270 Mounting Entomostraca, 
It should be borne in mind, that some species of Entomostraca 
are strictly local, limited even to a small part of a particular pool. 
Daphnia mucronata, for example, will be obtainable by hundreds, 
from the space of a very few square yards, whilst but a solitary or 
perhaps not a single specimen will be found beyond the well-defined 
area. In such cases, local knowledge can alone avail the collector. 
The Entomostraca thus secured should be picked out under the 
dissecting microscope, transferred to watch-glasses of filtered 
water, and allowed to remain for twenty-four hours, in order that 
the contents of the laden intestine may be discharged, some of which 
if this precaution be not taken, would, under the pressure of the 
covering glass, inevitably be squeezed out, and sully the mount ; 
drawing off the water, a little spirit of wine speedily deprives them 
of life ; and all dirt having been removed by the aid of a camel's 
hair pencil, they are to be placed in a few drops of diluted medium 
(half medium and half water) on a glass slip, protected from dust, 
until saturation is complete, and not until then, put up in the me- 
dium ; shallow cells being mostly necessary. 
After many and repeated experiments, attended with variable 
success, Mr. Clayton found Mr. Farrants's modification of his 
medium, by the omission of the arsenic, and the reduction of the 
glycerine to a minimum, on account of the known efiects of that 
fluid in slowly dissolving the carbonate of lime of shell, gave the 
best results, in the greatest amount of transparency and permanence 
of which such subjects are susceptible. The receipt is as follows : — 
Gum arabic (picked), 1 oz. ; distilled water, 1 oz. ; glycerine, ^ oz. 
The gum to be dissolved in the water, the glycerine added, and the 
whole filtered through white blotting-paper previously moistened 
with distilled water. 
In giving this brief account of the late Mr. Clayton's practice, 
I can only express the hope, that some of our members, through 
the information now afibrded, may be induced to emulate that 
manipulative skill which made his preparations unrivalled as yet 
in excellence, and that through them, his endeavours to preserve 
the Entomostraca as permanent objects for the microscope may be 
carried to a still higher degree of perfection. 
