98 LEONE LL C. STRONG 



i. Sex (dBrB). ^^^lether sex is a determining factor underly- 

 ing susceptibility to transplantable tumor is a disputed question. 



By dividing all the data into the classes according to the sex 

 of the mice, we obtained the following result (fig. 12, p. 97): 



Tabulation 



Males 313 negative : 46 reactions ±4.27 or 12.81% ± 1.19 



Females 476 negative : 34 reactions ±3.80 or 6.66% ± 0.75 



Difference 6.15% ± 1.40 



The difference (6.15% ± 1.40) is 4.39 times its probable error 



There is, therefore, a significant difference between the sexes, 

 the males giving a preponderance of reactions throughout the 

 experiment. 



Because certain investigators, with carefully controlled ex- 

 periments, were not able to determine any difference between 

 the sexes as a factor underlying susceptibility to transplantable 

 tumors, it seemed advisable to analyze our findings relative to 

 this point more completely. 



Analyzing the data from class 4 (adults) individuals only, it 

 appears that there is no significant difference between the sexes 

 in that particular group (fig. 13, p. 97). 



Tabulation 



Males 177 negative : 17 reactions ±2.66 or 8.76% ± 1.37 



Females 304 negative : 17 reactions ±2.70 or 5.29% ± 0.85 



Difference 3.47% ± 1.61 



The difference is thus 2.15 times its probable error 



We are, therefore, confronted with the phenomenon that there 

 is no significant difference between the sexes for adult individuals, 

 whereas, if all five age classes are considered together, there is 

 a significant difference. 



Two statements relative to this point will suffice at this time: 

 1. According to a genetic interpretation, sex may or may not be 

 a contributing factor underljdng susceptibility. Indeed, sex 

 may be an important factor for certain types of tumors or be 

 entirely negligible for others. There maj^ or may not be ele- 

 ments in the tumor cell that react differently in the presence of 

 sex hormones, etc. We can expect, therefore, that certain trans- 



