General Botany 



C . S. DepL of Agriculture 



Fig. 187. A field of upland cotton, in South Carolina, attacked by the wilt disease. 

 The fungus that causes the wilt remains in the soil for many years. 



ing the ideal or standard he has in mind for further study 

 and testing. This process may be repeated year after year until 

 he has secured the desired qualities. 



Mass selection. For many years selection was carried on, 

 particularly in the case of cereals, by what is termed mass selec- 

 tion. This method consists in selecting seed from all those plants 

 that most nearly approach the breeder's ideal. The next year 

 these seeds are planted and the process repeated. In this way 

 yields of many crop plants were improved. But the method is 

 one that may require a long time to accomplish results, and the 

 results are usually uncertain, because the end product is still a 

 mixture of plants with a great variety of hereditary qualities 

 and, therefore, lacks uniformity. 



Selection of individual plants. In recent years, since the gen- 

 eral recognition of the importance of mutations and the Men- 

 delian behavior of hybrids, mass selection has been superseded by 

 the selection of individual plants. Instead of taking seeds from 



