50 VEGETABLE PHYSIOLOGY 
a fact which affords evidence that the primary meaning of 
both is the same. 
Like the substance of the raiddle lamella, both lignin 
and cutin are soluble in warm nitric acid containing potassic 
chlorate. 
In some cases the cell-wall of the epidermal protoplasts 
is impregnated with various matters that do not proceed 
from its own disintegration. Among these are various 
fatty bodies, while wax is sometimes very conspicuous. 
The bloom of such fruits as the grape and the plum is 
composed of very fine waxy particles; the impregnation 
Fie. 49.—SEction oF Portion 
or Lear or Ficus, sHow- 
Fic, 48.—CRYsTALS oF Cancium ING CYSTOLITH (cys) IN 
OxaLats IN WaLL or CELL LARGE CELL OF THE THREE- 
oF THE Bast or Ephedra. LAYERED EPIDERMIS (ep). 
in their case having been so great that certain particles 
have passed beyond the walls and formed a layer on the 
outer surface. The leaves of the wax-palm show an even 
denser deposit. 
Mineral matters are also of frequent occurrence in the 
cell-wall. The chief of these are salts of calcium, usually 
the oxalate, but often the carbonate. Some cell-walls show 
a copious deposit of regular crystals of one of these—such 
are the cells of the bulb scales of the onion, the fibres of 
the bast of Ephedra, and others (fig. 48). In many plants 
copious deposits of silica are formed in the cell-wall, 
especially in the epidermal cells of the Equisetacec, and in 
