THE EFFECTS OF HYBRIDIZING 53 



same plant, it usually produces smaller plants and poor ears. The 

 yield is usually reduced about one-half by inbreeding, as it is called. 



FIG. 22. Effect of crossing and self-fertilization on vigor of plants. (1) cross-fertilized; 

 (2) close-fertilized, i.e., from related plant; (3) self-fertilized, i.e., from own pollen. Theseare 

 typical plants after three years in each case. (From Corn Crops, by Macmillan Pub. Co.) 



When the pollen comes from an unrelated plant the vigor and yield 

 of the crop from this crossed seed is increased. 



In nature most of the corn is pollenized by other than its own 

 pollen, but at least some kernels must be self-fertilized on each ear. 



