46 CROSS-FERTILISATION IN THE INDIAN COTTONS. 



flower, therefore, undoubtedly becomes self-fertilised within a very 

 short perixl after the pollen is liberated. ^loreover, the flower is 

 ephemeral and the growth of the pollen tube is consequently rapid. 

 Cross-iertilisation, therefore, is only likely to occur if foreign pollen 

 reaches the stigma within the very limited period which elapses be- 

 tween the opening of the flower and the act of self-fertilisation. 

 The brevity of this period suggests that cross-fertilisation will not 

 be so common as the structural consideration would indicate. 



(6) The condition of the cotton crop. 



Indirect evidence as to the occurrence of cross-fertilisation is 

 to be found in the condition of the cotton crop as usually cultivated. 

 In Northern India the only types which are to any extent cultivated 

 on a considerable scale are those falling under the designation of G. 

 neglectum and G. roseum of Todaro and, in the Eastern districts of the 

 United Provinces and Bengal, the types which have been grouped 

 under G. intermedium, Tod. In both cases the field crop includes 

 a most diverse assemblage of forms which defy classification until 

 single plant cultures are grown under conditions which exclude 

 cross-fertilisation. It is then seen that the apparently wide diver- 

 sity of form resolves itself into a comparatively few types with which 

 are mingled immerous intermediate forms which, when subjected 

 to such rigid experiment, are found to be impure. The cause of 

 the original mixing of types is, and will, no doubt, remain obscure, 

 but the general occurrence of such impure forms must constitute 

 a strong argument for the occurrence of cross-fertilisation. 



For other parts of IncUa, and especially the Deccan, Fletcher* 

 has shown that the crop consists of a large mixture of types. In a 

 few cases only, those of Broach (Type 2) and Dharwar Saw-ginned 

 cotton (a form of G.hirsutum), is the croj^ pure. In the former case 

 purity is maintained by the different flowering period of the crop 

 while the latter form, as has been stated, does not cross with the 

 Indian Cottons. Here the original cause of the mixing of types is 

 no doubt in large measure due to the economic conditions mentioned ; 



• Agl. Journal of Imlia, 1, 1906, \\ 47l>. 



