RELATING TO SECONDARY SEXUAL CHARACTERS. 71 



The effect of removal of the ovary from female calves has been 

 studied by Tandler and Keller. The height of the ovariotomized female 

 is less than that of the cow. The same difference is found between bull 

 and ox. Tandler and Keller call attention to the similarity of the head 

 in male and female lacking the gonads. They conclude that the 

 ovariotomized female does not come to resemble the male, but that 

 removal of the gonad causes both sexes to converge to a common type. 



Castration is frequently performed in horses, dogs, and cats, but as 

 the secondary sexual differences, aside from size and behavior, are not 

 very well marked in these animals, the results need not be here con- 

 sidered. 



Steinach's experiments with rats are important, because by grafting 

 ovarian tissue into the castrated male, the male was caused to assmne 

 certain characteristics peculiar to the female. The mammary glands 

 that are rudimentary in the male became much enlarged — ^not only 

 the glandular tissue increased in amount, but the mammae themselves 

 were greatly developed. The hair of the male is coarser than that of 

 the female. In the feminized male the hair was soft Uke that of the 

 female. The size was smaller than that of the male. The skeleton also 

 was affected, and Steinach thinks that it changed in the direction of a 

 female skeleton. Even more striking was the sexual behavior of the 

 feminized rat. The individual no longer reacted as male, but showed 

 some of the reflexes peculiar to the female. These results, that stand 

 almost alone, appear to show that several of the secondary sexual 

 characters of the female rat are due directly to the presence of the 

 ovary. 



One of the most striking and definite results shown by castrated 

 rats (Steinach), guinea-pigs (Pirsche, Steinach), rabbits (Pauncet), 

 hedgehog (Marshall), and man is to be seen in the effect on the acces- 

 sory glands connected with the male ducts as well as on the penis. 

 These remain small and infantile. Some substances produced by the 

 testes are essential for the development of these parts. Natural 

 selection rather than sexual selection would be the agency that here 

 comes into play. 



In man the effects of castration have been often described. Eunuchs 

 have had a commercial value in some coimtries, as in Turkey and 

 China, and castration has been deUberately practiced on young 

 children. Certain religious sects, such as the Skops of Russia, have 

 advocated and carried out the operation. Disease has also at times 

 necessitated the removal of the testis, more often in adults than in the 

 young. The full effects are shown only when the operation has been 

 carried out before the secondary sexual characters have developed. 

 The more striking difference between the sexes involve the beard, and 

 the hair on other parts of the body, the voice, the shape of the pelvis, 

 and the mammary glands. For a detailed account of the results, 

 the publications of Tandler and Grosz and Marshall's book on the 

 "Physiology of Reproduction" should be consulted. 



