of a corpus luteum seems to be as follows. The epithelial cells of the membrana granulosa become hypertrophied ; there is also probably a proliferation of these cells. The follicular membrane between the membrana granulosa and the theca interna ruptures; both cells intermingle, if the origin of the corpus luteum is a mixed one, as possibly is the case in some species, since the epithelioid cells of the theca interna often resemble the cells of the granulosa to such a degree as to be indistinguish- able from one another. Connective tissue with blood vessels grows into the mass of epithelioid cells, and the whole structure becomes vascularized in such a manner that every cell seems now to be in direct communication with a blood vessel. Fatty inclusions appear in the cells; these inclusions are sometimes of a yellow colour — the so-called lutein. In the ovary of man or of the horse the corpus luteum may occupy half of the ovary, in the cow much more. The corpus luteum persists only for a certain time, undergoing afterwards sclerotization or hyaline degeneration; it may be that in some species, as in the rabbit, the corpus luteum becomes converted into interstitial tissue. No essential difference exists between the corpus luteum graviditatis and the corpus luteum menstruationis ; the difference is only that in pregnancy the corpus luteum persists for a longer time. We mentioned that there are in the mammal transitions between the atretic follicle and the corpus luteum. In the preceding sections we pointed out that there are transitions between the interstitial tissue, like that in the ovary of the rabbit, and the masses of epithelioid cells of the theca interna remaining in the wall of an atretic follicle. I think it is clear enough that there is a close histological and genetic relation- ship between all the epithelioid cells in the ovary, between the INTERNAL SECRETION OF OVARY 251 interstitial cells, the cells of the atretic follicle and those of the corpus luteum. In view of this close relationship it is easy to understand why there are so many terms for the derivatives of the folhcle in the ovary of the mammal and why so many contrary opinions have been held as to the origin of the corpus luteum. It would seem that the first of the questions put at the beginning of this section may be settled in a positive sense. The second question, dealing with the physiological relationships between the interstitial tissue and the corpus luteum, will be discussed in the following section. (b) The functional relationship between the corpus luteum and the interstitial tissue. Different authors, such as Beard, Prenant, and Born, have emphasized that the corpus luteum is a gland with an internal secretion, that the corpus luteum causes by its hormonic action the cyclical uterine changes of menstruation, and the changes which the uterus undergoes in pregnancy. A glance at a microscopical section of the corpus luteum shows that the closest relations between epithelioid cells and blood vessels are present, just as in the liver. And we can fully agree with Fraenkel (1910) that there could, indeed, be no better example to show to the beginner to illustrate the structure of a gland with an internal secretion than the corpus luteum {Fig. 112; see also Fig. 94 a), where each cell is in direct relation with a blood vessel, and for the most part surrounded by blood vessels on every side. Fraenkel (1903) showed that pregnancy can be brought to an end in the rabbit, if the corpora lutea are destroyed by cauterization during the first six days after conception ; a result like that obtained by castration. Fraenkel performed 163 of these experiments, and always with the same result. Further, Fraenkel (1903, p. 480) demonstrated that the next menstruation can be prevented in man by cauteriza- tion of a fresh corpus luteum; Fraenkel made this experiment several times when performing abdominal operations, and he pointed out that such a cauterization is not only without any danger, but may be positively useful, as convalescence is furthered if not interfered with by menstruation too soon. Fraenkel concluded (1903, p. 480) from his experiments that the corpus luteum has in all mammals the same glandular 252 INTERNAL SECRETIONS functions after whatever intervals it reappears ; the function of the corpus luteum is to prevent the return of the uterus to an infantile state or to prevent climacteric atrophy of the uterus, and, further, to render possible the transformations in the uterine mucosa necessary for the fixation and growth of a fertihzed ovum. If fertilization has really taken place, the corpus luteum remains functional for a further period, assisting in the uterine transformation and in the development of the Fig. 112. — Section through fresh corpus luteum of rabbit (Prot. Nr. 104). X 40. The c.l. protruding out of the surface of the ovary. — Prepar. of Wagner; photo of KuU. ovum. If fertilization does not take place, menstruation sets in, and the corpus luteum enters into regression. The experiments of Fraenkel were controlled and confirmed by several authors; the question was studied especially by L. Loeh (1910, 1917, 1918) and Bouin and Ancel (1910, 1911). L. Loeb has shown in numerous experiments that the produc- tion of a deciduoma or a maternal placenta in the absence of a fertilized ovum can be evoked, if a few days after spontaneous ovulation incisions are made in the uterine mucosa. If the ovaries or the corpora lutea are extirpated, the deciduoma is not produced INTERNAL SECRETION OF OVARY 253 In the rabbit there is generally no spontaneous periodical ovulation such as is observed in various other mammals (according to Bouin and Ancel in the dog, horse, pig and cow, in monkeys, and in man). But ovulation takes place in the rabbit after coition or sexual excitement. Now, Bouin and Ancel caused an artificial rupture of Graafian follicles in virgin rabbits by puncturing the ripe follicles. They also arranged for coition with males in which several months previously the vasa deferentia had been ligatured; in these experiments ovulation took place without pregnancy following. Ancel and Bouin stated that in these animals a growth of the uterus and the mammary glands occurred such as is normally observable at the beginning of pregnancy {Fig. 113). The mam- mary gland remained in this state of hypertrophy for about two weeks; the climax of the uterine development was attained in about ten days. Afterwards both organs began to decrease, and in about 25 days passed back to their original state. There is for a certain time a state of pseudo-pregnancy , to use an expression of Hammond and Marshall. The examination of the ovaries showed that after the artificial rupture of two or three ripe follicles, these cease to develop, but other ripe follicles of the same or the second ovary transform themselves into corpora lutea. If all ripe follicles are punctured or destroyed by cauterization, there is no formation of corpora lutea. In the latter case no changes occur in the uterus or in the mammary gland. There is a formation of corpora lutea also after sterile coition with a ligatured male. If the corpora lutea formed are destroyed, the characteristic changes undergo rapid reversal. Niskoubina, a pupil of Bouin, showed that these experimentally produced corpora lutea resemble, in their appearance and in their duration, normal corpora lutea as present in the first half of pregnancy. As Bouin and Ancel point out, there is also a striking time relation between the development of the experi- mentally produced corpus luteum and the changes which the uterus and the mammary gland undergo ; the regression of the corpus luteum begins about two weeks after puncture or sterile coition, i.e., at the same time as regression of the uterus and the mammary gland sets in. From all these experiments Bouin and Ancel concluded that the characteristic changes which take place in the uterus and in the mammary gland in the beginning of pregnancy are caused by the corpus luteum. The 254 INTERNAL SECRETIONS the mammary gland of the rabbit. Two mammary glands of a normal rabbit during heat. PiQ^ 113^ — Influence of the corpus luteum — From Ancel and Bouin. A. B. Virginal rabbit 5 days after a sterile coition. highly developed glands. C. Virginal rabbit about 5 days after punction of ripe follicles Confluence of both INTERNAL SECRETION OF OVARY 255 placenta and the foetus are evidently not necessary for the occurrence of these changes. The conclusions of Bouin and Ancel are in accordance with those of Fraenkel. Hammond and Marshall (19 14) confirmed Ancel and Bouin's description of the uterine changes occurring under luteal influence in the rabbit. It is not intended here to give a full account of all the con- troversies concerning the question as to the endocrine function of the corpus luteum. This organ is, indeed, not the only factor involved in the uterine changes in pregnancy, as is shown by the above-mentioned experiments of L. Loeb, in which deciduomata were experimentally produced at the time of "heat" by mechanical stimulation of the uterine mucosa. On the other hand, Loeb showed it to be probable that the longer persistence of the corpus luteum is due to the presence of the maternal placenta. He stated that after degeneration of the experimentally produced deciduomata ovulation again occurred, i.e., the corpus luteum which hitherto inhibited ovulation now ceased to do this. Possibly the embryo con- tributes towards the preservation of the decidua, and the decidua to the persistence of the corpus luteum, which in its turn inhibits a new ovulation and assists in the further develop- ment of the decidua. The observations of Biedl, Peters and Hofstdtter (1921), who, like Heape, implanted fertilized ova into the uteri of non-pregnant rabbits, give some experimental evidence for such an assumption. These observers stated that the implanted ova can undergo further development for some time in the foster-mother. They state further that they some- times observed changes in older corpora lutea in the ovary of the uterine foster-mother, and these ma}^ be considered as of the nature of a process of reactivation. The question needs more detailed investigation before a complete solution can be reached. In a preceding section of this chapter we have seen that an intensified follicular atresia, as caused by X-rays or by trans- plantation into the male, and as augmenting the quantity of the epithelioid interstitial cells in the ovary, is followed by changes in the uterus and the mammary gland such as are characteristic of pregnancy; in these latter experiments the changes were even more pronounced than in those of Bouin and Ancel. An hypertrophy of the mammary gland and milk secretion can evidently take place without real corpora lutea having been 256 INTERNAL SECRETIONS formed. After all it seems clear that the hormonic function accomplished by the corpus luteum can be performed also by different kinds of follicles becoming atretic, by epithelioid interstitial cells passing from the latter into the stroma. A similar statement was made by Sand (1919, pp. 141 and 175) as a result of experiments upon ovarian transplantation. As to the hormonic effect, there is no essential difference between the cells of follicles undergoing atresia and the cells in process of being changed into those of corpora lutea. The corpus luteum graviditatis seems to represent merely a new and plentiful supply of very active endocrine cells resembling all the other epithelioid interstitial cells of the ovary. We see that the second question we have set ourselves must be answered also in a positive sense. There is evidently a close functional relationship between the interstitial cells and the corpus luteum. We must assume that, as to the hormonic function, they differ from one another only quantitatively. There are many other proofs of this contention. It is known that the number of atretic follicles in the human ovary is much increased in pregnancy. All authorities have made similar statements, although they disagree very much as to the interstitial tissue in the ovary; the latter disagreement is evidently due, as already mentioned, rather to a difference in terminology than to conflicting observations. Now it is of great interest to note that, according to Aschner, the increase in follicular atresia in the human ovary takes place in the second half of gravidity, i.e., when the corpus luteum has already undergone degeneration. If this statement of Aschner is true, one might agree with Biedl (p. 337) that evidently the interstitial cells derived from the atretic folhcles take up the function of the lutein cells of the corpus luteum after degenera- tion of the latter; possibly lutein cells of the theca interna take up the function of the lutein cells of the granulosa. A further proof of the above thesis seems to be given by the observation of Aschner that the interstitial tissue is more developed in those species where the number of young in the litter is greater. The view taken by Aschner is worth further comparative investigation. (See the statement of Athias on p. 217.) The observations made by Athias (1921) on the motility of the uterus are also a proof that the corpus luteum is not the only organ concerned in hormone-production. Athias stated INTERNAL SECRETION OF OVARY 257 that the spontaneous movements of the uterus, which, as he showed experimentally, depend on the sexual hormones, appear in the guinea pig at an age of one month, and attain their maximal height at an age of about two months. Now the first ovulation takes place long afterwards. Athias suggests that the chromatolytic processes going on in the granulosa of the follicle during atresia (Salazar, 1919), and resembling secretory processes very closely, are a source of sexual hormones. Pro- duction of hormones is evidently possible only when a certain degree of development is attained by the follicle and the inter- stitial cells ; this is shown by the following observation of Athias. The ovary of the guinea pig, according to Athias, already con- tains interstitial cells and normal follicles in the first month; since uterine movements are absent, it seems clear that at this stage follicles and interstitial cells are not capable of furnishing the hormones acting on the uterus. Interesting experiments on the question of functional relationship between the corpus luteum and the interstitial tissue have been performed lately by Haberlandt (1921, 1922). It has long been known that ovulation is inhibited by the corpus luteum. L. Loeb (1910, 1918) showed that in the guinea pig extirpation of the corpora lutea in the first week after ovulation hastens the next ovulation. By extirpation of the corpora lutea an ovulation can be experimentally produced even in pregnancy, whereas there is normally, in the guinea pig, an atresia of all but the smallest follicles. These experiments show that the persistence of corpora lutea, not pregnancy itself, is what prevents ovulation. Ovulation can be experimentally inhibited by injection of an extract of corpus luteum, as shown by the experiments of Pearl and Surface (1914) on fowls, and Herrmann and Stein (1916) on rabbits and rats. Now Haberlandt engrafted subcutaneously into rabbits which previously had given birth to young the ovaries from pregnant animals ; the normal ovaries remained untouched. One to four weeks after the operation the animals were put with males. Whereas normally fertilization takes place after two or three coitions, the experimental animals remained sterile for one and a half to three months, or after 14 to 21 coitions. Similar results were obtained with guinea pigs. The histological examination of the grafts revealed that no corpora lutea were present, but there was a small number of atretic follicles and 258 INTERNAL SECRETIONS a highly developed typical interstitial tissue. Since ovulation in the normal ovary was inhibited without corpora lutea being present in the graft, one must assume that the atretic folhcles or the interstitial tissue produced hormones similar to those of the corpus luteum, and thus suppressed ovulation. We have hitherto compared the interstitial tissue with the corpus luteum of pregnancy only. But the experiments of Fraenkel show that menstruation also depends upon the corpus luteum. Is there a similar functional relationship between the interstitial cells and the corpus luteum menstruationis ? As already mentioned, the number of atretic follicles which constitute, in the human ovary, an organ homologous with the interstitial tissue of other animals, according to Aschner decreases in man gradually until puberty, when the first corpus luteum menstruationis appears. So one might suppose that the first corpus luteum menstruationis takes over the function of the atretic follicles in the same manner as the latter take over the functions of the degenerating corpus luteum gravidi- tatis in the second half of pregnancy. But the statements of the different observers as to the quantity of interstitial cells, in the broader sense of the term, in the human ovary at different times are very conflicting. Aschner thinks that just as the corpus luteum menstruationis replaces functionally the interstitial tissue of the human ovary, so the corpus luteum appearing at the time of heat in the ovary of the lower mammals also replaces interstitial cells to a certain degree in respect of hormonic function. Bouin and Ancel (1909) have discussed fully the question of functional relationship between the interstitial tissue and the corpus luteum menstruationis, or, to be more accurate, the periodic corpora lutea. They assumed that in those species where there is a spontaneous ovulation, as in man, monkeys, dog, horse, pig and cow, and where there is no interstitial tissue, in the sense of a parenchyma of epithelioid cells, but only nests of epithelioid cells in the form of atretic follicles, the periodic corpora lutea represent a physiological equivalent of the interstitial tissue. On the contrary, the interstitial tissue is well developed in those species where, according to Bouin and Ancel, no spontaneous ovulation occurs, as in the rabbit, guinea pig and cat. Here no periodical formation of new epithelioid cells takes place, and here the function of the latter INTERNAL SECRETION OF OVARY 259 is performed by the interstitial tissue in the restricted sense of the term. The authors pointed out that the interstitial tissue and the periodic corpus luteum are both derived from follicles, and both consist of similar cells, and that in species with spontaneous ovulation the first periodic corpus luteum appears at the time of puberty, at which time in species without spontaneous ovulation the interstitial tissue just attains full development. Bouin and Ancel hold the opinion that the interstitial tissue and the periodic corpus luteum are responsible for the development of the female sexual characters in the same kind of way as is effected in the male by the interstitial cells of the testicle ; but they think that the corpus luteum graviditatis is functionally different from the interstitial tissue or the periodic corpora lutea. Objections may be made to some of the details in the classification of Bouin and Ancel. A spontaneous ovulation may occur in the rabbit and in the guinea pig. This was already known to Bouin and Ancel. I have convinced myself that real corpora lutea may occur also in virgin rabbits even at an age of about seven months;^ but in other cases, indeed, I could not detect real corpora lutea in the ovaries of virgin rabbits even 12 to 20 months old. Corpora lutea in virgin guinea pigs are described by Aschner (1914 b, p. 459). Corpora lutea have been found several times by various observers also in engrafted ovaries of guinea pigs and rats. There is also no sharp distinction between the real corpus luteum and the atretic follicle. It must be borne in mind further that in those species where a compact interstitial tissue is absent, atretic folhcles are present in the ovary, and that there is no essential difference between these two formations (see also p. 227). This is why I proposed in the first edition of this book to alter the classification of Bouin and Ancel in the following manner: first, species in which periodic corpora lutea are not always formed and there is a well developed interstitial tissue, and, secondly, those with periodic corpora lutea and less developed interstitial tissue. In species where the periodic corpora lutea play a smaller role, the compact interstitial tissue acts as a compensa- tory organ. Notwithstanding the objections which have been 1 Dr. Hammond has drawn my attention to the possibility of this being caused by the sexual intercourse between females as often observed. Then the corpus luteum of the virgin rabbit is to be explained on similar Hues to those in the experiments of Bouin and Ancel. 26o INTERNAL SECRETIONS raised to some details, it must be acknowledged that the classification of Bouin and Ancel marked an extremely import- ant step in the development of the theory of the hormonic action of the ovary, as this classification implies that there is no essential functional difference between the foUicles undergoing atresia or the interstitial tissue on the one hand, and the periodic corpus luteum on the other. Both furnish endocrine cells, and they can functionally replace one another. The objections which may be made against the assumption of Bouin and Ancel that the corpus luteum graviditatis is functionally wholly different from the interstitial tissue or from the periodic corpus luteum, are of more importance. We have already discussed the functional relationship between the interstitial tissue and the corpus luteum graviditatis; the experiments of Steinach and Holzknecht provide definite proof of this. But the physiological relationship between the corpus luteum menstruationis and the corpus luteum graviditatis can also be proved. Hitschmann and Adler (1913) have shown that about ten days before menstruation the uterus undergoes changes characteristic of the beginning of pregnancy. The mucosa may resemble a decidua of early pregnancy to such a degree that there is no microscopical difference between the two; the cells are polygonal, the glands are long and curved, the blood vessels are enlarged. Evidently the essential part of the process is not the menstrual bleeding, but the early transformation of the mucosa into a decidua. The menstrual bleeding is only a sign of the beginning of involution, which takes place if there is no fertilization. Now we know from the observations of Fraenkel on the ovaries of women in abdominal operations undertaken for other reasons, that the new corpus luteum is already present about ten days before menstrual bleeding occurs, just at the time when, according toHitschman and Adler, the premenstrual changes set in. There is also a swelling of the breasts, occasionally followed by secretion. Similar observations concerning the corpus luteum and the premenstrual uterine changes have been made also by other workers such as Robert Meyer (1913) and Carl Ruge II (1913). These time relations between the corpus luteum menstruationis and the cyclic changes in the uterus and in the breasts, which are characteristic of the beginning of pregnancy, are a sufficient proof that a functional relationship exists between the corpus INTERNAL SECRETION OF OVARY 261 luteum menstruationis and the corpus luteum graviditatis. The menstrual bleeding is only one of two alternative processes which the uterus undergoes after the premenstrual changes have set in; these premenstrual changes are followed by pregnancy when an egg has been fertilized and has entered into the uterus, or else they end by an expulsion of the hyper- aemic mucosa if fertilization has not taken place. There is not,, however, complete unanimity among the different authors in regard to the dependence on the corpus luteum of the cyclic uterine changes in man. This question we shall return to in the next section. The statements of Marshall and Hainan (1917) on the corre- lation existing between ovarian changes and those in the uterus and in the mammary glands of non-pregnant dogs after the period of heat, are of interest here. The authors kept under observation bitches for about 30 to 40 days after the beginning of bleeding from the vaginal opening. Histological examina- tion of the ovaries revealed the persistence of corpora lutea, which were in different stages of development. The uterus and the mammary glands were found to undergo changes of a similar kind to those which take place during pregnancy, but not to reach the same degree of development. Retrogression of these organs set in about 30 days after ovulation, but the mammary gland remained for a longer period in a state of activity. Marshall and Hainan conclude that in the case of the non-pregnant dog after "heat," a series of changes homo- logous with the changes occurring in the pseudo-pregnant rabbit takes place ; in both cases the changes are correlated with luteal development in the ovary. The persistence of corpora lutea in the ovary of the non-pregnant dog, "which is possibly greater in some individuals than in others, elucidates the not uncommon phenomenon of bitches which had not been im- pregnated secreting milk at or near the end of the pseudo- pregnant period." An investigation on the correlation existing between ovarian and uterine changes was made also by Gerlinger (1923 b) in the laboratory of Bouin. There is no doubt that the phenomena of heat are correlated with follicular processes in the ovary. It is a question of a different order as to why after fertihzation further changes take place in the uterine wall, and especially in the mammary glands, which are a long distance off from the 262 INTERNAL SECRETIONS foetus. We must assume that an influence is exerted by the placenta and the foetus by means of hormones. This influence might be either a direct or an indirect one. In the first instance substances from the placenta would be carried by the blood to the mammary glands, and so act on them. In the second, which is very probable, these substances would act also on the ovary; that such an action really takes place is rendered likely by the fact that the corpus luteum of pregnancy per- sists longer than the corpus luteum of menstruation or the periodic corpus luteum. The above-mentioned observations of L. Loeb on the relation existing between an experimentally produced placenta and the ovarian changes may be again referred to in this connection. One may assume that the influence the placenta has on the mammary glands may here be indirect, the development of the mammary gland being caused by an increased formation of endocrine cells in the ovary, depending upon the placenta. Weighty evidence for such an assumption is given by the above-mentioned experi- ments of Steinach and Holzknecht on guinea pigs treated with X-rays, where growth of the mammary glands and milk secretion were observed without a placenta having been formed. A further proof is given by the numerous experiments of Steinach, Athias, Sand, Moore, Lipschiitz and his co-workers, who observed milk secretion in male animals after implan- tation of ovaries. But, on the other hand, it seems clear that besides the influences exerted on the mammary gland by the ovary, there must be still other factors at work, since we know that the growth of the mammary glands does not cease if castration is performed in the second half of pregnancy. It may be that the changes produced during pregnancy in the ovary are followed by changes in other ductless glands, and there are many indications that this actually happens, All these manifold factors must be taken into consideration in dealing with the question as to the factors responsible for the hypertrophy of the mammary glands in pregnancy and for milk secretion after birth. INTERNAL SECRETION OF OVARY 263 (c) Objections to the theory of the internal secretion of the corpus luteum. Objections have been made to the assumption that the corpus luteum causes menstrual changes or the characteristic cycUcal changes of heat. These objections have been discussed especially by Aschner (1918, pp. 46-57) for menstruation, by Marshall (1910, pp. 336-345), and by Marshall and Runciman (1914) for the oestrous cycle. It has been pointed out by different authors that the time relations between the formation of the corpus luteum and the appearance of the menstrual changes in the uterine mucosa cannot be taken as a proof that a connection exists between the two. It has been claimed that the uterine changes begin before the folhcle is ruptured, i.e., at a time when the ripe Graafian foUicle is stih present. More recently Schickele (1921) has insisted on the fact that the premenstrual uterine changes may occur when no corpus luteum is to be detected in the ovary, and that there may be a corpus luteum in the ovary without premenstrual changes taking place in the uterus. A similar standpoint is taken by Henry (1922). It has been also found that after removal of an ovary with a corpus luteum menstruation occurred two or four days after the operation. The authors concluded from the latter observation that the corpus luteum inhibits menstruation. A further proof of this assumption, according to Aschner, exists in the fact that several days after removal of one or both ovaries a bleeding from the uterus may often occur, and that women with a uni- lateral cyst of the corpus luteum show amenorrhoea. We shall show below that these chnical observations are by no means contrary to the conception of the endocrine function of the corpus luteum. Menstruation occurs also in monkeys without ripe folHcles or fresh corpora lutea being present at the time of menstruation (Heape). The same is true for "heat" in the lower mammals. In various species of bats heat and copulation occur in the autumn, whereas ovulation takes place only in the following spring; the spermatozoa are kept during the whole hibernation in the uterus It seems clear that in this case the heat cannot be caused by a corpus luteum or by a ripe Graafian folUcle. In 264 INTERNAL SECRETIONS most animals ovulation is preceded by the so-called "pro- oestrum," which is the first stage of heat; this is further evidence that there are no corpora lutea at the beginning of heat. In those cases where an ovulation takes place sometimes only after coition (see above), heat cannot be caused by a real corpus luteum. Marshall and Runciman performed experi- ments on the question of time relations between ovarian changes and heat. They concluded tentatively that in the dog the commencement of heat does not necessarily depend upon ripe Graafian follicles or corpora lutea. In subsequent experiments by Marshall and Wood (1923), however, it is shown that the occurrence of heat is normally correlated with the presence of follicles in what is called the " pre-inseminal stage." Marshall and Wood destroyed in dogs the ripe Graafian follicles by cauterisation a short time before a heat period was due; the period was missed; on the contrary, heat was not postponed, or only sHghtly so, if the follicles were cut into without being destroyed. The results were the same as in the former experiments of Marshall and Runciman, the Graafian follicles having been only pricked and ruptured. According to Aschner, one must assume that the follicle, and especially the ovum itself, produces the internal secretion of the ovary. As to the ovum, this conception is absolutely unfounded and unacceptable; only a few of those who are consistently antagonistic to the conception of the endocrine function of the interstitial cells, have adopted this standpoint. There is, indeed, no evidence whatever that the ovum itself acts in the mammal as a gland with an internal secretion. In one of our experiments already mentioned only a small percentage of the normal quantity of ova was present in the hypertrophied ovarian fragments, and nevertheless this animal had a uterus better developed than that of a control animal of the same litter. The ripening of the ovum seems to be an essential influence, since the transformation of hitherto inactive cells into active endocrine cells evidently depends on some process going on in the ovum and connected with its ripening. The view that the follicles in general can cause menstrual changes by an internal secretion is not contrary to the assumption that the corpus luteum has this function. From what we have learnt in the preceding paragraphs of this section it seems clear enough that INTERNAL SECRETION OF OVARY 265 there is no definite histological or functional distinction between the different formations which are derived from the follicle. I think that at all the stages of follicular development, beginning with a very early one up to a ripe Graafian follicle and to a corpus luteuni, the follicle can produce an internal secretion, but its activity varies according to the respective stages. A similar view is held by Bucura (1913), by Sand (1918, 1921), and by Athias (1923); but I cannot agree with Bucura that the inter- stitial cells of the ovary act only as a store for the hormones produced in the cells of the follicle. There is no evidence for such an assumption. This conception of Bucura follows from his belief that there is a sharp histological distinction between the "follicle " and the " interstitial tissue," the first consisting of epithelial cells of granulosa, the second of connective cells in the theca interna. But we have seen that such a distinction has no real existence. When we have realised that, in regard to function, only quantitative differences exist between the different stages of follicular development, we can understand why cyclical uterine changes, as in the premenstrual phase, can begin before a ripe Graafian follicle or a corpus luteum is present. The ruptured and vascularized follicle on the one hand, and the premenstrual changes in the mucosa on the other, represent only stages in the chain of causation. Evidently the follicles at different stages of development differ from one another as to this endo- crine activity only quantitatively; this explains why after irradiation by X-rays, when an increased follicular atresia is caused, and when an increased number of interstitial cells is activated, the same hormonic effect can be obtained as by means of a corpus luteum. By assuming that only quantitative differences exist in endocrine activity at different stages of foUicular development, we can also understand why menstrua- tion may occur in some animals (as with monkeys) in the absence of either a ripe Graafian follicle or a corpus luteum. The same is no doubt true also for the heat periods of the lower mammals. It does not seem to me justifiable to centre the whole problem around the question as to whether a ripe Graafian follicle or a corpus luteum is present at the time of the prooestrum or not. It is necessary to determine rather whether at the prooestrum those changes take place in the ovary, which could be considered as signs of increased activity on the part 266 INTERNAL SECRETIONS of the endocrine cells. And it must be remembered that probably different sorts of endocrine cells come into play, and that the cells of the theca interna of atretic folhcles, the cells of the granulosa of ripening follicles, and lutein cells of the corpus luteum may all participate. It follows that it is absolutely necessary to examine the whole follicular apparatus together with the stroma, regarding them as a unity, if we wish to investigate the question as to the dependence of menstrua- tion, heat, and the changes of pregnancy upon the ovary. Marshall and Wood (1923) hold that the interstitial cells, the ripening follicles and the corpus luteum produce qualitatively different hormones ; the secretion of the interstitial cells may be responsible for maintaining the normal nutrition of the uterus, the secretion of the ripening folhcles may account for the phenomena of heat, and the secretion of the corpus luteum may cause the uterine and the mammary hypertrophy during pregnancy. I do not think that there is as yet sufficient experi- mental evidence for such a definite delimitation between the different endocrine elements of the ovary. The objections Aschner made as a result of chnical observa- tions to the view that menstruation is caused by the corpus luteum are without foundation. Menstrual bleeding is evidently caused by the fact that the premenstrual uterine changes suddenly cease instead of continuing till pregnancy; this, we assume, is due to the corpus luteum entering upon regression. Now we can understand how it is that a corpus luteum which persists longer than usually can retard menstrual bleeding; a persisting corpus luteum is evidently correlated with a persist- ing premenstrual stage, and that means that menstrual bleeding will be retarded. Menstrual bleeding is nothing else than a pregnancy which has failed to come about, or a very early abortion. As Labhardt (1920) has rightly pointed out, it is gravidity, not menstruation, which is monthly prepared for in the uterus. The amenorrhoea observed in cases of unilateral cysts of the corpus luteum can be explained as a prolonged premenstrual stage, or a prolonged persistence of pregravid uterine changes. To decide this question it would be necessary to examine the uterine mucosa in such clinical cases. Aschner says that the menstrual bleeding is "inhibited" by the corpus luteum, this "inhibition" being one of the functions of the corpus luteum. This view to my mind is absolutely INTERNAL SECRETION OF OVARY 267 unacceptable. The dynamics of the corpus luteum and of the uterine mucosa must be taken into account, if one is to under- stand the manifold clinical cases of amenorrhoea. These dynamics will also explain why under certain conditions a premature disappearance or destruction of the corpus luteum can accelerate menstrual bleeding. It is clear that a premature menstrual bleeding may occur if the corpus luteum disappears at a time when the premenstrual changes have already attained a certain degree. And there will be no bleeding at all when the destruction of a fresh corpus luteum is brought about very early, when the developmental uterine changes have not yet taken place, as in the clinical cases of Fraenkel. (See p. 251.) 