ye” Bk My 7 7% », | , On , vine , *. >» bl y 4. Le 
ys dé . ~ Se of : 
ag or) wo4 % Wp Pg “vw yj c / o-oo 
y j Pi y 7 oe ; a ! : ’ 
poe The Collas.an Individual.” “Br 
; poutetly Bswolved in the cell-sap, often as eranular masses, more 
rarely in a crystalline form, as protecne-crystals or crystalloids. They 
exhibit all the essential properties of protoplasm, and are not true 
crystals, differing from these essentially in many respects. The cubic 
crystalloids of the potato, for example (Fig. 52), are not dissolved by 
water, but break up in a peculiar manner so as to appear as if composed 
of several layers. Crystalloids generally occur in the cells in which 
reserve food-materials are stored up for future use, especially in ony. 
seeds. 
Grains of enone occur frequently in the endosperm and the cotyle- 
dons. In seeds which contain starch this albuminous substance includes 
only a little oil, and does not form granules, as in the grasses, bean, 
-vetch, sweet chestnut, &c. In oily seeds, on the contrary, such as the 
Brazil nut, nutmeg, Umbelliferze, &c., it replaces the starch-grains. 
Crystals of calcium oxalate, or roundish or clustered granules (g/obozds), 
a double calcium and magnesium phosphate in which the latter is 
greatly in excess, are frequently found in the grains of aleurone, im-— 
bedded in albuminous substance. 
The roots of Compositz, as the dahlia, sunflower, &c., and less often 
the stems, contain a peculiar substance called zudine. In the living 
cell it occurs only in solution, and is only precipitated on evaporation 
or on the addition of alcohol or of some other substance that has a 
s'rong attraction for water. Ifthe process is successfully and rapidly 
performed, the inuline has the form of fine granules which have often ~ 
a frothy appearance ; but if the process goes on for a considerable time, 
it forms remarkably beautiful spherical bodies, called sphere-ca Tae 
(Fig. 53). 
Besides these substances and those already mentioned, others often 
- occur dissolved in the cell-sap, the presence of which is. proved by- 
chemical tests, but which cannot be detected in the cell itself even by 
_ the microscope. To this class belong especially the alkaloids, strych- 
nine, brucine, chinine, cinchonine, &c. 
\ 
By the term cel/-formation is understood the mode of — 
origin and multiplication of cells. These two processes 
are identical, if we confine ourselves to what has at present 
_been determined by direct observation, and do not assume 
an equivocal or spontaneous generation by which new cells 
are formed without being derived from mother-cells, simply 
by the concourse, under favourable circumstances, of organic 
