894 PHYSIOLOGY OF DIGESTION AND SECRETION. 



it is found that the sexual elements are lacking, but the interstitial 

 cells are increased in amount. It would appear from this work 

 that sexual puberty is dependent upon the internal secretion 

 furnished by these cells, and Steinach proposes to designate them 

 collectively as the "puberty gland." This observer reports further 

 remarkable experiments in which young males (rats, guinea pigs) 

 were first castrated and then had transplanted under the skin or 

 in the peritoneal cavity the ovary from a female of the. same 

 species. Under such conditions the graft of the ovary takes, and 

 unlike the grafted testicle both the reproductive cells and the 

 interstitial cells survive. In such animals the secondary male 

 characteristics do not develop, his genital organs remain infantile; 

 he exhibits, on the contrary, the female characteristics, as shown by 

 his size, the character of the hair, and especially by the develop- 

 ment of mammae and nipples. So far as the external charac- 

 teristics are concerned the animal is completely feminized, and 

 Steinach states that such an animal is sought by the male as 

 though it were a true female. It would follow from these experi- 

 ments that the internal secretion of the interstitial cells in the ovary 

 and in the testis has each its specific influence in guiding the de- 

 velopment of the sexual characteristics, one causing the formation 

 of male, the other of female characteristics. Many experiments 

 and observations indicate that the internal secretions of the ovaries 

 and testes are important, not only as regards so-called secondary 

 sexual characteristics, but also in regard to the body-metabolisms in 

 general. Some evidence for this general view is found in the 

 functional relationship that appears to exist between these organs 

 and other ductless glands. This relationship is most clearly 

 marked with the thymus, the pituitary, and the cortical portion of 

 the adrenal glands. Castration or spaying causes an enlargement 

 of the thymus gland, even in the mature animal in which this gland 

 has undergone considerable involution. The same operation 

 affects the hypophysis and adrenals, although, according to Hatai,* 

 the effect in this case varies with the sex. In the male castration 

 causes a marked increase in the weight of the hypophysis, while in 

 the female the effect is less distinct. As regards the adrenal glands, 

 castration in the male causes an increased weight of the adrenals, 

 while spaying in the female causes a decrease in weight in these 

 glands. On the other hand, as has been stated above, thymectomy 

 seems to accelerate the development of the reproductive glands, 

 and removal of the posterior lobe of the hypophysis retards their 

 development. The nature of these reciprocal relationships can- 

 not be explained at present, but it may be assumed that they are 

 concerned with modifications of the nature of some of the processes 



* Hatai, "The Journal of Experimental Zoology," 18, 1, 1915. 



