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 otx 



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 



