PROCEEDINGS OF SOCIETIKS. Al 
Closterium didymotocum (Corda), not uncommon. 
59 striolatum (#.), very common, 
a attenuatum (#.), rare. 
se juncidum ( Neh ss 
. rostratum (Zhr), ,, 
Spirotenia condensata (Bredb.), common, 
Ankistrodesmus faleatus (Corda), very common. 
Pediastrum tetras (#/r.), not uncommon. 
- heptactis (Zhr.), mn 
= Boryanum (Zurp.), ,, [I have met (rarely) in two or three 
of the cells the contents receded from the walls, and massed 
together into a single, globular, green body in the centre, so 
as to leave the remainder of the otlierwise normally formed 
cell quite empty. This took place in the outside row of, and 
not in neighbouring, cells. This body is possibly a gonidium 
destined for the propagation of the organism. I have seen 
somewhat similar bodies in the cells of a species of Spirogyra, 
not the result of conjugation. | 
i ellipticum (Z/r.), common. 
Scenedesmus quadricauda (7wrp.), very common. 
fp obliquus (Zzrp.), not uncommon. 
5 obtusus (Meyer), 
39 
Britiso AssociaTION FOR THE ADVANCEMENT OF SCIENCE. 
Dublin Meeting. 
Saturday, August 29th, 1857. 
Section D.—ZOOLOGY anp BOTANY, tnctuptne PHYSIOLOGY. 
Dr. Reprern described a method of applying the com- 
pound microscope to the sides or top of aquaria less than 
two feet in height. The arrangement consists of a vertical 
stem, supported by a heavy foot. On the stem a short trans- 
verse tube slides vertically and rotates on the axis of the 
stem, as well as on an axis at right angles to the direction of 
the stem. This transverse tube carries a long sliding arm, 
made use of as a lever, with arms of very unequal length. 
The short arm of the lever terminates in the cup of a ball- 
and-socket jomt. A short stem attaches a tube to the ball, 
and this tube allows that which carries the objective and 
ocular to slide through it in coarse adjustment; whilst a 
fine adjustment is made by acting on the long arm of the 
lever. The body of the microscope may thus be placed 
either vertically or horizontally, and placed either over an 
aquarium or applied to its side with equal ease in the use of 
the two-inch, the one-inch, and the half-inch objectives. 
For the purpose of illumimation, Dr. Redfern employs a 
small mirror, which is let down into the fluid, and is capable 
of being moved in any direction by a simple arrangement of 
brass wires shown to the Section. 
