THE SEEDLING AND YOUNG PLANT. 65 



As a rule, the outer and inner side of these bast 

 groups are in contact with vertical rows of nearly cubi- 

 cal parenchyma cells, strongly thickened on the side next 

 the bast, and each nearly filled with a crystalline clump 

 or with an imperfectly formed crystal of oxalate of lime. 

 Similar vertical rows of crystal cells may also occur 

 within the groups of bast fibers, the walls of the cubical 

 cells being more or less thickened and simply pitted. 

 Occasionally a cell here and there retains thin walls. 

 The vertical rows result from cross-divisions of prosen- 

 chymatous mother-cells, the conical ends being found in 

 macerations. 



Within the groups of bast fibers are yet other rows, 

 similarly formed, of parenchyma (Fig. 17, bp), the cells 

 of which are longer, however, attaining the length of 

 the wood-parenchyma; like the latter also their walls 

 are lignified and rather thick, and they contain starch 

 in the winter. Thus we have parenchyma in the bast. 

 Transitions between these two forms of parenchyma 

 cells are also found. 



The cells of the rays between the bast fibers are 

 thickened and pitted ; they are rounded, and not in 

 vertical series as in the rest of the rays, but are scattered 

 in no particular order. Sometimes they are few, and 

 one or all with very thick walls perforated by pit-canals 

 (Fig. 17, bs). 



The remaining younger part of the bast consists 

 chiefly of delicate, apparently irregular parenchyma 

 cells with cellulose walls; this is easily traced to the 



