ELEMENTARY STRUCTURE. 



31 



Fig. 56. Fig. 51. Fig. 58. 



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of Liber-cells, from their common occuiTence in the inner bark or 

 liber of stems. This inner bark 

 is also commonly termed bast or 

 bass, hence the tissue formed by 

 the combination of such cells is 

 called Bnst Tissue. The liber- 

 cells are sometimes branched 

 (Jig. 56). Besides the common 

 occurrence of this tissue in the 

 liber, it also occm's as a consti- 

 tuent of the vascular bundles of 

 Monocotyledonous stems (see 

 page 72), and also on the out- 

 side of many stems in the same 

 class of plants, and in the stems 

 of Mosses. The veins wliich 

 form the framewoi'k of all 

 leaves are also chiefly composed 

 of this kind of tissue. The 

 liber-cells are among the longest 

 that occur in any of the tis- 

 sues ; according to Schleiden, 

 they are frequently four or five 

 inches in length, and in some 

 plants they considerably exceed 

 even this 



From the peculiar qualities of woody tissue, and especially 

 of the woody tissue of tlie liber, it is admirably adapted for vari- 

 ous manufacturing purposes; thus, common Hemp, Flax, New 

 Zealand Flax, Pita Flax, Sunn, Jute, Chinese Grass Fibre, and 

 many others, are all composed of the Avoody tissue of different 

 plants, and will afford illustrations of those in common use for 

 such purposes. DeCandolle has given the following Table of 

 the relative strength of some kinds of woody fibres as compared 

 with silk, thus : — 



•./^ 



Fig. 56. Upper end of a liher-cell. 



Fig. 57. Branched liber-iiell. 



After Schleiden. Fig. 58. 



Transverse section of liber-cells, 

 showing the thickness of their 

 walls. 



Silk supported a weight of 

 New Zealand Flax 

 Common Hemp 

 Common Flax 

 Pita Flax 



34 



23i 



111 



Other fibres brought recently from India are even stronger than 

 the above. While woody tissue is thus shown to possess great 

 strength when used in the form of what are called fibres, these 

 also, Avhen macerated sufficiently, form a pulp from which paper 

 is chiefly manufactured. 



All articles manufactured from cotton, which is composed of 



