102 LEONELL C. STKONG 



Tabulation 



Males 621 negative : 72 reactions ±5.41 or 10.38% ± 0.79 



Females 894 negative : 44 reactions ±4.37 or 4.69% ± 0.47 



Difference 5.69% ± 0.92 



The difference is thus 6.18 times the probable error 



From the foregoing data we may conclude that the role of sex 

 as a factor underlying susceptibility to transplantable tumor is 

 influenced by two entirely distinct agents: 1) The characteris- 

 tic of the tumor cell (inherent within itself) and, 2) the changing 

 age factor which determines the degree of activity of the gonads 

 and possibly of physiological changes in general. 



m. Gonadectomy. Since sex is a secondary factor underlying 

 susceptibility to the transplantable tissue, as shown when the 

 data are massed, it becomes important to find out what effect 

 gonadectomy will have. Figure 17 gives the data for the first 

 inoculation series after the gonads had been removed. 



Males 308 negative : 16 reactions ±2.63 or 4.94% ± 0.81 

 Females 319 negative : 12 reactions ±2.29 or 3.62% ± 0.70 

 Difference 1.32% ± 1.07 



The difference is thus 1.23 times the probable error 



There is therefore no significant difference between gonadec- 

 tomized individuals of either sex for percentage of reactions. 

 The two curves, however, are quite different in type. The female 

 curve gradually drops to the base line, whereas the male curve 

 continues to rise. In fact, those males (for this experiment) 

 that gave positive reactions at the end of the six-week observa- 

 tion period continued to grow the tumor mass progressively. 

 We never encountered progressive growth in a normal wild 

 individual. Gonadectomy must therefore be considered to have 

 had two effects: 1) on the number of percentage reactions and, 

 2) on the progressive growth reaction of the tumor cell. 



The same gonadectomized individuals were reinoculated with 

 the same two tumors some time after the end of the first 

 six-week observation. Figure 18 gives the data for this second 

 inoculation. 



