PHYSIOLOGY, CHEMISTRY AND PATHOLOGY 437 



although small scurs may appear. Therefore, horns, in this type of sheep, 

 must be considered as secondary sexual characters which are dependent 

 upon the proper functioning of the testes. 1 



Perhaps the most convincing evidence of the dependence of the somatic 

 structures related to sex upon the primary reproductive organs is afforded 

 by the results of cross-grafting of gonadal tissue into previously castrated 

 animals. Steinach and Sand have clearly shown that the ovaries of the 

 female rat and guinea pig can be successfully grafted into previously 

 castrated males. These "feminized males" develop characters peculiar to 



? 



A B CD 



Fig. 2. Photograph of guinea pigs showing the effects of "feminization" on somatic 

 development. A, castrated brother; B, normal virgin sister; C, "feminized" brother; 

 D, normal brother. (Steinach and Holzknecht, 1916, Fig. 2, p. 494.) 



the female. The mammary glands, rudimentary in the male, become 

 greatly enlarged, the hair assumes the texture of the female, the size and 

 skeleton takes on proportions resembling those of the female more nearly 

 than those of the normal or castrated male (Fig. 2). "Masculinized fe- 

 males" take on the somatic characteristics normally associated with male- 

 ness (Fig. 3). In these cases, as in that of the triton, somatic structures 

 respond, not to their previous habit, but to the type of gonadal influence 

 exerted upon them. 



The striking alterations in growth and development, following castra- 

 tion of men, with resulting eunuchism, probably afford the earliest recog- 

 nized information regarding the influence of the reproductive tissue on 

 the body. Gonadectomy, prior to the advent of puberty, prevents the 

 complete development and the perfect functioning of the nervous system, 



*The relation of horn formation to the gonads has been thoroughly reviewed in 

 the works of Biedl, Geddes and Thompson, Marshall, and Morgan. 



