1884.] Entomology. 104) 
of a rapid death and drying of the insect by means of a current 
of heated air. The Aphis, previously attached to some suitable 
support, is suddenly and momentarily subjected to the heat of a 
spirit or other flame, by which it is immediately killed and caused 
to retain its natural position. Several examples are then carefully 
roasted in a current of hot air, such as that passing through an 
inclined glass tube duly made hot, or dried on a sheet of paper 
moved over a heated metal plate. 
When dry, the specimens are mounted on card by attachment 
with gum tragacanth, or, as Mr. T. W. Douglas suggests, more 
conveniently on mica, called “talc,” in the shops, which, as it is 
incombustible, is well suited for a support both before and after 
tying. 
Methods and operations in science, like events in history, re- 
peat themselves. Fifty years ago films of mica were used to cover 
objects for the microscope, and before the manufacture of the thin 
gass now so commonly used, it admirably answered its purpose. 
Under deep magnifying powers, such as one-half inch, it will be 
fourid even now of great service. The mineral may be split by 
the lancet into films much thinner than glass can be blown in a 
flat state. Small unscratched pieces may be selected which are 
perfectly transparent, and their cost is quite trifling. 
On account of the high refracting power of Canada balsam, 
the colors of recently immersed Aphides show themselves very 
brightly ; and it sometimes happens that tints, quite lost through 
irradiation or glance on the surfaces, become distinct by treatment 
with this resin. z 
The bright colors and markings of some species are due to the 
hue of the internal juices of the insects. These cannot be pre- 
Society, June, 1884, p. 467. 
