364 TEXTBOOK OF BOTANY 



simply in choosing the seeds of a good many plants in a patch 

 or in a field that were above the average with respect to the 

 desired qualities, and in repeating the same process year 

 after year. But the results of this method of selection have 

 not always been satisfactory. Although the average of the 

 variety can usually be raised in the direction wished, the 



FIG. 205. The improvement of corn by selection. The well-formed, 

 well-filled ears at the left belong to a variety that was developed from one 

 represented by the ears on the right. 



improvement is sometimes small ; moreover, many plants in 

 each generation are below the average, and if the practical 

 growers do not continue to select their seed carefully each 

 year, the seed of the inferior plants will be mixed with that 

 of the better ones and the variety will deteriorate rapidly. 

 To a certain extent these disadvantages are avoided by an- 

 other method of selection which is now largely used. 



The newer method is based on the fact that the inherited 

 qualities of a plant cannot always be judged from Us appearance. 