7. The Phases of Puberty in the Female. Usually a marked distinction is drawn between the changes which take place in the genital organs and the mammary glands at the time of sexual maturation, and those which take place in these organs in pregnancy. There is evidently a tacit as- sumption that the attachment of the ovum and the placenta and foetus produce the changes characteristic of pregnancy which are indeed in many wa^^s different from those occurring during sexual maturation. There can be no doubt that the placenta and the foetus are responsible to a certain degree for the changes of pregnancy. But, as already remarked, we have as yet no certain knowledge concerning the mechanism of this interaction. On the other hand it has been demonstrated that changes characteristic of pregnancy can be caused experi- mentally in virgin females by provoking certain changes in the ovary (X-rays, transplantation). So it seems impossible to separate rigorously the changes of pregnancy from those of sexual maturation, and we agree with Steinach that it depends upon the endocrine apparatus of the ovary whether the genital organs and the mammary glands shall attain the stage characteristic of the normal sexually mature virgin female, or whether these organs shall attain, after fertihzation, the stage of development characteristic of pregnancy. It can scarcely be denied that other parts of the organism also and other ductless glands besides the ovary contribute to the changes of pregnancy. But nevertheless it seems more than probable that this interaction of the other internally secreting glands 268 INTERNAL SECRETIONS does not take place until the ovary has initiated the whole chain of changes. We have seen also that there is no reason for assuming any essential differences between the corpora lutea graviditatis and those corpora lutea which are periodically formed after ovulation. There is in both cases a formation of luteal cells, the number of which is merely greater in the first case. As already remarked, the attachment of the ovum evidently produces a longer persistence and a greater development of the corpus luteum than is possible in connection merely with menstruation. We have seen further that the premenstrual changes in the uterine mucosa resemble those of early pregnancy. In view of these considerations it seems justifiable to regard the changes which occur in the organism during pregnancy as a further link in the chain of changes which begin in the organism at the time of sexual maturation. Every menstruation and every pregnancy are really of the nature of a repeated and highly intensified sexual maturation. If the first corpus luteum menstruationis can be called a "puberty gland" in a narrower sense of the term as causing sexual maturation or puberty, all the subsequent corpora lutea menstruationis and all the corpora lutea graviditatis are nothing else than parts of this puberty gland. Just as we have compared all the changes occurring in menstruation, heat and pregnancy with those which take place at the time of sexual maturation or puberty in the narrow sense, so in the same way we may compare with the latter the different stages of development preceding sexual maturation. There is indeed at the time of puberty no process which is essentially new to the organism. There is in reality only an extraordinary acceleration of processes which were going on up to this time at a slow rate. This would be true even for an animal like the male rabbit, where there is possibly no internal secretion produced by the gonad between birth and early puberty. Furthermore, the formation of the first corpus luteum is not an essentially new process, since we have seen that there is no real difference as to fimction between atretic follicles and interstitial tissue arising from them on the one hand, and corpora lutea on the other. The first and all the following corpora lutea menstruationis and all the corpora INTERNAL SECRETION OF OVARY 269 lutea graviditatis are to be understood as parts of the female endocrine sex gland, originating together with all the other endocrine cells from the follicular apparatus from soon after birth till sexual maturity. All the various endocrine cells which are to be found in the ovary represent an essential unity, the endocrine gland of the ovary. The manifold changes and rhythms undergone by the female, both somatically and psychically, in sexual life may he regarded as phases of puberty in a broader sense of the word, caused by developmental changes in the endocrine gland of the ovary. These quantitative changes evidently play in the female a much greater role than in the male. We have supposed that there are for man two great phases of puberty corresponding to two climaxes in the develop- ment of the sexual gland. In a similar way we may suppose that there are two great phases of puberty for woman. The second great phase is the time when the first corpus luteum menstruationis develops, and this leads to the climax of puberty in woman, that is to say, to pregnancy. As to the hypothetical first great phase, we have at present little knowledge concerning the endocrine gland or, in other words, concerning the ovarian changes during em- bryonic life. Unanimity does not yet exist as to follicular atresia during extrauterine life, and there is still less know- ledge of the follicular apparatus during embryonic hfe. Ac- cording to some authors (see Aschner, 1914b, p. 479) follicular atresia already occurs^ in the fifth month of embryonic de- velopment. Would it be possible to attribute to this follicular atresia the production of endocrine cells and hormones necessary for the development of the somatic sexual aharacters ? It is conceivable also that the endocrine cells originate during embryonic life from other parts of the ovary. Lacassagne (1913, p. 201) is of the opinion that in the rabbit the epithelioid cells of the interstitial tissue may originate from ordinary stroma cells. According to Athias (1919) interstitial tissue is considerably developed in the bat during foetal life, the cells originating from the ovarian stroma. Evidently in the early embryonic development epithelioid endocrine cells arising from stroma cells predominate, the follicle becoming later the most important or even the sole seat of origin for these cells. But, as Athias states, the interstitial cells also of the young 270 INTERNAL SECRETIONS female bat all take origin from the ovarian stroma, and there is even in the adult bat a transformation of connective cells of the stroma into interstitial cells. The condition of the ovary during embryonic development may indeed be different in individual species. As far as I can understand from an ex- tensive Dutch paper published by Van Beek (1921), a pupil of Krediet, follicular atresia begins in the cow at a very early period. But many authors state that no such process occurs before birth (see Zietschmann, 1921, pp. 242-43). What we know concerning the parallelism between the differentiation of endocrine elements in the ovary and the differentiation of sex characters during embryonic develop- ment is still very vague. It is possible that there is in women no embryonic climax in the endocrine gland. We have mentioned in Chapter II. that the bodily proportions of women resemble infantile ones more than those of men do; possibly transformation of an asexual or a bisexual soma into the female requires less hormonic activity than transformation into the male. In Chapter IX. we shall learn that with twin calves the female partner may be influenced by the sex gland of the male and even, as shown by Lillie and his co-workers, the female sexual organs be partly transformed into male ones; but the male partner is never affected by the female. I know very well that I am treading on uncertain ground in discussing these very hypo- thetical matters. But what I wish to emphasize is that all these questions concerning the endocrine sex glands during embryonic life must be investigated, not only by histological methods, but also by experimental ones. This has recently been done for the first time by LilHe's pupil Minoura. Conclusions. It is highly probable that the internal secretion of the ovary of the mammal is elaborated, partly by cells of the membrana granulosa, and partly by cells of the theca interna, and that these cells originate from follicles undergoing atresia or from ripe folHcles rupturing and transforming themselves into corpora lutea. It is difficult to decide whether the increased internal secre- tion of the ovary is caused by a proliferation or only by an activation of the endocrine cells. As with the interstitial cells INTERNAL SECRETION OF OVARY 271 of the testicle, which increase before or at the time of heat, mitosis seems to be rare in the epithehal and epithehoid cells of the ovary. It is very probable that in man and in many other species the endocrine cells of the ovary become transformed, when they are not undergoing degeneration, into common connective tissue cells or into fibrous connective tissue. In these species there is, from a certain age onwards, a periodic new growth of endocrine cells (corpus luteum periodicum or menstrua- tionis); also, these new endocrine cells persist only for a certain time. The new growth of the endocrine cells is especially pro- nounced when ovulation is followed by implantation of a fertilized ovum, i.e., when gravidity takes place (corpus luteum graviditatis). The endocrine cells of the corpus luteum graviditatis do not remain in functional activity for the whole duration of gravidity, and the organ finally undergoes sclerotization. Now, in the second half of gravidity other endocrine cells replace the degenerating corpus luteum; these cells originate from the theca interna, and possibly also from the granulosa of the follicles, which at that time undergo atresia in an increased number. After gravidity is over new ova ripen and new endocrine cells are produced; a new menstruation or a new heat begins. The cyclical uterine changes and the cyclical increase in sexual activity as observable in menstruation and heat, evidently depend upon an activation or a functional increase of the endocrine cells in the ovary. From what we have seen above it seems clear that the endocrine function of the ovary is intimately connected with processes taking place in the follicle. Possibly these processes depend upon the ripening of the ovum, though it is not necessary that the ovum should attain maturity. Moreover, it is not even necessary that the ovum should remain alive. There seems to be a far-reaching analogy between the endocrine mechanism of the ovary and that of the testicle in the mammal. In both sexes the post-embryonic transformation of inactive cells of mesodermic or mesenchymatic origin may depend upon impulses coming from the generative tissue without full maturation or without even the further presence of ripening 272 INTERNAL SECRETIONS generative cells being necessary (' 'follicular theory "). Another possibility must also be taken into consideration. It is con- ceivable that the processes which take place in the cells of the granulosa or the theca interna are primary processes, both causing the development of the ovum, and at the same time being connected with hormone-production in the cells of the follicular wall itself. B. OTHER VERTEBRATES. It would be of great interest to know whether endocrine cells of a nature similar to those in the mammal occur also in the ovaries of other vertebrates. But we have already mentioned (Part A, Sect. 6, a) how conflicting the statements of different authors are concerning follicular development and the existence of the corpus luteum among lower vertebrates. It was claimed that in amphibians the hormonic action which the ovary has on the soma, must be due to the ova, since there are no epithelioid interstitial cells present. We related in Chapter IV. the experiments of Harms (1914, p. 117) on Bufo vulgaris. He removed the testicle while leaving un- touched the Bidder's organ. Harms relates that he observed in the operated animals the cyclical hypertrophy of the pads; the animals showed also the clasp reflex. If both the testicles and the Bidder's organ were removed, signs of castration showed themselves. But the cyclical changes took place in those animals into which after removal of the testicle and of the Bidder's organ, the latter was engrafted into the dorsal lymphatic sac. Harms considers the Bidder's organ as a rudimentary ovary in which interstitial cells are not to be found. So he concludes from his experiments that the germi- native cells of this organ are capable of producing sexual hormones. The experiments of Harms were repeated, and by no means confirmed, by Guyenot and Ponse (1922, 1923). These authors stated that removal of the Bidder's organ alone does not inter- fere with the normal cyclic changes of the pads or with the sexual behaviour. And contrary to the results obtained by Harms those animals whose testicles were removed (the Bidder's organ remaining untouched), showed no development of the pads when operated upon in June ; those animals which were operated upon in October at a time when the pads of the INTERNAL SECRETION OF OVARY 273 next year's cycle are already partly formed, showed an antici- pated regression of the pads. There was also a total lack of the clasp reflex, and the animals were not capable of copulation. The authors conclude from their experiments that the sex characters of the toad do not depend upon the Bidder's organ. They go so far as to suggest that this organ, being a rudi- mentary one, has no function at all ; they consider it as some kind of progonad which stops functioning early, and is to the functional gonad somewhat as the pronephros is to the definite mesonephros in Batrachia. The experiments of Lauche (1915) upon partial castration of frogs may also be mentioned here. He removed the greater part of the ovaries in two frogs, and stated that the number of young ova which entered upon development was greatly increased. There was, as he says, an acceleration in the development of ova. He concludes from his experiments that this is caused by an increased demand on the endocrine function of the generative tissue of the ovarian fragment. I do not find that this conclusion is justified. The experiments with partial castration in mammals, which we related above, show that the question is probably a much more complicated one. What we know about the seat of hormone-production in the ovary of birds is also very incomplete, although several authors have contributed much to this question in the last five years. Goodale (19 16) observed that castrated hens which had assumed the male plumage reassumed the female one, and afterwards again assumed the male one; Goodale observed six similar hens. One might suppose at first that there was in these cases a regeneration of ovarian tissue left unwittingly in the body; for some this may, indeed, have been so. But on the other hand Goodale states that in certain of his cases there was no trace of ovarian tissue. In these birds he found a new organ which developed in the place of the removed ovary. The histological examination, which was, however, incomplete, revealed that this organ resembled that which is to be found sometimes in normal hens and ducks on the right side in the place corresponding to the left ovary .^ It is impossible to say whether there was any relation between the body on the ^ It may be remembered that in birds the sexual organs develop only on the left side, whereas they degenerate on the right side. 274 INTERNAL SECRETIONS right side and the organ which developed in the castrated hens on the left side ; according to Goodale there may have been one. In castrated ducks, which showed a similar change from male to female plumage, Goodale found this organ only once. The observations of Goodale make it highly probable that there was in his experiments a periodic change in hormone- production. "It is evident that if the organs are concerned with the changes, there must be some change in the activity of the organs either preceding the changes in plumage or accompanying them" (Goodale, 1916, p. 292). Goodale mentions that these organs are very likely identical with the bodies described by various observers in cock-feathered females. We shall return to this important question in Chapter IX., when discussing some experiments by Pezard and Zawadowsky. The observations of Goodale leave no doubt that production of sexual hormones or production of hormones identical with the latter is possible without any ovum being present in the body. A thorough investigation into the follicular development and the seat of production of sex hormones in birds has been made by certain American authors, especially by Pearl and Boring (1917, 1918 a, 1918 b). According to these observers there is during follicular development a complete degeneration of the granulosa, whereas the theca interna undergoes hyper- trophy. The interstitial cells are derived from the theca interna. In the theca interna are located also groups or nests of epithelial cells, which are very different from the usual glandular inter- stitial cells. These cells, which they call "lutear cells, " are about three times as large as the interstitial cells; their nucleus is bigger, the cytoplasm is usually clear and vacuolated in appearance; a few acidophile granules are occasionally present, while the real interstitial cells are crowded with granules. When follicular atresia is completed the big clear cells contain a yellow pigment, and this is why the authors call these cells lutear cells. There is, according to Boring and Pearl, no difference between an atretic follicle and a corpus luteum; "they are practically identical in the hen" (Pearl and Boring, 19 18 a, p. 15). The lutear cells of the corpus luteum also are formed from the cells of the theca interna. The interstitial cells in the ovary of birds are homologous with those in the ovary of mammals; according to Boring and INTERNAL SECRETION OF OVARY 275 Pearl there cannot be the sHghtest doubt as to this. The interstitial cells of the ovary are identical, as to their structure, with the interstitial cells of the testis. Since the interstitial cells, according to Boring and Pearl, are not a constant element in the anatomy of the testis of the domestic fowl, the authors hnd it very difficult to suppose that these cells have any causal influence upon the sex characters. Thej^ consider the lutear cells only to be the seat of hormone-production in the ovary. This assumption is based mainly on a thorough study of several cases of hermaphrodite birds which revealed certain male characters. They examined the question as to how far the intermingling of male and female sex characters in any individual case could be explained by an abnorrfiahty in the structure of the respective gonads. From this detailed examination. Boring and Pearl concluded that the "amount of lutear cells or pigment is in precise correlation with the degree of external somatic female- ness exhibited by the individual." We shall return to this paper of Boring and Pearl in the chapter on" Intersexuality." It may be insisted here that the conception of Boring and Pearl does not agree with the statements of Goodale (19 19), and especially with those of Nonidez (1920, 1922). They consider the granule-containing interstitial cells of the ovary, like those of the testis, to be modified lymphoid elements. But besides these cells there is, according to Nonidez, in the ovary and in the testis of the fowl still another type of interstitial cells originating from degenerating sexual cords. These are the lutear cells of Boring and Pearl. In * Part A' of this chapter we learned the very interesting fact that ovarian fragments in the mammal undergo hyper- trophy, this being caused by a relatively greater number of ova entering upon follicular development, and the absolute number of developed follicles after partial castration approaching the total number present in two normal ovaries. Similar statements were made by Pearl and Schoppe (1921), on exact quantitative lines, on the fowl long before the experiments of Arai and those of myself on the mammal. These authors found that in the ovary which regenerated from an ovarian fragment, originally of about ^ to | of a normal ovary, almost the normal quantity of visible oocytes was present. As there is in the fowl no new formation of oocytes, the "regene- ration" of an ovarian fragment can here be explained 276 INTERNAL SECRETIONS only by the assumption that a relatively increased number of primary oocytes proceed to develop till the normal number of follicles is attained. Since a similar conclusion can be drawn from the experiments of Lauche on the frog (see above), it seems very likely that the same quantitative law holds for all vertebrates. We have already pointed out the fact that testicular hyper- trophy is b}^ no means a compensatory one caused by an increased demand for sex hormones after partial castration. There is likewise no reason to explain by such an assumption the increased follicular development in an ovarian fragment. BIBLIOGRAPHY FOR CHAPTER V. [* Not seen in the original.] Ancel et BouiN. 1909. Sur les homologies et la signification de& glandes a secretion interne de I'ovaire. C. R. de la Soc. de Biol., 67, p. 464 et 497. 1910. Recherches sur les fonctions du corps jaune gestatif. I. Sur le determinisme de la preparation de I'uterus a la fixation de I'oeuf. Jl. de Physiol, et Pathol. Gener., 12. 1911. Sur les fonctions du corps jaune gestatif. II. Sur, le determinisme du developpement de la glande mammaire aux cours de la gestation. Jl. de Physiol, et Pathol. Gener., 13, p. 31. Aral 1920a. On the postnatal development of the ovary (albino rat), with special reference to the mmiber of ova. Amer. Jl. of Anat., 27, p. 405. 1920b. On the cause of the hypertrophy of the surviving ovary after semispaying (albino rat) and on the number of ova in it. Amer. Jl. of Anat., 28, p. 59. Aschner. 1914 a. tJber den Kampf der Teile im Ovarium. Arch, f. Entw.-Mech., 40, p. 565. 1914 b. tJber Morphologic und Funktion des Ovariums unter normalen und pathologischen Verbal tnissen. Arch. f. Gynd- kologie, 102, p. 446. 1918. Die Blutdriisenerkrankungen des Weihes und ihre Be- ziehungen zur Gyndkologie und Gehurtshiilfe. Wiesbaden. INTERNAL SECRETION OF OVARY 277 Athias. 1915. L'activite secretoire de la glande mammaire hyper- plasee, chez le cobaye male chatre, cons^cutivement a la greffe de I'ovaire. C. R. de la Soc. de Biol., 78, p. 410. 1916a. Etude histologique d'ovaires greffes sur des cobayes males chatres et enleves au moment de retablissement de la secretion lactee. C. R. de la Soc. de Biol., 79, p. 553. 1916b. Sur le determinisme de I'hyperplasie de la glande mammaire et de la secretion lactee. C. R. de la Soc. de Biol.^ 79, p. 557. 1919. Recherches sur les cellules interstitielles de I'ovaire des Cheiropteres. Arch, de Biologie, 30, p. 89. 1920. Invagination de 1' epithelium superficiel et neoformation ovulaire dans I'ovaire transplante chez le cobaye. C. R. de la Soc. de Biol., 83, p. 1647. 1921. Sur la secretion interne de I'ovaire. Arch, internal, de Physiol., 18, p. 296. 1922. Etudes histologiques sur la greffe ovarienne. Lihro en honor de D. Santiago Ramon y Cajal. Madrid. 1923. Sur la signification physiologique des phenomenes d'atresie folliculaire et des cellules interstitielles de I'ovaire. C. R. de la Soc. de Biol., 88, p. 1315. Van Beek. 1921. Microskopisch- en macroscopisch anatomisch onderzoek naar de ontwikkeling van het ovarium bij het rund. Diss. med. vet. Utrecht. Bell (W. Blair). 1920. The Sex-Complex. 2nd ed. London. BiEDL. 1913. Innere Sekretion. 2 Aufl. Berlin- Wien. Vol. II., p. 320 ff. Peters und Hofstatter. 1921. Experimentelle Studien iiber die Einnistung und Weiterentwicklung des Eies im Uterus. Zeitschr. f. Geburtsh. u. Gyndkolog., 84, p. 59. BORINC4 and Pearl. 1917. Sex Studies IX.: Interstitial cells in the reproductive organs of the chicken. Anatomical Record, 13, p. 253. and Pearl. 1918b. Sex Studies XI.: Hermaphrodite birds. Jl. of Experim. Zool., 25, p. 1. BouiN, Ancel et Villemin. 1906. Sur la physiologic du corps jaune de I'ovaire. Recherches faites a I'aide des rayons X. C. R. de la Soc. de Biol., 61, p. 417. 1907. Glande interstitielle de I'ovaire et rayons X. C. R. de la Soc. de Biol, 62, p. 337. BucuRA. 1913. Zur Theorie der inneren Sekretion des Eierstocks. Zentralbl. f. GyndkoL, 37, p. 1839. Carmichael and Marshall. 1908. On the occmTence of compensa- tory hypertrophy in the ovary. Jl. of Physiol., 36, p. 431. 278 INTERNAL SECRETIONS Corner. 1923. Oestrus, ovulation and menstruation. Physiolog. Reviews, 3, p. 457. Fraenckel (L.) 1903. Die Funktion des Corpus luteum. Arch. /. Gyndcol, 68. 1905. Vergleichende histologische Untersuchungen liber (Jas Vorkommen driisiger Formationen im interstitiellen Eierstockgewebe (glande interstitielle de I'ovaire). Arch. f. Gyndkol., 75. 1910. Neue Experimente zur Funktion des Corpus luteum. Arch. f. Gynakol., 91. 1914. Normale und pathologische Sexualphysiologie des Weibes. In Liepmann, Handbuch der gesamten Frauenheilkunde, III. Leipzig. Gerlinger. 1923 a. Corps jaunes partiels de I'ovaire de Chienne. Bull, de la Soc. Anatotnique, Mai. 1923 b. Le cycle oestrien de I'uterus chez la Chienne et ses rapports chronologiques avec le cycle oestrien de I'ovaire. C. R. de la Soc. de Biol., 89, p. 193. Good ale. 1916. Further developments in ovariotomized fowl. Biolog. Bulletin, 30, p. 286. 1919. Interstitial cells in the gonads of domestic fowl. Anatom. Record, 16, p. 247. *GooRMAGTiGH. 1921. Organogenese et histogenese de la capsule surrenale et du plexus coeliaque. Arch, de Biol., 31, p. 83 (quoted from Ber. iih. d. ges. Physiol., 8, p. 228). GuGGiSBERG. 1922. Die Arbeitsteilung im Eierstock. Zentralhl. /. Gyndkol., 46, p. 402. GuYENOT et PoNSE. 1922. L'organe de Bidder et les caracteres sexuels secondaires du Crapaud (Bufo vulgaris). C. R. de la Soc. de Biol, 86, p. 751. 1923 a. L'organe de Bidder du crapaud est il indispensable a la vie ? C. R. de la Soc. de Biol, 89, p. 63. 1923 b. Nouveaux resultats concernant le determinisme des caracteres sexuels secondaires du crapaud {Bufo vulgaris). C. R. de la Soc. de Biol, 89, p. 129. Haberlandt. 1921. tJber hormonale Sterilisierung des weiblichen Tierkorpers. MiXnch. Mediz. Wochenschr., p. 1577. 1922. Tiber hormonale Sterilisierung weiblicher Tiere durch subkutane Transplantation von Ovarien trachtiger Tiere. Pfliigers Archiv, 194, p. 235. ♦Hammond and Marshall. 1914. The functional correlation between the ovaries, uterus and mammary glands in the rabbit. Roy. Soc. Proc. B., 87. Harms. 1914. Experimentelle Untersuchu?igen ilber die innere Sekre- tion der KeimdrHsen. Jena. INTERNAL SECRETION OF OVARY 279 Henry. 1922. Recherches anatomo-cliniques sur les rapports entre revolution du corps jaune et F apparitions des regies (23 observations). C. R. de la Soc. de Biol., 86, p. 1162. Herrmann U7id Stein. 1916. Uber die Wirkung eines Hormones des Corpus luteum auf mannliche und weibliche Keimdi'iisen. Wien. klin. Wochenschr., 29, No. 25. Hewer. 1915. The direct and indirect effects of X-Rays on the thymus gland and reproductive organs of white rats. Jl. of Physiol., 50. HiTSCHMANN und Abler. 1913. Ein weiterer Beitrag zur Kenntnis der normalen und entziindeten Uterusmucosa. Arckiv f. GyndkoL, 100. HoNORE. 1900. Recherches sur I'ovaire du lapiu. II. Recherches sur la formation des Corps jaiuies. Arch, de Biol., 16, p. 563. Hussy und Wallart. 1915. Interstitielle Driise und Rontgen- kastration. Zschr. f. Gehurtsh. u. GyndkoL, 77. KoHN (Alfred). 1914. Morphologische Grundlagen der Organo- therapie. In Jauregg und Bayer, Lehrbuch der Organo- therapie. Leipzig. Labhardt. 1920. Uber das Verhalten des Corpus luteum zur Menstruation. Zentralhl. f. GyndkoL, 44, No. 8. Lacassagne. 1913. Etude histologique et physiologique des effets produits sur Vovaire par les rayons X. These med. Lyon. Lauche. 1915. Experiment. Untersuch. an den Hoden, Eierstocken und Brunstorganen erwachsener und jugendlicher Grasfrosche (Rana fusca Ros.). Arch. f. mikroskop. Anat., 86, Abt. II., p. 51. Limon. 1901. Etude histologique et histogenique de la glande ijitersti- tielle de Vovaire. These de Nancy. * 1904. Observations slu- I'etat de la glande interstitielle dans les ovaires transplantes. Journ. de Physiol, et Pathol. Gener., 6 (quoted from Marshall, 1910). Lipschutz, Wagner et Tamm. 1922a. Sur I'hypertrophie des frag- ments ovariens dans la castration partielle. C. R. de la Soc. de Biol., 86, p. 240. et Wagner. 1922b. Nouvelles observations siu* I'hypertrophie des fragments ovariens. C. R. de la Soc. de Biol., 86, p. 1122. {in collaboration with Wagner, Tamm and Bormann). 