170 PROCEEDINGS OF SOUIETIES. 
Oxrorp Microscoricat Socrecy. 
November 27th, 1866. 
Mr. Robertson exhibited some beautiful injections of Helix 
pomatia—the Roman or edible snail. He stated that, after more 
than two hundred attempts, he had succeeded in demonstrating 
what was, to the best of his belief, as yet unknown to comparative 
anatomists—the existence, viz., in this animal, of a completely 
closed capillary system, differing in no respect from the same 
system in the higher animals. These capillaries were most 
strikingly displayed in the crop, the intestine, and the mantle. 
In some of the preparations the distribution of the arteries was 
shown and explained to the Society. In one specimen, in parti- 
cular, the minute branches of anastomosis between the arteries 
and veins on the wall of the pulmonary chamber were very clearly 
defined. He has thus proved that the pre-existing notion of a 
lacunar circulation in these animals is a mistaken one; the mis- 
take having, as he supposes, arisen principally from the way in 
which the operation of injection has hitherto been performed 
(it being the custom to introduce the injecting-pipe into the foot 
or tentacle, whereas his own successful injections were made from 
the heart), partly also from the improper consistence of the 
injecting fluid employed. 
Mr. Robertson next drew attention to a glass trough made in 
one piece, without any joint, and devised by himself for the pur- 
pose of receiving dissections to be photographed. The dissection 
1s first stitched on talc, with a piece of blue paper behind it, and 
then placed in spirit in the trough. Owing to the absence of any 
joint in the trough, the light is admitted equally on all sides, 
and a perfect image of the object can, with a little careful mani- 
pulation on the part of the photographer, be thus produced. 
Several photographs of dissections taken in this way by an Oxford 
photographer were likewise exhibited. 
Dusxiin Microscopican Crus. 
October 18th, 1866. 
Mr. Archer exhibited a very minute new species of Cosmarium, 
with its zygospore, gathered at Kilbride, near Blessington, county 
of Wicklow. This little form he had taken on previous occasions, 
but never before conjugated. As the mature plant itself is one 
of exceeding simplicity and very minute, it is hence liable perhaps 
to be overlooked, or at least regarded as possibly but some simple 
Palmellaceous cell. Nevertheless, Mr. Archer had always felt it 
