OF MICROSCOPIC OBJECTS. 83 
paper; for the scales will become detached by their leaps 
against the glass, and will fall upon the paper.” These 
scales are removed to the slide, and mounted as those from 
gnats, &. When the podura has been caught without the 
aid of meal, it may be placed upon the slide, under a test- 
tube, or by any other mode of confinement, and thus save 
the trouble of transfer from the paper before mentioned. 
Another method is to seize the insect by the leg with the 
forceps and drag it across the slide, when a sufficient quan- 
tity of scales will probably be left upon it. 
Mr. McIntyre procures the scales in the following man- 
ner :—He makes what he terms a breeding-cage, by taking 
a piece of plate-glass four inches long by two inches wide, 
_ and over this places a few sheets of blotting-paper. Upon 
these he lays a sheet of cork about a quarter of an inch 
thick, with a circle cut out of the centre one inch wide. 
This gives a kind of box, which he covers with glass, kept 
firm by two elastic bands. He says :— After capturing 
the insect by means of a tube and a camel-hair pencil, I let 
it remain for some days in one of the breeding-cages, into 
which I always transfer the newly-caught podura, until it 
has changed its skin; then I stupefy it with chloroform, 
and drop it out on to a thin glass cover (previously cleaned) 
and with a very clean needle-point roll it backwards and 
forwards upon the cover till sufficient scales are removed. 
A very light pressure is indispensable, so as not to squeeze 
out any of the insect’s fluids.” 
These scales are usually mounted dry; but Hogg re- 
commends the use of Canada balsam (Chapter IV.) as ren- 
dering their structure more definite when illuminated with 
Wenham’s parabolic reflector. Some advise other methods, 
which will be mentioned in Chapter V. As most insects 
when undissected are mounted in Canada balsam, the dif- 
ferent modes of treatment which they require will be stated 
in another place. 
In mounting blood of any kind to show the corpuscles, 
or, as they are often called, globules, which are round or 
G2 
