306 THE FORAGE AND FIBER CROPS IN AMERICA 



G. Paper material 



1. Textile papers. 



2. Bast papers. 



3. Palm papers. 



4. Bamboo and grass papers. 



5. Wood pulp and cellulose. 



393. Classification According to Source. This book will 

 deal only with those plants which produce spinning fibers, al- 

 though they may be used for other purposes. Spinning or tex- 

 tile fibers are used either for producing fabrics or for making 

 corciafe ranging from the finest threads to the largest ropes. 

 A somewhat immediate use may be recognized in various forms 

 of netting ranging from laces to hammocks and fish nets. 



Spinning or textile fibers may be classified according to their 

 source into bast fibers, structural fibers, and surface fibers, or 

 into soft fibers, hard or leaf fibers, and cotton fiber. Bast 

 fibers come from the inner bark of certain exogenous plants. 

 They are especially valuable because of their fineness, strength, 

 and flexibility for the production of high grade fabrics and 

 their use is made economically possible when the tissue of the 

 stems and bark is easily disintegrated and removed. 



Structural fibers are fibrovascular bundles occurring in the 

 leaves or leaf stems of certain endogenous plants. In some 

 cases the fibrovascular bundles occur in isolated groups through- 

 out the tissue, as in sisal hemp, while in other cases they occur 

 more thickly grouped near the surface, as in the case of abaca 

 or manila hemp. These fibers are frequently of great length, 

 but usually lack the flexibility of bast fibers. 



394. Classification According to Spinning Units. Looked 

 upon as spinning units, fibers may be classified into two kinds : 

 (i)fibers consisting of single cells, as cotton, or at most two 

 or more simple cells end to end; (2) fibers made up of bundles 

 of spindle-shaped cells overlapping each other and fastened to 

 gether more or less firmly by various kinds of cementing mate- 

 rial. In the case of cotton, therefore, the length of the fiber 



