12 BOTANY. 
may become active again upon the access of water and the 
proper temperature. Possibly some of it serves as food 
for protoplasm in the germination of seeds. 
Practical Studies.—(a) Mount in alcohol a thin slice of a ripe pea. 
Note the small granules (along with large starch-grains) in the cells 
(Fig. 5). Apply iodine, which will stain the aleurone yellow or 
brownish-yellow. 
() Make a similar study of the aleurone of the bean. 
(c) Make sections of the foregoing and mount in water to observe 
the solution of the aleurone grains. Tie process may be hastened 
by adding a very little potassic hydrate. 
(d) Make thin cross-sections of a wheat-kernel and study the gluten 
(aleurone) cells of the inner bran. Add iodine. 
(€) Make a similar study of the bran of rye, oats, and Indian corn. 
26. Crystals.—Some cells of certain plants contain crys- 
tals (Fig. 7). These are of 
various shapes, one of the 
most common forms being 
needle-shaped, while others 
are cubical, prismatic, ete. 
They are frequently clus- 
tered into little masses. 
27. Crystals are for the 
most part composed of cal- 
Fia. 7.—Crystals of caleinm oxalate. cium oxalate. That is, they 
The right-hand portion of the figure gre a combination of lime 
shows two cells of the Rhubarb, with 
their contained crystals, and one en- is . 
larged. On the left is a crystal from and oxalic acid. A few have 
the beet. Much magnified. 
a different chemical compo- 
sition—as the calcium carbonate crystals found in nettles, 
hops, hemp, etc., besides others of still more infrequent 
occurrence. 
28. Crystals appear to be the residues from chemical re- 
actions which take place in the interior of plants, and they 
probably have no further use. 
