114 LEONELL C. STRONG 



Castrated males 640 negative : 19 reactions ±2.89 or 2.88% ± 0.44 

 Normal males 282 negative : 5 reactions ±1.50 or 1.74% ± 0.52 



Difference 1.14%, ± 0.68 



The diiTerenee is thus 1.68 times its probable error 



The curve for castrated males does not approach zero, as 

 does the curve for the normal males, because of the fact that a 

 few castrated males continue to grow the tumor mass progres- 

 sively (this was also found to be the case in the dBrB tumor). 



A similar result is obtained when the normal females are com- 

 pared with the spayed individuals (fig. 30, p. 113). 



Normal females 388 negative : 10 reactions ±2.10 or 2.51% ± 0.53 

 Spayed females 721 negative : 21 reactions ±3.05 or 2.83% ± 0.41 



Difference 0.32% ± 0.67 



The difference is thus 0.48 times its probable error 



It may be well to repeat again that the rise in the normal 

 female curve near the end is not real, but due to the dying off of 

 several negative individuals. The spayed female line remains 

 parallel with the base line for the last three points. This indi- 

 cates a similar condition to be found in the castrated male line, 

 namely, that a few spayed females continue to grow the tumor 

 tissue progressively. 



By adding the observations for both males and females together 

 we are able to demonstrate more completely this slight increase 

 in percentage reactions of the gonadectomized individuals over 

 the controls for the latter end of the curve (fig. 31, p. 113). 



Operated 1361 negatives : 40 reactions ±4.20 or 2.86% ± 0.32 

 Controls 670 negatives : 15 reactions ±2.58 or 2.19%, ± 0.38 

 DitTerence 0.67% ± 0.49 



The difference is thus 1.37 times its probable error 



The gonadectomized individuals gave a slight increase of pos- 

 itive reactions, which is not, however, mathematically significant. 



The following figure 32 shows the effects of gonadectomy upon 

 mice, regardless of the tumor employed. It is constructed by 

 adding the percentage reactions of both tumors for both the 

 normal and operated individuals. 



