economic; classification. 



27 



from the cornstalk, the flower stems of broom corn, and .from reeds, 

 sedges, and the true grasses. Still another form is the fibrous mass 

 surrounding the fruit of the coacoanut, known as coir, and as a curious 

 example may be noted the fiber from pine needles; a notable excep- 

 tion of a structural fiber derived from an exogenous plant, the fibrous 

 mass filling the sponge cucumber being another. 



The surface fibers are still more varied in form. They may be the 

 elongated hairs surrounding the individual pods which contain the 

 single seeds of the thistle, familiarly known as thistledown, or they 

 may be the hairy growths covering the clusters of seeds contained 

 within large pods, as the cotton boll, the pod of the milkweed, or the 

 seed envelop of species of Bombax found in tropical countries. See 

 fig. 4, a highly magnified example of the fiber of cotton. In this 



$E&® 



Fig. 4. — Cotton fibers: a, half ripe fibers of cotton, transverse section; 

 6, mature fibers ; c, half ripe fibers with thin cell wall ; d and e, mature 

 fiber with definite cell wall. X 325. (After Bowman.) Surface fiber. 



group also is placed the leaf scales or tomentum found on the under 

 surfaces of leaves, etc., or on the leaf buds of both endogenous and 

 exogenous plants, which can only be used for upholstery, or as tinder. 

 Epidermal strips of palm leaves, raffia being an example, are also 

 included with the surface fibers. 



The pseudo-fibers are not fibers, but substances used as their substi- 

 tutes. However, they are so clearly defined in the scheme of classifi- 

 cation it will not be necessary to describe them farther or to give 

 examples. Fig. 5 represents sphagnum moss, used as a packing 

 material. 



ECONOMIC CLASSIFICATION. 



The highest use for which a fiber may be employed is in the manu- 

 facture of cloth or woven fabric. As these fabrics vary greatly in tex- 

 ture from the fineness of delicate linen cambric to the coarseness of jute 

 bagging, it would seem that a large number of fibers might be consid- 

 ered spinnable forms and capable of manufacture. In point of fact, 

 however, a comparatively small number are actually spun and woven 



