THE AMERICAN NATUBALIST [Vol. LV 



the variation in length of life in lots 7-9 and less than 

 7 per cent, in lots 10-14. The separate contributions of 

 the various factors can be calculated with results given 

 in the following table. 



TABLE V 



age and weight 

 age and rate of g 











































































\ 

































































\ 

















IHf 



















\ 























5' 















































X- 





























\y - 







\ 





\ 

































\ 





















RT 























While these figures can not be trusted in detail, owing 

 to the large size of the probable errors of the correla- 

 tions on which they are based, they indicate that age 

 within the limits of one to three months has virtually no 

 direct effect whatever on resistance to tuberculosis. 

 There seems to be a slight direct effect of absolute weight 