1922c. Further experimental investigations on the hypertrophy of the sexual glands. Proceed, of the Roy. Soc, 94, p. 83. 1923. tjber die kompensatorischen Reaktionen der Gesch- lechtsdriisen. Skand. Arch. f. Physiol., 43, p. 75. — 1924 a. Condition de I'uterus apres la castration partielle. C. R. de la Soc. de BioL, 90, p. 197. ■ et Voss. 1924 b. Dynamique de I'hypertrophie ovarienne. Experiences sur des chattes. C. R. de la Soc. de BioL, 90, p. 199. 28o INTERNAL SECRETIONS LoEB (L.) 1910a. tJber die Bedeutung des Corpus luteum. Zen- tralbl.f. Physiol., 23, p. 73. 1910b. Weitere Untersuchungen iiber die kiinstliche Erzeugiing der miitterlichen Plazenta und iiber die Mechanik des sexueUen Zyklus des weiblichen Saugetierorganismus. Zentralbl. f. Physiol, 24, p. 203. 1917. The relation of the ovary to the uterus and manunary gland from the experimental aspect. Surgery, Gynecol, and Obstetrics. 1918. Corpus luteum and the periodicity in the sexual cycle. Science, 48, p. 273. Marshall. 1905. The development of the Corpus luteum. A review. Quart. Jl. of Microscop. Sc, 49, p. 189. and Jolly. 1907. Results of removal and transplantation of ovaries. Transact. Roy. Soc, Edinburgh, 45, Part III., No. 21. 1910. The physiology of reproduction. London, 1910. 2nd edition, 1922. and RuNCiMAN. 1914. On the ovarian factor concerned in the occurrence of the oestrous cycle. Jl. of Physiol., 49, p. 17. and Halnan. 1917. On the post -oestrous changes occurring in the generative organs and mammary glands of the non- pregnant dog. Proceed. Roy. Soc, 89, p. 546. 1923. The internal secretions of the reproductive organs. Phy- siolog. Reviews, 3, p. 335. and Wood. On the ovarian factor concerned in the occurrence of oestrus. Jl. of Physiol., 58, p. 74. See also Carmichael and Marshall. Meyer (Robert). 1913. Uber die Beziehimg der Eizelle und des befruchteten Eies zum Follikelapparat, sowie des Corpus luteum zur Menstruation. Archiv. f. Gyndkol., 100. 1921 a. Ein Mahnwort zum Kapitel " Interstitielle Driise.\ Zentralbl. f. Gyndkol., No. 17. 1921 b. Beitrage zur Lehre von der normalen und krankhaften Ovulation und den mit ihr in Beziehiuig gebrachten Vor- gangen am Uterus, Arch. f. Gyndkol., 113, p. 1. Moore. 1921a. On the physiological properties of the gonads as controllers of somatic and psychical characteristics. III. Artificial hermapliroditism in rats. Jl. of Experim. ZooL, 33, p. 129. 1921b. IV. Gonad transplantation in the guinea-pig. Jl. of Experim. ZooL, 33, p. 365. INTERNAL SECRETION OF OVARY 281 NoNiDEZ. 1920. Studies on the gonads of the fowl. I. Hemato- poietic processes in the gonads of embryos and mature birds. Amer. Jl. of Anatomy ^ 28, p. 81. 1922. Estudios sobre las gonadas de la gallina. II. El tejido intersticial del ovario. Lihro en honor de D. Santiago Ramon y Cajal. Madrid. OcHOTERENA and Ramirez. 1920. The origin and evolution of the interstitial cells and of the ovary, and the significance of the different internal secretions of the ovary. Endocrinology, 4, p. 541. ♦Pearl and Surface. 1914. Studies on the physiology of reproduc- tion in the domestic fowl. IX. On the effect of Corpus luteum substance upon ovulation in the fowl. Jl. of Biol. Chem., 19, p. 263 (quoted from Loeb, 1918 and Haberlandt, 1922). and Boring. 1918a. Sex Studies X. The Corpus luteum in the ovary of the domestic fowl. American Jl. of Anatomy y 23, p. 1. See also Boring and Pearl. and ScHOPPE. 1921. Studies on the Physiology of reproduction in the domestic fowl. XVIII.: Further observations on the anatomical basis of fecundity. Jl. of Experim. Zool., 34, p. 101. Plaut. 1923. Demonstration von Praparaten von Mamma, Uterus und Ovarien. Klin. Wochenschr., 2, p. 953. Rasmussen. 1918. Cyclic changes in the interstitial cells of the ovary and testis in the woodchuck (marmota monax). En- docrinology, 2, p. 353. REirrERSCHEiD, 1911. Experimentelle Untersuchungen liber Regener- ation durch Rontgenstrahlen geschadigter Ovarien. Zeitschr. f. Rontgenkunde, 13, p. 285. 1914. Die Einwirkung der Rontgenstrahlen auf tierische und menschliche Eierstocke. Stahlentherapie, 5, p. 407. 1922. Zur Frage der biologischen Wirkung der Rontgenstrahlen aiif die Ovarien. Strahlentherapie, 14, p. 628. RiBBERT. 1898. tJber Transplantation von Hoden, Ovarien und Mamma. Arch. f. Entw.-Mech., 7, p. 688. RuGE 11 (Carl). 1913. tJber Ovulation, Corpus luteum und Men- struation. Arch. f. Gyndhol., 100. Sainmont. 1906. Recherches relatives a I'organogenese du testicule et de I'ovaire chez le chat. Arch, de Biol., 22, p.' 71. 282 INTERNAL SECRETIONS Salazar. 1919. Sur la periode chromatolytique de la granulosa atresique de la lapine. Mem. publ. par la Soc. Portug. d. Sc. Natur., Ser. biolog., No. 2. 1922. Sur I'existence de faux corps jaunes autonomes dans la glande interstitielle de la lapine. Anatom. Rec., 23, p. 189. Sand. 1919. Experimentelle Studier over K(pnskarakterer hos Pattedyr. Copenhagen. 1921. Etudes experimentales sur les glandes sexuelles chez les mammiferes. Jl. de Physiol, et Pathol. Gener., 19, p. 305. ScHAEFFER. 1911. Vergleicheude histologische Untersuchungen iiber die interstitielle Eierstockdriise. Arch. f. Gyndkologie, 94. *ScHiCKELE. 1921. Etudes sur la fonction des ovaires (ovulation, corps jaune et menstruation). Gynecol, et obstetr., 3, p. 170. *ScHULTZ (W.) 1900. Transplantation der Ovarien auf mannliche Tiere. Zentralbl. f. allgem. Pathol, u. pathol. Anat. (quoted from Schultz, 1910). 1910. Verpflanzungen der Eierstocke auf fremde Spezies, Varietaten und Mannchen. Arch. J. Entw.-Mech., 29, p. 79, Seitz. 1906. Die Follikelatresie wahrend der Schwangerschaft, insbesondere die Hypertrophie und Hyperplasie der Theca- interna-Zellen (Theca-Lutein-Zellen) und ihre Beziehungen ziir Corpus luteum-BUdung. Arch. f. Gyndkol., 11. 1921. Primat der Eizelle, Corpus luteum, Menstruationszyklus und Genese der Myome. Arch. f. Gyndkol, 115, p. 1. SoBOTTA. 1895. tjber die Bildung des Corpus luteum bei der Maus. Anatom. Anz., 10, p. 482. 1896. Uber die Bildung des Corpus luteum bei der Maus. Arch. f. mikroskop. Anat., 47, p. 261. 1898. Uber die Entstehung des Corpus luteum der Saugetiere. Ergebn. d. Anat. u. Entw.-Gesch., 8, p. 923. 1901. tJber die Entstehung des Corpus luteum der Saugetiere. Ergebn. d. Anat. u. Entw.-Gesch., 11, p. 946. 1906. Uber die Bildung des Corpus luteum beim Meerschwein- chen. Anatom. Hefte, 32, p. 91. Steinach. 1912. Willkiirliche Umwandlung von Saugetier -Mannchen. Pfliigers Archiv, 144. 1916, Pubertatsdriisen und Zwitterbildung. Arch. f. Entw.- Mech., 42, p, 307. und Holzknecht, 1916, Erhohte Wirkungen der inneren Sekretion bei Hypertrophie der Pubertatsdriisen. Arch. f. Entw.-Mech., 42, p, 490. INTERNAL SECRETION OF OVARY 283 Tandler und Gross. 1913. Die hiologischen Orundlagen der sekun ddren Geschlechtscharaktere, p. 91-97. WAI.LART. 1907. Untersuchungen iiber die interstitielle Eierstock- driise beini Menschen. Arch. f. Gyndkolog., 81. Werner (Paul). 1918. Beitrag zur Kenntnis des Verhaltens der Eierstockfunktion nach der Rontgentiefentherapie. Arch. /. GyndkoL, 110. Winiwarter. 1908. Das interstitielle Gewebe der menschlichen Ovarien. Anat. Anz., 23, p. 1. et Sainmont. 1909. Nouvelles recherches sur Fovogenese et I'organogenese de I'ovaire des mammiferes (chat). Arch, de Biol., 24, p. 97. * 1920. Quelques remarques sur la secretion interne (A propos d'un ouvrage recent). Liege Med., No. 34 (quoted from Athias, 1921). ZiETzscHMANN. 1921. tJber Funktionen des weiblichen Genitale bei Saugetier und Mensch. Vergleichendes iiber die zyklischen Prozesse der Brunst und Menstruation. Arch. /. GyndkoL, 115, p. 201. Chapter VI. The Sex Specific Action of the Testicular and Ovarian Hormones. Hitherto in the present work we have refrained from discussing the important question as to the sex specific action of the testicular and ovarian hormones. Yet we have tacitly assumed that the hormones have a sex specific action, since we concluded from the castration experiments that the soma is asexual during embryonic life, and that it does not develop sex characters before the gonad is differentiated. But we have not yet presented any incontestable argument in support of the view that there is a sex specifity for the respective hormones. This question has been investigated by various authors, and in this chapter we shall deal with their experiments. A. EXPERIMENTS ON AMPHIBIANS. Steinach (1910) injected into castrated male frogs triturated ovaries of females on heat. He stated that the clasp reflex is evoked by this stimulus in just the same way as it is by injecting testes. However, by injecting ovary the reflex is not so fully e vocable, and the experiment is not so regularly successful as when testicular substance is employed. Harms (1910) and Meisenheimer (19 12) also found that the clasp reflex in castrated male frogs may return after injection of ovary. Relying on these experiments, we may suppose that hormones are formed also in the ovary, which may thus condition the oestral phenomena in the male. Meisenheimer has studied carefully the behaviour of the thumb pad in male frogs after introduction of ovarian sub- stance, the ovaries having been put into the dorsal lymphatic sac. By so doing the growth of the pad was induced, and an hypertrophy of the epithehum and the glands was brought about. The pad of the castrated male injected with ovary is 285 286 INTERNAL SECRETIONS easily distinguished from that of an ordinary "castrate." But there is a striking difference between a castrated male injected with ovary and one injected with testicle, as shown particularly by histological examination. The epidermis is not so thick, the epithelial tuberosities are much smaller in numbers and the surface of the pad remains generally smooth. As to the behaviour of the epidermis, the castrated male injected with ovary is somewhat intermediate between an ordinary "castrate" and a "castrate" injected with testicle. The influence of the ovary was particularly evident upon the glands ; their number was considerably enlarged in comparison with that found in the "castrate." We see that the oestral changes of the pad can be effected by the testicle and by the ovary alike, although the action of the ovary is less pronounced than that of the testicle. The experiment on frogs cannot, indeed, be considered as a proof of a sex specific endocrine action of the sexual glands in am- phibians, though, on the other hand, they cannot be used as a proof against such an assumption. Meisenheimer has drawn from these experiments the general conclusion that the sexual glands in mammals also do not act in a sex specific manner. That this conclusion, however, is not justified follows from what is said below. Heterosexual transplantation in tritons was attempted by Herlitzka (1900, quoted from Kammerer, 1919); the grafts underwent degeneration in the course of a few months. But Bresca (1910) succeeded in transplanting the tissue of the yellow dorsal line of a female Molge cristata on to the back of a male, where normally at time of "heat " a comb develops. He stated that the graft became transformed at the time of heat into a typical indented male comb. This was due not to a regenera- tion of the removed normal male comb, since such a one did not develop in control animals from which the male comb was also removed but on to which no female graft was placed. Harms (1921) made experiments on toads, dealing with the question as to the sex specifity of the hormones. He stated that in about 10 per cent, of the males examined oocytes were present in the Bidder's organ. He removed the testicles from these animals, and then kept them under obser- vation for three years. He found that the Bidder's organ showed an increased tendency to form ovarian tissue. Harms SEX SPECIFIC ACTION OF HORMONES 287 concludes, therefore, that normally the testicle inhibits develop- ment of ovarian tissue in the Bidder's organ. Notwithstanding the presence of ovarian tissue the toads remained typical males in somatic appearance and sexual behaviour. Harms concluded that no transformation of sex can be produced in adult animals. But two years later Harms (1923) stated that all the animals operated on in the above manner became transformed about 4 to 5 years after the operation, somatically and psychically into females. The uteri masculini changed into female uteri and oviducts; the form of the head became female-like. Ponse (1923) by testicular transplantation has provoked development of pads on both thumbs in a young castrated female toad. The pads appeared about seven months after the operation. Wagner (1922), on my incentive, made experiments on tad- poles, which were fed with frog ovaries and testicles, but no sex specific influence was observed. B. FEMINIZATION AND MASCULINIZATION IN MAMMALS AND BIRDS. Experiments undertaken to influence the organism of the mammal and bird by implanting a gland of the other sex have been made by different authors, as by Hunter as early as 1780, and in later times by Foges, Meisenheimer, and Bucura. Numerous authors have grafted testicles and ovaries upon the castrated or normal organism of the other sex in order to study the behaviour of the transplanted sexual gland itself. The successful experiments of W. Schultz (1910) may be mentioned here. But Steinach was the first to attempt to clear up the question of the specific hormonic action of the male and female sexual glands by experiments systematically performed by means of " crossed transplantation." ^ In his experiments, Steinach (1912) started with the following considerations. If the action of the male and female sexual hormones is the same, then it should be possible to cause complete development of young castrated males to full sexual iThe term "crossed transplantation" was first, used by Caullery (1913. p. 113). The term ''sex specific" was introduced by myself {Lipschiitz, 1914, p. 408), V 288 INTERNAL SECRETIONS maturity by implanting into them ovaries instead of testicles. But, if male and female sexual hormones differ from one another, a successful implantation of an ovary into a young castrated male should cause it to develop not into a mature male, but into a mature female, and the converse result should occur by implantation of a testicle into the body of a castrated female. If the action of the sexual hormones is a sex specific one, it ought to be possible to produce arbitrarily, to a certain degree at any rate, the respective sexual characters by implant- ing an ovary or a testicle into a castrated animal. Or, in other words, it should be possible to "feminize" a castrated male by an implantation of ovaries and to "masculinize" a castrated female by an implantation of testicles. As we shall see, this supposition proved correct. Steinach has demonstrated the feminizing action of the ovary and the masculinizing action of the testicle in rats and guinea pigs. All the investigators who have repeated the experiments of Steinach have verified liis results, including Brandes on the fallow-buck, Sand and Moore on the rat and the guinea pig, Athias and Lipschiitz and his co-workers on the guinea pig, Goodale on the cock and the drake, and Pezard and Zawadowsky on the cock and the hen. I. Experiments on Mammals.^ ( a) Feminization . Implantation of ovaries has been carried out by Steinach on rats at the age of three or four weeks, and on guinea pigs at the age of two or three weeks. In a series of experiments on rats the ovaries were transplanted on to the peritoneal surface of the abdominal wall; in another series of experiments on rats and guinea pigs on to the external surface of the abdominal wall. According to Steinach, the graft "takes" only if the animal has been castrated beforehand. The graft was put on a wounded place, produced by scraping the peritoneal covering or the muscle. According to Steinach this method, involving probably an hypersemia and a good vascularization for the graft, is very satisfactory. In order to secure a better vasculari- zation. Sand (1918 a) "punctured" the graft by piercing the surface in many spots with the point of a very fine needle. ' With the experiments on man we shall deal in Chapter IX. SEX SPECIFIC ACTION OF HORMONES 289 In such a way, perhaps, as Sand beheves, the resistance is overcome which the albuginea offers to the ingrowing of blood vessels. But in spite of all these measures, the grafts did not always "take," either in the experiments of Steinach or in those of Sand.^ The number of the unsuccessful experiments was greater than that of the successful ones. One might suppose that the ovaries were in some way influenced and injured by male hormones still active in the host. Sand, who performed a great number of experiments, deferred trans- plantation for one to five weeks after castration with a view to getting the male animals as far as possible into an " indifferent " or neutral condition. The chances of success, however, were not improved thereby, as may be seen from his experimental results. The subcutaneous transplantation on to the external surface of the abdominal muscles is to be preferred to the peritoneal graft, since in the first case the progress and fate of the transplanted organs may be followed by external inspection and palpation. We have given particulars concerning the histological changes in the graft in a previous chapter. In a rat four weeks old the penis is still very undeveloped. The prostate is just visible with the naked eye, and the seminal vesicles are much smaller than in the adult animal. In the prepuberally castrated animal these conditions do not change much; the organs remain in an infantile stage of development, although the penis may continue to grow to a certain degree. Now we learned that these organs fully develop if testicular implantation is made after castration. On the contrary, the development of the penis, prostate and vesicles is not promoted if ovaries are implanted. Steinach relates that the development of these organs is even inhibited by the ova.rian graft, the penis of the feminized rat being shorter than that of the ordinary castrated animal. The question as to whether the ovary has an inhibitory action is of the greatest theoretical importance, as we have already seen when dis- cussing the results of castration in birds, in which such an inhibitory action is beyond any doubt. But this question has not yet been studied sufficiently in mammals. I examined the penis of tv/o fully grown feminized guinea pigs, operated on by Steinach some years ago; I found that the penis was * We shall deal in detail in Chapter IX. with the supposed antagonism of the sex glands. 290 INTERNAL SECRETIONS shorter and narrower than that of an ordinary "castrate." But having examined in the last three years a great many castrated guinea pigs, I now see that the proportions of the penis after castration depend on the age at which castration was performed (Bormann, 1922); there is also great individual variation. So I am now rather inclined to the view that the question of an inhibitory action of the ovary in the mammal is not yet definitely settled, although such an action is more than probable. Fig. 114. — Influence of ovarian transplantation on the teats of the castrated maU guinea pig. — Photo of Steinach. A. Normal male. Steinach implanted in one case into a castrated male, to- gether with the ovaries, the uterus and the tubes ; the latter developed. Rudimentary organs of the male, such as the teats and the mammary glands, develop in the male organism under the influence of the implanted ovary, and become finally like those of a normal female {Fig. 114 A, B). In the first weeks after birth there is no difference between the teat of the male and that of a female guinea pig. The teats and the mammary glands begin to grow in the female at about the age of two SEX SPECIFIC ACTION OF HORMONES 291 months and become transformed into the organ characteristic of the virgin female. A further growth of the teats and the glands takes place during gravidity and lactation. In the same manner the teats develop in the feminized male. The teats are long, thick, and red, and the area around them is shiny and protruding, as in a normal female during gravidity. As shown by microscopical examination the mammary glands themselves really develop as in the normal female during gravidity and lactation. There is sometimes even a secretion of milk which Fig. 114. — Influence oj ovarian transplantation on the teats of the castrated male guinea pig. — Photo of Steinach. B. Feminized male (during period of lactation). can be pressed out from the gland. Such animals are sought out by young ones which attempt to suck. Sometimes the feminized male takes care of the 3^oung and suckles (Fig. 115). The milk secretion persisted in certain cases for quite a pro- longed period, but there were intervals without milk secretion. Steinach's discovery has been fully confirmed by Athias (1915), by Sand (1918, 1919), by Moore (1919 a, 1921) and by Harms (1922), by Lipschutz and Krause (1923 b and c) and by Lipschutz and Voss (unpublished experiments); the state- ments of these authors differ from those of Steinach only in 292 INTERNAL SECRETIONS details. In the experiments of Athias the teats in the feminized male attained a length of 7-5 mm.; they were enlarged at their base; there was a protruding area around them; after D Fig 11'^.— Feminized male guinea pig suckling young.— Frora. Stemach. A. Feminized male. C. Suckling one young. B. Demonstration of penis. D. Suckling two young. a short interval an abundant milk secretion set in. Sand observed a considerable hypertrophy of the teats and glands, but no milk secretion, but, as Sand points out, this was SEX SPECIFIC ACTION OF HORMONES 293 probably due to the fact that he removed one of the two implanted ovaries, and that soon afterwards the second graft underwent degeneration. Moore observed development of teats and glands to an extent similar to that of pregnant females. But his animals showed no feminine inclination towards young ones and repelled any attempts on their part to suck. In our own experiments on guinea pigs the teats and the mammary glands were like those of a pregnant female, and there was milk secretion. Sometimes only colostrum could be pressed out. Steinach's results were confirmed also by Brandes (1914) in an experiment on a stag on to which ovaries were engrafted after castration. The mammary glands hypertrophied. There were no horns in the feminized stag, and the ponium adami was not visible at all. Unfortunately Brandes made no detailed communication on his results ; only a short account was given by him in a daily paper, and in letters published in the scientific press. It is noteworthy that the committee of the Zoological Garden of Dresden, of which Brandes is the director, pro- hibited him from continuing his experiments, on the ground that they were opposed to morality and to the good reputation of the Garden. In view of these experiments there can be no doubt that male and female sexual hormones act differently. They act in a sex specific manner, i.e., they transform the organism so as to accord with the characteristics of one or the other sex. The microscopical examination of the ovarian graft in the male "castrate" reveals that the cellular elements to which we ascribe the endocrine function of the ovary are more numerous than in a normal organ, as with an ovary exposed to X-rays. There is an increased follicular development and atresia. This explains the fact that specific sexual characters may develop in the feminized male in a more pronounced manner than in the normal virgin female. There is, as Steinach points out, not only a feminization, but really an hyper feminiza- tion. If, on the contrary, the graft undergoes degeneration and transformation into fibrous connective tissue, the teats of the feminized animal revert to the rudimentary structures characteristic of the normal male or the castrated female. One of Moore's experiments confirming those of Steinach's is very significant in this respect (Moore, 1921, p. 371). 294 INTERNAL SECRETIONS gr 400 370 320 270, Athias performed the following experiment. Three days after the beginning of milk secretion he removed the ovarian grafts. The milk secretion persisted for nine days; then the mammary glands began to regress, and in about a week the regression was already very pronounced. It may be mentioned that the sex specific influence of the ovary on the teats and the mammary glands cannot be studied on the rat, as no teats are macroscopically visible in the male rat {Myers, 1917). Steinach describes also the changes which the feminized animal undergoes in body weight and body proportions. According to King and ^ Donaldson (see Donaldson, 1915) a striking difference in body weight between the male and female Norway rat f ^ may be observed at an age r ^ of about three months. 150 days after birth the male J^ has body weight about 60 gr. greater than that of the female; at an age of 365 days this difference is about 85 gr. In adult guinea pigs the difference between male and female may be as much as about 200 gr. to the advantage of the male. According to Steinach the feminized male rat has a much lower weight than that of a normal male or a "castrate" (Figs. 116 and 117), and he concludes that the weight of the castrated male is inhibited by the ovarian graft, the growth capacity becoming Hke that of a female. Similar observations were made by Steinach on the guinea pig. One might object that this inhibition of growth is caused not by the ovarian graft, but rather by the operation itself when performed on such young animals; but Steinach has pointed out that there was no inhibition of growth in those cases in which the ovarian graft did not "take." There is, according to Steinach, an even greater difference in body weight between a normal male and a 220 ,'-l.; I I ] I I U I .j~.ill 182 214 246 278 150 days Fig. 116. — Body weight of normal and feminized male rats. At an age of 9 months the feminized animals weighed about 100 gr. less than normal males. — Drawn from figures of Steinach (191 2, table i, p. 94). SEX SPECIFIC ACTION OF HORMONES 295 feminized one, than between a normal male and a normal female ; Steinach speaks here also of an hyperfeminization due to an increased hormonic action of the proHferated endocrine cells of the ovary during the period of body growth. It must be pointed out, however, that normal animals show great indi- vidual variation in regard to body weight. Definite conclusions in this field can be drawn only from very extensive data. We have already mentioned that after the disappearance or degeneration of an ovarian graft which had a feminizing effect, the teats and the mammary glands ceased to develop. Steinach observed in these cases also an increase of body weight, the animals attaining in a few weeks the weight of normal males. Sand has not directed his attention to the ques- gr ^ tion of the body weight; he had his experimental animals under observation no longer than a few months, whereas a striking difference in body weight betwen normal and femi nized male was observed by Steinach at an age of about six months. The question as to the influ- ence of the sex gland on body weight is discussed more fully by Moore (19 19) in the section on 310 ... ,.- --, / - ,•' ,.' '- ^sn 1 y . — / 1 ^ r' 170 ^ /^ 182 214 246 278 150 days Fig. 117. — Body weight of castrated and feminized male rats. — Drawn from figures of Steinach (19 12, table 2, p. 95). We shall deal with his criticisms Masculinization. " There are, according to Steinach, striking differences also in the body proportions between the normal and the feminized male (Figs. 118 and 119). Steinach made for this purpose several direct measurements and examined X-ray plates of normal and experimental animals. Further, Steinach describes differences in the coat of the rat, the long, coarse and rough hair of the male becoming transformed in the feminized animal into the short fine and soft hair of the normal female. Steinach claims also to have observed an accumulation of fat in the pelvic region of the feminized male in a manner characteristic of the female; he believes further that this accumulation of fat is absent in those castrated males in which the engrafted ovary 296 INTERNAL SECRETIONS did not "take," and in which no other signs of feminization were present. I think Steinach was mistaken as to this detail; the accumulation of fat in the abdomen of the castrated male animal being in my experience sometimes absolutely enormous. Fig. 11^. —Litter of normal guinea pigs, about 7 months old. Female between two males. This accumulation of fat after castration was indeed only absent in cases of chronic disease. Notwithstanding all the objections which have been made in regard to details, there can be no doubt that the experiments castrated male. normal female. feminized male. normal male. Fig. 119. — Influence — From Steinach. iirian transplantation on size of male guinea pig. of Steinach and of those who have repeated them show that the development of fern ale sex characters in the male animal is induced by the ovary, and it is very probable that the de- velopment of male sex characters is inhibited by this organ. SEX SPECIFIC ACTION OF HORMONES 297 The ovary turns the development of the whole organism on to female hnes. There can be no doubt that the soma is influenced by the ovary in a sex specific manner. Harms (1922, p. 242) draws attention to the fact that the "uterus masculinus" of the guinea pig does not become trans- formed into a female organ, but remains in the same infantile stage as at the time of the operatiom. Harms is mistaken in thinking that what he calls "uterus masculinus," i.e., the vesiculae seminales of the guinea pig, is an organ homologous with the female uterus. This is not the case, the vesiculae seminales being in genetic relation to the vas deferens and not to the ducts of Miiller. It can be further demonstrated that not only the somatic sex characters, but also the psycho-sexual behaviour is in- fluenced by the ovary. We learned from experiments with castration, injection and transplantation that the sexual hormones have an erotizing effect. Experiments performed on the frog have shown, that the clasp reflex can be evoked to a certain degree also by injection of ovarian substance ; evidently the ovary produces some erotizing hormone which is identical with or similar to that of the testicle. But this observation on the frog is not sufficient for drawing the general conclusion that there is no sex specifity in the erotizing action of the ovary. That this conclusion is erroneous follows from the fact that the psycho-sexual behaviour of the somatically feminized male resembles that of a female. Evidently the hormones of the ovary do not erotize in a male direction, but in a female one. The indications of a female erotization are, according to Steinach, the following: — 1. The feminized male rat exhibits the "tail-reflex" characteristic of the female and consisting in the raising of the tail when followed by the male. Some kind of tail-reflex can be observed also in the normal male and in the castrated male ; but according to Steinach this is not the true tail-reflex characteristic of the female. 2. The feminized male rat is treated by the normal male as though it were a female. The feminized male is followed by the normal male, which makes repeated attempts at coitus. 