350 



THE AMEBIC AN NATURALIST [Vol. XLVIII 



From these figures it is readily seen that reduction in 

 the first post-acrostichals is not entirely consistent with 

 the direction of selection. 



Let us test the same matter for reduction in the second 

 post-acrostichals. 



Offspring. 



).453 ± .016. 

 U13 ± .018. 



- =n.420 ± .17: 



AF 3 c =0.370 ± .019. . 



In this case also the results are not consistent with the 

 direction of selection, although there is better agreement 

 here than in the case of the first post-acrostichals. This 

 is probably due to the fact that the numbers are larger. 

 As regards the irregularities that do occur, I consider 

 them as evidence of recombinations of multiple factors, 

 insofar as they are not due to probable error. 



1912— c (Table II) is a strain that especially tends to 

 lack the first post-acrostichals. Thus for the entire 

 strain 



