CELL-CONTENTS AND FORMS OF CELLS. 271 



abundant than bast fibers in the same plant, and, while the bast 

 fibers may be wanting, the wood fibers, with few exceptions, are 

 always present. Wood fibers seldom attain the length of bast 



WF 



'.'"' * * ' 



CF BF 



FIG. 141. Longitudinal-transverse section of licorice rhizome including the cambium: 

 P, parenchyma; T, tracheae or ducts; WF, wood fibers; C, cambium; S, sieve; CF, crystal 

 fibers; BF, bast fibers; MR, medullary ray. 



fibers. They are not infrequently branched at the ends, and, 

 besides a thin protoplasmic layer, they usually have no other 

 contents than water or air. They frequently have yellowish 

 walls, characteristic of stone cells, and also exhibit a similar 

 lamellation and refraction of the wall. 