3. The feminized male, like the normal female of the rat and guinea pig, shows the "averting-reflex," consisting in the 298 INTERNAL SECRETIONS raising of one of the hind legs and moving it for averting the leaping of the male. It must be said that it is very difficult to draw conclusions concerning the psycho-sexual behaviour of the rat and guinea pig. Sand was uncertain as to whether female erotization of his somatically feminized rats really occurred, although there were some indications of this happening; there was no tail-reflex and no averting-reflex. On the contrary, Moore relates that in his experiments some of the male rats with successful ovarian grafts exhibited unmistakable maternal behaviour towards young ones. In the experiments with guinea pigs into which ovaries were successfully engrafted, and which showed a marked hypertrophy of the mammary gland, the same author was uncertain about the occurrence of female erotization; the behaviour of his four feminized male guinea pigs was masculine in every respect. They showed no feminine instincts towards young animals, and even frightened them away when the young made attempts to suck. We see, therefore, con- siderable discrepancy in the results of different investigations. We shall meet with similar disagreement when deahng with the experiments upon mascuHnization. But notwithstanding all these contradictory details, the experiments of Steinach and of his successors leave no doubt that the sexual hormones in the mammal erotize the central nervous system in a sex specific manner. It has been claimed by different authors that the female has a higher body temperature than that of the male {cf. Tiger- stedt, 1910; Przibram, 1923). vSimilar results were obtained by Hans Przibram (1915, 1923) and his pupils (Bier ens de Haan, 1922) on the rat, and by Steinach and myself on the guinea pig {1916 a, 1917 c). Our figures seemed to show also that the body temperature of the castrated female is lower than that of the normal female, whereas the temperature of the castrated male remains unaltered. Steinach stated that the body temperature of the feminized male is as high as that of the normal female. In view of these considerations it seemed justifiable to conclude that there is a feminization of the castrated male by the ovary in regard to body temperature. One might suppose that the sexual hormones act in a specific manner on those parts of the central nervous system upon which the regulation of the body temperature depends; it SEX SPECIFIC ACTION OF HORMONES 299 woiild be an. action similar to that on the sexual reflexes. I should state, however, that I lost confidence in my own measurements on the guinea pig after Bormann, Brunnow and Savary (1923, see also Lipschiitz, 1923 a) in our Institute repeated these experiments on the rabbit. In their experi- ments, performed with great care, there was no difference between the normal male and female; there was also no difference between the castrated and the normal female; Bormann and Brunnow examined rabbits of different ages, as I thought that possibly the sex difference in body tempera- ture would become more pronounced after full sexual maturity was attained. But they found subsequently no difference between male and female in animals of full sexual maturity. The animals were as far as possible of the same litter. Recently Ocaranza (1922) stated that there is no difference in the body temperature of male and female guinea pigs. Steinach's and my conclusions derived from records on the guinea pig are erroneous. Evidently the number of our records was not sufficient, and the individual variation was too great. As Brunnow and Bormann showed, the result of the reading depends largely on technical details, especially on the position of the animal at the time of measurements, and on the depth to which the thermometer is introduced into the rectum. (b) Masculinization, Steinach (19 13) performed experiments with implantation also of testicle into castrated female rats and guinea pigs. The number of successful experiments was very small, but wholly sufficient for demonstrating the sex specific action of the testicle in the body of a female. In one experiment the testicular graft remained in a female guinea pig for more than three years, i.e., as long as some ovarian grafts in the male organism {Steinach, 1916). Similar experiments were afterwards recorded by Sand (1918, pp. 89-91); 'in guinea pigs the grafts underwent resorption, whereas a number of experiments with rats were successful. Successful experiments on the rat and the guinea pig have been recorded also by Moore (1919 a, 1921). We have seen in the preceding section that the development of the teats and mammary glands of the male is induced by the ovarian graft. On the contrary the teats remain unde- veloped rudimentary organs if a testicle is engrafted in a 300 INTERNAL SECRETIONS castrated female. The uterus undergoes atrophy, as in the ordinary "castrate"; some years ago Bucura (1907, 1913, p. 145) observed that a successful testicular graft was not able to prevent the atrophy of the uterus in a castrated female hare. It would be of great interest to determine whether there is also an inhibitory action on the part of the male hormones towards the teat, the mammary glands and the uterus. The influence of the testicular graft on the corpora cavernosa of the clitoris is of an especial interest, the clitoris being trans- formed into a penis-Hke organ (Fig. 120). This I showed (1916 b, 1917 a, 1918) when examining guinea pigs in Steinach's laboratory, and operated on by him a long time ago. The external examination of a female with a successful testicular graft revealed that the urogenital region underwent mascuUniza- tion {Fig. 120 C). In the place of the httle female urethric tubercle, as the prominence in the aperture of the urethra of the female may be termed, there is a long fold of skin. It differs only from a normal male preputium in having a split on the under side. The preputium can be easily drawn back when an extraordinary picture reveals itself {Fig. 120 D). Two red excrescences are seen, which in their mutual posi- tion, their colour and their dimensions, are just like normal corpora cavernosa penis, only their length is much less than in the normal male. Between these excrescences lies the aperture of the urethra, evidently at the normal place for a female. There can be no doubt that it was owing to the action of the male sexual hormones that the corpora cavernosa of the cUtoris grew and changed into corpora cavernosa penis, and that the preputium of the clitoris changed into a preputium of a penis. It is remarkable, however, that the corpus cavernosum urethrae was absent ; the developed organ gave the impression of a totally hypospadic penis. A frontal section through the penis-like organ of the masculinized female would present the appearance of one through the glans of a normal penis. The absence of a corpus cavernosum urethrae might be explained in the following manner. Castration, feminization or mascu- linization is performed on an animal in which the sex characters are already "fixed" to a certain degree. Profound changes take place in the genital region of the male and female animal during the second half of embryonic development. These transformations result in producing the long urethra in the SEX SPECIFIC ACTION OF HORMONES 301 ^ m^ M ' ,;-4fes*^5A" 7;/-$' D Fig. 120.— Influence of testicular transplantation on the clitoris of the guinea pig. A. Normal female guinea pig. B. Castrated female guinea pig. No change. C. Masculinized female guinea pig. D. Masculinized female guinea pig. Praeputium drawn back. A penis-like organ is formed. For details see text. Nat size 302 INTERNAL SECRETIONS male; in the female the vagina between the perineum and the opening of the bladder is formed. We may suppose that these sex characters, already fixed under the influence of the sexual gland, will not be changed in experimental feminization or masculinization in the same manner as during intra- uterine life. This question will be discussed more fully in Chapter XI. Next to the hypertrophied corpora cavernosa of the clitoris in the masculinized female there are two spikes to be found, which are very similar to the horny styles in the cavity of the intromittent sac of the corpora of the normal male. The styles of the masculinized female differ from the normal ones in colour, size and position. The last-mentioned difference may be explained by the absence of the corpus cav. ur. and of the intromittent sac. We have seen in a preceding chapter that the horny styles are to be seen in the prepuberally castrated male as very small spots, or else they are absent altogether; they are much reduced after postpuberal castration. Now we see the reverse of this phenomenon : the engrafted testicle causes formation of horny styles, which are, however, somewhat different from the normal ones. It may be remarked that all these transformations are absent in the ordinary castrated female, and it is clear that they are produced by a sex specific action on the part of the engrafted testicle. When the preputium of the masculinized female is drawn back, one finds the red excrescences covered with a whitish- yellow secretion, evidently a preputial secretion like that present in great quantity especially on the short penis of the prepuberal "castrate" {cf. p. 21). The same factors which cause an accumulation of preputial secretion in the "castrate" are obviously at work also in the masculinized animal. The process of transformation of the clitoris into a penis-like organ under the influence of the testicular graft is different from the process of transformation of the teats and the mam- mary glands in the feminized male, in that the penis-like organ does not attain the normal size and the normal shape of the penis. This question will be discussed more full}^ in Chapter XI. The observations on the penis-like organ of the masculinized SEX SPECIFIC ACTION OF HORMONES 303 female are of interest also in relation to the theory of inter- sexuality.^ (See Chapter IX.) Sand has described (1918, 1919) some observations made by him on a penis-like organ in the mascuHnized rat. In the normal female rat the clitoris is a very rudimentary organ. In masculinized rats, the psycho-sexual behaviour of which was male, Sand found a pronounced hypertrophy of the clitoris, which was transformed into an organ 4 to 5 mm. long, turgescent and full of blood. It may be added, that Sand's observations were entirely independent of mine. Moore (1921) also observed the formation of a penis-like organ in two masculinized guinea pigs (out of 18 animals operated). He relates that the genital region resembled that of the male considerably more than that of the female, and he adds that the condition differed in no material respects from that which I described. On the contrary, Harms (1922, p. 242) states that in his experiments no change took place in the copulatory organ. In view of the observations of Sand and Moore and m^/self the negative result obtained by Harms can only be explained as due to a degeneration of the testicular graft. He supplies no details. As we have seen in the preceding section, there is, according to Steinach, an inhibition of body growth brought about under the influence of the ovary. On the contrary, the testicle seems to favour body growth {Fig. 121). The masculinized guinea pig of Steinach, which I myself also observed, was much bigger than a normal female or an ordinary female "castrate"; its proportions were more those of a normal male. According to Steinach there may be even an hypermascuKnization in the growth of the skeleton and body generally. But the same objections may be made to this conclusion as to the similar conclusions about the feminized male (see p. 295). Moore (1919) claims that there was little evidence that the engrafted testicle affected the weight of rats ; on the other hand, Stotsen- burg (quoted from Moore, 1919, 1922) showed that removal of the testicle does not influence the body growth of the rat, 1 Recently we stated that an hypertrophied clitoris and horny styles some- times are present also in otherwise normal female guinea pigs. I saw four animals of this kind. The hypertrophy was however mostly not so pronounced as in the masculinized animal. The internal organs were quite normal. The phenomenon is an hereditary one. An offspring of one of the above animals showed the same phenomenon. We have not yet made a detailed investiga- tion of the problem which is indeed of a very great interest. w 304 INTERNAL SECRETIONS whereas removal of the ovary causes an increase of 17 to 30 per cent, above that of the normal females. So Moore (1919) considered the possibility that the greater weight of the masculinized guinea pig was caused rather by removing the ovary than by engrafting the testicle. But new experiments of Moore (1922) showed that his criticism was by no means justified, as castrated female guinea pigs attained only the same weight as normal ones. Steinach describes also differences in the coat of the normal and masculinized females, claiming to have observed a trans- formation of the fine and soft hair of the female into the coarse and rough hair of the male. masculinized castrated normal normal female. female. female. male. Fig. 121. — Influence of testicular transplantation on size 0/ female guinea pig, — From Steinach. The psycho-sexual behaviour of the masculinized female guinea pig of Steinach was decidedly male. I had the oppor- tunity of observing this animal under different conditions. When a female on heat was put into its cage it behaved towards the female like a normal male, and followed her about. The characteristic call of the male was emitted. Moreover, towards an ordinary male the masculinized female behaved like a rival male and vigorously fought it. The psycho-sexual behaviour of masculinized rats has been systematically studied by Sand who attributed their behaviour to the engrafted testicle. Moore also has described the psycho-sexual behaviour of masculinized guinea pigs, and his observations fully corrobo- rate those described above. In view of all this it is clear that SEX SPECIFIC ACTION OF HORMONES 305 the testicular graft may cause a masculinization, not only of the somatic sex characters, but also of the psycho-sexual behaviour. The masculinization of a female stag was brought about by Brandes. The female showed the "Adam's apple," which is characteristic of the male, and jumped like a male. There were signs of a beginning of horn growth on the forehead. Microscopical examination has shown that the testicular graft in females often undergoes a degeneration in the semini- ferous part. There is frequently a more or less complete degeneration of the tubules, and an increase of the interstitial cells, as in auto- and homoiotransplantation. In the fore- going section of this chapter we saw that there may be certain indications of an hyperfeminization, as seen in the great development of the mammary glands. We have explained this hyperfeminization as due to the histological changes which the ovarian graft undergoes ; an increased number of endocrine cells caused by intense folicular atresia is the factor involved. Now the question arises as to whether there is a correspondence between the histological changes in the graft and the hormonic effect produced in the masculinized female. According to Steinach (19 16) the vigorous psycho-sexual behaviour of the masculinized female and its greater size and weight are to be considered as signs of an hypermasculinization caused by an increased activity of the interstitial cells, which are now present in an augmented number. On comparing the histological results of eight experiments on rats, Sand came to the conclusion that the degree of masculinization of the female (psycho- sexual behaviour and hypertrophy of the clitoris) is the more intense the greater the number of the interstitial cells in the testicular graft. But against all these quantitative conclusions may be set the same objections as were considered in Chapter IV., in describing other experiments with transplantation as well as observations on cryptorchid animals. The question has been lately discussed by Moore (1921) who describes microscopical sections of testicular grafts in two cases of masculinization in guinea pigs. There was little or no hypertrophy of the interstitial cells in one case, the germinal epithehum being not so greatly degenerated as usually in testicular grafts. There was a considerable degeneration of the seminiferous tubules in the second case, the entire mass of germinal epithelium having disappeared, and only a single 306 INTERNAL SECRETIONS layer of cells being present. There was a wide separation of the degenerated tubules by large threads of interstitial tissue, consisting of well-stained cells of Leydig. As to the degree of mascuhnization, the second animal showed a slightly less pronounced transformation in regard to the psycho-sexual behaviour and the external genital organs. Since the inter- stitial cells were present in greater abundance, Moore concludes that his observations do not support the theory of these cells being the seat of the endocrine function of the testicle. But as we have seen in Chapter IV., the reaction of the soma to the male sexual hormones seems to be governed by other quantitative laws than those postulated formerly ; and in view of these considerations Moore's conclusions can hardly be accepted. * * * All the experiments recorded above, in which a gonad of one sex was engrafted into the castrated organism of another sex, leave no doubt, that in mammals one and the same organ or tissue reacts in a different manner to the hormones of the gonad according to the sex of the latter. This means that the sexual hormones of the testicle act differently from those of the ovary, or that the sexual hormones act in a sex specific manner. The same conclusion can be also demonstrated by engrafting the gonad of one sex into the uncastrated organism of the other sex. We shall deal with this matter in Chapter IX. Experiments on castration have shown that after removal of the sex gland the male and female organisms converge to a type common to both sexes; the experiments recorded in this chapter show that the "castrate," which approaches the asexual or neutral type, becomes more or less transformed somatically into the sex to which the engrafted gonad belongs. All these experiments support the theory that there is in mammals during embryonic development an asexual soma identical for all individuals, and that this becomes trans- formed into the male or female type after a differentiation of the endocrine apparatus of the gonad has taken place, and after the sexual hormones have begun their action of stimulating or inhibiting the growth of the different tissues. Objections have been raised to this hypothesis on the ground that there is never a complete reversal of one sex into the SEX SPECIFIC ACTION OF HORMONES 307 other after heterosexual implantation. These objections will be dealt with in Chapter XI. 2. Experiments on Fowls. Castration of the fowl leads to the conclusion that there is an asexual or a neutral form common to both sexes, which is transformed by the action of the hormones of the ovary, or of the testicle into the female or the male type. We learned from the experiments that the plumage and the spurs are hardly influenced by the hormones of the testicle, whereas they are much changed by the hormones of the ovary. This conclusion has been confirmed as a result of numerous ex- periments by Goodale, performed on the cock and the drake. Similar experiments have been performed by Pezard and Zawadowsky. Goodale (19 14, 19 16) castrated a Brown Leghorn cockerel twenty-four days old and engrafted into this bird the ovaries from two pullets of the same strain; the ovaries were cut in several pieces and dropped into the abdominal cavity without any attempt to suture the pieces in position. The immature plumage of the male Brown Leghorn resembles that of the female; later on the characteristic male plumage appears. We saw in Chapter II. that this is true also for the ordinary "castrate," which acquires the brilliant male plumage. On the contrary, a castrated cockerel with an ovarian graft had the plumage of a hen (Fig. 122). "The bird was shown to several experienced poultrymen without knowledge of the history of the case, and they all pronounced it a female." The spurs, which remain unchanged in the capon, were in Goodale's operated cockerel undeveloped for a long time. There was no doubt that a feminization of the castrated cockerel had taken place under the influence of the ovarian graft. During the next spring some changes took place, showing that the influence of the ovarian graft was an incomplete one, or else that this influence began to decline ; there was possibly also an effect due to small regenerating pieces of testicle. The comb and wattles began to grow and became very red. The bird was observed to crow and to tread the hens. The spurs attained a length of one inch. The weight approached that of a hen. The plumage remained a female one; there were, however, some deviations from the normal female plumage, but "no trace of any of the 3o8 INTERNAL SECRETIONS male feather characters" was seen. The bird was killed a year after the operation ; ovarian tissue was found in the abdominal cavity in different positions. No oviduct and no vasa deferentia were detected. Later on Goodale (1918) described further experiments with successfully feminized cocks. The results were similar to those described above. There were, however, differences in the con- dition of the various individuals. Goodale points out that in the second series of experiments the spurs were well developed, whereas the bird mentioned above showed an inhibition, though not a complete one, of the growth of the spurs. The Fig. 122. — Feminized cockerel. Female plumage. — From a photo kindly lent by Goodale. body-size resembled that of the male. The psycho-sexual behaviour was in some of the experimental birds more or less like that of a normal cock, whereas in others no sexual instincts were to.be observed. On the contrary, the comb, wattles and plumage became indistinguishable from that of a female. In discussing the results of these experiments Goodale deals with three different possibilities: (i) that the portion of the ovar}/ which survived the implantation was not sufficient to control the sex characters entirely; (2) that there was a different genetic basis in each bird, so that each individual reacted differently to similar hormones; (3) that a portion of SEX SPECIFIC ACTION OF HORMONES 309 the testicle remained in the feminized animal. The latter conclusion is, I think, the most probable. Experiments per- formed by Pezard support this assumption. In an experiment in which ovaries were implanted in a castrated cockerel, Pezard (1918, pp. 147-52) described a slower growth of the spurs, whereas the comb and the plumage remained male. The sexual instincts, which disappeared after the operation, reappeared later. The autopsy showed that the castration of the cockerel was an incomplete one. It is possible, however, that the slower growth of the spurs was caused by the engrafted ovary exerting a feminizing action for a certain time. Pezard performed also experiments upon the trans- plantation of testes into castrated hens; but here too castration was not completely effectual. Both hens with en- grafted testicles exhibited a female plumage; no spurs were present. But in one case the comb was much bigger than in a normal or castrated hen, and the curve of growth of the comb resembled that of a normal cock. Evidently there was an endocrine action on the part of the engrafted testicle in the incompletely castrated hen, a condition of hermaphroditism or intersexuality such as possibly existed also in some of the above-mentioned experiments by Goodale. Such a condition of hermaphroditism was apparently present also in older experiments of Foges (1903, pp. 53-54; 19^4^ P- 383; 1920). Having engrafted testes into a hen (most likely a normal or an incompletely castrated one) Foges observed a growth of the comb and wattles similar to that in a cock. Owing to the insufficient knowledge of endocrinology at that time Foges* results could not be explained as due to the simultaneous presence of both the male and the female gonad. Feminization experiments have been carried out by Goodale (1918) on five drakes, of which three were definitely feminized. The plumage resembled that of the normal female, excepting that some feathers preserved the male characters. The femini- zation of the plumage was especially pronounced on the head and on the neck. The curl in the tail which characterizes the normal or the castrated drake was absent in the feminized animals as in the normal duck, although the feathers concerned were present; further, in the feminized bird these feathers were not black as in the normal drake, but brown or yellowish brown. In two feminized birds the sexual instincts were 310 INTERNAL SECRETIONS changed by the ovarian graft. Whereas the castrated drake preserves the male voice, that of the feminized birds was not a male one, but was something between the male and female voice, or a sort of broken "quack." Feminization and masculinization experiments on the fowl were performed about four or five years later by Zawadowsky (1922, 1923). Abdominal implantation of ovary into the castrated cock was successful in two cases out of six. There was a complete feminization in regard to plumage, shape of body, and voice ; the growth of the spurs was inhibited to a certain degree; certain sexual instincts remained un- changed. There were three successful mascuhnization experi- ments. The engrafted testicles (subcutaneous transplanta- tion) developed in one case so well as to increase in length four to five times in a month and a half. Histologically the graft represented a fully developed testicle with spermatozoa. The comb began to grow as soon as ten days after the operation. The general behaviour was that of a male. The mascuhnized hen spreads out the tail and wings, and follows the hens with rapidity and great persistence, offers them food with a truty masculine gallantry, and crows with a clear, well developed male voice. In view of these experiments the existence of a sex specific endocrine action on the part of the ovary and of the testicle in birds is beyond any doubt. The differences in details in the various experiments are of small moment. We must bear in mind that the result of each experiment may depend on the time at which the heterosexual implantation is made, and possibly also on the quantity of the hormone. We shall deal with this question more fully in Chapter XL Very important experiments on the sex specific action of the gonad in fowls have been performed by Minoura (1921) in the laboratory of Lillie. Minoura engrafted testicles and ovaries on the surface of the chorio-allantoic membrane of hens' eggs cutting out a small piece of the shell and replacing that piece and sealing it with paraihn after effecting the graft. In a great many cases the graft "took" and became well vascularized; there was a growth of the seminiferous tubules or a development of the follicles consisting of oocytes sur- rounded \>Y granulosa cells. The best results were obtained when the graft was made in the second week of incubation. SEX SPECIFIC ACTION OF HORMONES 311 The embryos were dissected at about two weeks after im- plantation. "Whenever the grafts exhibited a good growth the embryos were affected, but when the grafts grew sHghtly or not at all the resulting embryos were nearly normal or apparently not affected." By affected embryos Minoura means those in which male and female characters were present simultaneously. Whereas both Miillerian ducts completely disappear in the normal male embryos in the third week of incubation, there were in the experiments of Minoura embryos with testicular grafts, having gonads in siiti of the male type and at the same time Miillerian ducts; or there were embryos with testicular grafts, having gonads of the female type, but with a deviation from the normal, in as much as the right gonad also developed, and at the same time the Miillerian ducts were not differentiated to the normal extent; in many cases where testicular grafts were made Wolffian ducts more or less of the male type were present simultaneously with Miillerian ducts. On the other hand embryos with ovarian grafts revealed gonads of the male type with Miillerian ducts partially differentiated as in the female, or gonads of the female type with Wolffian ducts more of the male type. Where the engrafted gonad was a testis, the Miillerian ducts were undifferentiated and showed signs of degeneration. Where the grafted gonad was an ovary, the Miillerian ducts were retained, degenerative changes in the ducts were absent, and the left duct was better developed and more differentiated than the right one. It is naturally impossible to say to which sex the individual egg originally belonged. But there are some indications as to this. The presence and degree of differentia- tion of the Miillerian ducts in embryos with testicular grafts and gonads of the male type can be only explained by the assumption that these embryos originally developed and differentiated to a certain extent in the direction of femaleness but that their original ovaries became transformed under the influence of the testicular graft into gonads of the male type. Minoura rightly concludes from his experiments "that the sexual characters are reversible and that these characters after having differentiated to a certain extent in the direction of one sex may be altered and modified in the direction of the opposite sex . . . the development and differentiation of one sex is stimulated by the secretion of the gonads of the same 312 INTERNAL SECRETIONS sex and inhibited by the secretion of the gonad of the opposite sex." It is of great interest to note that the castrated hen or duck can acquire some male characters which depend normally upon the internal secretion of the testicle. Such observations were made by Goodale (hens and ducks), by Pezard (hens) and by Zawadowsky (hens). In the experiments of Goodale the comb developed in castrated hens in varying degrees, becoming very large and male-like in some of them, but remaining com- paratively small in others; there is according to Goodale no clear evidence as to the cause of this difference. The trans- formation of female characters into male ones seems to be related to a transformation of the rudiment of the sex gland on the right side in the female bird. Now Zawadowsky (1922, p. 82) observed a development of male sex characters (comb, wattles, and, to a certain degree also, sexual activity) in castrated hens in which there was no transformation of the right rudiment. One of his castrated hens showed a growth of the comb as in the male. In this bird a regeneration of the left ovary occurred, but no ova were present. After removal of this regenerated gland a regression of the comb took place as in the ordinary "castrate." Zawadowsky concludes from these observations that the ovary may in certain circumstances elaborate male sexual hormones. The question arises as to whether the specific hormonic effect characteristic of the testicle or the ovary can be exhibited also by other endocrine glands. It cannot be denied that in every specific hormonic effect produced by the gonads other endocrine glands are actively involved; but there is no ex- perimental evidence that a sex specific action similar to that of the gonad is exhibited by other glands, with the one possible exception of the adrenals. We shall deal with these questions below in the chapter on "Intersexuality." C. EXPERIMENTS ON ARTHROPODA. Experiments on moths have been performed by Meisen- heimer (1909) and Kopec (1912). Meisenheimer castrated the male Lymantria dispar at the caterpillar stage and implanted ovaries. The latter developed quite normally, but the animals never showed any transformation of the sex characters. The vasa deferentia, the vesicles, the accessory glands and the SEX SPECIFIC ACTION OF HORMONES 313 ductus ejaculatoriuswere always normal. Kopec made similar feminization and masculinization experiments using younger caterpillars than those employed by Meisenheimer (cater- pillars immediately after the first moulting); he also made repeated transplantation experiments. The grafts "took" and the testicles even showed an hypertrophy; histologically they were like the normal organ. But no influence of the engrafted testicle or ovary on the host of the other sex was ever seen. Injections of blood or of a pulp from the gonad of the other sex into castrated caterpillars made by Kopec also had no influence even though great quantities were injected. Experiments on the fiddler crab have been performed by Morgan (1920). Boring a hole in the carapace of the male crab he inserted pieces of the ovary taken from a female fiddler; he also did the converse experiment. The small pieces engrafted often got lost, and it coald not be determined subsequently how far the graft degenerated and how far it grew, but no effect was ever produced on the claws. The state of things in the Arthropoda seems to be wholly different from that in mammals. It is of course conceivable that in the Arthropoda the endocrine cells which produce the sexual hormones are widely separated from the gonad or the generative cells. BIBLIOGRAPHY FOR CHAPTER VI. [* Not seen in the original.] Athias. 1915. L'activite secretoire de la glande mammaire hyper- plasee, chez le cobaye male chatre, consecutivement k la greffe de I'ovaire. C. R. de la Soc. de Biol, 78, p. 410. 1916. Sur le determinisme de I'hyperpiasie de la glande mam- maire et de la secretion lactee. C. R. de la Soc. de Biol., 79, p. 557. BiERENS DE Haan. 1922. Die Korpertemperatur jmiger Wander- ratten (Mus decmnanus) und ihre Beeinflussimg durch die Temperatm- der Aussenwelt. Arch. f. Entw.-Mech., 50, p. 1. BoRMANN. 1922. tJber die Folgen der Kastration in ihren zeitlichen Beziehungen. Skandinav. Arch. f. Physiol., 42, p. 240. Brunnow und Savary. 1923. Uber den Unterschied in der Korpertemperatur beim mannlichen luid weiblichen Kanin- chen und fiber die Abhangigkeit der Korpertemperatur von den Geschlechtsdriisen. Skandin. Arch. /. Physiol, 4:4:, p. 248. 314 INTERNAL SECRETIONS Brandes. 1914. See Berliner Tageblatt, 7th June, 1914 (No. 283, 2 Beiblatt); Kammerer, Geschlechtsbestimmung und Gesch- lechtsverwandlung. Wien, 1918, p. 77; Hirschfeld, Sexual- pathologie, II., Bonn, 1918, p. 100. Bresca. 1910. Experim. Untersuchungen iiber die sekund. Sexual- charaktere der Tritone^. Arch. f. Entw.-Mech., 29, p. 403. *BucuRA. 1907. Beitrage zur inneren Funktion des weiblichen Genitales. Zeitschr. f. Heilkunde, 28. 1913. Geschlechtsunterschiede heim Menschen. Wien-Leipzig. CAUiiLERY. 1913. Les prohlemes de la sexualite. Paris, p. 113. Donaldson. 1915. The rat. Philadelphia. -FoGES. 1903. Zur Lehre von den sekundaren Geschlechtscharak- teren. Pfliigers Archiv, 93 (see espec. p. 53a, 54). 1914. Keimdriisen. In Jauregg und Bayer, Lehrhuch der Organotherapie, Leipzig, 1914, p. 383 u. 384. 1920. Historischer Beitrag zum experimentellen Hermaphro- ditismus. Zentralbl. f. Gyndkol., 44, p. 87. Gerhardt. 1909. Der gegenwartige Stand der Kenntnisse von. den Kopulationsorganen der Wirbeltiere, insbesondere der Am- nioten. Ergebnisse u. Fortschritte d. Zoologie. Good ALE. 1914. A feminized Cockerel. Science, 41, p. 594. 1916. A feminized cockerel. Jl. of Exper. Zoology, 20, p. 421. 