PRATT: CYCLOLOMA ATRIPLICIFOLIUM. 91 



their cells. The outer area of the pericycle is made up of small 

 cells, which contain chloroplasts in very young stems (fig. 7, e), 

 and the inner area of the pericycle i§ made up of much larger cells 

 (fig. 7, /). There are three areas of pericycle in region II (fig. 8, e', 

 e" and /), and all the pericycle cells are larger in region II than in 

 region I (fig. 7). The areas of pericycle e' and e" in fig. 8 corre- 

 spond to the area of pericycle e in fig. 7. The cells in the outermost 

 area of the pericycle (fig. 8, e') have cellulose walls. In the areas 

 of pericycle e" and / of fig. 8 the cell walls are lignified. 



There is also an outer area of unlignified pericycle in regions 

 III and IV (figs. 9, e', and 10, e'). These cells are shown in longi- 

 tudinal section of region III in fig. 21. The outer longitudinal 

 strip of these cells, two cells deep radially, includes bast fibers. 

 As seen in a cross section of region IV (fig. 10, /') the bast fibers 

 are arranged single or in short chains. This arrangement is found 

 in nearly all the Chenopodieae, according to Solereder ('08), who 

 states, "it rarely consists of a closed sclerenchymatous ring, and 

 is mostly composed of isolated groups of sclerenchymatous fibers." 

 The occurrence of a sclerenchymatous pericycle is held to be an 

 ordinal character in the Chenopodieae by Georghieff {fide Sole- 

 reder ('08). 



A few bast fibers, irregularly arranged, also occur in three 

 tangential rows of pericycle cells, just interior to the outermost 

 row, in cross sections of region V (fig. 22, /') and below. The bast 

 fibers are approximately twice as broad as the wood fibers (figs. 

 23 and 24). The fibers stain a reddish-brown or a brilliant yellow 

 in chloroiodide of zinc. 



The lignification of cell walls in the areas of pericycle e" and / 

 of fig. 9 in region III is more complete than in the corresponding 

 areas of pericycle in region II (fig. 8). The cells of the area of 

 pericycle e" of region III are shown in longitudinal section in 

 fig. 25. In certain cross sections of region IV the two outer rows 

 of cells of the central area of pericycle (fig. 11, e") have thick 

 lignified walls, and the outer cells in this area of pericycle have 

 cellulose walls. The cell walls in the innermost area of pericycle 

 are cellulose (fig. 11, /). 



Generally all the cell walls in pericycle areas e" and / in fig. 11 

 of region IV are cellulose, or are very slightly lignified. The cell 

 walls of the corresponding areas of pericycle in all regions of the 

 stem below region IV are cellulose, or are very slightly lignified. 

 (See the areas of pericycle of fig. 26, e" and /, in region V.) The 



