1048 General Notes. [October, 
For mounting microscopically, five or a dozen spots of fluid 
Canada balsam should be dotted on a slide from the head of a 
pin, and by means of a hair pencil as many living insects trans- 
ferred to them. The specimens at once adhere, and if the spots 
are small the insects spread out their limbs naturally, with a view 
to escape. They may be fixed on their backs or otherwise, ac- 
cording to the views desired. 
A very thin glass cover, or, if very high magnifying powers are 
wanted, a small disk of clear mica, is laid over the insects, and 
then one or more drops of the fluid balsam are delivered from a 
glass rod at one of the sides of these covers. The balsam runs 
slowly under by capillarity, and it drives all the air before it, the 
small weight of the cover assisting it to spread, until the whole 
area is filled. No pressure is to be used, or the elastic bodies of 
the Aphides will change shape; and besides this, the juices will 
be forced through the cornicles and pores. If the balsamis thick, 
a very gentle heat, hardly exceeding that of the cheek, may 
applied, but as a rule, the temperature of a room is better than 
that which exceeds it. The insects die immediately they are cut 
off from air, and in almost every case their position will be good 
for examination. To spread the wings of a small insect, the above- 
mentioned small dots may be made in a row. The belly of the 
specimen is applied to the middle spot, and by a bristle one wing 
may be applied to a dot on the one side, and the other wing to 
the third dot. The cover is then placed as befare, and when tie 
balsam runs in it will not disturb the position of the spread wings. 
It will be noticed that very soon after live insects have 
mounted in a resinous substance that will not mix with es 
white cloudiness forms around each specimen. This !s fore 
the watery juices of the insect, which chill. the medium and 
it opaque. : 
This cloudiness, however, entirely disappears after perhaps 
month, the moisture being slowly carried outwards. oe 
to be said of stray air-bubbles. The oxygen of the air unites cut 
the balsam, and thus hardens it ; but what combination 1S eff oil 
with the nitrogen is not so clear. However, air-bubbles 11 ere 
isappear in time, provided the former is not in too hard a 
dition. : small 
_ In cases when the above small pressure is undesirable, oe 
circles, cut by round punches of different sizes out © var 
sheet lead, will be found more convenient to insert between s 
glass slip and its cover than circles of card, which are spe 
recommended. The thin sheet lead from the Chinese pase it 
yields no air-bubbles by heat. which it 
would appear that all the characters of form and colour er 
be preserved in Aphides and other insects. The method com" 
