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 



