THE AMEBIC AN NATURALIST [Vol. XLVI 



For Navy the positive difference is trivial ; the negative 

 difference for Ne Plus Ultra and for White Flageolet is 

 much larger. 



Considering statistical significance to be indicated by 

 a difference thrice its probable error, we find that 8 are 

 significantly negative and 4 significantly positive. These 

 4, and 2 of the 8 significantly negative differences, fall in 

 the comparisons between the two strains of Navy and 

 hence can not be given much weight. Of the 20 inter- 

 ramal comparisons, direct and cross, within the same 

 strain, 11 are negative and 9 are positive in sign. Of the 

 10 direct comparisons 5 are positive and 5 negative in 



TABLE XVIII 



USSC 

 USHC 

 USHHC 

 USDC 



isddc 



4.1045 ± .0226 

 4.0832 * .0204 

 3.9718 =t .0213 



.3333 ± .0145 

 ,3403 * .0150 



