42 CROSS-FERTItlSATlON IN THE INDIAN COTTONS. 



and, as a result, nine fruits were obtained. Of 1909 full details 

 are again lacking, but from fifty-four flowers of the first culture 

 bagged ninety-one seeds (representing some eleven bolls) only were 

 obtained, while of the second culture, in which crossing had taken 

 place during the previous year, ten protected bolls gave sixty-nine 

 seeds (representing some eight bolls). In both cultures in this 

 year a further series of fertilisations was carried out in which 

 flowers were fertilised by hand with (1) the pollen of a second 

 flower of the same plant, or (2) the pollen of a sister plant. 



In the former culture ten and nine fruits set out of twelve 

 and thirteen flowers respectively, while in the latter three fruits 

 set out of the seven flowers fertihsed with pollen of the same plant, 

 while all (three) set when pollen of a different plant was used. In 

 1910 the combined offspring of the second culture numbering 

 forty-five plants have been protected by a single net and given 

 eleven and three quarters oz. seed. 



In this type, though both cultures exhibit the phenomenon 

 of abortion to some extent, there appear indications of the exis- 

 tence of an individual difference in the degree of sterility induced 

 by self-fertilisation. How far self-steriUty in the cottons is a 

 function of the individual can, however, only be determined by 

 a defijiite series of experunents designed to elucidate the parti- 

 cular point. Sufficient has here been noted for the present purpose 

 which is to show that it occurs to such an extent that it cannot be 

 ignored if pure races are to be raised from single plant cultures 

 without a loss of fertflity. 



These results are collated in Table 1. 



Other forms of sterility. 

 So far sterility has only been considered in its relation to pure 

 types and there remains the case of the oifspriug of a cross. This 

 forms a subject of considerable difliculty since, superimposed upon 

 the steiihty above dealt with, there may also exist that which arises 

 as the result of specific or racial diversity. It is well known 

 that the power to effect cross-fertiiiaation is strictly limited, that 



