PHYSIOLOGICAL PROPERTIES OF THE GONADS. 2Q3 



would have shown that the animal had increased 20 per cent, in 

 weight, as a result of the experiment, even had the testis not 

 grown. 



Without further discussion of the above point, it should be 

 clearly demonstrated to the reader that such a comparison of 

 weights of two or three animals, chosen at random, is absolutely 

 unreliable as evidence of their sexual nature. As the writer has 

 pointed out previously, the same criticism applies to rats. Since 

 the fallacy of such comparisons can not but be realized, it follows 

 that as evidence of masculinization and femininization such data 

 should be ruled out when considering the value of the various 

 types of data presented to support this idea. 



Turning to the literature for actual data supporting the well- 

 established idea that castration or spaying causes an overgrowth 

 in body weight in animals (particularly the former), one realizes 

 that there are indeed few experiments adequately controlled that 

 give results supporting this idea. 



Stotsenburg is apparently the first to carry out experiments on 

 mammals determining the effects of gonadectomy wherein a suffi- 

 cient number of animals were utilized to warrant definite con- 

 clusions. Reference was made above to these results. He found 

 that the growth curves of normal and castrated male rats were 

 very similar, and that castration in the rat did not result in a 

 relative increase in weight from birth to maturity. In spayed 

 females, however, there was a decided relative increase in weight 

 as compared with normal females ; the increase amounted to from 

 17 per cent, to 30 per cent, above the normal. 



Hatai ('13, '15) confirms in general the above conclusions of 

 Stotsenburg, though in a late paper he is inclined to believe that 

 castration of male rats causes a slight relative increase in body 

 weight over the control males; this, however, is not more than 

 3 per cent, to 5 per cent. And in spayed females there is both an 

 increase in relative body weight and body length. 



Livingston ('16) studied the effect of castration and spaying in 

 the rabbit, but it is difficult to properly interpret his data, since 

 the relative ages of his animals were unknown. Furthermore, he 

 states that at the time of operation the ages varied from a few 

 weeks to about one year, and that body weights ranged from 300 



