298 HOW CEOPS GEOW. 



All the vegetable textile materials employed in the man- 

 nfacture of cloth and cordage, with the exception of cot- 

 ton, as flax, hemp, New Zealand flax, etc., are bast-flbers. 

 (See p. 248.) 



In some plants the annual layers of bast are so sepa- 

 rated by cellular tissue that in old stems they may be 

 split from one another. Various kinds of matting are 

 made by weaving together strips of bast layers, especially 

 those of the Linden (Bass-wood or Bast-wood) tree. The 

 leather-wood or moose-wood bark, often employed for 

 tying flour-bags, has bast-fibers of extraordinary tenacity. 

 The bast of the grape-vine separates from the stem in 

 long shreds a year or two after its formation. 



The epidermis of young stems is replaced, after a cer- 

 tain age, by the corhy layer. This differs much in dif- 

 ferent plants. In the Birch it is formed of alternate 

 layers of large- and small-celled tissue, and splits and 

 curls up. From the Plane-tree it is thrown off period- 

 ically in large plates by the expansion of the cellular tis- 

 sue underneath. In the Maple, Elm, and Oak, especially 

 in the Cork-Oak, it receives annual additions on its 

 inner side and does not separate : after a time it conse- 

 quently acquires considerable thickness, the growth of 

 the stem furrows it with deep rifts, and it gradually 

 decays or drops away exteriorly as the newer bark forms* 

 within. 



Pith Rays. — Those portions of the first-formed cell- 

 tissue which were interposed between the young and 

 originally ununited wood-fibers remain, and connect the 

 pith with the cellular tissue of the bark. They inter- 

 rupt the straight course of the bast- cells, producing the 

 netted appearance often seen in bast layers, as in the 

 Lace-bark. In hard stems they become flattened by 

 the pressure of the fibers, and are readily seen in most 

 kinds of wood when split lengthwise. They are espe- 

 cially conspicuous in the Oak and Maple, and form what 



