i60 HOMER WHEELON 



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trophied prostate is due to the loss of the internal secretion of the gland 

 which acts as an excitant to the vesical muscles. Removal of the growth 

 permits the return of micturition. 



Observations on the functions of the prostate lead to a rather complex 

 explanation of the relations existing between the genito-vesicular reflex 

 and the gonadal hormone. As previously shown castration and senility are 

 followed by atrophy of the prostate, whereas hypertrophy occurs with the 

 cessation of the sexual life. Hence, if the prostatic function is conditioned 

 by the proper functioning of the gonadal hormone, and only normal pros- 

 tates excite the genito-vesicular reflex,, it would seem more logical to 

 assume that alterations in this reflex are dependent more upon the internal 

 secretion of the testis than upon an influence mediated by the prostate. 



Relation of Spermatic Nerves to the Interstitial Cells. Section of the 

 nerves contained in the spermatic cord is said to result in the atrophy of 

 the interstitial cells ; recent work, however, in no way corroborates such a 

 statement. Resection of the nerves to the testes is followed by degenera- 

 tion of the seminal epithelium and hypertrophy of the interstitial tissue. 

 Such degenerative changes, according to Kuntz (a), are due in all proba- 

 bility to vascular changes resulting because of paralysis of the blood vessels. 

 The blood vessels and all other structures in the testis which contain 

 smooth muscle receive an abundant nerve supply, but such fibers are sot 

 distributed to the seminal epithelium or the interstitial cells. If the 

 interstitial cells are dependent upon the reception of nerve impulses for 

 the discharge of their secretory function, it would seem as though the 

 results following testicular transplants and the use of extracts must be 

 due to factors other than the secretion from the interstitial cells. 



4. Influence of the Internal Secretion of the Testes upon Growth 

 and Metabolism. Metabolism in Different Sexual Stages. While it can- 

 not be said that metabolism, as such, is in any way a sexual character, 

 nevertheless the gonadal hormone must be considered as a metabolite 

 which has the power to influence the functions of many tissues. The 

 appearance of the secondary sex characters at the breeding season of 

 animals is indicative of a very rapid metabolism in certain tissues. For 

 instance the stag and American prongbuck develop horns which are shed 

 immediately following the breeding season. Many fishes exhibit marked 

 coloration at this time, a condition indicating active metabolism. The 

 tail of the lyre-bird, which is shed at the close of the mating season not 

 to be renewed again in the same form until the following summer; the 

 brilliant plumage of the breeding drake; the remarkable plate of horn 

 developed in the upper mandible of the pelican during the breeding season, 

 and then shed and the enormous increase in the size of the testes of 

 certain animals are examples of seasonal bodily changes, the existence of 

 which must be connected, either directly or indirectly, with the contem- 

 poraneous increase in sexual activity and enhanced vitality. The ap- 



