LABORATORY STUDY OF COTTON 117 



pound of cotton, while in some of the small varieties 100 to 

 130 bolls are required to weigh a pound. 



Each boll usually contains four lobes or cells which split 

 open as the cotton ripens, exposing the dark-colored seeds 

 which are covered with white fibers. The seed cotton in 

 each cell is called a lock of cotton, and will have from six 

 to ten seeds. The short staple, upland cotton grown in 

 America has lint varying in length from I to Ij inches, while 

 the long staple has fibers greater than IJ inches in length. 

 The Sea Island cotton produces lint from 1^ to 2| inches in 

 length. In proportion to the diameter of their fibers, silk 

 has a greater tensile strength than cotton and wool a less. 

 All of these fibers, however, have great tensile strength. 

 It is estimated that wool fiber must be five miles, cotton 

 fifteen miles, and silk twenty miles long before it will break 

 of its own weight. 



