vin HEREDITY 143 



give rise to plants which bear no sign of any Hindi 

 ancestor. 



Plants bearing seed with entire fuzz are occasionally 

 found, but these appear to originate from crossing with 

 Hindi. 



Hindi cotton, on the other hand, always bears naked 

 seeds, while typical American Uplands are entirely fuzzy. 

 Naked-seeded sports occurring in the Upland crop have 

 been discussed by Allard (l) and in the Indian crop by 

 Fyson. 



Several natural hybrids have been bred on from 

 Egyptian cottons. In all cases they have given a simple 

 3 : 1 ratio, more fuzz being dominant over less fuzz, 

 and expectation has been fulfilled in F 3 . The cross of 

 Afifi x Sultani behaved in the same way ; some fluctuation 

 was shown, but the groups were clearly 116 : 41 in F 2 . 



In crosses of any Egyptian with American Upland, we 

 meet with complications. The entire fuzz is dominant, 

 and the F 2 has given such 15:1 ratios of " entire : slight " 

 as 97 : 6, 180 : 11, &c. The naked seed breeds true in F 3 , 

 and has continued to do so till F 6 , while the entire fuzz 

 either breeds true, or breaks up. There are indications 

 that the latter process may give either a 3 : 1 ratio, or a 

 15:1 "ratio, but the figures are too small. Further, there 

 are indications of constant differences in the entire fuzz 

 group, some being woolly, while others are felted ; if a 

 woolly seed does not breed true, it may throw out felted 

 seeds in a 3:1 ratio. Felted seeds, which may be 

 regarded as a step towards the Egyptian fuzz type, do. not 

 throw woolly ones. 



It would seem that two pairs of allelomorphs are here 

 implicated, giving a 15 : 1 ratio in F 2 . The fifteen appear 

 to consist of 12 woolly and 3 felted. In F 3 we find all the 

 nakeds breeding true, some woollys throwing felted only, 

 some throwing naked only, and some throwing both, while 

 the felted forms either breed true or throw nakeds only. 



