No.564] STUDIES ON DIFFERENTIAL MORTALITY 741 



probably statistically significant with respect to their 

 probable errors. Thus if we throw ont the 26 cases which 

 are less than 2.5 times their probable error, we find that 

 15 are positive and 9 negative, a deviation of 3 ± 1.65. 



If we consider only differences which are four times their 

 probable error, we find 12 positive and 6 negative, a 

 deviation from equality of 3 ± 1.43. 



When, however, we turn to the averages— both abso- 

 lute and relative — we see very little support for the view 

 that there is a tendency for the weight of surviving seeds 



