No. 564] STUDIES ON DIFFERENTIAL MORTALITY 751 



For differences 2.5 or more times their probable errors : 



Plus differences 6 +.505 +24.41 



Minus differences 9 -.560 -25.08 



All differences 1 15 1 -.134 | - 5 .29 



It is clear that in passing from the seeds producing 

 abnormal seedlings to those germinating normally there 

 is in general a reduction in absolute variability of weight. 

 This point will be discussed in greater detail when rela- 

 tive variabilities are taken up. 



If now the comparisons be drawn between all seeds 

 which germinate (whether normally or abnormally) and 

 those which do not germinate at all, i. e., (A+B) — C, 

 we have : 



Or restricting the comparison as usual to those which 

 are more probably statistically trustworthy (> 2.5JE7) : 



The comparison involving the other extreme in the 

 treatment of the abnormal seedlings is A — (B + C). For 

 all the series this gives : 



