CHAPTER XXIV 

 FIBER PLANTS 



609. Classes of Fibers. The fibers we use are obtained 

 from two general sources, animal and vegetable. Only two 

 kinds of animal fiber are in common use, wool and silk, but 

 there are numerous classes of vegetable fiber. The usual 

 definition of the word " fiber " makes it include not only the 

 material used for spinning, but also that used for upholster- 

 ing, weaving, and the making of paper. A classification of 

 fiber according to use, as made by the Office of Fiber Investi- 

 gations of the U. S. Department of Agriculture, includes 

 spinning fibers, tie materials, natural textures, brush fiber, 

 plaiting and rough weaving fiber, various forms of filling, and 

 paper material. Of these, the most important are the spin- 

 ning fiber and paper material. Spinning fiber includes all 

 grades from those made into the finest thread to the largest 

 ropes. It is only the class of plants used principally for the 

 production of spinning fiber that will be considered here, 

 though these plants may also be used for several of the other 

 purposes mentioned. 



610. What Spinning Fiber Is. Fibers, or wood cells, are 

 an important part of all plants. The young, growing parts 

 of plants are made up of soft-walled cells which have little 

 strength and soon decay when removed or when the plant 

 dies. The cells of the older and more permanent parts have 

 thick, tough walls, and are of two kinds. One kind is placed 

 end to end without partitions, forming continuous channels 

 or ducts through the stems and other parts of the plant, thu s 

 providing for the movement of water and plant food; the 



