100 LEONELL C. STRONG 



There is, therefore, no difference between the sexes in the 

 reaction toward the normal dBrA tumor, either when animals 

 of all age groups are considered or when adult mice only are 

 compared. 



A very remarkable result appears when we compare the sexes 

 in their reaction to the exceptional dBrA and to the normal 

 dBrA tumor (fig. 14). 



Tabulation 

 Males 307 negative : 28 reactions ±3.42 or 8.36% ± 1.02 

 Females 418 negative : 10 reactions ±2.10 or 2.33% zb 0.49 



Difference 6.03% ±1.13 



The difference is thus 5.34 times the probable error 



Again, only considering individuals from the fourth age group 

 (adults) we obtain (fig. 15) : 



Males 178 negative : 19 reactions ±2.71 or 9.64% ± 1.42 

 Females 299 negative : 1 reaction ±0.67 or 0.33% ± 0.23 

 Difference 9.31% ± 1.05 



The difference is thus 8.86 times its probable error 



The exceptional dBrA tumor shows a significantly different 

 reaction between the sexes, whereas the normal dBrA tumor did 

 not. This change of reaction in the exceptional dBrA may 

 possibly have been the result of the mutational process that 

 produced it. In other words, the mutation has produced a 

 timrior, the exceptional dBrA, of greater reactive capacity. The 

 reaction between the sexes is so marked that even the changing 

 factor of age has little or no influence on it. 



I. Sex composite dBrB and dBrA. Grouping the males and 

 females for figure 12 (dBrB for all classes) and similar data for 

 dBrA for all classes together, figure 16 (dotted lines) was obtained. 



Tabulation 



Males 595 negative : 51 reactions ±4.62 or 7.89% ± 0.71 



Females 864 negative : 44 reactions ±4.37 or 4.84% ± 0.49 



Difference 3.05% ± 0.86 



The difference is thus 3.55 times its probable error 



Adding figures 12 (dBrB for all classes) and 14 (both dBrA 

 for all classes) together, figure 16 (solid lines) was made. 



