z68 



THE QUARTERLY REVIEW OF BIOLOGY 



that in some anurans the interstitial cells 

 produce the testicular hormone. But 

 where prespermatogenesis is found the 

 hormone is produced by this abortive 

 spermatogenesis. In urodeles he believes 

 that the hormone is produced by a "corpus 

 jaune testiculaire," which is a product of 

 the abortive spermatogenic process. 

 Aron maintains that a "glandular body," 

 which he describes as a product of Sertoli 

 cell division, produces the testicular 

 hormone in urodeles. Both of these au- 

 thors therefore point to germinal elements 

 as the chief source of the hormone pro- 

 duction. Their individual theories are 

 very much weakened by Humphrey's 

 observations, which indicate that this 

 abortive spermatogenesis in American 

 urodeles is a result of unfavorable environ- 

 ment, that it is not present in many species 

 and in those species where it is sometimes 

 seen it is not constant. We cannot call 

 this a parallelism but a coincidence, for 

 which Humphrey has offered a satisfactory 

 explanation. 



There is, however, one parallelism that 

 is constant in all species. A glance at the 

 charts will make it apparent that there 

 is always an abundance of germ cells, 

 either developing or mature, immediately 

 before and during mating. In all animals 

 there is some germinal tissue throughout 

 the year. It increases slowly after mating 

 and becomes abundant when the next 

 mating season approaches. In some 

 species the increase immediately before 

 mating is rapid, while in others it is more 

 gradual. These are individual variations 



of cell activity, but in all vetebrates the 

 germinal tissue is maximum in quantity 

 at the time of mating. This of itself does 

 not show that this tissue produces the 

 testicular hormone. Spermatogenesis is 

 the preparation of cells whose function is 

 that of fertilizing the egg. But may not 

 these anatomic and physiologic changes of 

 mating be induced by a substance produced 

 by the metabolic processes of these cells? 

 This substance may be a waste product of 

 cell metabolism or a by-product (an 

 unused material) split off from the ma- 

 terial furnished to the cell by the blood. 

 We know, for example, that the lymph 

 from the arm or leg differs from that of 

 other parts of the body. This appears 

 to be a result of the cell metabolism of the 

 particular tissue concerned. 



Germ-cell development is the only 

 parallelism at present found between any 

 particular testicular element and the 

 physiological changes accompanying 

 mating. Champy (10) states that though 

 there is no positive demonstration there 

 is presumptive evidence favoring a cor- 

 relation between appearance of sex char- 

 acters and maturity of spermatozoa in 

 Cysprinodentes various. The writer is not 

 ready to commit himself to such a definite 

 correlation. It seems that the presence 

 of any active germinal epithelium is sufficient 

 to insure what is commonly thought of 

 as hormonal activity. 



The charts for this paper were made 

 in the Illustration Studios of the Univer- 

 sity of Illinois College of Medicine and 

 Dentistry. 



(i) Aron, M. 1911. Sur l'existence et le role 

 d'un tissu endocrinien dans le testicule des 

 Urodeles. Heb. deSci. del 'Acad, de Sciences, 



173: 57-59- 



(z) . 1911. Sur le conditionnement des 



caracteres sexuels secondaires chez les Batra- 



LIST OF LITERATURE 



ciens Urodeles. Compt. rend. Soc. de Biol., 



(3) . 192.4. Recherche s morphologiques et 



experimentales sur le determinisme des 

 caracteres sexuels males chez les Urodeles. 

 Arch, de Biol., 34: 1-163. 



