mm oh, ay 3 NN oy »x* Dad ee ae oF Ae k ¢ BO. op tice fie gee Vee i,j he SORT) dad 
on ara 4 ’ \“ . - Le, . , 7 
a Y 4 oes . 4. 
v a 
Ko 
Z l ins 
saa Cer i 
Fhe Cell as an Individual. Ct) ee 
by which cellulose is converted into Zgwine or cork. The various cases of 
the second kind, in which the transformed and absorbed portions of the 
cell-wall are retained to support the life of the plant, have been comprised 
under the term resorption. To this class belong the disappearance of 
particular portions of the cell-wall in the coalescence of cells to be here- 
after described, as well as the resorption in the formation of bordered 
pits, in which the cell-walls between the canals have become absorbed. 
As examples of excreta produced from cellulose by transformation, and 
no longer of service for the life of the plant, at least in the formation 
and nourishment of cells, we may regard gum-arabic, cherry-gumn, gum- 
tragacanth, and other similar substances. In some cases only particular 
39.—Transverse section of a piece of the testa of the seed of Polemo- | 
nium ceruleum. After moistening with water the layers of swollen cells 
emerge above the outermost cells in the form of a jelly (after Unger). 
/ 
cells are subject tothese transformations ; in others all without distinction. 
Thus, for example, in the stem of the cherry or plum-tree, gum may be 
produced from any kind of cell. Of a somewhat similar nature to this 
formation of gum is the conversion into mucilage of the epidermal cells 
_ of many seeds, as in linseed and quince seeds. In these cases the cell- , 
wall is excessively thickened ; but, while otherwise retaining all its 
special characteristics, the innermost layers swell up to an extraordinary - 
extent in water, so that they burst the outer layers which have not the 
same property, and emerge as a transparent mucilage (Fig. 39). The 
secretions of cells, which will be referred to hereafter, must not be con- 
founded with these products of transformation of the cell-wall. | 
Besides protoplasm, the nucleus, the watery cell-sap, 
~~. ) ore. 
