PROSKXCIIYMATOUS TISSUE 



255 



them the protosplasm strands extend, as shown in the 

 figure. Their exact function Is not known. 



414. prosenchymatous TISSUE. Several elongs 

 and strong tissues, which greatly strengthen the stems in 

 which they are found, are 

 collectively known as pros- 

 enchyma. The cells of 

 these tissues become much 

 thickened by the addition 

 of layers to the inner sur- 

 face, and finally lose their 

 protoplasm. They may. at 

 times, serve as store-rooms 

 for starch and other nu- 

 trients, and take an im- 

 portant pari in t he trans- 

 fer of the plant juices. 

 Some writers call this 

 group of tissues scleren- 

 chyma . 



115. There are four 

 main varieties of tissues 

 which may be included 

 under prosenchj ma. ( 1 ) 

 Fibrous tissue, composed 

 of very thick-walled cells 

 wit 1 1 \it\ small central 

 saviti es. I'. Fig. 101. 

 They are verj long and tapering al the ends, \n. 1 i i - 1 i lap 

 Such tissue is Found in man} plants where it often 

 wholly or in pari Burrounds the fibro ulur bundles 



It is more often bul aol always found near the sofl 

 bast: bence the cells are sometimes called bant fibers or 

 hard ba8t. (2) Wood tissue, or WOOd fibers. Tin- 

 composed <>t cells much like the preceding in structure, 



pan ion oell ; p, ihow a top \ 



li 



the 



the II l 



i '.in Hi.- . 



