41 



abnormalities, and feeding young animals the gland substance 

 seems to stimulate growth or the testes. 



Many arguments have been brought forward to show that the 

 prostate produces an internal secretion. It is a well known fact 

 that this organ atrophies after castration, and enlarges as the sex 

 life dwindles. As has been previously stated, Serrlach and Pares 

 reached the conclusion that the gland prodvices an internal secre- 

 tion which controls the testicular functions and regulates the pro- 

 cess of ejaculation. Also they state that if the prostate is re- 

 moved, spermatozoa are no longer produced in the testes, and that 

 the secretory activity of the accessory genital gland ceases. The 

 secretion is, at any rate, a stimulus to the internal secretion of the 

 testis. 



The thyroid bears a distinct biological relationship to the sexual 

 glands. Removal of the gland results in imperfect development of 

 the gondas. infantilism, and general torpor. Bell (42) believes 

 that the association between ^:he thyroid gland and the genitalia is 

 as intimate as the relation of the pituitary to the genital functions. 



Of all the endocrines, perhaps the anterior lobe of the hypophysis 

 is in most intimate correlation with reproduction. Castration 

 results in hypertrophy of this organ, while removal of the anterior 

 lobe usually leads to death. In those cases in which death does 

 not ensue, it results in genital atrophy, stunting, and- reduc- 

 tion of sexual activity. In young animals, spermatogenesis ceases 

 entirely even after partial extirpation of the anterior lobe, Biedl 

 (45) states that " in disease of the hypophysis, derangement of 

 sexual acti^-ity occurs very early in the course of the disease. sho'v\Ti 

 in women by the cessation of menstruation, and in men by im- 

 potence," 



The thymus, as is well known, is quite intimately associated 

 with the development of the genital organs. Its normal disap- 

 pearance is always associated with the development of sexual 

 maturity in the individual. Hewer (46) conducted experiments to 

 ascertain the effect of thymus feeding on the activity of the re- 

 productive organs in the rat. She concludes in part : ' ' Male rats 

 appear more susceptible to the influence of thymus feeding than 

 female rats. With moderate doses of thymus, sexual maturity in 

 the animals treated is delayed, a phenomenon which is attributed 

 to delayed development of the testis. AYith large doses of th\nnus, 

 in the male, the testis is structurally affected : in the young animal 

 in the direction of retardation of development, in the mature ani- 

 mal in the direction of degeneration. This degeneration is con- 

 fined to the testes. In the degenerating testis, cells of Sertoli ap- 

 pear to be absent : the spermatogonia are present, also dividing, and 

 may lie free in the lumen of the tubule ; spermatids, many with 

 abnormal nuclei, are shed into the lumen in large numbers ; sper- 

 matozoa are practically nbsent. In the later stages, only a few 

 dividing spermatogonia appear among the debris of the other un- 

 recognizable cells of the tubide. In the epididymis Avhich itself is 



