2 
MORPHOLOGY OF THE CELL. 
consisting of a peculiar substance, which we call Cellulose (Fig. i, B, C, h). Close 
to the inner side of this membrane, which forms a closed envelope, is a second 
layer, also entirely continuous, the substance of which is soft and inelastic, and 
which always contains albuminous matter; to this substance H. v. Mohl gave the 
distinctive appellation of Protoplasm^. In the cells now under consideration it 
forms a sac enclosed by the 
cell-wall, in which sac other 
portions of protoplasm are 
also usually present in the 
form of plates and threads 
(Fig. I, B, C, Absent 
from some of the lowest or- 
ganisms, but present in all the 
higher plants without excep- 
tion, there lies imbedded in 
the protoplasm a roundish 
body, the substance of which 
is very similar to that of the 
protoplasm, the Nucleus {A, 
C, k). The cavity enclosed 
by the protoplasm-sac is filled 
with a watery fluid, the Cell- 
sap (B, C, s). In addition to 
these, there are also very com- 
monly found in the interior of 
the cell granular bodies, which 
however may be passed over 
for the present. 
Cells, in the stage of deve- 
lopment now described, consist 
therefore of a firm membrane, 
semi-solid protoplasm (includ- 
ing the nucleus), and fluid cell- 
sap. At first, however, the cell- 
sap is wanting. If the same 
cells are examined in a very 
early stage of their development they are smaller (A), their cell-wall thinner, and 
the protoplasm forms a continuous mass, in the middle of which lies the nucleus, at 
FIG. I. — Parenchymatous cells from the median cortical layer of the root of 
Fritillaria imperialis ; long-itudinal sections ( X 550). A very young- cells lying 
close to the apex of the root, still without cell-sap. B cells of the same description 
about 2 mm. from the apex of the root, the cell-sap s forming separate drops in the 
protoplasm/; between the drops are plates of protoplasm; C cells of the same 
description about 7 — 8 mm. from the apex of the root ; the two cells to the right 
below are seen in a front view ; the large cell to the left below is in optical section ; 
the cell to the right above is opened by the section; the nucleus shows, under the 
influence of the penetrating water, a peculiar appearance of swelling (jc, y). 
^ H. V. Mohl, Ueber die Saftbewegungen im Inneren der Zellen, Bot, Zeitg. 1846, p. 73. The 
importance of this substance to the life of the cell was recognised at the same time by Nageli, 
who, in conjunction with Schleiden, termed it ' Schleim.' (Zeitschr. für wissensch. Bot. von 
Schleiden u. Nägeli, Heft III, 1846, p. 53.) [The 'nucleus' was figured by F. Bauer in 1830 in 
the stigmatic cells of Bletia TankervillicE from a sketch made in 1802. Meyen in the former year 
indicated it in his ' Phytotomie.' It was first described by Robert Brown (see Misc. Bot. Works, vol. I. 
p. 512) in 1833. Schwann in 1839 applied the term 'nucleolus' to the body previously discovered 
by Schleiden (Schwann and Schleiden's Researches, p. 3). Cohn in 1850 pointed out the analogy 
of the ' protoplasm ' of botanists with the ' sarcode ' of zoologists.] 
