uniformity very soon sets in at various spots. 
especially manifested at the corners and edges, the cell- 
+ a \ \ yo e:9 + nw Kom , , ’ " 
hs . a NY, f ¢ A 5 y ‘ <n 
Yer me NE t ; Shae y, me ' i, \ AX Ch y Shi ih \ : / ed SR a! 
pony j 
RF j é 5 i Neaph a ‘ ; 
ee <The Cell as an Individual.: 19 
several spiral bands (Fig. 18, p. 14). . The thickening-layers 
-often increase so considerably that the space enclosed by the 
cell-wall, the ced/-cavity, almost entirely disappears (Fig. 20). 
The increase of the cell-wall in thickness is almost in- 
variably uniform only in its earliest stage ; a want of 
This is 
-- cavity being always more or less rounded off; but it sub- 
Fic. 30.—A spiral cell 
from a cactus, JZamezt- 
laria, with flattened 
Fic. 31.—Piece of aa 
annular cell from the 
from Arundo donax, 
stem of the Turkish with strongly thickened 
Fic. 32.— Annular cell 3 
spiral band. (x 400.) 
wheat; the edges of con= 
tiguous cells are visible 
on the cell-wall. (x 500.) 
rings placed at different 
distances and different 
angles, (x 400.) 
sequently often takes place only on one side (Fig. 21), or so 
slightly at particular spots that petted or fore-canads are formed 
at those spots. These are sometimes simple (Figs. 19, 20), 
sometimes branched (Fig. 25). The canals from adjoining 
cells constantly meet; sometimes they are widened at their 
base into bordered pits (Fig. 22) ; and the membrane between 
these frequently disappears, so that cells become thus actually 
perforated (Figs. 23, 24). According to the development of 
| C2 3 
