ag | (Bee fe Chap. v. Ve se ss 
ae “Crystals occur in particular cells in almost all the pigher Bees i oe a 
-. plants, less often also in the less highly organised Cryptogams ; and in Bes 
pe i Conifers are also frequently found imbedded in the cell-wall. They ie 
Hate consist of calcium oxalate. The crystals, when separate, contain six equi- gs 
valents of water of crystallisation ; their stem-form is a blunt quadrate 7 
-octohedron (Fig. 48). ‘lhe bundles of acicular crystals or vaphides 
have, on the other hand, only two equivalents of water of crystallisa- 
ait -\ «tion, and are klinorhombic columns or hendyohedra (Fig. 50), often 
eee very similar in form to those of calcspar. The groups of crystals ~ By 
...~ , ‘have one or the other form according to their chemical constitution — = 
iy © (Figs. 49, 51). ae 
vies The albuminous or proteinaceous substances contained in the cane Aree any 
of special importance, since they stand in the closest relationship to ~- | 
t 
* 
2 ‘ Vd 
ae 
j! Y 4 
q 
Fic. 52.—Crystalloid £7, in a paren- Fic.53.—Sphere-crystals of ‘hae NDE 
.. -chymatous cell of the potato-tuber ; in a parenchymatous cell from © _ 
a & nucleus. (x 420.) a tuber of the dahlia preserved = 
we 
i 
} 
t 
LV 
y 
in alcohol, after addition of ni- Eat 
tric acid. ( x 420.) : 
! “protoplasm. Their presence is generally detected with tolerable eae ibs 
under the microscope, being coloured red by the addition of water | we 
and sulphuric acid or mercury subnitrate. They usually apres to Be eat 
