106 LEONELL C. STRONG 



l^abulaiion 



Normal females 476 negatives : 34 reactions ±3.80 or 6.66% ± 0.75 

 Spayed females 319 negatives : 12 reactions ±2.30 or 3.62% ± 0.70 



Difference 3.04% ± 1.02 



The difference is thus 2.98 times its probable error 



Since, as has already been shown, there is no significant dif- 

 ference between the sexes of gonadectomized individuals, we 

 are justified in combining the data together. Figure 21 gives 

 the total observations for both sexes for both normal and gona- 

 dectomized mice for the first inoculation series. 



Tabulation 



Normals 789 negatives : 80 reactions ±5.75 or 9.20% ± 0.67 



Gonadectomized 627 negatives : 28 reactions ±3.49 or 4.27% ± 0.54 



Difference 4.93% ± 0.86 



The difference is thus 5.74 times its probable error 



The significant difference between the two classes lies only 

 in the first two points of the curve (two and three weeks). No 

 mice from class 5 (old age) group were castrated. In order to 

 get a better comparison, therefore, between the controls and the 

 gonadectomized classes, class 5 individuals should be subtracted 

 from the control group. Figure 21 also shows the results ob- 

 tained after this correction has been made (light solid line). 



Tabulation 



Normal (-class 5) 732 negatives : 62 reactions ±5.10 or 7.82% ± 0.63 

 Gonadectomized 627 negatives : 28 reactions ±3.49 or 4.27% ± 0.54 



Difference 3.55% ± 0.83 



The difference is thus 4.28 times its probable error 



The normals still show a significantly greater percentage of 

 reactions. The significance (5.3 X P. E.), however, is confined 

 to the second-week observation period only (first point in the 

 curves) . 



The observations on the reinoculated gonadectomized mice 

 can now be given. (The reader will remember that these re- 

 inoculated mice are approximately ten to twelve weeks older 

 than when first inoculated.) (Fig. 22.) 



