HOWARD AND HOWARD. 45 



III. The Basis of Selection. 



The results obtained in the present paper have a considerable 

 bearing on selection. It has been shown in wheat that characters, 

 which appear at first sight to be simple, are in reality made up of 

 several factors, each inherited independently of one another. The 

 total number of factors in this crop will no doubt be found to be 

 considerable. Natural cross-fertilization has been shown to be much 

 commoner than was at one time suspected, and this supplies the 

 means by which these factors can combine together to form a very 

 large number of wheats, differing from each other by small amounts. 

 The known complexity of botanical varieties in wheat is at once 

 explained by the interplay between the numerous factors rendered 

 possible by natural crossing. Consequently, the wheats of any 

 region and especially those of a country like India, in which 

 agriculture has been practised from time immemorial, supply 

 material, which may well turn out to be a veritable gold mine, for 

 the exercise of systematic schemes of selection. The careful 

 comparison of the offspring of single plants may yield results of 

 great value to the country. A similar state of affairs appears, 

 from our observations in India, to obtain in several other crops 

 in which self-fertilization is the rule. The comparison of the pure 

 lines of these self-fertilized crops offers a line of work which may 

 prove to be of the very greatest importance in agriculture and is 

 moreover much simpler than hybridization investigations. The 

 only difficulties involved are those relating to the interpretation 

 of the results of the field trials in deciding whether or not an 

 improvement has really been obtained. 



These results also concern the question of the improvement of 

 plants in which crossing is common. Here there is little doubt also 

 that numerous factors are involved. These, however, have crossed so 

 much among themselves that there has been no opportunity for the 

 production of pure lines, so that the crops are a network of freely 

 intercrossing forms. A large amount of systematic selection, 

 extending over a considerable period, is therefore necessary before 

 material, in any sense approximating to pine lines, can be obtained. 

 While, therefore, the question of selection in self-fertilized crops is 



