Nos. 622-623] HYBRIDS IN EGYPTIAN COTTON 



499 



No evidence of segregation in definite ratios was ob- 

 tained. 



It is well know that complete dominance in the F, 

 and 3:1 segregation in the F 2 are exceptional in size and 

 shape characters such as chiefly distinguished the Pima 

 and Gila varieties of cotton. On the other hand, the 

 question whether the behavior of the Pima X Gila hy- 



brids with respect to such characters might be inter- 

 preted by the multiple factor hypothesis is extremely 

 difficult to answer. The differences between the means 

 of the parents for most of the characters, while small, 

 are highly significant, but the parental ranges, in most 

 cases, overlap to such an extent that Mendelian analysis 

 would seem to be out of the question. 



