10 
PLANT MORPHOLOGY. 
The cell-contents naturally group themselves into two 
distinct classes : one in which the life-processes of the 
plant are manifested, and which may be looked upon 
as constituting plant organs, and another which are 
the direct or indirect products of these. The former 
may also be termed the organized cell-contents, and 
include the protoplasm, nucleus and plastids. The 
other class consists of the unorganized cell-contents, 
and includes the various carbohydrates, calcium oxa- 
late, tannin, aleurone, oil, and a number of other sub- 
stances. 
B. ORGANIZED CELL- CONTENTS. 
PROTOPLASM. 
Protoplasm was first accurately described by von 
Mohl, in 1846, who referred to it as “ a mass of fibers, 
or a fibrous network, the meshes of which are filled 
with a fluid.” About 1850 it was shown that the pro- 
toplasm of plants was the real seat of their vitality and 
activities, and about the same time a similar discovery 
was made in regard to the “ sarcode ” or primary sub- 
stance of animals. The term protoplasm is now used 
to designate the fundamental living substance of both 
plants and animals. 
Protoplasm occurs as a more or less semi-fluid, 
slimy, granular, or foam-like substance, which lies 
either close to the walls of the cell, as a relatively thin 
layer and surrounding a large vacuole of cell-sap, or 
from this protoplasmic layer threads or bands may 
extend to a central or excentral mass of protoplasm, 
in which a nucleus is usually embedded. As to the 
chemical composition, or even the physical structure, 
of living protoplasm, our knowledge is but frag- 
mentary. With microchemical reagents it behaves 
like the albuminoids; and with staining agents certain 