1918. Feminized male birds. Genetics, 3. Grtjbbr. 1907. Bau und Entwicklung der ausseren Genitalien bei Cavia coboya. Morphol. Jahrbuch, 36. Harms. 1910. Hoden- und Ovarialinjektionen bei Rana-fusca- Kastraten. PfliXgers Archiv, 133. * 1921. Verwandlung des Bidder'schen Organs in ein Ovarium beim Mannchen von Bufo vulgaris Laur. Zool. Anz., 53, p. 253. 1922. Keimdriisen und Alterszustand. Berlin-Wien. {Fortschr. d. naturwissensch. Forschung, 11, p. 189.) 1923 a. Die physiologische Geschlechtsumstimmung (Demon- stration). Verhandl. d. Deutschen Zool. Gesellsch., 28, p. 37. 1923 b. Untersuch. iiber d. Bidder'sche Organ der mannl. u. weibl. Kroten. II. Mitt. Die Physiol, des Bidder'schen Organs u. d. experimenteilphysiolog. Umdifferenzierung vom Mannchen in Weibchen. Zeitschr. f. Anat. u. Entw. -Gesch., 69, p. 598. Kammerer. 1919. Steinachs Forschungen iiber Entwicklung, Be- herrschung und Wandlung der Pubertat. Ergebn. d. Inneren Medizin u. Kinderheilk, 17, p. 295. Kope6. 1912. Untersuchungen iiber Kastration und Transplantation bei Schmetterlingen. Arch. f. Entw.-Mech., 33, p. 1. SEX SPECIFIC ACTION OF HORMONES 315 LiPSCHUTZ. 1914. Steinachs Forschungen iiber Feminierung und Maskulierung. Umschau. 1916a. Korpertemperatur als Geschlechtsmerkmal. Anzeiger d. Akad. d. Wissensch., Wien, No. 22. 1916b. Entwicklung eines penisartigen Organs beim masku- lierten Weibchen. Anzeiger d. Akad. d. Wissensch., Wien, No. 27. 1917a. On the internal secretion of the sexual glands. J I. of Physiology, 51. 1917b. Uber die Abhangigkeit der Korpertemperatur von der Pubertatsdriise. Pflilgers Archiv, 168. 1918. Umwandlung der Clitoris in ein penisartiges Organ durch experimentelle Maskulierung. Arch, /. Entw.-Mech., 44. BoRMANN, Brunnow ct Savary. 1923 a. Sur la question des differences de temperature entre les deux sexes. G. R. de la Soc. de Biol, 88, p. 1261. et Krause. 1923 b. Recherches quantitatives sur I'hermaphro- disme experimental. C. R. de la Soc. de Biol., 89, p. 220. 1923 c. Temps de latence dans I'hermaphrodisme experi- mental. C. R. de la Soc. de Biol., 89, p. 1135. Meisenheimer. 1909. Experimentelle Studien zur Soma- und Gesch- lechtsdifferenzierung, I. Jena. 1912. Experimentelle Studien zur Soma- und Geschlechtsdiffe- renzierung, II. Jena. MiNOTJRA. 1921. A study of testis and ovary grafts on the hen's egg and their effects on the embryo. Journ. of Experim. ZooZ., 33, p.l. Moore. 1919a. On the physiological properties of the gonads as controllers of somatic and psychical characters. I. The rat. Journ. of Experim. Zool., 28, p. 137. 1919b. II. Growth of gonadectomized male and female rats. Journ. of Experim. Zool., 28, p. 459. 1921. IV. Gonad transplantation in the guinea-pig. Journ. of Experim. Zool., 33, p. 365. 1922. V. The effects of gonadectomy in the guinea-pig, on growth, bone lengths, and weight of organs of internal secre- tion. Biol. Bulletin, 43, p. 285. Morgan. 1920. Variations in the secondary sexual characters of the fiddler crab. American Naturalist, p. 220. 3i6 INTERNAL SECRETIONS Myers. 1917. Studies on the mammary gland. III. A comparison of the developing mammary glands in male and female albino rats from the late fetal stages to ten weeks of age. Anatomical Record, 13. OcARANZA. 1922. La temperatura normal del cuy de nuestros laboratorios. Revista Mexicana de Biologia, 3, p. 53. Pezard. 1918. Le conditionnement physiologique des caracUres sexuels chez les oiseaux. These, Paris. Edition du Bull. Biol, de la France et de la Belgique. (See esp. p. 147-152). Sand et Caridroit. 1923. Feminisation d'un coq adulte de race Leghorn dore. C. R. de la Soc. de Biol., 89, p. 947. PoNSE. 1923. Masculinisation d'une femelle de crapaud. C. R. de la Soc. de phys. et d'hist. nat. de Geneve, 40, Nr. 3. Przibram (Hans). 1915. Die Umwelt des Keimplasmas. VI. Direkte Temperaturabhangigkeit der Korperwarme bei Ratten. Anzeiger d. Akad. d. Wissensch, Wien, No. 25. 1923. Temperatur und Temperatoren im Tierreiche. Leipzig- Wien. Sand . 1918a. Experimentelle Stvdier over Kcjynskarahterer hos Pattedyr. Copenhagen. 1918b. Experimenteller Hermaphroditismus. PfiiXgers Archiv, 173. 1919. Experiments on the internal secretion of the sexual glands, especially on experimental hermaphroditism. Journ. of Physiology, 53, p. 267. See also Bibliography of Ch. IX. ScHULTZ. 1910. Verpflanzungen der Eierstocke auf fremde Spezies, Varietaten u. Mannchen. Arch. f. Entw.-Mech,, 29, p. 79. Steinach. 1910. Geschlechtstrieb und echt sekundare Geschlechts- merkmale als Folge der innersekretorischen Funktion der Keimdriisen. Zentralhl. /. Physiologic, 24. 1912. Willkiirliche Umwandlung von Saugetier-Mannchen in Tiere mit ausgepragt weiblichen Geschlechtscharakteren und weiblicher Psyche. PfiiXgers Archiv, 144. 1913. Feminierung von Mannchen und Maskulierung von Weibchen. Zentralhl. /. Physiologic, 27. 1916a. Pubertatsdriisen und Zwitterbildung. Arch. /. Entw.- Mech., 42, p. 307. und HoLZKnsTECHT. 1916b. Erhohte Wirkungen der inneren Sekretion bei Hypertrophic der Pubertatsdriisen. Arch. f. Entw.-Mech., 42, p. 490. SEX SPECIFIC ACTION OF HORMONES 317 TiGEBSTEDT. 1910. Die Produktion von Warme und der Warme- haushalt. Handbuch der vergleich. Physiol., III. 2. Jena. Wagner. 1922. Experimentelle Untersuchungen liber die Um- wandlung des Geschlechts beim Frosch. Arch. f. Entw.- Mech., 52, p. 386. Zawadowsky. 1922. Das Geschlecht und die Entwicklung der Oesch- lechtsmerkmale. (Russian with Summary in German.) Mos- cow, State edition. 1923. The sex of animals and its transformation, (Russian.) Moscow-Petrograd, State edition. Chapter VII. The Question as to the Isolation of the Sexual Hormones. A. EXTRACTS OF THE WHOLE SEX GLAND. In Chapter HL we considered the experiments which have been made upon the injection of the sexual glands and their extracts to show how greatly our knowledge of internal secretion has been influenced thereby. We must never forget that it was through the experiments of Brown-Sequard^ with subcutaneous injection of testicular extracts that our know- ledge not only of the internal secretion of the sexual glands, but of internal secretion in general began. It is well known that the experiments of Brown-Sequard have been much disputed; we have already discussed this question at some length in the third chapter. But notwithstanding all the objections which have been made, the fact remains that here, as so often in the history of science, new scientific principles and new knowledge were established on disputed, or even really erroneous, data. After Brown-Sequard, repeated attempts were made to obtain from the gonads the chemical substances corresponding to the sexual hormones. The determination of the characters of these substances by an elementary chemical analysis, or the establishment of their chemical constitution was not attempted until later. Several investigators, however, tried to isolate the hypothetical hormones from the gonad. The great thera- peutical successes with preparations of the thyroid, and the new exact knowledge of adrenaline gave a powerful incentive to similar attempts to isolate the internal secretions of the gonads. But so far the results of all recorded experiments with injecting these extracts have been disappointing. It is true that many effects have been described — effects on the nervous system, on the circulation, on the metabolism, and 1 On the role played by Brown-Sequard in the estabhshment of endo- crinology see G/ey'5 book (1914), especially p. 22. 319 X 320 INTERNAL SECRETIONS on the sex characters. But the observations of the different investigators disagree very considerably. This is easy to understand if one takes into consideration the fact that the chemical nature of the various extracts must differ greatly according to the special technical methods of preparation. The disagreement is so great that we find one authority attributing to the extract of the gland the capacity for raising the blood pressure, and another describing precisely the opposite effect. Biedl (1913, p. 292 of Vol. II.) has strongly criticised all these experiments, pointing out that very probably the effects obtained by these extracts, which are considered as specific of sexual hormones, are often nothing else than effects which can be obtained with extracts of any organ. Possibly profound chemical alterations take place when an extract is made, and we must suppose that the extract contains different products derived from the common proteins of the respective organ. It is known that these derivatives of proteins may have toxic effects on the organism. These products are characteristic not of certain proteins, but of proteins in general. The severe verdict of Gley (19 14, p. 43) on the experiments concerning the effects of organic extracts in general seems to be justified for the experiments made with extracts from the sex glands: "presque tons les travaux faits depuis quinze ans sur cette question I'ont ete avec une methode, non pas absolu- ment defectueuse, mais incomplete, done insuffisante."^ It cannot be denied that it is possible to produce with extracts from the sex glands some specific effects characteristic of these glands in situ, as was shown in Chapter III., especially for the frog. Similar specific effects of sexual hormones have sometimes been obtained also by injection of these extracts into birds and mammals. The reappearance of the turgor of the comb and of the sexual instincts after injection, as in the experiments of Pezard (1911), may be mentioned here. We have noted also the successful experiments of Bouin and Ancel (1906) on injected guinea pigs, and we shall describe in this chapter similar experiments by Fellner and Herrmann on rabbits. But on the other hand one must never forget that the effect of an extract, as already remarked, varies much according to the rnethods used for its preparation, and this is ^See also the new edition of Biedl's "Internal Secretion'' (1922); the book of Maranon (1922, ch. XI.) may also be consulted here. ISOLATION OF SEXUAL HORMONES 321 why we must be very careful in drawing conclusions about such experiments. The impression one gets when reading of- the contradictory results obtained by different authors with extracts of testes, ovaries, placenta and foetus is not a favour- able one (see especially Gley, 1914, p. 42). Further, such experiments are of a scientific value only when simultaneously controlled- by experiments made with extracts from other organs prepared in just the same manner without any technical deviation. But even in this case the value of injection experi- ments must remain a very limited one, because these experi- ments are liable to give a very erroneous idea of the effects of the sexual hormones produced by the gonads in the organism. It is most likely that the extract contains only some of the substances which normally are secreted by the sex glands; most probably the manifold effects produced are due to different hormones being secreted. There is little justification for supposing that there is one male and one female sexual hormone; as little justification as there would be in supposing that adrenaline is the only hormone secreted by the adrenals. Further, we have already mentioned the possibility that by introducing extracts into the body, substances are introduced which normally are never secreted by the sex glands. It must also be taken into consideration that it is not possible to imitate by injection the real quantitative and time relations of the normal glandular function, to imitate, so to speak, the rhythm of the normal function. There can be no doubt that the normal functional rhythm of an endocrine gland is of the greatest importance to the organism, and we must suppose that the effects of the substances by which one organ acts on another are subject to the general laws of stimulation. Quanti- tative and time relations in internal secretion have so far been very insufficiently studied on an experimental basis. But we have seen in the foregoing chapters to how great an extent quantitative problems are involved in investigating the internal secretion of the sex glands. The experiments of Pezard, as well -as our own, made on more or less quantitative Unes, showed from the beginning that we are here on an almost wholly unexplored terrain, where many special problems await to be investigated. 322 INTERNAL SECRETIONS B. EXTRACTS OF DIFFERENT PARTS OF THE SEX GLAND. The question as to the effects of extracts of the sex gland becomes still more complicated if we take into consideration the probability that different parts of the testicle and of the ovary are involved in the endocrine functions of these organs in different ways, as we have seen already in Chapters IV. and V. Many experiments have been made dealing with this problem. In Chapter III. we have discussed similar experi- ments by Bouin and Ancel on the guinea pig, and by Pezard on the cock. In these experiments crypt orchid testicles have been employed for the preparation of extracts. Since all the higher stages of spermatic cells were absent in these testicles, as shown by histological examination, the experi- ments give further support to the assurhption that the produc- tion of sexual hormones is possible without maturation of the generative part taking place. The negative results obtained by Bamabo (quoted from Harms, 1922), who, in experiments similar to those of Bouin and Ancel, used extracts prepared from testicles after resection of the vas deferens, do not nullify this conclusion, since they may quite easily have been due to the mode of preparation of the extract. The experiments of Pezard are of especial interest also in another respect. Since the growth of the comb and of the wattles in the capon can be promoted by injecting an extract prepared from the retained testicle of the pig, it is shown by these experients that the sexual hormones are not specific for each kind of animal. There is a "sex specifity," but not a specifity for the particular species. The question as to the effects of extracts prepared from different parts of the ovary has attracted much more interest on account of the great practical significance of these problems in gynaecology. As far as I know the first experiments with injection of corpus luteum were those performed by Fraenkel (1903, p. 491; 1910, p. 753). This investigator introduced these extracts into medical practice in the form of tablets prepared from the corpus luteum of the cow. Similar experi- ments have been made by several others. We need not discuss here the many details concerning the use and the results of this treatment in gynaecological practice, but the ISOLATION OF SEXUAL HORMONES 323 papers of Fraenkel (1914, p. 692), Foges (1914, pp. 401, 407), and Blair Bell (1920) may be referred to. Most authorities claim to have observed specific effects from extracts of corpus luteum, but the results seem to be contradictory. This we can easily understand, since the effects, as explained above, must vary according to the mode of preparation. As to the chemical isolation and definition of the specific sexual hormones the experiments of Fellner and of Herrmann are of an especial interest. These experiments will be dealt with below. Iscovesco (quoted from Herrmann and Stein, 19 16) first drew attention to the action of lipoid-containing extracts of endocrine organs. He succeeded in producing a very marked increase of the volume of the uterus by injecting an extract prepared from the ovary by treating it with alcohol and then desiccating the alcoholic extract and treating with acetone, ether and chloroform. This was the method followed by Fellner and Herrmann. Fellner (1913) worked with extracts of placenta, of ovaries of pregnant animals containing corpora lutea, and of ovaries of non-pregnant animals. He used for extraction a solution of sodium chloride, alcohol and ether. He stated that injection of extracts from pregnant animals caused in rabbits an hyper- aemia and a thickening of the muscle layer of the uterus. The epithehum thickened and the number of uterine glands increased. There was an increased growth of the mammary glands and of the nipples ; this phenomenon could be observed even in injected male animals. On the contrary, extracts of ovaries of non-pregnant animals had no effect. But ex- tracts of testicle and of thymus had an effect similar to that of organs of pregnant animals. Extracts of the brain were without any effect. Fellner thinks that the specific substance which causes the above-mentioned effects is possibly a lipoid present in the corpus luteum in greater quantity than in other organs. In recent papers Fellner (1917, 1920) puts forward the view that the hpoid which he isolated from the corpus luteum is really the specific sexual hormone or possibly one of the sexual hormones secreted by this organ. Of great interest are the later experiments of Fellner, in which he investigated the question as to whether the same substance is present also in the interstitial cells of the ovary. He prepared 324 INTERNAL SECRETIONS an extract from that ovary of the pregnant cow which contains no corpus luteum, but in which the interstitial tissue is highly developed during pregnancy. The extract showed a very marked effect on the uterus. Since such an ovary differs from the ovary of a non-pregnant cow^ only in the fact that the interstitial tissue is hypertrophied, Fellner is inclined to adopt the view that the interstitial cells of the ovary of the pregnant animal secrete the same substance as the corpus luteum. Fellner even suggests that the action of the inter- stitial cells of the ovary during pregnancy is quantitatively similar to that of the corpus luteum. When comparing the intensity of the effect of an extract prepared from the corpus luteum excised from the ovary with that of an extract pre- pared from the whole lutein-containing ovary of the pregnant animal, Fellner found that the intensity in the second case was greater than in the first. He explains this result by as- suming that in the second case the effect was produced by the combined action of the lipoids extracted from the corpus luteum together with the lipoids of the interstitial cells, whereas in the first case only the lipoids of the corpus luteum were present in the extract. Finally Fellner states that an extract of a corpus luteum of a non-pregnant animal has quantitatively the same effect as that of a corpus luteum of a pregnant animal. The result of these experiments of Fellner may be explained also by the fact that there is in the ovary during pregnancy an intensified development and atresia of follicles, from which interstitial cells are formed. As we have seen in Chapter V., this explanation is in reality identical with Fellner 's. In all the above-mentioned experiments the augmentation of the uterus was made use of as a quantitative test of the hormonic effect of a given extract. By the same method Fellner arrived at the conclusion that the extract of a placenta is equivalent to that of an extract of forty corpora lutea. There were never any changes in the kidneys. Though there was a great hypertrophy of the mammary gland, milk secretion was never observed. Herrmann (1915) investigated the effects of extracts pre- pared by ether. He made a comparative study of extracts of corpora lutea excised from ovaries, of extracts of ovaries without corpora lutea and of extracts of the placenta. By ISOLATION OF SEXUAL HORMONES 325 different chemical methods Herrmann obtained a thick yellow oil which became solid when cooled. This substance showed the characteristic reactions of cholesterine and contained carbon, hydrogen and oxygen. According to Herrmann it is possibly a derivate of cholesterine, soluble in alcohol, ether, petrol-ether, acetone and benzol, but insoluble in water. Herrmann examined the physiological effects of all the dif- ferent fractions obtained in preparing the above-mentioned oily substance. The experiments were made on fully grown castrated rabbits and on young animals eight weeks old. By injecting the extracts the atrophy of the uterus which normally follows castration was inhibited, and the changes characteristic of the normal "heat" took place in the uterus. Very striking results were obtained on young animals {Fig. 123). After three injections an extraordinary development of the uterus began; there were changes in the mucosa and in the muscle layer. The infantile uterus increased enormously, and the blood vessels were very enlarged. There were glands in the mucosa and the muscle layers were much more pronounced after the fifth injection. The stroma of the mucosa now con- sisted of cells very like decidua cells. Extraordinary changes took place also in the vagina, in the tubes, and in the mammary glands. The latter began to secrete, and a quantity of clear fluid could be pressed out. These phenomena were observed also with young animals previously castrated. Similar changes in the mammary gland occurred with injected males. It is of great interest- that the ovary also is influenced by the extract {Fig. 124). The ovary of the young rabbit consists mainly of primary follicles {Fig. 124 A), but there are also some follicles just entering upon development. In the ovary of an animal which received five injections numerous ripening follicles were to be found {Fig. 124 B), and some of them had even already attained maturity. It follows from these experiments that the extract prepared by Herrmann may cause in animals of about eight weeks a development of the sex characters such as is found at an age of about six to seven months. The genital organs may even develop so far as to become like those during heat or at the beginning of pregnancy. As far as I am aware, Herrmann obtained all these changes by injecting preparations of the corpus luteum and the placenta, but not by preparations of 326 INTERNAL SECRETIONS ovaries from which the corpora lutea had been excised. Herrmann concludes from his experiments that the corpus luteum and the placenta contain a substance which can excite the development of the genital organs and mammary glands. Herrmann (19 17) has employed his extracts in cases of Circular muscle layer Mucosa f \ Glands ~_,r>-=^ Circ. muscle layer — Longitud. m. layer -^^ Fig. 123. — Influence of extracts of corpus luteum on the uterus. — From Herr- mann. A. Uterus of a rabbit 8 weeks old. Normal, x 22. B. After 3 injections, x 22. haemorrhage of ovarian origin and found that there were good results in 95 per cent, of 73 cases after injection of ex- tracts of the corpus luteum or placenta. His paper may be consulted for details of the cases. We have already mentioned that the influence of the extract was observed also on the mammary glands of male rabbits. This shows that the extract of the ovary or of certain parts ISOLATION OF SEXUAL HORMONES 327 of the ovary may act in a sex specific manner. The question of the sex specifity of this action has been studied lately more fully by Herrmann and Stein (1919, 1920, 1921) and by Fellner (1921). Herrmann and Stein stated that the extract of the corpus luteum inhibits the development of the generative tissue in young male rats; if spermatogenesis has already Long. m. layer Circ. m. layer Mucosa W Fig 123. — Influence of extracts of corpus luteum on the uterus.— From Herr- mann. C. After 5 injections, x 22. started, degeneration of the generative tissue takes place. All the male sex characters— the penis, the prostate, the vesiculae seminales, etc. — were in a state of extreme under- development (signs of castration). In male rabbits there was on the one hand hypertrophy of the mammary glands and in some cases even secretion of colostrum, and on the other signs of castration in the different accessory genital glands. It is 328 INTERNAL SECRETIONS t B . , ..,. of corpus meu,n on iU ovary. ^^rom Hermann. „,_ „- ^Influence of extracts oj ^"'f "^ ^ t Ovary of young normal rabbit. X 35 B. After 5 injections. X 35- ISOLATION OF SEXUAL HORMONES 329 of great interest to note that the uterus mascuhnus, which is greatly developed in this species, showed marked thickening of the muscle layers of the wall after injection of the above- mentioned extracts. The muscle layers of the uterus masculinus of the rabbit are considered by some authors as arising from the Miillerian ducts. If this is really so, we have an example of an organ homologous with the uterus (that is, an essentially female organ) reacting to female sexual hormones in the male organism. Stein and Herrmann (1921) have made similar statements about male guinea pigs in which an hypertrophy of the mam- mary glands also took place. But on account of certain dis- crepancies in their individual experiments on rabbits they think that farther confirmation is needed in regard to the matter of the transformation of the uterus masculinus.^ Fellner (1921) has made the interesting statement that the inhibitory action which female extracts have on the testicle, may be obtained also by injecting Hpoid-containing extracts of other organs, and even by injecting an extract from the testicle itself. This testicular extract also promotes hyper- trophy of the uterus and of the mammary gland. Fellner concludes from his experiments that female sexual hormones are present in the testicle though in a lesser quantity than in various parts of the ovary. There is an interesting disparity between the results of Herrmann and Fellner. Whereas Herrmann and Stein have described, as already recorded, an inhibition of the develop- ment of the vesiculae seminales and of the prostate gland in rats, rabbits and guinea pigs, injected with an extract of the corpus luteum, no such effects were observed by Fellner (1921, pp. 200, 204). The latter author failed also to observe the secretion from the hypertrophied mammary glands in injected males as noted by Herrmann. I think that this absence of agreement is to be explained by differences in the quantity of the injected hormones. Where the injected quantity is relatively small there will be a reaction only on the part of the generative tissue of the testicle which is very sensitive; where the injected quantities are greater there will be an inhibition of other sex characters also. In Chapter IX. we shall 1 According to Wertheimer and Dubois (see Ch. VIII., p. 338) the "uterus masculinus" of the rabbit is nothing else than a seminal vesicle. Stein and Herrmann were possibly mistaken when making all the above statements. 330 INTERNAL SECRETIONS see again that the results of the transplantation experiments in which male and female hormones were simultaneously present in the same organism were also very conflicting; and I think that in these latter experiments the disparity can be explained only on quantitative lines. Basing his position on Herrmann's and Stein's results, Harms (1922) drew attention to the fact that there may be signs of castration, though interstitial cells are present in the degenerated testicle. He declared these experiments to afford further evidence for the conclusion that the interstitial cells are not the hormone-producers in the testicle. The absence of agreement between Fellner and Herrmann on the question of the behaviour of the sex characters of injected male animals shows clearly enough that the conclusion of Harms is without justification. Harms has evidently over- looked the disparity between Fellner and Herrmann, as he quotes Fellner's experiments in support of his assumption. It seems at first thought that the changes obtained by Fellner and Herrmann in their experiments correspond with those of normal puberal development and early pregnancy. It may be pointed out that the transformation of the mammary gland caused by injection of the extract into the male animal corresponds with that observed by Steinach and others after transplantation of ovaries into the male organism. But have we any guarantee that all these changes, as described by Fellner and Herrmann, are really caused by a definite chemical substance? This is not very probable. As we have already pointed out, it is most likely that the internal secretion of the sex gland does not consist of one hormone, but rather of many different hormones. An experimental comparison between the action of extracts of the corpus luteum and that of the hilum ovarii was under- taken by Itagaki (19 17) in the laboratory of Schafer. He stated that the action of these extracts upon the movements of the living uterus of the rat are antagonistic to one another, the first causing a distinct increase of tone, the second causing inhibition. But the uterus of other animals reacts differently; in the rabbit, cat and guinea pig extracts of both the corpus luteum and the hilum produce an increase of tone. Sometimes however the extract of corpus luteum may produce inhibition. Itagaki suggests that this difference of effect is possibly due ISOLATION OF SEXUAL HORMONES 331 to a difference in the samples of corpus luteum. He assures us that there are apparently two principles in the corpus luteum having an antagonistic action upon the uterus. Both these principles can be extracted, according to Itagaki, by Locke's solution; the principle causing inhibition of the uterine contractions is soluble in alcohol, the principle causing increase of tone is soluble in water. Athias (1920) has recently confirmed the stimulating action of the ovary and of the corpus luteum on the uterus. It may be of interest to note that Weil (1920) recorded a difference in reaction to subcutaneous injections of testicular extracts according to the sex of the injected animal. There was a sudden decrease in the output of COg followed by a sudden increase beyond the normal output in young males, "castrates" and pregnant females, but no influence in adult males and females. On the other hand, ovarian extracts were without any influence on adult males, but caused de- crease and increase in the CO2 output in females and young or castrated males. Weil refers to this as a "sex specific" reaction. The experiments of Dittler (1920) may be mentioned here, though only in an indirect relation to the problems discussed in this chapter. Dittler made intravenous injections of fresh sperm into female rabbits and stated that sterility can be caused by repeated injections. Sterility was not caused when the sperm of a man instead of rabbit's sperm was used. This effect is at first thought similar to that caused by injection of extracts of corpus luteum. But there is a very marked differ- ence between sperm and corpus luteum, since sperm does not inhibit ovulation, according to Dittler, whereas the corpus luteum has this effect. BIBLIOGRAPHY FOR CHAPTER VII. Ancel et BoTJiN. 1906. Action de I'extrait de la glande interstitielle du testicule sur le developpement du squelette et des organes genitaux. G. R. de VAcad. d. Sc, 142, p. 232. Athias. 1920. Action d'extraits et produits derives d'organes a secretion interne sur 1' uterus isole, particulierement apres la castration totale. Arch, internat. de Pharmacodynamie et de Therapie, 25, p. 423. 332 INTERNAL SECRETIONS BiEDL. 1913. Innere Sekretion, II., 2nd edit. Berlin-Wien. 1922. Innere Sekretion, I. 1, 4th edit. Berlin-Wien. Bell {W. Blair). 1920. The Sex-Complex. 2nd edition. London. DiTTLER. 1920. Die Sterilisierung des weiblichen Tierkorpers durcli parenterale Spermazufuhr. Miinch. 7nedizin. Wochenschr., p. 1495. 1920. Studien zur Physiologie der Befruchtung. Zeitschr. f. Biol., 72, p. 273. Fellner. 1913. Experimentelle Untersuchungen iiber die Wirkiing von Gewebsextrakten aus der Plazenta und den weiblichen Sexualorganen auf das Genitale. Arch. f. Gyndkol., 100. 1917. Uber die Tatigkeit des Ovariums in der Schwangerschaft (interstitielle Zellen). Monatsschr. f. Geburtsh. Gyndkol. , 54, p. 88. 1920. Uber das spezifische Ovarialsekret. Zentralbl. f. Gyndkol., 44. 1921. Uber die Wirkung des Placenta- und Hodenlipoids auf die mannlichen und weibhchen Sexualorgane. Pflilgers Archiv, 189, p. 199. Foges. 1914. Keinidriisen. In Jauregg u. Bayer, Lehrbuch der Organotherapie. Leipzig. Fraenkel. 1903. Die Funktion des Corpus luteum. Arch. f. Gyndkol., 68. 1910. Neue Experimente zur Funktion des Corpus luteum. Arch. f. Gyndkol., 91. 1914. Normale u. patholog. Sexualphysiologie des Weibes. Handb. d. ges. Frauenheilkunde, III. Leipzig. Oley. 1914. Les secretions internes. Paris. Harms. 1922. Keinidriisen und Alterszustand. Fortschr. d. natur- wissensch. Forsch., 11, p. 189. Herrmann. 1915. tJber eine wirksame Substanz im Eierstocke und in der Plazenta. Monatsschr. f. Geburtsh. u. Gyndkol., 41. und Stein. 1916. Uber die Wirkung eines Hormones des Corpus luteum auf mannliche und weibliche Keimdriisen. Wiener klin. Wochenschr., 29, No. 25. 1917. Der Einfluss eines Corpus luteum-resp. Plazenta-Lipoids auf Blutungen, menstruellen Zyklus und Ausfallserscheinun- gen. Monatsschr. f. Geburtsh. u. Gyndkol., 54, p. 152. und Stein. 1919, Heterologe Reizstoffwirkung auf bestimmte System-bezw. Geschlechtsmerkmale bei mannlichen Kanin- chen. Zentralbl. f. Gyndkol., 43. und Stein. 1920. 1st die aus Corpus luteum bezw. Placenta hergestellte wirksame Substanz geschlechtsspezifisch ? Zen- tralbl. f. Gyndkol., 44. ISOLATION OF SEXUAL HORMONES 333 Itagaki. 1917. The influence of Corpus luteum extracts upon plain muscle, especially that of the uterus. Quart. Jl. of Experim. Physiol., 11, p. 1. 1917. On the action of various extracts obtained from the cow's ovaries upon the muscular tissue of the uterus, intestine and blood-vessels. Ibid., p. 27. 1917. The action of certain gland extracts and drugs upon the uterus of the rat. Ibid., p. 39. Maranon. 