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tg01-1902.] The Entomostraca of Mid-Lothian. 313 
containing the name of the species, with locality and date of 
collection. When we began mounting our specimens, we tried 
balsam and Farrant’s solution, but we found Griibler’s glycerine 
jelly to be more satisfactory. In the case of thick specimens, 
such as Eurycercus, we used vulcanite ringcells, in order to 
obtain sufficient depth of jelly; but these, we found, are lable 
to leak after a time. For our thinner specimens we adopted 
the plan of building up a cell of the proper depth with gold size, 
and we are told that this method succeeds perfectly well with 
deeper cells. 
Some of our small difficulties were overcome only by re- 
peated experiments. First, we found that the jelly became 
cold, and set too quickly, before we could get the proper 
number of specimens placed in the cell. This was obviated by 
heating the slides beforehand. Then there was some difficulty 
in placing the cover-slip on the jelly; either the jelly would 
run halfway across the cover-slip and then stick, or else 
bubbles would find their way in. This was easily remedied 
by putting some of the liquid jelly on the cover-slip before 
placing the latter on the slide. One of our most serious 
troubles was, that a few of our specimens were too delicate to 
be put direct into glycerine jelly; and unfortunately we had 
no means of telling beforehand which were the delicate ones. 
Several times we have, as we thought, made some almost per- 
fect slides, and put them away to dry; and on examining 
them later, found that the specimens were grotesquely distorted 
and sometimes almost unrecognizable. It took us some time 
to find out what had happened; but at last we came to the 
conclusion that the failure was due to osmosis—i.e., that the 
juices of the body ran out at a greater rate than they could be 
replaced by the jelly, and that the latter was too strong a 
medium. We then put fresh specimens into G.W.A. (a 
mixture of one part glycerine, two of water, and three of 
alcohol). This plan was very successful, except for some of 
our most fragile creatures; these had to be left for days in a 
- much diluted solution, and were then transferred by degrees to 
a stronger and stronger one. 
We had a curious experience with regard to Diaptomus 
gracilis. We had a large number of specimens preserved, from 
several different localities; some of these had died a natural 
