FIBER CROPS 315 



130 small bolls. The large bolls are desirable for picking, and 

 are less liable when open to drop the cotton. 1 As the average 

 of twelve years' experiments, larger bolls gave the larger yields 

 of lint, but the differences are not marked. 2 



There are three to five, under cultivation usually four, lobes 

 or cells. These cells extend from the base of the boll to the 

 apex. When ripe the cells open by separating along their central 

 axis, and at the same time splitting down the middle of the 

 back, thus exposing the dark-colored seeds covered with the 



Outside structure of cotton bur. The small, thin bur opens flat and twists backward, re- 

 moving all support to the locks which fall out. The big, tough bur does not fold 

 back and leave the locks unsupported 

 (From photo by Bennett) 



usually pearly white hairs or fibers for which the plant is 

 primarily cultivated. This method of opening produces three 

 to five, usually four, more or less three-sided valves collectively 

 called the bur with characteristically curved, pointed tips. These 

 valves vary in shape. The small, thin burs open and twist back- 

 ward, removing the support to the locks or seed cotton, while 

 the large, tough burs do not turn back, and thus the locks 

 are supported. 3 



The number of bolls per plant may vary with variety, soil, 

 climate and cultural conditions from few or none to seventy 



1 Texas Sta. Bill. No. 75 (1904), p. 10. 

 -Ccorgia Sta. Bui. No. 70 (1905), p. 70. 

 3 Texas Sta. Bui. No. 75 (1904), p. 12. 