1922. Problefnas actuales de la doctrina de las secreciones internas. Madrid. P]6zARD. 1911. Sur la determination des caracteres sexuels secon- daires chez les Gallinaces. C. R. de VAcad. d. Sc, 153, p. 1027. Stein und Herrmann. 1921. Uber kiinstliche Entwicklungshem- mung mannhcher sekundarer Geschlechtsmerkmale. Arch. f. Entw.-Mech., 48, p. 447. Weil. 1920. Geschlechtsspezifische Wirkungen von Keimdriisen- extrakten. Pflilgers Archiv, 185, p. 33. Chapter VIII. The Seminal Vesicles and the Prostate Gland in Relation to the Development of the Sex Characters, Is there an influence on the part of the seminal vesicles and prostate gland on the somatic sex characters and on the psycho-sexual behaviour? This question was discussed more than thirty years ago by Tarchanoff (1887) in relation to the seminal vesicles; a similar question was recently raised in connection with the prostate gland by various cUnical ob- servations. It seems, however, to have been demonstrated recently that the seminal vesicles and the prostate have no influence on the sex characters, more especially by Steinach (1894) and Lichtenstern (1915, 1916), who performed experi- ments deahng with this question in Steinach' s laboratory. Further, the experiments of KolHker, Fiirbringer, Steinach, Nussbaum, Exner, Hirokava and Wischnewsky have shown that the seminal vesicles and the prostate have distinct functions apart from the production of hormones.^ A. PHYSIOLOGY OF THE SEMINAL VESICLES. I. Experiments on Frogs. It was already known to Spallanzani (1786) that even serious injuries to the male frog, as, for instance, mutilation of both hind legs, do not necessarily inhibit the clasp reflex. Tarchanoff showed that the male continues to clasp for some time even when internal organs are mutilated or excised. But he claims to have shown also that incision and emptying of the seminal vesicles or extirpation of the latter inhibit the clasp reflex in Rana temporaria. Tarchanoff suggests that the stimulus which makes the male seek the female, and which excites the clasp reflex and causes its persistence, originates 1 For the literature on this question see the papers of Tarchanoff, Steinach and Lichtenstern quoted above; see also Marshall (1922, ch. VI.), Busquet (1910), Nussbaum (1912), Biedl (1913, vol. 11 of the 2nd ed.), Stigler (1918). 335 Y 336 INTERNAL SECRETIONS in the seminal vesicles. According to Tarchanoff a distention of the walls of the vesicles by the fluid content produces a mechanical irritation of the nerve-endings, and he suggests further that their excitation may be increased by the sper- matozoa hitting against the walls of the vesicles. Steinach was able to show that Tarchanoff' s assumptions were not justified. In frogs which had already been clasping for several days the seminal vesicles were found to be empty, for the filling of the vesicles takes place only after the clasp begins. It is clear that the sexual instincts of the frog during "heat" and the clasp reflex cannot be caused in the manner supposed by Tarchanoff. Further, Steinach showed experimentally that spontaneous clasping or clasping after stimulation is still possible when the seminal vesicles have been extirpated. In animals from which the seminal vesicles have been removed, however, the clasp continues for only about ten days. But according to Steinach, this is to be explained by the fact that in extirpating the seminal vesicles the ureters are severed, and the urine flows into the abdominal cavity. The experimental animals show many pathological symptoms and die about twenty days after the operation. Nussbaum's experiments gave further support to Steinach's conclusions. It is clear that in the frog the seminal vesicles have nothing to do with the erotization of the central nervous system. This effect is due only to the testicle. 2. Experiments on Mammals. Steinach removed both seminal vesicles from rats ten to eleven months old. The experimental animals about ten days after the operation displayed a marked sexual behaviour, just like normal ones. But breeding experiments performed by Steinach showed that by removing the seminal vesicles the fertility may be much diminished. Only a very small percentage of the females with which the operated males copulated became pregnant; the number of young in the litter was about half that of the normal. One might object that the diminished fertility was possibly caused by obstruction of the vas deferens, but such an objection is not justified, since each male was able to impregnate at least once. Similar observations were made by Camus and Gley (quoted from Camus et Gley, 1899) on the guinea pig, the fertiHty of INFLUENCE ON SEX CHARACTERS 337 which was likewise diminished after removal of the seminal vesicles. One might indeed object that the diminution of fertility was caused by the testicles having suffered from the abdominal operation. As we pointed out in Chapter IV. the testicle is of an extraordinary sensitiveness. If the abdominal operation is performed without complete aseptis one often notices consider- able changes in the generative part of the testicle. But it is naturally impossible to say how far this factor might have been involved in the experiments of the authors referred to. But what is the real function of the seminal vesicles? It was formerly thought that they serve as receptacles for sper- matozoa, and hence the name of the organ. But spermatozoa are not always present in the seminal vesicles, and if present they are only in small quantities. In guinea pigs I have many times examined the contents of the seminal vesicles without having found spermatozoa. Most probably the mucosa of the seminal vesicles has a secretory function, the secretion not always having exactly the same significance for the various species. Leuckart seems to have been the first to call attention to the fact that in the guinea pig the fluid secreted by the seminal vesicles has the power of coagulation. Any one working experimentally with guinea pigs is familiar with this fact. The ejaculated fluid becomes solidified in about one minute. It is the so-called "botichon vaginal." Camus and Gley (1896, 1921, 1922) have carefully examined the mechanism of the coagulation. They showed that the prostate produces an enzyme which causes coagulation of the secretion of the seminal vesicles; they called this enzyme " vesiculase." Only traces of it are present in the new-born animal; its quantity increases during sexual maturation. The enzyme is not specific for a given species (1922 b). The bouchon vaginal is found in the vagina of the female, and according to Leuckart prevents the spermatozoa from leaving the vagina Mechanical functions were ascribed to the bouchon vaginal by Gley in another sense also. He suggested that the more abundant secretion of the vesicles and of the prostate favours the transportation and ejaculation into the vagina of the small quantities of secretion which are produced in the testicle and in the epididymis. This question was lately examined more fully by Amantea in the laboratory of Baghoni. For 338 INTERNAL SECRETIONS the study of this question in the guinea pig Amantea (1920) employed what he called an "artificial vagina." He stated that the seminal fluid containing the spermatozoa does not mix with the secretion of the seminal vesicle. He could always find these two portions of the genital secretion dis- tinctly separated from one another in the artificial vagina of the guinea pig, and only a very small number of spermatozoa could be discovered in the coagulated secretion of the seminal vesicles. There may be a difference as to the function of the seminal vesicles in different species. In the seminal vesicles of man sper- matozoa are said to be always found. This has again been affirmed lately by Wertheimer and Dubois (1921). On injecting a fluid into the vas deferens of a man, they obtained a dis- tension of the vesicles before so much as a drop had entered the urethra (the experiment of Regnier de Graaf). On the contrary, in the bull and in the ram the injected fluid passes directly into the urethra ; in these species spermatozoa are not to be found in the seminal vesicles. Also the "uterus masculinus" of the rabbit, according to Wertheimer and Dubois (1922), is nothing else than a seminal vesicle containing spermatozoa which are more mobile than those in the vas deferens. The experiment of Regnier de Graaf gives a positive result in the rabbit, contrary to what is to be observed in the guinea pig and in the rat. B. PHYSIOLOGY OF THE PROSTATE GLAND. It is known to the surgeon that various nervous and psychi- cal troubles sometimes follow the removal of the prostate in man. It has been said, that prostatectomy involves an even more severe operative interference than castration, especially in young individuals. But the number of patients showing nervous troubles after prostatectomy is relatively small. Lichtenstern relates having observed psychical troubles in only one out of a great number of individuals after prostat- ectomy. As Haherern (quoted from Lichtenstern, 19 16) pointed out, these troubles are due to injuries in the neigh- bouring tissues; a conclusion with which Lichtenstern (1916) concurs. INFLUENCE ON SEX CHARACTERS 339 I. The Effect of Prostatic Injections. Some authors are of the opinion that the troubles arising after prostatectomy are caused by lack of an internal secretion of the prostate. A great number of experiments has been made with a view to demonstrating this internal secretion. Especial attention has been paid to the changes which are caused by injection of extracts of the prostate. Very profound changes have been observed after injection of a glycerine or water extract of the prostate of the bull ; a remarkable rise of blood pressure followed by a fall, and a stoppage of the heart to- gether with convulsions, were observed. An acceleration of the respiratory movements also has been recorded after injection of smaller quantities of the extract. Similar ex- periments have been performed also by 5^^^/ (1913) on the dog. Biedl points out that these observations are totally insufficient for demonstrating the existence of a specific internal secretion of the prostate, and that the changes observed can be ex- plained as due to intravascular coagulation. Some authors claim to have observed specific effects of the prostatic secretion on the muscles of the bladder. But as we have pointed out already in Chapter VII., experiments with injection of extracts are of a theoretical value only in those cases where control experiments have been made with ex- tracts of other organs prepared in exactly the same manner. We never know what changes the complex chemical compounds of the different tissues undergo when preparing an extract, and it is very likely that the effects of an extract are often merely the result of substances which are artificially pro- duced in making it. Due consideration is not always taken of this possibiHty. Much critical study is necessary in this field of experimental and clinical research, and this is especially true for experiments with extracts of the prostate. This applies to the experiments of Bogoslavski and Korencevski (1921) who stated that an emulsion of prostate gland may give rise to a very considerable increase in the metabolism in dogs, especially if they are previously castrated. The experi- ments of Macht and his co-workers (1920) are also of interest here. Macht fed tadpoles of different amphibians with dried prostate gland for several weeks; controls were fed with liver, ovary, corpus luteum and other glands. He recorded 340 INTERNAL SECRETIONS an acceleration of growth and metamorphosis under the influence of the prostate. He stated further that the prostate gland of the bull is more efficient than that of the ox. Macht and Matsumoto examined the influence of prostatic extracts on different organs such as the bladder, the ureter, the uterus, etc., of rats, guinea pigs and other animals. There was always an increase of tone. None of these experiments supply evi- dence of an endocrine action for this organ. The same may be said about experiments with removal of the prostate; we shall deal with these experiments in the following section. 2. Simultaneous Removal of the Seminal Vesicles and OF THE Prostate. Steinach removed the seminal vesicles together with the prostate from rats about ten months old. Only the lateral lobules were removed, the prostatic tissue surrounding the urethra remaining intact, since removal of this part of the gland causes severe injury to the animal. The sexual behaviour was peculiar for some weeks, but afterwards the operated animals behaved normally. Against these experiments the objection may be made that the prostate was not completely removed, and that the small quantities of prostatic tissue which remained were sufficient to replace functionally the whole prostate in relation to sexual instincts. We shall discuss this question later. With rats from which the seminal vesicles and the prostate gland had been removed, Steinach performed breeding ex- periments which lasted about three months. The operated males copulated with normal females as frequently as normal males do. But, nevertheless, not one of all the twelve normal females became pregnant, though spermatozoa were detected in the vagina of the females after coition. From these experiments Steinach concluded that by simul- taneous removal of the seminal vesicles and prostate fertiHty is definitely destroyed. Since spermatozoa passed into the vagina, he thought that evidently the functional activity in regard to the power of fertilization of the spermatozoa is influenced by the secretions of the seminal vesicles and prostate. But experiments have been performed which do not corrobo- rate this conclusion. Iwanoff induced pregnancy in various mammals by injecting into the female passages a fluid taken INFLUENCE ON SEX CHARACTERS 341 directly from the epididymis. It is very likely, as supposed by Rauther (quoted from Marshall, 1922), that the diminished fertility after removal of the seminal vesicles and the absolute sterility after removal of both the vesicles and the prostate were due in the experiments of Steinach to failure to form the bouchon vaginal. On the other hand, it may be mentioned that Iwanoff diluted the seminal fluid obtained from the epididymis with a five per cent, solution of sodium carbonate; we shall see later that alkalinity is a very important factor in functionally activating the spermatozoa. It is possible that by mixing the seminal fluid with a solution, as just mentioned, one is really replacing the normal secretion of the seminal vesicles and of the prostate. 3. Removal of the Prostate. As already mentioned above, the first experiments of Steinach with removal of the prostate are open to the objection that here a small quantity of the prostate remained unaltered, and performed the hypothetical endocrine function of this organ necessary for a normal erotization. One might object that a complete removal of the prostate would cause a complete disappearance of sexual desire and sexual activity. This objection has been studied experimentally by Lichtenstern. He removed the prostate from male rats at an age of five to eight months when they were already sexually mature. In this first series of experiments Lichtenstern never succeeded in removing the prostate completely, small pieces of glandular tissue always remaining around the bladder. Neverthe- less, sexual activity was only seen in some of these animals. This was evidently due to the many injuries to the neighbouring tissues which cannot be avoided if the attempt is made to remove the prostate completely from an adult animal. But in a second series of experiments on young rats four to five weeks old, Lichtenstern succeeded in completely removing the prostate without any injury to the surrounding tissues. Sexual instincts and sexual activity developed in these animals in normal strength, though with some delay. Also such somatic sex characters as the seminal vesicles and the penis, which are markedly affected by the absence of sexual hormones, were normal. The experiments of Lichtenstern show that development 342 INTERNAL SECRETIONS of the somatic sex characters and of the psycho-sexual behaviour is independent of the presence of the prostate and of any endocrine function which this organ might possess. When there is, as in man or in the adult animal, an effect on the behaviour following prostatectomy this is merely due to operative inter- ference in a region very sensitive to injury, and not to the absence of some specific prostatic hormones. The fact that there may be considerable abnormality in the psycho-sexual be- haviour, even when the prostate is not completely removed, is very significant. Unfortunately, Lichtenstern has not ex- amined the question as to whether sterility follows complete prostatectomy without removal of the seminal vesicles. Similar experiments have been performed by Macht and Bloom (1921). They examined the psychical behaviour of twenty young rats from which the prostate gland was removed. In their experiments they employed a labyrinth or maze through which the rats learned to pass, the time taken being a test of intelligence or memory. The experimental animals passed through the labyrinth as quickly as the control animals in which the abdomen had been opened without prostatectomy being performed. In later experiments by Macht and Ulrich (1922) rats trained to walk along a rope did not lose their power to do so after prostatectomy. But when prostatectomy wasjperformed before the rats were completely trained, they could not be properly trained afterwards. But, according to Macht and Bloom, the mental deficiency shown by these animals could be alleviated by the administration of dried prostatic tissue. Serralach and Pares claimed to have shown that prostatec- tomy is followed by azoospermia. In three dogs after prosta- tectomy they found an atrophy of the testicle which showed no signs of spermatogenesis. Further, the same authors point out that two to three days after injection of an extract of the prostate spermatozoa reappeared in the ejaculation. They concluded from their experiments that the prostate produces an internal secretion which influences the testicle and stimu- lates spermatogenesis. But the experiments of Serralach and Par^s are by no means convincing. It is highly probable that in those cases where a degeneration of the generative part of the testicle took place a seminal passage was interfered with during the operation; this objection, I think, cannot be INFLUENCE ON SEX CHARACTERS 343 avoided in such an operation as prostatectomy. Further, Lichtenstern showed that spermatogenesis proceeded quite normally in his rats from which the prostate was completely removed at an early age. These observations are opposed to the conclusion of Serralach and Pares, especially as in the experiments of the latter it is probable that there was never a complete removal of the prostate, this operation being almost impossible in the adult animal. The interstitial tissue of the testicle in animals prostatec- tomized at an early age was found by Lichtenstern to be also quite normal. C. THE SECRETION OF THE GENITAL PASSAGES IN RELATION TO THE VITALITY OF THE SPERMATOZOA. It was stated above that, although the seminal vesicles and the prostate have no influence on the somatic sex characters and on the psycho-sexual behaviour, they are nevertheless necessary for normal fertility. As we have learned that sper- matogenesis also is independent of the seminal vesicles and the prostate gland, it seems likely that decrease or absence of fertility after removal of the seminal vesicles and the prostate is due to a change in the vitality of the spermatozoa. We have already touched upon this question above. The question as to the influence of the secretion of the male accessory glands on the spermatozoa is a very old one. Kolliker stated that the secretion of the uterus masculinus of the rabbit and that of the seminal vesicles of man has the power of stimulating the movements of spermatozoa, these becoming quicker and lasting longer. Similar statements have been made by Fiirbringer about the secretion of the prostate. Steinach studied the influence of the secretion of the seminal vesicles and of the prostate on the spermatozoa of the rabbit, guinea pig, mouse and rat. He found that in the secretion of the prostate the movements of spermatozoa last longer than in a physiological salt solution. The most effective fluid, according to Steinach, is a solution of the prostatic secretion with a few drops of physiological salt solution. According to Hirokava the alkalinity of the prostatic secretion is of a special importance for the vitality of the spermatozoa ; it was already 344 INTERNAL SECRETIONS known to Kolliker that weak alkaline solutions can stimulate the movements of the spermatozoa. Recently Amantea and Krzyskowsky (1920 b) repeated these experiments using different physiological solutions, and again showed how spermatozoa can remain alive in salt solutions for a very considerable period, though in the secretion of the sex gland itself the normal movement is more prolonged. A more exact investi- gation of the question of the hydrogen ion concentration most suitable for mammalian spermatozoa has been made by Wolf (1921a), who succeeded in keeping spermatozoa of the rabbit in movement for nine days. But there was no evidence that these spermatozoa were capable of fertilization (1921 b). In view of these considerations one might assume that the secretion of both glands has some influence on the spermatozoa ; this would not be contrary to the above-mentioned experi- ments of Iwanoff. It is possible that sterility as observed after removal of the vesicles and of the prostate is due to the fact that the spermatozoa have lost the great vitality by which they are normally able to swim from the vagina to the tubes where fertilization takes place. This would explain why ferti- lization occurred in the experiments of Iwanoff, where the seminal fluid obtained from the epididymis was directly introduced into the female passages. The question is a much more complicated one than was formerly supposed. It seems very likely that the vitality of the spermatozoa depends not only upon the secretion of the vesicles and of the prostate, but also on that from other accessory glands. According to Stigler and R. Pollitzer (1918) motility and resistance of sper- matozoa depend also on a secretion of the epididymis; they concluded from their experiments that there were in the secretion of the epididymis some stimulating substances not present in the secretion of the vesicles. The question of the secretory function of the epididymis, has been studied also histologically by various observers in such animals as the lizard, in which there is a periodical spermato- genesis and a secretory activity of the epididymis beginning dur- ing spermatogenesis and highly developed during the passage of the spermatozoa through the excretory ducts of the gonad. The question has been dealt with again by Courrier (1920 a), a pupil of Bouin. In the bat a great quantity of spermatozoa remain in the epididymis during the whole of hibernation. INFLUENCE ON SEX CHARACTERS 345 Now Courrier stated that in the epididymis of the bat a secretory activity also goes on during hibernation. Evidently, as Courrier points out, this exceptional secretory activity during hibernation is rendered necessary on account of the presence of living spermatozoa in the epididymis in this species at a time at which they are absent in other species. The spermatozoa seem to be attracted by the secreting cells. It may be noted that spermatogenesis is at this time suppressed in the testicle, only cells of Sertoli and spermatogonia being present in the seminiferous tubules. On the other hand the interstitial cells are very well developed; they are very active and full of secretory granules. It is probable that along the whole passage in the male and female there takes place a secretion of substances which influence the movements of the spermatozoa, and it seems possible that each of these secretions has its specific effect. Various histological observations tend to confirm this. As to the vas deferens the question has been recently studied in a more detailed manner in the mouse by Benoit (1920) in Bouin's laboratory. He records signs of very intense secretory activity in the epithelium of the vas deferens even more pronounced than in the epidid3miis. According to Benoit there is evidently some kind of tropism on the part of the spermatozoa towards the secretion of these cells, the spermatozoa being often found attracted to the secretory masses of the epithelial surface. A fine example of secretory activity of the uterine epithelium for maintaining alive the spermatozoa is that afforded by the uterus of the bat. In this animal the spermatozoa are intro- duced into the uterus before the winter begins, whereas ovulation and fecundation take place only in the spring. Courrier (1920 b, 1921) stated that the uterine epithelium assumes its secretory activity just before copulation and the introduction of the seminal fluid, and persists during the whole winter. According to Courrier the spermatozoa are attracted by those cells which are full of secretory granules. He considers the uterine secretion to act in a manner similar to that in the epididymis of the male bat. Bottcher (1920) assumes that the secretion of the prostate and of the seminal vesicles may inhibit the noxious influence on the spermatozoa of the acid content of the vagina. Ac- cording to J. Loeb and others (Clowes and Bachman, 192 1) the 346 INTERNAL SECRETIONS egg of a sea urchin also produces a substance stimulating the movements of the spermatozoa. The question as to the dependence of the spermatozoa both in their vitality and in their movements upon different factors is of a practical interest, since it is very probable that chemical substances present in the secretion of the vagina or the cervix uteri may exert a considerable influence. This suggestion was supported by Weil (1921). Weil's experiments are not very convincing, but the question deserves further experimental consideration. BIBLIOGRAPHY FOR CHAPTER VIII. [* Not seen in the original.] Amantea. 1920. Sulla funzione secretoria delle vesichette seminali. Gongres de Physiologie, Paris. et Kjizy§kowsky. 1920 b. Osservazioni sulla biologia degli spermatozoi. Congrks de Physiologie, Paris. * et Krzyskowsky. 1921. Ricerche fisiologiche sugli sperma- tozoi. Riv. de hiol., 3, p. 569 (quoted from "Berichte"). Benoit. 1920. Sur 1' existence de phenomenes secretoires dans le canal deferent. G. R. de la Soc. de Biol., 83, p. 1640. BiEDL. 1913. Innere Sekretion, Vol. II., 2nd edit. ♦BOTTCHER. 1920. tJber die Bedeutung der Sekrete der mannlichen akzessorischen Geschlechtsdriisen. MiXnch. med. Wochenschr., 67, p. 45 (quoted from "Berichte"). ♦BoGOSLAvsKi and Korencevski. 1921. On the influence of the internal secretion of the testicle and of the prostate on the metabolism. Russki Fisiol. J urn., 3, p. 48 (quoted from "Berichte"). BusQUET. 1910. La fonction sexuelle. Paris. ♦Camus et Gley. 1896. Action coagulante du liquide prostatique sur le contenu des vesicules seminales. G. R. de la Soc. de Biol., 48, p. 787. * 1897. Note sur quelques faits relatifs a T enzyme prostatique (vesiculase) et sur la fonction des glandes vesiculaires. Ibidem, p. 787. 1899. Role des glandes accessoirs de I'appareil genital male dans la reproduction (recherches de physiologie comparee). Bull, du museum d'hist. natur., p. 253. INFLUENCE ON SEX CHARACTERS 347 *Camus et Gley. 1921. Action du liquide prostatique sur le contenu des glandes vesiculaires des cobayes nouveau-nes ou tres jeiines. G. R. de la Soc. de Biol., 84, p. 250. 1922a. Action coagulante du liquide prostatique de la viscache sur le contenu des v^sicules seminales. C. R, de la Soc. de Biol, 87, p. 207. 1922b. Action coagulante du liquide prostatique de la gerboise sur le contenu des vesicules seminales. C. R. de la Soc, de Biol, 87, p. 320. *Clowes and Bachman. 1921. On a volatile sperm-stimulating substance derived from marine eggs. Proc. of the soc. f. exp. hiol. a. med., 18, p. 120 (quoted from "Berichte"). CouRRiER. 1920a. Sur I'existence d'une secretion epididymaire chez la chauve-souris hibernante et sa signification. C. R. de la Soc. de Biol., 83, p. 67. 1920b. Sm" I'existence d'une secretion de I'epithelium uterin chez la chauve-souris hibernante. Sa signification. G. R. de la Soc. de Biol., 83, p. 243. 1921. Sur le role physiologique des secretions uterine et tubaire chez la chauve-souris hibernante. G. R. de la Soc. de Biol., 84, p. 571. LicHTENSTERN. 1915. Auz. d. Akod. d. Wissensch., Wien, No. 16. 1916. Untersuchungen iiber die Funktion der Prostata. Zeit- schr.f. Urologie, 10. *Macht. 1920. Physiological and pharmacological studies of the prostate gland. I. Effect of prostate feeding on the growth and development of tadpoles. Journ. of Urol., 4, 115 (quoted from "Berichte"). * and Matsumoto. 1920 b. II. The action of prostatic extracts on excised genito -urinary organs. Journ. of Urol., 4, 255 (quoted from "Berichte"). * and Bloom. 192L III. Effect of prostatectomy on the be- haviour of albino rats. Journ. of Urol., 5, 29 (quoted from "Berichte"). * — — and Ulrich. 1922. Effect of prostatectomy on integration of muscular movements of the white rat. Americ. Jl. of Physiol, 59, p. 482 (quoted from "Berichte"). Marshall. 1922. The physiology of reproduction. 2nd edition. London. NussBAUM. 1912. tJber den Bau und die Tatigkeit der Driisen. Arch. f. mikroskop. Anat., 80, Abt. II. Spallanzani. 1786. Versuche uber die Erzeugung der Tiere und Pflanzen. German translation. Leipzig. 348 INTERNAL SECRETIONS Steinach. 1894. Untersuchungen zur vergleichenden Physiologie der niannlichen Geschlechtsorgane, insbesondere der akzessori- schen Geschlechtsdriisen. PfliXgers Archiv, 56. Stigler. 1918. Der Einfiuss des Nebenhodens auf die Vitalitat der Spermatozoen. PfliXgers Archiv, 71. Tarchanoff. 1887. Ziir Physiologie des Geschlechtsapparates des Frosches. Pfliigers Archiv, 40. Weil. 1921. Die chemischen Ursachen der Spermatozoenbewegung. Arch. f. Frauenkunde u. Eugenik, 7, p. 238. Wertheimer et Dubois. 1921. L'experience de Regnier de Graaf et les fonctions des vesicules serainales. C. R. de la Soc. de Biol, 85, p. 504. 1922. Sur les fonctions des vesicules serainales de quelques rongeurs. C. R. de la Soc. de Biol., 86, p. 35. *WoLF. 1921a. The sui'vival of motility in mammalian spermatozoa. Jl. of Physiol., 55, p. 246 (quoted from "Berichte"). * 1921b. The survival of motility in mammalian spermatozoa. Jl. of agric. science, 11, p. 310 (quoted from "Berichte"). Chapter IX. Intersexuality/ A. TRUE HERMAPHRODITISM AND PSEUDO- HERMAPHRODITISM. There are individuals which combine within themselves char- acters of both sexes. Such individuals are generally divided into two groups: the so-called true hermaphrodites and the pseudo-hermaphrodites. An individual is said to be a true hermaphrodite when within the organism there are combined not only somatic characters but also generative cells of both sexes. We speak of pseudo-hermaphrodites when only somatic characters of both sexes are combined in an individual in which generative cells of one sex are to be found. Most hermaphro- dites in man and other mammals belong to the second group. In many species of invertebrates both generative cells and accessory organs of both sexes, serving for the expulsion of the secretion of the gonad and for copulation, are normally present in the same individual. When speaking of true herma- phroditism occurring rarely as a monstrosity in mammals and man we are thus referring to a condition which is normally present in these species of invertebrates. When speaking of pseudo-hermaphroditism we imply a condition which deviates from normal hermaphroditism, since, although generative cells of only one sex are present, somatic characters of both sexes are combined in the same individual. There is another principle tacitly implied in such a classifi- cation. After learning that somatic sex characters are con- ditioned by the internal secretion of the gonad, it seems to be very strange to find somatic characters of both sexes in one individual with generative cells of only one sex. The want of consistency apparently implied in this condition could not be better expressed than in the term pseudo-hermaphroditism. Now, we have seen in Chapter IV. that male sex characters can be normally developed when no spermatozoa or different stages of male seminal cells other than spermatogonia are present; and we learned further that female sex characters ^ The term has been introduced by Goldschmidt (1917). 