GONADS AS CONTROLLERS OF CHARACTERISTICS 465 



DISCUSSION 



The primary object of these experiments was, first, to de- 

 termine to what degree constant weight differences between the 

 normal male and female rat were determined by the sex glands, 

 and, second, to provide a basis for interpretation of weight 

 differences in case of homoplastic transplantation of the gonads. 



In studying the effects of the influence of the gonad of one 

 sex on modifying the somatic and psychical development of the 

 opposite sex (a repetition of the experiments of E. Steinach), 

 the writer has differed from Steinach in the interpretation of 

 the results obtained. Steinach has placed considerable emphasis 

 on modification of body weight of rats and guinea-pigs following 

 removal of the normal gonads and the substitution of the oppo- 

 site one by transplantation. If these transplantations were 

 successful — i.e., if the graft persisted and grew — according to 

 Steinach, the male became 'feminized' and, compared with 

 normal males, relatively decreased in weight as development 

 proceeds, while the female became 'masculinized' and corre- 

 spondingly increased in weight in comparison with unoperated 

 females. These changes from the normal weight for the sex he 

 associates with the presence of the secretion of the implanted 

 gland; the female increased in weight because a secretion from 

 the testis was present in the female into which it had been 

 placed, and having this male secretion the weight of the indi- 

 vidual increases toward the normal weight of a male and away 

 from that of a female. In case of a secretion of the ovary in a 

 male animal, the weight of this feminized male approaches that 

 of a normal female. 



Stotsenburg ('09), however, has shown for rats, that the 

 presence of the secretion of the testicle has absolutely no in- 

 fluence upon the growth of the individual. Also ('13) he has 

 proved that the mere removal of the ovaries of young rats 

 results in an increase of from 17 per cent to 33 per cent compared 

 with unoperated females. 



Considering these findings, the writer has found it impossible 

 to associate weight differences with different degrees of maleness 



