50 AGRICULTURE 



most parts of the South yields less, than our native corn. 

 Likewise, when the cotton-boll weevil invades any region, 

 early varieties of cotton grown on the northern edge of the 

 cotton belt ripen a considerable part of their crop before 

 the weevils destroy the squares and blossoms. 



A change of seed should not be made unless there is 

 good reason for it or unless better seed can thus be ob- 



FIG. 38. PREPARING COTTON BLOOMS FOR CROSSING 



On left, flower bud; in center, bud after removal of corolla, showing stamens; 

 on right, pistil from around which stamens have been removed. 



tained. A crop suited to the South does not " run out " 

 or grow worthless if properly managed. A plant usually 

 becomes better fitted for its new home by being grown 

 there for a number of years. Seed grown from our 

 own field crops in nearly the same climate should be 

 preferred. 



Improvement by crossing plants. Sometimes the plant- 

 breeder must resort to crossing in order to unite in one 

 plant the good qualities of two different varieties. Sup- 

 pose, for example, he wishes to improve a variety of corn 

 the ears of which are too small, by using the pollen from 



