136 THE COTTON PLANT IN EGYPT CHAP. 



White and creamy petals are not difficult to find in 

 Egyptian field crop, but their ancestry is dubious ; some 

 may be true Egyptians, but most are splitting-forms from 

 Hindi x Egyptian hybrids. 



The hybridisation of these forms has not given a simple 

 result in any cross yet made by the author. Mr. Fyson 

 has published details from large families of Indian cottons, 

 which indicate that the character was there controlled by 

 a single pair of allelomorphs, but the data are not quite 

 convincing as to this simplicity, and the same uncertainty 

 is found by Mr. Leake (3). 



The cross Afifi x Sultani was a cross of golden petal x 

 lemon petal. The F! was intermediate. In F 2 we 

 matched the offspring to the three forms, taking three 

 flowers from each plant on different days. It should be 

 remembered that the colour differences between these 

 three forms are not very great, although the parents are 

 quite distinct from one another. Many plants were 

 matched to the same type-colour each time, but many 

 others were matched first to one and then to another. 

 The probability seems to be that there are more than 

 three colour types in the F 2 , just as in Tammes' work on 

 hybrids of Linum, so that our matchings may mean very 

 little. 



On the simplest interpretation of the data we might 

 imagine that the heterozygote was a simple intermediate, 

 throwing out a 1:2:1 ratio in F 2 . The figures are too 

 discrepant to admit of this view. They tend more towards 

 the interpretation based on two pairs of allelomorphs, 

 giving a ratio of 9:3:3:1, where the last two are 

 externally similar, making the ratio into 9:3:4. 



The crosses of Egyptian with Upland have behaved in a 

 similar way. The cross of yellow whether lemon or 

 golden with white or cream has always given an inter- 

 mediate F!. In F 2 we have obtained ratios which 

 approached very closely to 1:2:1, but with a constant 