349 350 INTERNAL SECRETIONS attain their climax after the expulsion or degeneration of the ripened ovum when follicular cells are histologically prevalent in the ovary. There is evidently no direct relation between fully developed generative cells and full development of somatic sex characters. It is clear that a knowledge of these facts renders the case of the pseudo-hermaphrodite less contra- dictory. Furthermore, if one adopts the view that the internal secretion is to a certain degree independent of the generative part of the gonad, the contradiction presented by the pseudo-hermaphrodite may quite disappear, generative cells not being necessary at all, according to this view, for full development of the sex characters. Various authors have tried to introduce this standpoint into the discussion of herma- phroditism. Biedl (1913, p. 209) pointed out, that the normal gonad is in the beginning possibly " bisexual," and that remains of endocrine tissue of the other sex persist after a sexual differentiation of the gonad has taken place, and that pseudo- hermaphroditism may thereby be caused. Steinach (1912, p. 86) speaks of an incomplete differentiation of the gonad, which may be sexually indifferent in the beginning ; such an incom- plete differentiation implies persistence of male endocrine cells in the ovary and persistence of female endocrine cells in the testicle, and these heterosexual endocrine cells may exert under certain circumstances their respective hormonic influences on the body. The opinion that the hermaphrodite state of an individual may be caused by an hermaphrodite state of the endocrine tissue of the gonad without an herma- phroditism of the generative part being necessary, was also held by Tandler and Gross (1913, p. 83). We see that two important questions are to be considered in regard to intersexuality in mamimals and man. First, the question has to be experimentally examined whether com- bination of male and female somatic sex characters is really caused bj^ simultaneous presence of gonads of both sexes in the same individual. And secondly, if the first question is to be answered in a positive sense, whether such an "hormonic intersexuality," to adopt an expression of Goldschmidt, is caused by male and female endocrine cells other than generative cells of any stage simultaneously functioning in the same organism. These two great questions will be examined in this chapter. INTERSEXUALITY 351 There is still another question to be discussed here. We saw that the psycho-sexual behaviour also depends on fhe internal secretion of the gonad. It seems possible that pathological deviations of all kinds in the psycho-sexual behaviour may be caused by deviations in the endocrine function of the gonad. As I have said already (see Chapter III., p. 102) this may be true, but only to a certain degree. We should never forget that the psycho-sexual behaviour must depend partly upon the state of the nervous system which is principally involved in all psycho-sexual reactions. It thereby follows that external conditions are very important factors in the psycho-sexual behaviour. But on the other hand, there can be no doubt that deviations in the psj^cho-sexual behaviour may be caused also by the interference of sexual hormones. Now the question arises whether some cases of homosexuality can be considered as a kind of hermaphroditism or condition of intersexuality in the psycho-sexual behaviour as caused by an intersexuality in the production of sexual hormones. Halhan (1903, p. 291) suggested that homosexuality was a kind of pseudo-herma- phroditism, and Block (1909, p. 590) pointed out that it might be really caused by some defect in the endocrine function of the sex gland. Such an assumption would be in agreement with the opinion of Hirschfeld, the most learned expert in this special branch of sexual pathologj^ that homosexuality is in the majority of cases a congenital condition. ^ B. EXPERIMENTAL HERMAPHRODITISM. Steinach (1916) and Sand (1918 a, pp. 152-182) have shown experimentally that the simultaneous presence of the male and female sex gland in the same individual can transform the latter somatically and psychically into an intersexual individual. It is very interesting to note that Steinach and Sand performed their experiments on mammals independently of one another, the experiments of Steinach with feminization ^ Hirschfeld's view is best expressed in the following passage: "It seems to me quite certain that the homosexual individual bears from the beginning the stamp of its somatic and psychical peculiarity. The latter is present from earHest youth, whereas it is absent in other people educated in a similar manner and grown up in a similar milieu. Every homosexual indi- vidual remembers to have been different from ordinary boys. In many cases the condition is already clearly seen at the age of the schoolboy, though the real cause is not yet understood. More than himself, his relations and those with whom he comes into touch, recognize that he possesses certain girlish peculiarities in his behaviour." {See Hirschfeld, 1918, p. 207.) 352 INTERNAL SECRETIONS and masculinization having been for Sand an incentive to carry out experiments upon the simultaneous implantation of both glands, and he started on these in 1914. Afterwards similar experiments were performed by other investigators on mammals and fowls, especially by Pezard, Goodale, Moore and Minoura (in Lilhe's laboratory), Zawadowsky, and by Lipschiitz and his co-workers, Krause and Voss. Most of these experiments gave full support to the conclusions of Steinach and Sand. I. The Antagonism between Testis and Ovary. We learned in Chapter VI. that there is a certain antagonism between the male and female sex glands. We discussed the question whether sex characters which are favoured in their development by male sexual hormones, could be inhibited by female sexual hormones, and vice versa. The antagonism between the male and female sex gland was a subject of dis- cussion also in another sense. According to Steinach (1916) an ovary which had been implanted in an ordinary male guinea pig, and a testicle which had been implanted into an ordinary female, will not "take" and will not continue to function in the new host, but will finally undergo resorption. A similar statement was made about the guinea pig by Athias (1915). Numerous experiments have been made by Sand (1918) on rats and guinea pigs, the result always being a negative one. Any parts of the graft which were still present were found to be in a state of degeneration. According to Steinach and Sand this antagonism between the male and female gonad can be overcome if the host is previously castrated and both testis and ovary are simul- taneously engrafted into such a sexually "neutralized" organism, as Steinach says. But even by this method Steinach did not succeed as well as in ordinary experiments with testicular or ovarian grafts, the number of successful experi- ments with simultaneous implantation being much smaller than those with ordinary crossed or heterosexual trans- plantation. According to Steinach, in simultaneous trans- plantation the graft does not survive so long as in an ordinary transplantation, and he explains this as due to the antagonism between both glands persisting to a certain degree also in the previously castrated host. In the experiments of Sand there INTERSEXUALITY 353 was only one successful case, a castrated male guinea pig, into which testis and ovary were simultaneously engrafted; in all the other experiments the gonad of the opposite sex or even both gonads underwent degeneration. Sand obtained better results by a new method introduced by himself. He implanted the ovary directly into the testicle Fig. 125. — Artificial ovaviotestis in the guinea pig, 4 months after transplantation of ovary into an animal i month old. Ripe follicles and theca-lutein cells; no cor- pora lutea. The testicle remained in- fantile; no spermatozoa. Normal quan- tity of interstitial cells. — From Sand. in situ. By this ''intratesticular" transplantation of the ovary performed on rats and guinea pigs, Sand succeeded in pre- serving the engrafted ovary for several months {Fig. 125), often without interfering with normal spermatogenesis {Fig. 126) or normal development of interstitial tissue in the testicle, whereas follicles, interstitial tissue and even corpora lutea were present in the" engrafted ovary .1 Both the testicle and the ovary iSand speaks of an ovaviotestis (M?511er-S^rensen) instead of an " ovo- testis "; the first expression is indeed more suitable. 354 INTERNAL SECRETIONS performed their characteristic endocrine functions. Sand con- cluded from these experiments that the antagonism of the two kinds of gonads is not such as to involve a direct influence of one on the other, but that there is in the normal organism some kind of "immunity" against the heterosexual gonad. According to Sand this "immunity" arises owing to the presence of certain substances in the organism which are necessary for the normal development of both gonads ; the gonad which is in its normal JriLr. I'zv. — Arnjicial ovariotesiis in the rat, 4 months after transplantation of an infantile ovary into an animal 5 weeks old. Both ovary and testicle have developed ; ripe follicles and corpus luteum in the ovarj% spermato- genesis in most of the tubnles.^ — From Sand. place has more facility for obtaining these substances than the engrafted gonad; the latter perishes on account of lack of the necessary substances. When both glands are in the role of grafts, or when an intratesticular implantation is made, both glands are similarly conditioned, neither of them having a preference. Certain observations have been made which seem to be contrary to the statements of Steinach and Sand. W. Schulfz INTERSEXUALITY 355 (1910) found that in the guinea. pig the ovary can survive and develop normally even when engrafted into a normal male. Lately new experiments on this question have been published by Moore (1920, 1921), who like Schultz succeeded in successful transplantation of ovaries into male rats possessing a normal testicle. The graft became vascularized and was observed for at least eight and a half months. All the characteristic structures of the normal ovary, excepting corpora lutea, were present. On the other hand, pieces of testis were engrafted into female guinea pigs possessing one normal ovary; the graft persisted for at least eight months. The graft behaved Uke the testicular graft in general, i.e., the seminiferous tubules underwent degeneration. In view of all these experiments Moore comes to the conclusion that there is no indication of an antagonism between the ovary and the testis. Fisher (1923) at the sug- gestion of Moore engrafted intraperitoneally or subcutaneously two ovaries into male rats having both testicles in situ ; in seven out of eight animals operated, one or both grafts persisted for at least three to five months. But it may be added that with guinea pigs Moore, like Steinach and Sand, always had negative results (Moore, 1921 a, p. 136). This, however, does not signify much in view of the older experiments of Schultz on guinea pigs and of those of Moore and Fisher on rats. I think that the question of the antagonism between the glands of both sexes is by no means negatively decided by Moore's and Fisher's experiments. It is very significant that, according to these observers, there was never any influence upon the somatic and psychical sex characters in those experiments in which an ovary or a testicle was implanted in the body of the other sex without previous castration of the host; on the contrary, in the related experiments of Steinach and Sand where ovarian and testicular grafts were made simultaneously, or w^here an intratesticular ovarian graft was performed, both glands exhibited a very pronounced influence on the somatic and psychical sex characters, as we shall see below. It must, how- ever, be pointed out that male rats are not very suitable for ob- serving the feminizing influence of the ovary, since teats and mammary glands are absent in the male; as to the female with a testicular graft, Moore does not mention whether, like Sand, he examined the condition of the clitoris. But, on the other hand, a recent observation of Sand (1922 c) is of great 356 INTERNAL SECRETIONS interest in this connection; in guinea pigs, so suitable for demonstrating the feminizing effect of ovarian hormones. Sand found in three cases of intratesticular transplantation, persistence of normal ovaries without any influence on the sex characters having been exhibited. This statement of Sand was recently confirmed in our laboratory by Voss. It seems to me very hkely that the fate of the graft and its hormonic effect are not necessarily concomitant phenomena. The hormonic effect of the graft depends evidently upon quantitative relations between the two heterosexual glands. The experiments hitherto made were such as did not admit of the possibility of making definite statements on this point, but the question seemed to me well worthy of experimental study, in which the quantities of the respective grafts should be varied. With Krause and Voss I made an extensive experimental study of this question in guinea pigs on quantitative lines. These experiments proved (LipscMUz and Krause, 1923 ; Krause^ 1923) that an ovarian fragment can survive and reveal a maximal feminine hormonic effect when engrafted by the intratesticular method of Sand, both testicles being present in the body. If one testicle is removed previously to the ovarian implantation, the number of successful cases is highly increased and the time of latency, i.e., the time between the operation and the first appearance of the hypertrophy of the teats, is much diminished. If previously to ovarian trans- plantation the testicular mass is so far reduced that only a small testicular fragment is present in the body, which, however, is sufficient for normal masculinization, there will be almost 100 per cent, of positive cases, i.e., the fragment will "take" and exhibit its hormonic effect practically in all the cases operated (unpubUshed experiments with intrarenal ovarian grafts^, experiments with Voss). The time of latency is so extraordinarily diminished, under the indicated quantitative conditions, that the hormonic effect of the ovary may reveal itself as early as 12 to 14 days after implantation, even when the ovary is taken from an animal only two weeks old. Our experiments leave no doubt that ovarian fragments can resist against two testicles in situ and that testicular fragments can * Intrarenal ovarian grafts were first made by Marshall and Jolly (1908). The technique I adopted differs in some respects from the original method of Marshall and Jolly. INTERSEXUALITY 357 resist against two ovaries engrafted, both causing sex specific honnonic effects. But the chance of survival of the ovarian graft seems to depend upon the quantity of testicle simultane- ously present in the body, and the time of latency of the feminine hormonic effect surely depends upon the quantity of testicle. In those experiments in which an intrarenal ovarian transplantation was made, both testicles remaining in situ, we never obtained a positive feminine effect. If in similar negative experiments the testicles are removed about 7 to 8 weeks after the ovarian transplantation there may be a positive feminine effect after a short time of latency. These latter experiments show in a most striking manner that an antagonism exists between the gonad in situ and the engrafted gonad. But this antagonism is not necessarily to be understood in the sense that the development of the graft is definitely inhibited; an inhibitory influence might reveal itself in retarding follicular development and the production of sex hormones ; consequently again the time of latency might be lengthened, and the chance of survival also diminished. Whether this antagonism is an antagonism of hormones simultaneously circulating in the body cannot yet be said. Some experiments (Lipschiitz and Voss; Lipschiitz, Lange and Tiitso) in which there was only an operative interference on the testicle without the testicular mass being reduced, were also positive and the time of latency was rather a short one.^ It is possible that the antagonism between the gonad in situ and the engrafted gonad . is not of a sex specific order, i.e., that the ovarian graft also in females will exhibit an hohnonic effect only when the gonads in situ have been previously removed or reduced. We cannot go into further details here. But on the basis of our new experiments it seems clear that the problem of the antagonism of the sex glands is very far from being negatively settled. As to the fowl the situation seems at first glance a conflicting one, and I think that here also a quantitative factor is involved. Goodales experiments (1918, p. 283) on fowls gave mostly negative results. Nine young cocks were unilaterally castrated or one testicle was injured and an ovary was engrafted; the 1 The fact that the intratesticular ovarian graft can exhibit an hormonic effect, even when both testicles are present, might be due to the operative interference on the testicle as in the above experiments of Lipschiitz and his co-workers. 358 INTERNAL SECRETIONS birds were killed after sexual maturity was attained, and in seven cases ovarian tissue could not be detected. AU the birds showed normal somatic and psychical masculinity, even those birds in which ovarian tissue was found. Zawadowsky (1922) implanted one testicle into the normal hen. Six experi- ments of this kind were made. In one case the graft persisted for a longer time. There was no decided influence of the testicular graft on the ovary, and vice versa, as the hen showed all the female sex characters and even laid eggs at a time when the comb had already begun to hypertrophy. Further, Zawadowsky engrafted ovaries into normal cocks; five experi- ments of this kind were made. In one case the graft took and exhibited its influence on the sex characters. There was also a decided antagonism of the sex glands in the experiments of Minoura (see p. 311). This antagonism does not, however, exclude the possibihty of experimental hermaphroditism in the fowl as shown by the above-mentioned experiments of Zawa- dowsky and by those of Pezard, Sand and Caridroit (see p. 410), all depending, as I think, upon the quantities and the condition of testicle and ovary simultaneously present. It is of great interest to note that in Arthropoda, where there is no hormonic activity of the sex gland, the gonad develops normally in every respect when engrafted into an animal of another sex which has been unilaterally castrated. New experiments of Matsuyama (1921) should also be referred to here. Matsuyama made observations on rats in parabiosis, uniting normal and castrated males with normal and castrated females. He found that the testicle of a male united with a normal female several months afterwards undergoes degenerative changes like those after ligation of the vas deferens, transplantation, irradiation and so on; the ovary undergoes changes which seem to me to be similar to those after transplantation or irradiation. At first thought one might be disposed to consider these results as caused by an antagonism between the gonads of different sexes. Now, it is of great interest that- similar degenerative changes in the testicle occur also if the normal male or female has been united with a castrated partner of the opposite sex. There never was feminization or masculinization of the castrated partner. Evidently here certain factors are involved which are beyond our actual knowledge. As far as I can see from INTERSEXUALITY * 359 Matsuyama's experiments there was no endocrine influence even on the partner if a normal male was parabiotically united with a castrated male. When a castrated female was united with a normal one, degeneration of the ovaries took place as with a transplanted or irradiated ovary; there was an intensified development of the mammary gland of the normal partner, whereas the mammary glands of the castrated partner behaved like those in an ordinary castrated female. Similar observations were recently made by Goto (1922). It seems to me very difficult to judge from the description given by Matsuyama how far the question of the mutual influence of parabiotically united partners has been decided by his experiments, but I think that the experiments should provide incentive for further research by the method indicated. Lillie (1923) considers that the description of the organs of the freemartin (see p. 388) are a further proof of an antagonism between the male and female hormone-producing gonads. 2. Somatic Characters of the Experimental Hermaphrodite. In castrated male guinea pigs, into which a simultaneous implantation of both testicle and ovary had been made, the penis and the seminal vesicles were well developed; the pro- portions and also the filling of the seminal vesicles were normal (Sand, 1918); the coagulation of the vesicular content under the influence of prostatic secretion takes place in a normal way {Lifschutz and Krause, 1923 a). The honnonic action of the ovarian graft was easily seen in the teats ; the length of the teats was in Sand's experiments more than -5 cm., as compared with I to 2 mm. in the normal male; the teats were like those of an ordinary female, sometimes like those of a female during pregnancy or even lactation (Figs. 127, 128). In some of the cases recorded by Stcinach (1916 b, p. 322) and Sand (1918, pp. 163 and 171) milk secretion occurred as well. Evidently the testicle was not able to inhibit the development of the female sex characters, or to hinder the hormonic action of the ovarian graft, whereas the engrafted ovary was not able to inhibit the growth of the male sex characters. It seems that the stimulat- ing action of both sex glands can take place in the experimental hermaphrodite, but that the inhibiting action of both glands is suppressed. A similar statement was made by Moore: the 36o INTERNAL SECRETIONS B i ov. C 2 ov. Fig. 127. — Experimental hermaphroditism in guinea pigs. (Operated by Dr. W. Krause by the intratesticnlar method of Sand.) A. Normal male (610 gr.). B. Male (415 gr.) with both testicles in situ and half an ovary en- grafted into one testicle about six months previously at an age of 2-3 weeks and at weight of 160 gr. C. Male (450 gr.) with two whole ovaries engrafted into the testicles in situ about six months previously at weight of 170 gr. — Photos of Vesnjakov. INTERSEXUALITY 361 Fig. 127. — Experimental hermaphroditism in guinea, pigs. (Operated by Dr. W. Krause by the intratesticular method of Sand.) D. Normal virginal female (475 gr.). E. Normal female (430 gr.) which has been pregnant once (aborted). F. Normal adult female. — Photos of Vesnjakov. 362 INTERNAL SECRETIONS growth of the penis and seminal vesicles was not inhibited by the engrafted ovary. Moore and Fisher were evidently mistaken when writing that Steinach asserted that the ovarian graft will inhibit certain male sex characters in hermaphrodites. Steinach's statement is just the opposite of this. The fact that male characters are not inhibited by the ovary engrafted simultaneously with a testicle into a male animal, was explained by Steinach as due to the antagonism of the male and female sex glands continuing to exist to a certain degree also after A / .D B ^ov. -ir' ^- ? :■•: W:^0^:^^:■ :-:^:m:v^ v5^ ^V' ,^i 473 Chapin 388, 469 des Cilleuls 19 1-2 Clowes and Bachman 345 Cohn 249 Cordes 178 Corner 246 Courrier 58, 64-6, 172-3, 186-7, 191, 199, 344-5 Cramer 477 Crew 143, 381-2, 392, 398-9, 454 Crew and Huxley 397 Caenot 461, 463, 465 Darwin 50, 456, 458, 461, 464 Davenport 463 Dittler 331 Donaldson 294 Doncaster 390, 409-10, 458 Dragoiu 68 Els 86, 92 Exner 34, 160, 335 Falcone 88 Faure 34 Faure-Fremiet 68 2 I 496 INDEX OF AUTHORS Fell 381, 392-3 Fellner 320, 323-4. 327» 329-30 Fichera 474 Fisher 355, 362 Fitzsimons 44 Foges 36, 39-41, 82, 166, 195, 287, 309, 323, 363 Forel 409 Forster 86 Fraenkel 211-14, 220, 249, 251, 255, 260, 267, 322-3 Franz 30-2 Friedenthal 478 Friedmann 189 Fiirbringer 335, 343 Furno 424, 426-7 Ganfini 170 Gerlinger 249, 261 Giacomini 249 Giard 59, 66 Gley 79, 109, 319-21 Gley and Pezard 23 Goddard 125 Goette 183 Goldschmidt 58-9, 63, 65, 350, 369, 400-3, 412, 444~5, 447. 454 Goltz 53, 98-9 Goodale 36, 38-47, 63, 198-9, 273-5, 288, 307-9, 312, 352, 357-8, 394-6, 410, 442, 451-3, 466, 468 Goormaghtigh 227, 250 Goto 359, 390 Gorki 7 Gould 69 de Graaf, Regnier 338 Griffith and Duckworth 425 Gross, see Tandler and Gross Guggisberg 234-5 Guthrie 43 Gurney 390 Guyenot and Ponse 92, 188, 272, 399 Guyer 195 Haberern 338 Haberlandt 90, 243, 257 Halban 18, 29, 56, 351, 403, 426 Hammond 259 Hammond and Marshall 253, 255 Hansemann 170, 178 Harms 51-3, 58, 68, 96, 186-7, 272, 285-7, 291, 297, 303, 322, 330, 399, 447, 485, 487 Hartmann and Hamilton 392 Heape 255, 263 Hedinger 180-1 Henry 263 Herbst 56, 58, 466 Herhtzka 286 Herrmann 320, 323-9, 469 Herrmann and Stein 257, 323, 327, 329, 330 Hertwig 459 Hewer 230 Heymans 235, 475 Hill 249 Hirokava 335, 343 Hirschfeld 5, 7, 12, 13, 351, 368, 371, 403, 408, 424, 431 Hitschmann and Adler 260 Hofstatter 5, 178, 255 Holzknecht, see Steinach and Holz- knecht Houssay 167 Houssay and Hug 142 Houssay and Wallart, 230 Hunter 81, 287 Humphrey 188-9 Huxley 401-3, 473 ISCAVESCO 323 Itagaki 330-1 Iwanoit 341, 344 Jaffe 183 Josefson 424 Kammerer 5, 25, 29, 54, 57, 286, 442, 446, 449, 470 Kasai 125-6, 178-9 Keith 478 Kelker 87-8, 490-1 Keller 386, 388, 446 Keller and Tandler 383-4, 387, 469 Kellog 55 Kitahara 183 Koch 5, 12, 16, 426, 441 Kohn, Alfred 120, 163, 174, 181, 446, 492 Kolb 490 Kolhker 335, 343-4 Kolmer and Koppanyi 190 Kolmer and Scheminzky 186 Kon 12 Kopec 54-5, 57, 312-13 Kornhauser 66 Kostich 178 Krabbe 372, 431, 434-6, 438 Kraepelin 371 Krause 88, 291, 352, 356, 360-1 Krediet 270, 381 Kreuter 370 Kropman 129, 160 Krzy§kowsky 3^14 Kull III 2, 123-4, I39"40, 158-9, 162, 182, 215, 217-9, 221, 223-4, 240-1, 244-5, 252 Kuntz 128, 133 INDEX OF AUTHORS 497 Kyrle 143, 152, 154, 160, 174, 179-80 Kyrle and Schopper 178 Labhardt 266 Lacassagne 36, 133, 163, 166, 227-8, 269 Lane-Claypon 250 Langhans loo-i Lauche 161, 190, 273, 276 Lecaillon 171-3 Lehbert 27, 114-6, 151, 156-7, 164-5, 212, 216, 247 Lespinasse 84 Leuckart 337 Leydig no, in Lichtenstern 12, 19, 34, 85-6, 92, 148, 288, 335, 338, 341-2, 369-70, 442, 490 Lillie 270, 359, 383-9, 444-5, 452, 454, 467 Lillie and Bascom 389, 445-6 Limon 211-12, 222-4, 227 Lipschiitz vi., 17, 28, 79, 84, 102, 145, 150, 160, 162-3, 243-4, 2zj6, 262, 287-8, 291, 299, 301, 352, 388, 428, 442, 444, 447, 450, 454, 465, 476, 490-1 Lipschiitz and Ibrus 161 Lipschiitz and Krause 359, 363 Lipschiitz and Voss 246, 291, 352, 356-7, 362-3, 451 Lipschiitz and Wagner 131 Lipschiitz, Krause and Voss 352, 356, 362 Lipschiitz, Lange and Tiitso 357 Lipschiitz, Ottow and Wagner 87, 157 Lipschiitz, Wagner and Bormann 145 Loeb, J. 345 Loeb, L. 252, 255, 257, 382 Loewy 93 Loewy and Zondek 492 Loisel 196 Lucas and Adrian 168 Macht 339-40 Macht and Bloom 342 Macht and Ulrich 342 Magnusson 387-8 Maranon 320, 473 Marburg 436-7 Marey 168 Marshall 25, 36, 170, 172, 196, 246, 248-50, 253, 255, 263, 335, 341, 394, 477 Marshall and Hainan 261 Marshall and Jolly 89-90, 235-6, 239, 242, 356 Marshall and Runciman 263-4 Marshall and Wood 264, 266 Marshall, see also Carmichael Martin 8, 9, 11, 17, 462, 475 Masing 431-2, 434 Massagha 191, 194-5 Matsumoto 340 Matsuyama 358-9, 390 Matthias 373, 436 Mattill and Carman 184 Mauclaire 84, 86 Mayer 389 Mazzetti 189, 192 Meisenheimer 51, 55, 57, 96, 285-7, 312-3, 403, 409, 412, 442 Meyer, Robert 15, 222, 249, 260 Michon and Porte 142 Mingazzini 249 Minot 450 Minoura 270, 310-11, 352, 358, 388, 390, 404, 442, 444, 470 Mittasch 376 Moore 29, 33, 239, 262, 288, 291-3, 295, 299, 303-6, 352, 354» 359, 362, 442, 451, 467 Morgan 47-50, 65-6, 191, 313, 393-4, 452, 463-5, 478 Morgan and Goodale 461 Miihsam 86, 370 M^'ller-Sdrensen 353 Murisier 391 Myers 128, 133, 294, 451 Nemenov 154 Neugebauer 371, 379, 403 Neurath 431, 435 Niskoubina 253 Nothnagel 160 Nussbaum 51, 53, 90, 92, 95,97, 335 Nonidez 191, 198-9, 275, 394 Oberholzer 13 Obmann 431 Ocaranza 33, 299 Ochoterena and Ramirez 226, 250 O'Donoghue 249 van Oordt 50, 187 Ottow 87 Oudemans ^$, 58 Owen 476 Pares 342-3 Patzelt 191 Pearl and Boring in, 191 -3, i95, 274-5, 391-2, 484 Pearl and Schoppe 275 Pearl and Surface 257, 382, 458 Pease 191, 394 Perez 66 Peters 255 Peyron 375, 377 498 INDEX OF AUTHORS Pezard 37-44> 47. 63, 82, 95, 167- 70, 191-4. 196-7, 274, 288, 307, 309, 312, 320-22, 352, 358, 363, 388, 390-1, 395-6, 410, 436, 441-2, 451-3, 461, 463, 465-6 Pezard and Caridroit 461-3, 465 Pezard, Sand and Caridroit 358, 408, 410 Pfeiffer 370 Pfliiger 97, 98 Pick 375, 377, 379-81 Plato 1 74 Plant 234 Polano 376 Poll 36, 42, 46, T95, 409, 471-2 Pollitzer 344 Ponse 287 Posner 129 Potts 59, 64-5 Prenant 251 Priesel 376 Przibram 298 Punnett 191, 394 ' Rasmussen 170, 171, 189, 226 Rauther 341 Reeves 192 Regaud 171-3 Regaud and Policard 143 Regen 57 Reinke 115 Retterer 129, 476 Ribbert 157, 235 Richon and Jeandelize 23 Riddle 444 Romeis 390, 489 Rossle 1 2 Rubaschkin 118-9, 197, 396 Ruge II., Carl 260 Ru^icka 492 Sacchi 435 Sainmont 211, 218, 227, 249-50 Salazar 225, 257 Salen and Pick 375 Sand 83, 129-30, 133, 143, 145, 150, 152, 158, 163, 166, 170, 238-9, 256, 262, 265, 288-9, 291-2 295, 298-9, 303-5, 351-6, 358-9, 360-6, 375, 388, 442, 451, 473, 488-9, 490, 492 Sauerbeck 376, 378-9, 403 Schaeffer 211-13, 220 Schafer 330 Schickele 263 Schieidt 474 Schmidt, Peter 490, 492 Schmincke and Romeis 377 Schonberg and Sakaguchi 33, 474 Schrader 99-101 Schultz 148, 236, 287, 354-5 Seitz 211, 220, 222, 226, 250 Sellheim 28, 36, 39, 40 Serralach 342-3 Sexton 401-3 Shattock and Seligmann 41 Simmonds 153, 178 Sippel 90, 491 Smith, Geoffrey 59-65 Sobotta 249 Sollas 67-8 Spallanzani 98, 335 Stabel 88, 370 Starhng vi., 80 Stanley 87-80, 93-4, 490-1 Steinach vi., 17, 19, 20, 29, 34, 51,53, 63-4, 82-4, 93, 95-6, 99-101, 109, 128, 133, 148-52, 162, 166, 170, 233, 237-9, 262, 267, 285, 287- 300, 303-5, 330, 335, 340-1, 343, 350-2, 354-5, 359, 362-4, 366-70, 375, 378, 381, 386, 388, 403, 408, 438, 447, 450-1, 454-5, 462, 466-7, 473, 485-90, 492-3 Steinach and Holzknecht 230-34, 241, 262 Steinach and Kammerer 183 Sternberg 368, 377 Stigler 335, 344 Stocker 86, 88 Stotsenburg 303 Stricht, van der 249 Surface, see Pearl Takahashi 96, 142 Tandler 6, 16, 17, 153, 426, 441-2, 443 Tandler and Gross 5-8, 10, 12, 13, 16-7, 25, 32-3, 128-9, 171-3, 350, 424-7, 441-2, 447, 456, 459, 469 Tandler and Keller 29, 32-4, 42, see also Keller Tarchanoff 98-100, 335 Thaler 178 Thomas 457 Thorek 88, 148, 154, 462, 484, 491 Tiedje 128-9 Tigerstedt 298 Toldt 7, 425, 457 Torrey and Horning 397 Tribondeau 153 Tsuji 183-4 Unterberger 88, 90 Vandel 68-70 de la Vaulx 401, 447, 473 Verworn 168 Ve§njakov 360-1 INDEX OF AUTHORS 499 Veszi 1 68 Villemin 153 Voinov 183 Volker 249 Voronoff 88, 462, 484-5, 487, 491 Voss 356 Wagner 27, 52-3, 87, 93, 111-14, 116-18, 121-4, 126, 131, 134-8, 140, 151, 156-60, 164-5, 182, 189, 212, 215-7, 221, 223-4, 244-5, 247, 252, 287, 399 Wagner and Loeper 131, 139, 141 Waldeyer 1 1 1 Wallace 249 Wallart 211, 220-1 Watson 197 Weber 409 Weichselbaum 1 78 Weil 331, 346, 370-2 Welti 92 Werner, Paul 229 Wertheimer and Dubois 329, 338 Whitehead 116 Wildbolz 86, 424, 426 Wilhelm 486-90 Willier 388-9, 404, 469 Winiwarter 174, 21 1-2, 218, 220, 226, 249-50 Wischnewsky 335 Witschi 174, 398-9 Wodsedalek 447 Wolf 344 YocuM 394 Zawadowsky, M. M. 32, 46, 274, 288, 307, 310, 312, 352, 358, 363-5, 395-6, 410-12, 442-3, 447, 452, 461, 465-6, 470-1 Zawadowsky, B. M. 397 Zietschmann 249, 270, 387 I General Index. Adam's apple 293, 305 Adrenals 3, 80, 104, 211, 321, 372, 375, 377. 391, 395-6. 412, 435-6, 470 — functional relation to sexual glands 3 Albuginea 289 Alcohol, effect on interstitial cells 178 ff- 483 "All or Nothing," law of 166 fif. for ovary 243 Alytes, experiments in castration of 54 Amenorrhoea 267 Amphelopus 66 Amphibia 52, 54, 187, 285, 397 — - asexuahty of soma in 443 — intersexuality in 397 — corpus luteum in 249 Anorchism 426 Andrena 66 Antagonism between sex glands 352 ff. — between sex hormones 467 — between testis and ovary 352 Antennae after castration 56 Apes, testicular homoiotransplanta- tion 155 irradiation with X-rays 155 — testicles grafted on man 88, 462, 491 — interstitial tissue of ovary 214 — ovulation in 253 Appendix vesiculosa, etc. 460 — testis 460 Arthropoda, experiments on 55, 312, 358, 401 — • condition after crossed trans- plantation 358 — parasitic castration 59 ff. — results of castration 55 Ascaris megalocephaJa 68 Asexual embryonic soma 50-1, 71, 441 ff., 456 ff., 460, 465, 469- 70 and heredity 456 evolved characters 453 ff. — stage in development of soma 17' 175 Aspects, some practical 483 Atretic follicle and coipus luteum 249-50 and interstitial tissue 249 Autotransplantation 82, 235, 238, 242, 305, 484 Autotransplantation, definition of 81 — in fowls 82 — in guinea pigs 83 — in rabbits 235 — in rats 82-3, 235 — of ovary in woman 88, 90, 235 ff-. 451 — of testicle in man 86 Averting reflex 297-8 Azoospermia 178, 342 "Backward development" 148 Bat, cyclic changes 172 — corpus luteum in 249 — heat in 263 — interstitial tissue in 213, 269 — ovulation in 263 — spermatozoa in 344-5 Bidder's organ 187-8, 272, 286 Birds, intersexuality in 390 ff. — results of castration in 18, 36- 51, 194, 307 — {see also cock, hen, fowls, etc.) Bisexual behaviour 365 Bleeding of uterus after ovario- tomy 263 Body temperature of male and female 298 — weight after castration 94-5 Bombyx mori, castration of 55 Bones, condition in castrate after injection of testicular substance 94 "Bouchon vaginal" 337, 341 Brahma fowls 39 Breasts after castration, in man 16 in woman 14 Buffalo, hypophysis after castration 33 Bufo vulgaris 187, 272, 286 — pads in 287 — - (see also toad) Bull, castration of 5, 18. 28 — hypophysis after castration 32 Calves, mammae after castration 28 Campines 393 — results of castration 47 Cancer and interstitial cells 178 Capon 81-2 — after prepuberal castration 40 — feeding mth sexual gland 93 — psycho-sexual behaviour 40 50] 502 GENERAL INDEX Capon, spurs after castration 39 Carbonic acid 79, 331, 492 — in blood 79 Carcinus maenas, parasitic castra- tion of 64 Cardualis caniceps 48 Castrates, types of 8, 16 Castration, counteraction of results in cocks 41 - — effect on sexual characters 16, 17. 