282 INTRODUCTION. 



til {Sesmnmn indicum, L.), safflower {Carthamus tinctorius, L.), 

 niger (Guizotia ahyssinica, L.), cotton and opium poppy. In this 

 group both self and cross-fertilization are likely. 



C. Monoecious and dioecious crops or those in which the male 

 and female flowers are separated ; for example, maize, castor 

 oil, ganja {Cannabis indica, L.) and the various cultivated 

 CucurhitacecB. In such crops cross-fertilization on a large scale 

 is to be expected. 



It is principally with crops belonging to classes A and B that 

 this paper deals. 



The evidence on which we have based our opinion as to the 

 occurrence of natural crossing in the crops of India has been 

 entirely obtained from a study of single plant cultures. This is, in 

 our judgment, the most reliable method known at present of 

 obtaining accurate information on the subject. But little work 

 on these lines seems to have been carried out previously due no 

 doubt to the methods of mass selection till recently in vogue and 

 to the time and space involved in the growth of the pure Hne 

 cultures. 



