172 DISEASE IN PLANTS. 



resist Rust, or why the roots of American Vines 

 sufifer less from Phylloxera than others. 



One of the most extraordinary cases known to 

 me in this connection is the unconscious selection 

 on the part of native Indian cultivators, perfectly 

 ignorant of the principles involved, of spring 

 and autumn forms of Rice, Wheat, Castor 

 Oil, Sugar Cane, Cotton, and other crops. "It 

 has been estimated that Bengal alone possesses 

 as many as io,000 recognisable forms of rice." 

 Now there is not the slightest ground for doubt 

 that these have been unconsciously bred from 

 the semi-aquatic native species during the many 

 centuries of Indian agriculture, and nevertheless 

 they have, among other peculiar races, some 

 hill-breeds which they cultivate on dry soils and 

 without direct inundation. That is to say, they 

 possess tropical and temperate races differing far 

 more than our spring and summer wheats. 



Something has been gained, then, if we can 

 show that there is nothing absurd or hopeless in 

 the search for disease-proof or resistant races, and 

 I think this can be done. We must not forget 

 that the ideal usually set before himself by a 

 breeder of plants has hitherto been almost ex- 

 clusively some standard of size, form, colouring, 

 and so forth, of the flower, or of taste and texture 

 of the fruit, tuber, etc., though experiments with 

 Cinchona, with brewery yeasts, and other plants 

 remind us that variations in other directions have 

 been attended to also. 



Now it is obvious that in breeding sour limes 



