10 



USEFUL FIBER PLANTS OF THE WORLD. 



cells. These give toughness and flexibility to the structure, and 

 the extracted bundles of these cells form the filamentous product 

 known economically as fiber, such as flax, hemp, and jute, derived 

 from Dicotyledonous plants. "In Monocotyledons the fibrous cells 

 arc found built up with vessels into a composite structure known as 

 fibro vascular bundle." (Dr. Morris.) Such fiber occurs in the palms, 



and in the tie shy -leaved 

 Agaves, like the century 

 plant, the fibro-vascular 

 bundles being found, not in 

 the outside covering of the 

 trunk, as in bark, but 

 throughout the stem, or leaf, 

 forming what may be termed 

 (in an Agave leaf, for exam- 

 ple) the supporting struc- 

 ture, or that which gives 

 rigidity and toughness to 

 the leaf. These filaments or 

 bundles of elongated, thick- 

 ened cells, pressed firmly to- 

 gether, when extracted or 



FlQ. 2._SiBaH,e m p (Agave rigidavvr.sisalana). Transverse Separated from the Soft Cell 



section through a fibro-vascnlar bundle embedded in maSS by which they are Slir- 



(PAE) the cellular parenchyma :S.S. starch layer, form- r0U nded, may be kllOWn as 



ing a ring round the sclerenchyma (SCL.), "with the fiber ^ 



cells closely packed together; M.L., middle lamella; B. STRUCTURAL Fiber, of 



S., bundle sheath ; X., sylem, or wood cells ; P. H., phloem, ^vliich the fiber of Sisal heinp 



or bast cells, X 300. . ,«««., 



is an example. (See fig. 2.) 

 The simple, cells already described, when single or agglutinated 

 and produced on the surfaces of the leaves, stems, and seeds of plants 

 as hairs, form a fibrous material also valuable, to which the name Sur- 

 face Fiber has been given. Such hairs are found enveloping the seeds 

 of plants, and when they are produced in the bolls or capsules of spe- 

 cies of Gossypium form the cotton of commerce. 



The fiber bundles, therefore, whether occurring as bast fiber or struc- 

 tural fiber, or whether in the form of simple cells, as surface fiber, may 

 be regarded as the spinning units, and a flax thread is but an aggrega- 

 tion of bundles of bast cells purified and cleansed of all extraneous 

 matter and simply twisted together. In the perfecting of processes, 

 therefore, for separating, cleansing, and purifying the bundles of cell 

 structure known as fibers a knowledge of their physical structure is 

 absolutely essential. The rotting of a fiber is simply the breaking down 

 of the cellular structure or complete separation of the individual cells, 

 by which means the filament is resolved into its smallest parts, each 

 pari being measured by the length to which the original cell attains 

 during the period of its growth. 



