Rivett . — The Cytoplasm in the Cells of A licularia scalaris. 213 
plasm. The spaces of the net are clear, and are separated by threads and 
wefts of stained material associated with more deeply stained granules. In 
the cells of fully-grown leaves this structure has disappeared, the protoplasm 
is restricted to a thin layer, lining the cell-wall, and from this the films or sacs 
of the oil-bodies stretch into the vacuole. These sacs are distorted and 
contracted owing to the changes of tension undergone during the embedding 
process. Around their edges are drops and granules stained brightly with 
safranin ; some of these are undoubtedly the refractive granules of the 
cytoplasm, others have more the appearance of drops of glistening liquid 
which have taken up the stain. The appearance of these bodies is very 
constant in any preparation with the triple stain (see Text-fig. 3). 
In a series of sections treated with iron-haematoxylon and iron-alum 
the characters of the cytoplasm become even more distinct. In the apical 
cell and those adjacent to it, the nuclei with their nucleoli are large blue- 
black bodies; the surrounding cytoplasm consists of a colourless (i. e. not 
stained with the haematoxylon) ground in which are numerous small, 
disconnected bodies, some round and spherical, others thread-like, others 
irregular, but all are stained deeply grey or black with the haematoxylon. 
They seem to represent the chondriosomes, or chondriome-structure of the 
cytoplasm, which has been described in various plant tissues by Schmidt (8), 
Guilliermond ( 9 ), Lewitzky ( 10 ), and others. In the upper cells of the 
second pair of leaves folded around the growing point, the structure is 
different; around the bulky nucleus is a network formation; the strands of 
the net are stained deeply grey and the meshes are lighter or colourless; at 
the crossings of the strands and occasionally around the cell-walls are 
minute round bodies stained still more deeply. In the next pair of leaves 
this structure still remains, but in the fourth and succeeding pairs the 
development of the large central vacuole leaves the cytoplasm only adhering 
to the cell-walls. In some few cells the nucleus is visible, and in all there is 
a large development of chloroplasts. Occasionally the ‘ sacs ’ of the oil- 
bodies are stained faintly grey, but they do not readily absorb the iron- 
haematoxylon. Associated with them and occurring also around the 
cell-walls are round bodies, which are faintly stained and not very con¬ 
spicuous ; these are the bright, refractive bodies of the living protoplasm 
which stained most clearly with safranin (PI. VI, Fig. 6 and 7). 
To sum up shortly the cytoplasmic structure of the leaf-cells : 
(i) the actively dividing cells of the growing point and young leaf 
bases, where the protoplasm fills the whole cell, show a chon- 
driome structure; 
(ii) the maturing cells have a vacuolar protoplasm forming a ‘ spongy 
network ’; 
(iii) in the fully-grown cells, the lining layer is so reduced that it serves 
merely as a covering to its own products. 
