DUBLIN UNIVERSITY ZOOLOGICAL AND BOTANICAL ASSOCIATION. 259 
ating eitlier from the central point of the cell, or, as it appears to me, 
sometimes as it were from a central axis,—thus often giving, more 
especially when viewed under low powers, a somewhat stellate appear¬ 
ance to the contents (see Fig. 17). The contents, however, are not 
unfrequently irregularly scattered. So far, this description appears to 
apply equally to the Leipsic and Dublin plants. In the plant met with 
here there usually appears a darkish (under a low power almost black) 
central mass. This, with the whole of the remainder of the endochrome, 
can he expelled by fracturing the cell by pressure. This central portion 
is extruded in a cohering, somewhat stringy mass, but can be afterwards 
broken into granules. It is sometimes shot out with vigour, leaving the 
separate chlorophyll-granules behind, and which afterwards, in a conti¬ 
nuous stream, make their exit through the ruptured cell-wall. The ex¬ 
pelled chlorophyll granules, which at first are large and smoothly defined, 
by subsequent pressure can be broken up into smaller granules, which, 
when detached, as in other cases, often set up a u molecular” motion in 
the surrounding water. I have noticed, too (rarely), a molecular motion 
of the more minute particles within the uninjured cell. 
This organism has occurred not unfrequently in the Desmidian ga¬ 
therings I have made; but nowhere did I meet with the plant in such 
numbers, and so isolated from other forms, as in a small pool, close to the 
Sugarloaf Mountain, on the road to Boundwood. I have specimens 
still by me collected during last summer, and which, living ever since, 
have been healthfully preserved. A single specimen is visible to the naked 
eye, being from -rh to of an inch in diameter. The chief difficulty ad¬ 
verted to in reconciling'this with M. Hofmeister’s plant is the comparative 
dimensions, as he says with regard to this —“ Some are as much as *05 
millim. in diameter.” This is (roughly) about equal to shs of an inch, 
the dimensions of my specimens being thus often three times as great. 
When I first met with individual specimens of this organism, I imagined 
it might have been the sporangium of some Desmidian (possibly of a 
Tetmemorus), though, as I afterwards found, too large for that. M. Hof- 
meister compares his plant to the sporangium of Xanthidium armatum, 
as if similar in size, and which it no doubt resembles. But though 
Mr. Balfs met with but one. specimen of the sporangium of that (with 
us) rather common species, and does not give the dimensions, yet it is 
surely not much smaller, according to his figure (comparing it with 
others of known size, and all equally magnified), than of an inch. 
However, the conjecture that our plant can be sporangium seems to be 
dispelled by its undergoing self-division; and, as Hofmeister remarks 
with regard to his plant, “ this renders it in the highest degree probable 
that they are independent organisms,'—Desmidiae without a central con¬ 
striction, which may form the commencement of a series of forms termi¬ 
nating in Micrasterias.” 
M. Hofmeister does not describe the mode of division in his plant. 
That met with here, when about to divide, appears to be more densely 
filled with endochrome than in the ordinary condition, and its somewhat 
radiate appearance is less evident:—the first indication of the approach- 
