DESCRIPTION OF THE COTTON PLANT 11 



water acids which aid in dissolving fresh supplies of plant- 

 food. While the root-hairs constitute the absorbing organs 

 of the plant, a small quantity of food in solution is absorbed 

 directly by the epidermal tissues of the true roots. The 

 process of absorption by both the root-hairs and the true 

 roots is that of osmosis. 1 



9. The stem. The cotton plant possesses a cylindri- 

 cal, erect, gradually tapering central stem ranging in 

 length from two to six feet. From the nodes of this stem 

 the branches arise. The stem and branches are covered 

 with a tough greenish or reddish bark. Because of its 

 strength, due to the relatively large percentage of bast 

 fibers contained, cotton bark has been used to a limited 

 extent as a coarse fiber. Inside the bark the stem is com- 

 posed of brittle, white wood, which decays readily when 

 plowed into the soil. 



10. The branches. Like all true branches, the 

 cotton branches arise in the axils of the leaves. As they 

 are borne at the nodes on the stem their number is deter- 

 mined by the length of the stems and the distance between 

 nodes. The Texas Station has found that late planting 



1 "Osmosis. When two solutions of different density are sep- 

 arated by a porous membrane, there will be first a movement of the 

 weaker solution through the membrane into the stronger, and later 

 a return movement, the process continuing until the two solutions 

 have the same density. The contents of a root-hair being denser 

 than the soil solution surrounding it, there is a constant movement 

 of the soil solution into the root-hair. By some means the exosmosis, 

 which would take place in the case of an ordinary membrane (move- 

 ment of the cell solution outward), seems to be restrained in the 

 root-hair, probably by some functional activity of the cell. The 

 result is a much greater movement into the root-hair than exudation 

 out of it. The soil solution passes from the root-hair into the root 

 and is finally transmitted to the stem and leaves." E. G. Mont- 

 gomery. 



