134 CARL R. MOORE 



host. He, too, was able to obtain growth of both kinds of sex 

 glands if they were simultaneously grafted into a previously 

 castrated animal. Sand was also able to graft an ovary into 

 the substance of the testicle and have it persist in quite a normal 

 state. He does not agree with Steinach's idea of a sex-gland 

 antagonism, but supposes some kind of 'atreptical immunity' 

 of the non-castrated organism. 



In birds Hanau ('97) observed that a testis, transplanted into 

 hens possessing ovarian tissue, became encapsulated, necrotic, 

 and was absorbed, though if grafted into cocks it persisted with 

 living spermatozoa. 



The free-martin starts its development as a female (Lillie, 

 '17), but, supposedly due to the influence of an internal secretion 

 of the developing testicle (a hormone), the ovarian development 

 does not proceed in its normal fashion, but is partially or com- 

 pletely suppressed. Not alone does the indifferent gonad fail to 

 develop into an ovary, but it assumes many of the character- 

 istics of a developing testicle. The end result is that the 'deter- 

 mined' female genital system assumes during its development, 

 and in the adult of the free-martin, many characteristics of 

 that in a male individual. 



III. MATERIAL AND METHODS 



The common white rat (Mus norvegicus albinus) has afforded 

 excellent material for the study of the possibilities of sex-gland 

 antagonism. Previous experiments have demonstrated the ease 

 with which transplantation may be effected,^ especially when the 

 host of the graft had previously been deprived of its normal 

 gonads. In this paper, however, we shall only consider the four- 

 teen positive cases of persistence of sex-gland tissue grafted into 

 an animal of the opposite sex with one of its normal gonads 

 undisturb ed. The grafts have persisted for periods of 4^, 5, 

 and 71 months, and number twenty-eight grafts, over twenty 

 of which have been sectioned, stained, and studied microscopically 

 (table 1). 



6 Steinach, '10, '11, '12, and Moore, '19. 



