I 



THE GENITAL ORGANS 983 



characteristics of the opposite sex. Thus, while the ram lambs may- 

 develop horns, the further growth of the latter is arrested at an early- 

 stage. Quite similarly, the castrated cock shows an early withering of 

 the comb and wattles. The loss of these and other secondary char- 

 acteristics, however, may be prevented by removing only one testicle 

 or by grafting one in some other part of the body. 



Very similar effects have been noted in human beings. Thus, it 

 is a well-known clinical fact that castration inhibits the growth of the 

 prostate and actually incites retrogressive changes in this organ. In 

 castrated dogs, this atrophy may be greatly retarded by the subcu- 

 taneous injection of testicular extract. The stories of the East also 

 tell us that castration, when effected during the prepubescent period, 

 gives rise to a defective development of the sexual organs which, 

 however, involves the penis in a lesser degree than the purely glandular 

 tissues, such as the seminal vesicles and the prostate. This difference 

 is easily explicable upon the ground that the penis is chiefly composed 

 of connective tissue. In these individuals, the secondary sexual 

 characteristics are seldom fully developed, as is shown by the fact that 

 the pelvis of eunuchs generally retains its infantile character, and that 

 the amount of axillary and pubic hair is usually very slight. The 

 child-like soprano character of their voice is referable to an arrested 

 growth of the larynx. Moreover, they are prone to become phlegmatic 

 and to develop a heavy panniculus adiposus which smoothens their 

 contours and gives them a feminine appearance. These observations 

 may in a large measure be repeated by a study of hermaphroditism in 

 animals and man, but sexual dimorphism does not always remain 

 confined to the primary sexual characteristics but may also involve 

 secondary ones. The "feminine" man and ''mascuHne" woman 

 are instances of this type of hermaphroditism, showing unisexual 

 mechanisms but heterologous secondary characteristics. 



It cannot be doubted, therefore, that the testes control the develop- 

 ment of the sexual characteristics. This end they are able to attain 

 by means of a chemical agent and not by nervous reflexes. In seeking 

 the place of origin of this hormone, it is of interest to note that the 

 ligation of the vas deferens, brings about a retrogression of the sper- 

 matogenetic elements but not of the interstitial cells of these organs. 

 Contrary to the castrated animals, these animals show perfectly nor- 

 mal sexual characteristics and instincts.^ Furthermore, Steinach^ 

 has proved that the transplantation of the testes does not destroy 

 these tendencies and that the transplanted organ exhibits a proUfera- 

 tion of its interstitial cells and an atrophy of its spermatozoid cells. 

 In this connection, it is also of interest to note that transplantations 

 in very young animals may give rise to an almost complete reversion 

 of the secondary sexual characteristics. Thus, the grafting of an ovary 

 from a female rat or guinea-pig into a young castrated male of the 



1 Tandler, Wiener, klin. Wochenschr., 1908, 1910. 



2 Steinach, Pfliiger's Archiv, cxliv, 1912, 71. 



