130 STUDIES IN INDIAN COTTONS 



the Cotton Commissioner's report for 1869 but no detailed report 

 has been traceable. A similar cross is referred to by Fletcher (12), 

 but here again full details are not given. In as much as, however, 

 both red and yellow flowered plants appeared in the Fj generation, 

 it would appear that the red flowered parent was a heterozygous 

 form. More recently similar crosses have been effected by Main 

 (23). Here, again, the presence of yellow flowered forms in the F, 

 seems to indicate that the red flowered parent was not pure but it 

 must be admitted that the numerical results do not agree with 

 any Mendehan expectation. Further the appearance of plants 

 with white flowers in the F.^ generation would indicate that one of 

 the parents was heterozygous with regard to the yellow factor also. 

 That such heterozygous forms are of common occurrence in the 

 field is clear from our own experiments, and the latter case appears 

 to be similar to that observed and detailed by us (20 p. 52). 



(1) Tyye 3 x Tyfe 4. — This cross has been carried as far as 

 Fg generation and the results are tabulated in Tables VII, VIII 

 & IX. It is evident that in this instance a single pair only of alle- 

 lomorphic character is concerned. The two characters comprising 

 this pair are presence and absence of the red colouring-matter — the 

 former condition showing partial dominance over the latter. In 

 Type 3, therefore, the red sap colour masks the yellow colour in 

 the petal, which colour is present in both parents. The F^ gene- 

 ration is composed of two groups, one derived from protected 

 flowers of the F, parent, the second from unprotected parents. 

 The latter group, as Table VIII shows, contains numerous impure 

 plants, the result of natural cross- fertihzation. h\ 1911 when the 

 F5 generation of this cross was raised, the entire plants were pro- 

 tected under fine mosquito netting. A comparison of Table IX, 

 in which the results of this year are given, with section B of Table 

 VIII indicates that this method of protection, while it does not 

 entirely check cross-fertihzation, reduces the amount very consi- 

 derably. The petal colours of the parents and of the first two 

 generations are illustrated in Plates XV and XVI. 



(2) Tyfe 3 x Tyj)e 9. — This cross also has now reached the 

 F5 generation, and the results are tabulated in Tables X to XIII. 



