52 



ON THE PLANT-CELL. 



2. Spongiform Pa- 

 renchyma, which con- 

 sists of cells extend- 

 ing themselves irregu- 

 larly in a stellate form, 

 and which touch only 

 at the end of each ray 

 (fig. 37.). Such tis- 

 sue frequently fills up 

 the air-passages, and oc- 

 curs in all tissue which 

 dries rapidly, and also 

 in the under half of the 

 parenchyma of most 



37 



leaves. 



b. Complete Paren- 

 chyma, in which the 

 touching of the cells is 

 complete on every side. 



1. Regular or dode- 

 caedral parenchyma, 

 consisting of almost 

 pure polyedral cells, 

 without the predomi- 

 nance of any particular dimension, 

 of plants (figs. 38, 39.). 



It is found mostly in the pith 



2. Longitudinal, cylindrical, or prismatic parenchyma. It occurs 

 in rapidly growing plants, sometimes in the pith of monocotyledons 

 and in the interior of species of Fucacece (fig. 40.). 



3. Tabular parenchyma, consisting of four-cornered tabular 

 cells. They occur in the external bark, especially in the suberous 

 and cellular layers (fig. 41.). 



87 Spongiform parenchyma from an incomplete intercellular passage of Canna occi- 

 dentalis. 



83 Transverse section of the parenchyma of the stem of Balsamina hortensis. 

 39 Longitudinal section of the same. 



