DUBLIN NATURAL HISTORY SOCIETY. 
193 
On looking into the microscope I was much struck with the peculiar 
appearance of one of the forms that first presented itself in the field,—a 
Pleurosigma Spencerii. The usual colour of the endrochrome in this 
species is pale brown, hut in the present instance it was a beautiful 
green. A number of granules of a bluish-green colour were distributed 
through the cell. In a few minutes I observed that the greater portion 
of the granules, at least two-thirds, moved with a sudden jerk to the 
lower part of the cell. Some of the granules passed out of the valve, 
and immediately after an Anthozoid issued from the cell. Shortly after 
another made its appearance, and another, until six or eight had been 
extruded. 
All these organisms proceeded in the same manner from the valve, 
and exhibited themselves in the same spot, within what appeared, under 
a quarter-inch objective, with Ho. 2 eye-piece, about -fgth of an inch 
from the extremity of the valve. In form the Anthozoids, if at rest, 
would have presented very much the appearance of a spike of thistle¬ 
down. The head was of a pale green colour, and round it the tail was 
lashed from side to side with great activity. 
On the same occasion several forms were observed, presenting similar 
appearances, with Anthozoids moving rapidly about in their immediate 
neighbourhood. Among these were two or three of the species named 
Cymatopleura solea; hut in no case except the one just alluded to did 
I observe them issuing from the valve. 
On the evening following that in which the preceding observation 
was made, I examined a drop from the same gathering, when a great 
change was noticed to have taken place in the appearance of such diato- 
maceous forms as occurred, compared with that which they presented the 
evening before. But few granules were seen. The endochrome also 
had changed its colour from green to olive, and, instead of being diffused 
through the cell, was in many instances collected in a narrow hand along 
each side of the cell, or at the opposite ends of it. In some cases these 
bands had broken up into isolated portions, and in others the valve was 
as free from endochrome as if it had been treated with acid. 
The President dwelt on the value of the observation, which was, he 
believed, perfectly new, and he had no doubt, as such, would be con¬ 
troverted, or at least probably received with doubt. There was, there¬ 
fore, the more necessity for repeating the observation, and, if possible, 
confirming it. He thought it most probable that these bodies were 
Zoospores, and not Anthozoids; though this would not in the least de¬ 
tract from the value of the observation. Perhaps Mr. William Archer, 
who had devoted so much time to the study of the Desmidiae and other 
simple vegetable forms, would favour them with his views on the 
subject. 
Mr. Archer said that he felt inclined to look on these bodies as Zoo¬ 
spores, as suggested by Professor Harvey, otherwise we must suppose 
that two forms of the same mode of reproduction (that by dissimilar 
cells) existed among these plants. The observation was, nevertheless, 
a most valuable one. 
