The Cytology of two Species of Characiopsis. 181 
somewhat in thickness and gives the cellulose colour reaction. The 
projections do not seem to be solid, however, since a colourless gap 
is often seen in the middle of the thickening (Fig. 1, N). It looks 
as if the wall were laminate, and at certain points the lamellae 
separated, the inner layers being invaginated to form a kind of 
vesicle or hollow tubular process penetrating the cytoplasm 
(Fig. 1, M and O). The arrangement of the cell-contents is dis¬ 
turbed by these projections, and sometimes even in living 
specimens it is possible to distinguish the cavities in the dense 
cell-contents caused by them. These are far more obvious in 
stained specimens (Fig. 1, C, D, E and O). 
Bristol (T7) and Moore (T7) have described internal pro¬ 
jections of cellulose in the cells of two species of Chlorochvtrium 
but these are not exactly similar to those observed in Characiopsis 
Ncegelii. In Chlorocliytrium grande, according to Bristol, the 
internal projections were solid, lamellose and irregular in form, 
and were characteristic of cells about to be transformed into 
zoogonidangia. In the case of Characiopsis Ncegelii no evidence 
has been obtained in support of the suggestion that the particular 
cells showing the internal projections are zoogonidangia, since no 
reproductive stages have yet been observed in the culture. Here 
the projections also differ from those of Chlorocliytrium in their 
apparent hollow structure, and in that they are never so irregular 
in form as in the latter genus. 
In the living condition Characiopsis Ncegelii is very densely 
green, and there is apparently a large number of small green 
disc-like chromatophores which line the whole cell-wall. Very little 
else can be distinguished. 
After staining, the appearance of the cell is rather different. 
The disc-like chromatophores are no longer visible, and the whole 
cell appears to be full of very lightly stained protoplasm in which 
a coarse network, rather more deeply stained, can be distinguished. 
On focussing into the interior of the cell, numbers of small dark 
rounded bodies come into view (Fig. 1, C, D and E). 
The structure of the cell-contents is better understood from 
the examination of sections, cf. Fig. 1, J and O. There is a large 
number of rounded globular bodies, which may be angular by 
compression, and do not stain very deeply. These are the chroma¬ 
tophores. Between these, and filling up the space between them, 
is the colourless cytoplasm, which, being so compressed between 
the chromatophores is very dense in texture, and consequently stains 
rather deeply. Scattered throughout the films of cytoplasm are 
the nuclei, which are found chiefly at the angles between the 
