340 FIELD CROP PRODUCTION 



near the base of the plant are heart-shaped, while the ones 

 near the top are deeply lobed ; usually there are three 

 lobes, although five are quite common. 



356. The boll and fiber. The flowers are large and 

 conspicuous and are attached to the fruiting stems by 

 short branches. The flowers have five large petals and 

 five small sepals. The flowers open in the early morning 

 and are at first white or creamy yellow in color, taking 

 on a reddish tinge the second day and gradually becoming 

 darker until they wither and the petals fall the third or 

 fourth day, leaving the enlarged base of the pistil, which 

 is really the seed pod, enveloped in the leafy bracts. The 

 seed pod or boll develops as the plant matures, and finally 

 the bracts fold backwards and the several compartments 

 of the boll separate, exposing at first a mass of fiber which 

 retains the shape of the compartment in which it was com- 

 pressed, but in a short time dries and expands into a large, 

 white, fluffy mass. This white mass is made up of many 

 tiny fibers which, when separated from the seed, become the 

 cotton of commerce. Each fiber is in reality a single 

 elongated tube-like cell which has collapsed and become 

 twisted so that it resembles a long corkscrew. The twists 

 in the fibers are of ' great importance because they assist 

 in holding the fibers together, which makes possible the 

 spinning of them into long, stout threads. The number 

 of twists in the fiber varies with the maturity, the immature 

 fibers having only a few, while the number increases with 

 the ripening of the plant, until, when fully mature, as 

 many as 500 per inch have been found. The value of 

 the fiber is influenced to a considerable extent by the 

 number of twists it contains, since those with few twists 

 do not make a strong thread, and can be used only in 

 the making of cheap fabrics. The length of the fiber 



