108 LEONELL C. STRONG 



Tabulation 

 Normal ( — class 1) 741 negatives : 62 reactions ±5.10 or 7.72% ± 0.64 

 Gonadectomized 652 negatives : 35 reactions ±3.89 or 5.09% =fc 0.57 



Difference 2.63% ± 0.86 



The difference is thus 3.06 times its probable error 



Class 1 age group was subtracted from the normal controls, 

 since no reinoculated individual of the operated series could 

 fall into this class. No two homologous points in the curves 

 differ significantly, although when all six points are massed the 

 normal group shows a clearly greater number of reactions (3.06 

 times its probable error). 



Reinoculated gonadectomized individuals therefore approach 

 more closely the susceptibihty of the control mice than do mice 

 when first inoculated (4.38 times its probable error). How is 

 this result to be explained? Are reinoculated mice more sus- 

 ceptible to subsequent inoculations of the same tissue or is the 

 increase due to the wearing off of the ill effects of the operation 

 for gonadectomy? Figure 23 shows the comparison of the first 

 and second inoculations series for gonadectomized mice and the 

 normal controls. 



Tabiilation 

 Second inoculation 652 negatives : 35 reactions ±3.88 or 5.09% ± 0.59 

 First inoculation 627 negatives : 28 reactions ±3.49 or 4.27% ± 0.54 



Difference 0.82% ± 0.80 



The difference is thus 1.03 times its probable error 



There is no significant difference between first and second 

 inoculations. The most striking difference, however, lies in 

 the first observation period. The first point for the second 

 reinoculation series is probably significantly greater than the 

 corresponding one for the first inoculation series. The other 

 five points of the two curves are very similar. This tends to 

 show that the first point for the first inoculation series is too 

 low. The only conflicting element that may be present to 

 lower the first point in the first and not in the second inoculation 

 is the after effects of the operation. The complicating factor 

 introduced by the shock, etc., of the operation will be considered 

 again later. 



