113 
NOTES AND CORRESPONDENCE. 
Description of a Trough for exhibiting the Circulation of the 
Blood in a Fish’s Tail.—During the meeting of the British 
Association in Leeds last September there was an exhibition 
of microscopes and microscopic objects at one of the soirées, » 
when | showed the circulation of the blood in the tail of a 
small gold fish, using for that purpose a trough invented 
and made by Mr. T. Walker, a surgeon of this town. 
The trough appeared at the time to excite some attention 
from its convenience and efficiency, and as I have since 
received several applications on the subject, I am induced 
to think that a description of it may be of service to some of 
the readers of the Journal. 
As a proof of its efficiency, I may mention, that only one 
fish was used during the evening, and that, although it was 
kept for more than three hours under observation, it sus- 
tained no injury, and is still living. The trough consists 
of a piece of plate glass (a B c p), about six inches long, 
and two inches wide ; upon this three pieces of plate glass, 
about half an inch wide (£ B, B Dp), and pH, are cemented 










































































EE: 

with marine glue. Three pieces of strong covering glass; 
about a quarter of an inch wide ( F, FG), and eG 4H, are also 
cemented on to the plate. A piece of moderately strong 
covering glass (E, F, G, H,) is then cemented on to the top of 
the thin slips, and a piece of plate glass (2 H) cemented to 
the top of the thin glass( z r @ u), and abutting on the ends of 
the slips E B, H D. 
The whole then forms an bpen trough (ru B H D), termi- 
nating in a cell (e FG H), which is closed everywhere except 
where it communicates with the bottom of the trough at the 
line £ H. eek os 
The fish, wrapped in a little wet linen, is placed iif the 
