MALVACEAE 515 



seed. In some varieties, the lint may form 34 per cent, or 

 more of the seed. 



Distribution of Seed Hairs. — ^Lint and fuzz are mixed to- 

 gether over the entire seed surface in Upland cottons. In 

 Egyptian sorts, fuzz is limited to the ends of the seeds, with 

 long fibers between the two patches. The lint at the tip of 

 the seed in some Upland cottons is longer than that at the 

 base. 



Fiber Differences. — The fibers of Upland cotton are i to 2 

 centimeters long, and abiuidant; those of Sea Island are 2.5 

 to 4 centimeters long, but the yield is not as great as in the 

 preceding species. 



The following table is taken from Monie: 



Average length of Average diameter 

 staple in inches of staple in inches 



Sea Island i .61 0.000640 



New Orleans i .02 0.000775 



Texas i.oo o. 000763 



Upland 0-93 0.000763 



Egyptian 1.41 0.000655 



Form and Structure of Fiber. — Young cotton fibers are 

 circular in cross-section. As they increase in length, the 

 walls become thiimer, and the fiber takes on a flattened rib- 

 bon-like appearance. The thickness of the walls becomes 

 greater when the boll opens, due to the rapid consolidation 

 of the liquid cell contents, which become deposited on the 

 inner walls. The deposition is irregular, hence the twisting 

 of the fiber. This twisting is a characteristic of the cotton 

 fiber. The twist is not necessarily in one direction through- 

 out its length; there may be a reversal here and there. 



The fiber is uniform in diameter for about three-fourths 

 of its length, and then tapers gradually to a point. At the 

 point, it may be perfectly cylindrical and solid. The hair 

 cavity or lumen takes up about two-thirds of the entire 