306 — heat after 28-9 — in cases of criminal behaviour 13 — in disease 5 — influence on skeleton 8, 16, 474 — morphological signs of 18 — partial 168, 181, 243 ff., 273 — physiological 5, 14 — psycho-sexual behaviour after 40 — results in animals 5, 18 in amphibia 52, 54 in arthropoda 55 in birds 18, 36-51, 194, 307 in bulls 5, 18 in cocks 36-42 in cows 1 8 — ■ — in crabs 59 -in dog 24, 82 in drake 44, 47, 307 in duck 44, 195, 274, 312 in fishes 51, 54 in frog 51, 190 in guinea pig 20-24, 34 — — in hedgehog 18, 29, 36 in the horse 18 — — ^ in invertebrata 67, 459 in mammals 18, 25, 82 in man 5 ff. in rabbit 23, 82 — — in rat 19. 20, 34, 36, 82 — — in triton 190 in woman 13-15 — senile atrophy 5, 14 — tendency to common type after 17, 18, 32, 46 — therapeutic reasons for 5 — - unilateral, hypertrophy in 157-8, 1 60- 1 of ovary 243 — {see also prepuberal, postpuberal) Cat, interstitial cells in ovary 213 — section through ovary 247 — testicle of 113 Cattle, hypophysis after castration 32 — interstitial tissue of ovary — ovulation 253 . — twin pregnancy in 383 fl. — results of castration 5, 18 Cauterization 190, 251, 253, 264 Central nervous system 92, 97-8 — connection with clasp reflex 99, lOI Cerebellum in clasp reflex 99 Cheiroptera 217 Cholesterine 325 Chondriosoma 116 Chorion condition in twin pregnancy of cattle 386 Chorio-allantoic membrane graft 310 Choi lon-epithelioma of testicle 1 80 Chromosomes, sex 446-8, 464 Circulation in twin pregnancy of cattle 384 Clasp reflex 51, 53, 95. 98 ff., 273, 285, 297, 335, 399 — connection with internal secre- tions 98 — physiology of 98 — skin in loi Claws after castration (Inachus) 59 Climacteric in women 13, 14, 220 — after castration 13, 14 Clitellum in Lumbricus 67 Clitoris, atrophy of 231 - — hypertrophy in masculinization 300 fl. — influence of testicular transplan- tation on 300 ff. — in the freemartin 383 Cock, feminized 308 — hypophysis after castration 40 — injection experiments 94-5 — results of castration on 36-42, 307 — testicular transplantation 81-2 — unilateral castration 357 — {see also hen, fowl, capon, etc.) Cock-feathermg in birds 274, 390, 393, 442, 445, 457, 460 Colour alteration in wings after castration 57 Colostrum, after castration 28 — in feminized male 293 Comb of cock after castration 37-8 — hen after castration 43 Compensatory hypertrophy in testicle 155 fl. Copulation, after castration 53 Cornish Indian game 458 Cortex of cerebral hemispheres 104 Corpora bigemina and clasp reflex 99, 100 Corpora lutea 190, 212, 215, 235, 237-8 — and atretic follicle 249-50 — -and interstitial tissue 251 ff. — cauterization of 251 — endocrine function of 255 GENERAL INDEX 503 Corpora lutea, function of 252 — graviditatis 259, 260, 268, 271 — histogenesis of 248 ft. — hormonic function 256 — in testicle 190 — in twin pregnancy 383 — in virgin guinea pigs and rabbits '259 — injection of 322, 325, 330-1, 469 — internal secretion of 246 ft",, 263 ff. — menstruationis 269 — objections against theory of internal secretion of 263 £f. — "partial" 249 Corpora cavernosa, see penis Cow, castrated, skeleton 29 corpora lutera in 384 skull in 32 — {see also cattle, bull, freemartin) Crabs, parasitic castration 59, 66 Crepidula plana 69 "Crossed transplantation" 287, 352, 410, 449, 470 Crossoptilum auritum 48 Crustacea 65 Cryptorchism 186, 305 Crystaloids in testicle of man 115 Cynocephalus, testicular homoio- transplantation 155 Cystic degeneration of ovarian graft 238 Cyclic changes of the testicle 53, 170 in development of interstiti- al tissue 170 ^ in female sexual life 251 Daphnia atkinsoni 402 Darwinian theory 50, 456, 458, 461, 464 Deciduoma 252 Determination of sex 448 "Development, backward" 148 Dimorphism, sexual i, 454 Disease, interstitial cells in 1 78-1 84 Dog, castration of 82 — ■ interstitial cells in ovary 213 — lesion of infundibulum 142 — ligature of vas deferens 127 — relation between testicle and prostate gland 24 — retention of testicle 142 — senile, rejuvenation of 485 ff. — X-ray experiments 154 Dorking fowl 462 Dorset x Suffolk sheep, cross 461 Drake, results of castration 44, 47, 307 Drake, feminization of 309 — implantation in 309 Duck, castration of 44, 195, 274,. 312 Duodenum 80 Ductus epididymidis 128,129,163 Earthworm 67-8, 186 — sexual characters in 67 Endocrine' action, sex specific, in birds 310 — cells 177, 233, 266, 269, 271-2 — function 126-30, 133, 143, 157,. 158, 161, 175, 185, 188, 194,. 197-9, 231, 234-5, 239, 243, 271^ 322. 371, 396, 469, 471 — glands 33, 104, 219, 233, 269, 312, 321, 448, 463, 478, 483 — organs 80 Endocrinology 80 Engrafted testicle 81, 148 ff., 369 Eosinophile cells 198, 375, 474 Epididymis 86, 128-9, 163, 172, 337. 341, 344, 369, 476 Epididymitis 129 Epithelial cells 120, 122, 177, 226, 227. 248. 267, 373 Epithelioid cells 119, 121, 195, 211, 218-9, 220, 221, 223, 225, 236, 239, 250, 255, 258, 269 Epithelium 23, 28, 118, 121, 122, 233, 249, 250, 285, 305, 323, 345 Equipotentiality of soma 443, 446-8, 470 Erection, in castrated male 12, 13 — in castrated rat Erotization 36, 88, 97, 183. 297-8, 336, 364, 423, 429, 431, 435. 462, 484, 492 Erotizing effect of sexual hormones 297 Eugenics 483 Eunuch 85, 441 Eunuchoidism 86, 104, 142, 145, 152, 155, 163, 176, 185-6, 369-70, 423, 424 ff., 483 — four types of 426-7 — in woman 430 Exchange, gaseous, in fowls 475 Experimental hermaphrodite, so- matic characters 359 ff. psycho-sexual behaviour 364 ff. Extirpation of lumbosacral part of sympathetic nerve in guinea pigs T42 Extracts of whole sex glands 319 ff. — of parts of sex glands 322 ff. Eyesight, after homoiotransplanta- tion 491 504 GENERAL INDEX Fat in castration of animals 33 - — in castration of birds 40 — in eunuchoids 426, 430 ■ — in feminized male 295 — in interstitial cells 115, 116, 163 — in prepuberal castration 7 — in postpuberal castration 12- 14:85 Feeding with sexual gland 92 — with testicular substance 93 Female and male, transition be- tween 4 — phases of puberty in 267 Feminization 64, 287 ff., 393, 396, 408, 442, 448, 450, 453-4, 462 — change in body growth and pro- portions 294-6 — condition of hypophysis in 4 74 — rudimentary male organs in 290 Fertilization 252, 261, 267, 344, 401-2, 446, 448 Fetishism, sexual 36 Fiddler crab 313 Fishes, castration of 54 — corpus luteum in 249 — interstitial cells in 186 Fixation of sex characters 449 ff. Foetus, condition of, in freemartins 384-8 — ■ extracts of 321 Follicle, an endocrine apparatus I77> 234 — and corpus luteum 249-50 — internal secretions of 265 ■ — obhterated by X-rays 230, 239, 255 — puncture of ripe 253 Follicular atresia in ovar}^ 223, 231, 233, 236, 238, 255, 269, 270 — development 245 accelerated 241-2, 269 — theory of hormone-production 176-7, 185, 187, 272, 471 Fowls, comb in 396, 473 — experiments on 169, 307 ft. — plumage, 307 - — results of castration in 46 Freemartin 359, 383-90, 445, 452, 454. 469 Frogs, clasp reflex in, 51, ^^^, 95, 98-101, 273, 285 — difference from mammals in reaction of testicular fragment 161 — heat in 51 — hypertrophy of testicular frag- ment 161 — oestral sound in 52 — pad in 51, 53, 97, 285-6, 473 — partial castration 273 Frogs, results of castration 51 — - vesiculae seminales 51 — testicular injection experiments 95 — testicular transplantation 90 "Furtherance" 467, 469 Galvanocauterization 55, 190 Gammarus chevreuxi 402-3 Gasterosteus aculeatus 187, 199 Generative cells i, 3, 63, 120. 121, 126, 396, 460, 469 Genes 464 Genetic factors 47, 459-60, 464-5 — S5^stem of sexual characters 2-4, 411, 468, 470 Genital passages, secretion of, and vitality of spermatozoa 343 ff. Gipsy moth, see Moth Glandular cells 116, 188, 193 Glands of internal secretion, changes after castration 33 "Glande interstitielle " ' 109 Goat's testicle 88, 462 — interstitial tissue of ovary 214 Goldfinch 48 Gonads 15, 64, 103-4, 350, 424 — bisexual 411 — definition of 473 — not factor in intersexuality 402 — not necessary for development of secondary sexual characters 15 Graft, puncture of, in transplanta- tion 8^ Granules of protein nature in testicle of man 115 — in interstitial cells 116 Graafian follicles 263-4 rupture of 253 Graviditatis, corpus luteum of 259- 60, 268, 271 Gravidity, interstitial tissue during 222, 226-7 Growth, body, after castration 37 under testicular graft 303 — curve of, in interstitial tissue 188 — intensity 65, 368, 404, 450 Guinea pig, auto- and homoio- transplantation 83 — castration results 20-24, 34- 83 — experimental hermaphrodite 363 ff. — extirpation of lumbosacral part of sympathetic nerve 142 — feminization 288 — horny styles in 22, 24, 129, 302 — hypophysis after castration 32 — interstitial tissue in 122 — irradiation effect 154 — ligature of vas deferens 127, 133 GENERAL INDEX 505 Guinea pig, mammae in 28 — mammary gland in 327 — masculinization 299 — ovarian transplantation 88-9 — ovulation 257 — penis in 20, 23 — psycho-sexual condition after castration 34 — puberal development 123 — retention of testicle 142 — seminal vesicles in 21, 23 — sexual activity in 163 — testicle of 112 — unilateral castration 130 — uterus in 28, 88 Hair in normal and castrated man 6, 9-10, 12, 85 — in castrated woman 13, 14 ■ — • in eunuchoid state 85 — in sexud precocity 373, 345 Hair-growth, influence by sex hor- mones 15, 466 ft. — in feminized male 295 — in mascuhnized female 304 Hares, heat after castration 36 Head apparel of cock after castra- tion 38, 41, 192 ^ -^ in experimental herma- phoditism 364, 391, 395 Heat 99-101, 162, 172, 188, 195, 197, 261, 263-4, 268, 336 — in prepuberally castrated animal 28 — clasp reflex in heat 99 — corpus luteum in 255 Hedgehog t8, 29, 36 — after postpuberal castration 29 — changes in interstitial tissue 1 70-1 Hen, masculinization 309 — plumage 42-3, 207 — results of castration 42, 312 — {see also cock) Hen-feathering 393-4, 442, 463, 478 — dependence upon sexual glands 50 Hens' eggs, transplantation on 310, 378, 390 Heredity 456 ff. — sex-limited 458 Hermaphrodite birds 275, 309 — experimental, somatic charac- ters 359 ff. — gland 63, 367 — puberty gland 366 Hermaphroditism 349 ff., 436 — experimental 351 ff., 436 — psycho-sexual behaviour 364 ft". Heterotransplantation 64, 352, 484, 492 — definition of 81 — in man 88 — in rabbits and guinea pigs on hares 89 — in tritons 286 Hibernating mammals, change in interstitial tissue 171 Hibernation 344-5 — interstitial tissue during 171 Hilum ovarii, extract of 330 Holzknecht-units 230-34 Homoiotransplantation 238, 242, 305. 491-2 — definition of 81 — in fowls 82 — in rabbits' ovaries 90 — in rats and guinea pigs 83, 235 — in woman 491 Homosexuality 86, 351, 367 ft. — in moths 369 Hormones 80, 96, 99, 193-4, 19^, 235, 262, 266, 269, 342, 405, 441 ft., 443. 445, 448, 450, 453, 461, 463 — antagonism of 357 — bearing on sex characters 466 — difterent action of male and female 293 — excess of, in organism 165 — experiments in isolation 323 — isolation of 319 ft. — sex specific action of 285 ft., 306, 320, 446, 461-2, 465, 493 Hormone-production, 103, 199, 237, 256-7, 273-5, 322, 367-8, 396, 399, 429, 454. 459-60, 483, 492 — follicular theory of 176-7, 185, 187, 272, 471 Hormonic action, increased 162-3 of spermatogenetic cells 196 specific 287 — activity of sex glands, non-sex- specific 473 — effect 155, 181-2, 241-2 dependence upon quantity of testicular hormones 167 proportional 166 Horny styles in guinea pig 22, 129 in masculinized female guinea pig 302 Horse, castration of 18 — interstitial cells 122 — ovulation 253 - — sexual activity after castration 35 — with retained testicle 142 Hyaline degeneration 251 5o6 GENERAL INDEX Hyperfeminization 293, 295, 305, 450-1 Hypermasculinization 303, 305 Hypernephroma 372, 375 Hypertrophy, compensatory in testicle 155 ff. — of interstitial cells 155, 162, 169, 178 ff., 237 ff. — of ovarian tissue 244 — of testicle in unilateral castra- tion 161 Hypophysis 3, 8, 12, 32, 40, 80, 104, 431. 438, 474 — changes after castration 32, 40, 474 — in castrated woman 1 2 — increased volume and weight 33 Hypospadia 378 — a sympton of intersexuahty ? 378 — peniscrotalis 379 — frequency of 379 Impotent frogs 95, 97 Inactivity, atrophy by 476 Implantation of ovaries 262 ff., 352 ff. — of testicle 299 ff., 352 ff., 369 ff. Inachus, parasitic castration of 59 ff. Increased hormonic action under hypertrophy 162-3 with ligature of the vas deferens 162-3 Influenza, Spanish, effect on inter- stitial cells 181 Infundibulum, lesion of, in dog 142 "Inhibition" 467, 469 Injection experiments 93, 319 ff. on cocks 94-5 on frogs 95-7 on guinea pigs 94 — of entire sex glands 319 ff. — of ovanan substance 93, 484 — of partial sex glands 322 ff. — of testicular substance 93. 484 Insects, intersexuahty in 400 — parasitic castration of 66 — {see also Arthropoda) Intermediate phase of puberty 1 75 Internal secretions, accumulation of 97 meaning defined 79, 493 -of follicle 265 of gonads 319 of nervous system 97 — — of ovary 211 ff., 239, 270 of sex glands 79 ff., 97, 103-4, 319, 330 of testicle 82, 97, 100, 109 ff. what are 493 Intersexuahty. 58, 65, 275, 303, 312, 347 ff., 445, 453, 457, 483 — classification 403 ff. — gonadal 375 — hormonic 376-8, 393, 402-3, 408, 410 — in amphibians 397 — in birds 390 — in insects 400 — mammals 379 — in man 367 — latent 411 — lateral 409-10 — morphogenetic 403 — partial 407 — zygotic 402 Interstitial cells 109, 111-13, 118- 23, 125-7, 130, 147. 150-5, 163. 239. 345. 368, 380, 396, 399, 427, 445, 455, 469, 492 as chemical transformers 183 always present in testicle 125 cUmaxes in development of 126 conditions at different ages 125-6 in intoxication and disease 178-184 effect of higher temperature 183 hypertrophy of 130, 133, 146, 150, 155-7, 179 in amphibians 109, 187 in birds 109, 189, 191 in fishes 109, 186 in guinea pigs 11 8-1 20 in invertebrates 186 in mammals no in unilateral castration 157-8, 1 60-1 necessary part of endocrine apparatus 185 of ovary in mammals 2 1 1 ff . of testicle no ff. "Interstial gland" 109, 154, 222, 224, 226, 455 Interstitial tissue and corpus luteum 251 ff. and hormonic effect 155 ff. cyclic changes in 170-5 ■ during foetal life 269 hypertrophy of 234, 241 in intoxication 178-184 of ovary in man 220, 222, 227, 237, 242, 324 of testicle 120-2, 125-6, 131, 146, 150, 163, 166, 330, 343 time of development 172 Intoxication, interstitial cells in 178, 184 GENERAL INDEX 507 Intraienal grafts 356 Intratesticular transplantation 353, 355 363 Invertebrata, results of castration 67, 459 — internal secretions of ovary in 272 Iodine, effect in interstitial cells 1 79 Iriadiation of sex glands 484 — {see also X-rays) Isolation of the sexual hormones 319 ff. Katabolic substance 79-80 Langshan fowl 461 larynx in castrated man 8, 12 Law of "All or Nothing" 166 ff. for ovaiy 243 Leghorn fowl 38, 40, 42, 307, 394, 462 Leydig cells 109, no, 150, 179, 195 Ligature of vas deferens 127 Limicola 50 Lipoids 323-4, 329 Lizard 344 Lumbncus herculeus 67 Luteal , (lutear) cells 268, 274-5, 367-8. 392-4 Lutein cells 226, 233, 236-7, 242, 249, 324 — pigment m ovary 212, 250 Lymantria dispar 55, 57, 312, 369 Lymphocytes 198 Macacus (ape) testicular homoio- transplantation in 155 Male and female, transition be- tween 4 — phases of puberty in 1 75 Maleness, change to, in castrated hens 43 — complete, factors in 104 Mammals, castration in 18, 25 — feminization in 287 morphological signs 18 — internal secretions of ovary in 211 ft. — intersexuality in 379 ff. — mascuhnization in 290 — psycho-sexual behaviour of 33 — seminal vesicles in 336 ff. Mammae, hypertrophy after cas- tration in man 12 woman 14 animals 28 Mammary gland 253, 325-6 — after castration in animals 28 — after X-ray irradiation 262 Mammary gland, condition during menstruation 253 — hypertrophy of 324 — in experimental hermaphrodit- ism 363 — in feminized guinea pig 290 — in feminized rats 294 — in mammals after castration 32 Man, homosexuality 367 — intersexuality in 367 — interstitial cells of testicle 112- 125 — ligature of vas deferens in 490 — postpuberal castration 12 — prepuberal castration 6 — psychosexual behaviour in 102 — results of castration in 5 ff. — - retained testicle in 147 — testicular transplantation 81, 84-7. 90, 92. 399 Marmot 171 Marsupials, corpus luteum in 249 Mascuhnization 287 -ff., 356, 372, d>75> 378, 386-8, 393, 395-6, 408, 412, 442, 445, 448, 450, 452, 454, 470, 476 — effect on coat 304 — ■ psycho-sexual behaviour after 304. 305 Maximum in the building up of the male internal organs of secretion 126 Medulla oblongata 79 — importance of, in clasp reflex 99, 100 Menstruation 268, 430 — after castration 13, 28 — after cauterization of corpus luteum 251 — after X-ray treatment 230 — and corpus luteum 251, 258, 260, 263, 266, 268 — and interstitial cells 258 — and pregnancy — time relation 253 — in monkeys 263 — in pubertas praecox 434, 436-7 — significance of the bleeding 266 Mesenchyme cells 1 18-19, 122, 197-9 Mesothorium 154 Milk diet, effect on testicle 184 — secretion, after castration 28 after X-ray treatment 231 in experimental hermaphro- ditism 363 -in feminized animals 291 Mitosis 126, 154, 172, 180, 271 Mole 171 Molge cristata 189, 286 Mollusca 69 5o8 GENERAL INDEX Monotremes 249 Morphogenesis 441 ff., 454, 475, 477. 483 Moths, castration of 55 ff., 312 — Goldschmidt's experiments 63 E., 369, 400 ft'. — wings after castration 55 ff. Mouse, castration results 20 — testicle of 113, 150, 160 Moulting time 46 Mucosa 6, 25, 80, 325, 337 Miillerian ducts 311, 384, 398, 444, 457> 459, 467 phylogenetic origin 459 Nephridia 459 Nerve cells 122 Nervous system, internal secretions of 97 Neuroglia cells 121 "Neutral" form 59, 62, 70, 442, 461-2, 470 Nicotine, effect on interstitial cells 178 ... Non-sex-specific hormonic activity of sex glands 473 ff. Nuptial apparel 55, 189, 195, 197 Oestrus, see Heat Oocytes 243, 275-6, 286, 310 Olfactory stimuli 36 Ostrich, hen, after castration 44 Ova, metabolic difference 444 Ovarian hormones, sex specific action of 285 ff. — tissue changes 261, 395 hypertrophy 244 — - transplantation 88, 290-T, 299, 450-1 Ovanotestis 353, 373-4, 376, 380- 381, 391-2 Ovary and testis, antagonism between 352 — auto- and homoiotransplanta- tion of 88 — - crossed transplantation 352 — extracts of 321-4, 326, 331 — feeding with 93 — histology and histogenesis 211 — implantation of 262, 288 — in arthropoda 58 — in partial castration 243 — in pubertas praecox 435 — in twin pregnancy of cattle 383 — injection of corpus luteum 322 — internal secretions of 104, 21 iff. 270 — lipoids in 221 — transplantation of 88, 235 fF., 451 Ovary transplantation of, in mammals 88 in rabbits 90 in women 15, 88, 90 — X-ray irradiation of 228 Ovulation, inhibited by corpus luteum 257 — in mammals 253 — in rabbits 253 — spontaneous 253, 256 Pachygrapsus marmoratus, para- sitic castration 62 Pancreas 80-1 Parabiosis 358, 390 Parasitic castration of crabs 59 earthworm 67 insects 66 Partial castration 131, 168, 181, 243 ff., 273 Partridge, castration in 48 Pelvis in castrated man 8, 16, 17, 32 — in sheep 32 Penis, castration effect 476 — condition after castration 18 — condition after transplantation of testicle 85 — condition in castrate after in- jection of testicular substance 94 — in castrated guinea pig 20 ff. — in castrated rabbit 131 — in castrated rat 19 — in eunuchoid 425 — in experimental hermaphrodit- ism 363 — in feminization 289-90 — in feminized rat 289 — ■ in gelding 476 — in insects after parasitic castra- tion 66 — in masculinization 450-1 — in normal guinea pig 20 — in retarded development 145 — in sexual precocity 432 — {see also vesiculae seminales, etc.) Penis-like organ in masculinized guinea pig 300 rat 303 Persistence of sex characters 2, 64, 453 Phalaropus 49, 394 Phascolomys 214 Phases of female puberty 126-7, 267 ff. — of male puberty 175-6, 185, 269 Pheasants, castration results 44, 46 — crossing of 457, 462, 471 Phoxinus laevis, nuptial colouring 45 GENERAL INDEX 509 Phylogenetic phase 58, 442, 459- 60, 463 Physiology of the clasp reflex 98 — of the prostate gland 338 ff. — of the seminal vesicles ^^5 ft. Pigs, hermaphroditism in 390 — interstitial tissue in 122, 215 — ovulation 253 — retained testicle in 143, 145 Pineal body, functional relation to sexual glands 437 — gland 33, 436-7 in pubertas praecox 436 Placenta 255, 262, 267 — extracts of 321, 323-5 Planaria, castration of 68-9 Plasticity of the organs 404 Pleurodeles waltli 190 Plumage of fowls 37, 39, 43, 47, 49, 71. 451, 463 — of ducks 44 — in experimental hermaphrodit- ism 364, 391, 395-6 — in castrated cock 37 — in castrated hen 43 — in castrated duck 44 — persistence of 453 Plymouth rocks 38, 458-61 Poisons, eftect on interstitial cells 178 Portax pictus 443 Postpuberal castration 12, 15 in animals ^5 ■ in the cock 40 in man 1 2 in woman 13, 14 observation of eftect 1 2 persistence of sex characters after i 8 psychical disturbance in man and woman 14 sexual libido in 12 Practical aspects 483 ft. — classification system of sex characters 472 Precocity, sexual 167, 372, 423, 431 ft., 483 hormonic basis 438 Pregnancy 268-9 — and menstruation 260 — and puberty 267 — puncture of ripe follicles 253 Prepuberal castration, in animals 35 in cock (capon) 40 in man 6 in mammals 25 Prepuberally castrated man 6 effect on general intelhgence 14 Prepuberally castrated man, devel- opment after castration 18 — ■ — erection in 12, 14 genital organs in 6 prolonged prepuberal stage 1 7 psycho-sexual behaviour 12 psychical disturbance in 12 Prepuberally castrated rat, in fem- inization 289 Preputial secretion, in castrated guinea pig 22-3 in masculinized female 302 Primary sexual characters i, 471 Problem of rejuvenation 483 Pro-oestrum 264, 265 Prostate gland 172, 425 — in castrated rat 20 — • in feminization 289 — in transplantation of testicle 83 — influence of X-rays on 154 — influence on sex characters 335 ft. — injection of 339 — physiology of 338 — removal of 340-1 Prostatectomy 338, 342 Prostate tissue, dried 342 Prostatic injections, eftect of 339 Proteins, introduction in organism in excess 164—5, 320 " Protrahierte Unreife" 17 Pseudo - hermaphroditism 15, 349 ft-, 377 Pseudo-pregnancy 253 Psycho-sexual behaviour 33, 351, 367, 424, 430, 450, 469 after castration 33, 35, 40, 84. 129 and sex glands, relation be- tween 103. ^35, 342-3, 368 in experimental hermaphro- ditism 358, 364 ft. in fowls 40 in guinea pigs 129, 298 in man and mammals 35, 102-4 external factors 102 in pubertas praecox 435 in rat 84, 298 influence of ovary 297 of feminized cock 308 — ■ — quantitative laws 166 Puberal development of uterus 231 Pubertas praecox 167, 372, 432 — skeleton in 434 Puberty, phases of, in female 126, 267 ft. in male 175-6, 185, 269 Puberty gland 109, 152, 154, 268, 454, 493 ■ hermaphrodite 366 510 GENERAL INDEX Puberty gland, isolated 150 — {see also interstitial cells) Puncture method of transplanta- tion 83 Quantitative factors 143-5, 155 ff., 321, 356-7. 362, 364, 368, 389, 392, 402-3, 407-8, 411-12, 423, 428-30, 450, 454, 465, 469, 476, 478 — changes in female 269 — laws of hormonic effect 166, 170 — statements about sexual activity 163 Rabbits, castration results 23, 82 — development of interstitial tissue in ovary 212 — hypophysis after castration 32 — interstitial cells of ovary 212 — interstitial tissue in 122 — ligature of vas . deferens 127, 131, 133 — mammary glands 28 — ovulation 253 — penis in 23, 24 — puberal development in 123 — retention of testicle 143 — sexual activity in 35, 163 — testicle of 112 — unilateral castration 130 — uterus in 26-8 Race distinction, dependence on hormones 478 Rams' testicles grafted on man 88 Rana esculenta 188, 462 — temporaria 335, 462 (see also Frog) Rats, autotransplantation in 82-3 — castration results 19, 20 — condition in transplantation of testicle 133, 148 — development of interstitial tissue 222 — feeding with testicular substance 93 — feminization 288 — heat 34 — hypophysis after castration 32 — interstitial cells of ovary 222 — ligature of vas deferens in 128 — mammary glands 294, 299 — mascuhnization 299 — olfactory stimuli 36 — ovariotestis 354 — psycho-sexual behaviour after castration 34 — retention of testicle 142 — seminal vesicles 19 Rats, sexual activity in 34, 163 — testicle of 150 — transplantation 152 — unilateral castration 130 Regeneration 492 — of implanted testicle after X-ray irradiation 153 Rejuvenation 483 ff. — in man 490 Reptiles, corpus luteum in 249 Results of castration in frogs 5 1 fishes 51 mammals 18 morphological signs 18 psycho-sexual behaviour 33 — — summary 70 Retained testicie 142 ff. Retarded development of testicle and sex characters 163, 169 Rhythm in sexual life of female 269 Rhode island reds 394 Roedeer, after castration 129 — antlers in 129, 153 — ligature of vas deferens 129 — after X-ray irradiation 153 Rostratula capensis 49 Rudimentary organs 457, 460 Sacculina, parasitic castration by 59 ff. Sandpiper 50 Sclerotic tissue 476 Sclerotization of ovar}^ 233 Sea urchin 346 Seat of production of internal secretions of testicle 109 ff. ■ — — ^ of ovary 2 11 ff . Sebright fowls 47, 393, 463, 478 — — castration results 47 ff. Secondary sexual characters i ff., 456-8, 471 Secretion of the genital passages and vitaUty of the spermatozoa 343 ff . Sella turcica after castration 12 Seminal vesicles 297, 425, 477 condition after castration 19 ■ — • — function of 337 in earthworm after parasitic castration 67 ^ in experimental hermaphro- ditism 359 in eunuchoids 425 in frog after testicular trans- plantation 91 in freemartin 384 in postpuberally castrated rat 20 in rat after testicular trans- plantation 83 GENERAL INDEX 511 Seminal vesicles, influence on sex characters 335 ft. physiology of 335 removal of 340 {see also vesiculae seminales) Seminiferous tubules no, 124-5, 128-30, 133, 148, 158-9, 172-3, 180, 183. 193-4, 196, 427 " backward development ' ' 148, 174 degeneration of 133, 142-3, 148, 153-5. 178 ft"., 305 Senile dog, experiments on 486 ft. Senility and rejuvenation 485 ff. Sertoli cells 126-7, 130-1, 143, 145-6, 148, 150, 152, 153-5. 173, 176, 185, 189, 196, 345 Sex apparatus in moth aftei castra- tion 55 ft". — characters {see sexual characters) — determination of 448 — difterentiation 445-6, 450-1, 467 — endocrine glands 473 — glands {see sexual glands) "Sex-limited" characters 470 Sex specific endocrine action in birds 310 — specifity 68, 104, 322, 327, 331, 397-8. 410. 442. 475 Sexual activity in man after cas- tration 12, 13, 16, 18, 35, 36, 85 in woman after castration 14 in duck after castration 46 in mammals after castration 35 after ligature of vas deferens 133 [sex] characters 450 bearing of hormones on 466 classification of 465 fi., 471- 472 definition of 3 development of female, in- duced by ovary 296 development of male, in- hibited by ovary 296 difterentiation 270 full development possible without spermatogenesis and spermatozoa 143 full development possible without increase of interstitial cells 156 fixation of 449 ft. genetic system 2, 3, 405-6, 468 influence of testicle in 84 normal development 159, 160 Sexual [sex] characters, permanent 473 persistence of 453 persistence after postpuberal castration 18 puberal development of 123-4, 152 retarded development 163, 169 somatic 63, 168, 297, 335, 341. 343. 349. 367. 398, 401 temporary 473 what we mean by 3, 446 — dimorphism i, 454 — fetishism 36 — [sex] glands 2, 3, 15, 51, 80-1, 92, 102, 108, 150, 375, 397, 437, 442, 475 and heat 51 and psycho-sexual behaviour 103 antagonism 352 ft. basis of genetic system 3 ■ definition of 471, 473 dependence of man on 15 experiments with capons 93 ■ — ■ with rats 93 eftect on sexual characters 98, 103-4 extracts of whole 319 ft. extracts of parts 322 ft. feeding with 92 ft. how they act 50 influence on organism 477-8 influence on sexual organs 15 influence on other sexual characters 15, 79, 109 injection of 319 internal secretions of 79 fl., 97 morphogenetic influence 441 non-sex-specific hormonci activity 473 ft'. responsible for psycho-sexual behaviour 35 questions on 2 — hormones, isolation of 319 ft. and morphogenesis 441 • — precocity 167 372, 423, 431 ft., 483 Sheep, influence of castration on skeleton 32 — interstitial tissue in 122 — interstitial tissue of ovary Silk moth, castration of 55 Skeleton, influence of castration on, in animals 29, 32, 33, 446, 462 in man 8, 14-17 in birds 40 in eunuchoids 426 512 GENERAL INDEX Skeleton influence of sex glands in 15-16 in sexual precocity 434 Skopecs 6-8, 12-13, 16, 426, 441 Skull of castrated mammal 29, 32 Snipe 49 Soma, asexual embryonic 441 '■ evolved characters 453 and heredity 456 — equipotentiality of 443 — identical 47, 443 — intersexual 460 — neutral form 59 Somatic characters in experimental hermaphrodite 359 ft. "Somato-sexual" characters 470 Special organ controlling sex char- acters 65 Sperm, injection of 331 Spermatocytes 176, 187 Spermatogenesis 127-8, 130, 133, 142-3, '150, 163, 170-1, 173, 176-8, 181, 188, 327, 342-4, 353, 394. 427 Spermatogonia 131, 153-5, i?^, 187. 345. 349, 373 Spermatozoa 63, 81, 129, 130, 143, 147, 148, 150, 153, 187, 336-8, 342 ff., 349, 428 — vitality of, and secretion of genital passages 343 Spherical nucleus 112-3, 119 Spinal cord and clasp reflex 99-101 Spurs of cocks after castration 37, 39 after feminization 308 — hens after castration 43 — in experimental hermaphrodit- ism 364 396 Stag, feminized 293 — mascuhnized 305 Sterihty in man, effect of intoxica- tion on 184 effect of X-rays 153 Sterilization 484 Stylops 66 Suprenal tumour 393 Suprarenals after castration ^^ SyphiHs and interstitial cells 178 Tadpole, experiments on 93, 287, 339, 399 Tail reflex 297 Temperature, body, of female and male 298 Tertiary sexual characters i Testes, extracts of 321, ^2^, 331 Testicle 104, 122, 336 — and ovary, antagonism between 352 Testicle, Berthold's experiments 8r — compensatory hypertrophy i55ff — - crystalloids in 115 — cryptorchid 322 — endocrine function of 127, 196 — engrafted 81, 148-152, 369 — feeding with 92 -- Foges' experiments 81 — grafts from apes to men 88 — in amphibians 187 — in birds 191 — in disease 178 ff. — - in eunuchoid 426 — in fishes 186 — in frogs 90-1 — in invertebrates 1 86 — in the new-born 180 — in toads 91 — influence of X-rays on 153-5 — internal secretions of 109, 154, 195 — poles of 156-7, 159 — puncture of 129 — retained 142, 148, 155, 163 — retarded development 163 — • transplantation of, in man 81, 84-7, 90, 92, 399 — ■ tuberculosis, removal in 86 — unilateral castration 157-8, 1 60-1 — - unilaterally retained 142 — undescended 372 Testicular fragment compared with ovarian 245-6 — hormones, sex specific action of 285 ff. implantation 395 -section, incomplete 181 substance, injection of 85, 87, 92, 93 • transplantation 299 red corpuscles after 33 — influence on clitoris 300-1 Theca-lutein cells 226, 249, 366 Thelia bimaculata 66 Thistle-finch 48 Threshold quantity of hormones 167 ft"., 195, 410, 423-4, 428-9 Thymus, after castration 33 — extracts of 323 Thyroid gland 3, 8, 80, 92, 104, 183. 319, 399 — after castration 33 — feeding with 397, 438 — functional relation to sexual glands 3 — ■ in Skopecs 8 Time factor 65, 364, 389, 402-3, 407-8, 423, 454 Time relations 124,177, 253, 264,321 GENERAL INDEX 513 Toad, clasp reflex in 99-101 — transplantation in 91 Tortoise-shell cat, case of 390 Transmission of characters 460, 465 81 ff. Transplantation 81 ff., 104, 155, 166, 289, 305. 484 — failure 87 — forms of 81 — heterosexual 448 — ovarian 88-90, 92, 235 ft., 267. 284 more successful than testi- cular 89 — sexual glands 79. 81-2, 195, 330 — testicular 85, 92, 166, 484-5, 490 — •— in man 85, 86 Tree hopper 66 Triton 52, 188-9, 399. 443 Tuberculosis and interstitial cells 178 ff. — of testes 86 Turnicidae 49 Twin pregnancy in cattle 383 ff. Typhlocyba hippocastani 66 Underdevelopment aftei castra- tion 84 Ungulata, interstitial tissue of ovary 215 Unilateral castration 381, 394, 477 hypertrophy in 157-8, 160-1 in frogs 190 Urodele 189 Uterine mucosa 267-8 — changes 271 Uterus after auto- or homoiotrans- plantation 88 — after castration 13, 28 — after injection of corpus luteum 323-4 — after prepuberal castration in mammals 25 — after transplantation in femi- nized male 290 — • — in masculinized female 300 — after X-ray irradiation 231 — atrophy of, in woman, prevented by ovarian transplantation 89 — in castrated rat 90 — in eunuchoidism 430 Uterus masculmus 287, 297, 329, 338, 343 "Vagina, artificial" 338 Vas deferens 6, 67, 172, 338, 345 in castrated fowl 40 in earthworm 67 ^ in rabbits 131 ligature of 127 ff., 163, 194, 25^. 484-5, 488 ff. rabbits four years after hga- ture 130 Vesiculae seminales 67, 297, 327, 329. 335 ff- — — {see also seminal vesicles) "Vesiculase" 337 Veterinary medicine 484 Voice in castrated man 15, 16 Weight, in feminization 294 — in masculinization 303-4 — ■ increase of, after unilateral cas- tration 161 Wolffian ducts 398, 457, 459, 467 Woman, castration in 13 — cessation of function 14 — changes in metabolism 14 — condition of theca cells 236 — corpus luteum in 268 — ovary after X-ray irradiation 267 — ovulation in 268 — postpuberal effect of castiation 13. 14 — ■ results of castration not so marked 15 Woodchuck, changes in interstitial tissue 1 70-1 X-RAYS, influence on mammary gland 262 on ovary 227 ff., 255, 265, 267, 293, 484 on seminiferous tubules 153 on sexual activity 153 on testicle 153 ff. — observation of castrate by 8 Zootechnics 484 Zygotic determination of sex 444, 454 — intersexuahty 402 MASS. 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