108 PREPARATION AND MOUNTING 
mounting, though the difficulty is not so great as some seem 
to think. If they are first dried with gentle pressure, and 
then subjected to the action of the air-pump in a small 
quantity of turpentine until the air is thoroughly expelled, 
they can be easily finished upon the slide, especially when 
balsam and chloroform are used. 
Insects supply us with another series of beautiful objects, 
viz., the jfeet.* These are sometimes simply dried and 
mounted without any medium, as before mentioned; but’ 
most of them are rendered much more fit for examination 
by using balsam in their preservation, as it greatly increases 
their transparency. The smaller kinds may be dried with 
gentle pressure betwixt blotting-paper, and then immersed 
for some days in turpentine, without requiring the treat- 
ment with liquor potassee. This immersion will render them 
beautifully transparent, when they may be mounted in 
balsam, in the usual manner. 
It is, however, sometimes found difficult to fix the feet 
when expanded, in which state the interest of the object is 
greatly increased. Mr. Ralph recommends the following 
mode :—* First wash the feet, while tke insect is yet alive, 
with spirits of wine; then, holding it by a pair of forceps 
close to the edge of a clean piece of glass,the insect will 
lay hold of the upper surface by its foot; suddenly drop 
another small piece of glass over it, so as to retain the foot 
expanded, and cut it off with a pair of scissors, tie up 
and soak to get rid of air.” Mr. Hepworth says that he 
never found any difficulty in expanding the foot on a 
drop of water or well-wetted slide, and laying a thin glass 
cover over it, tying with thread, drying, and immersing ir 
turpentine. 
The mouth, also, with its organs, is an interesting object 
in many insects. That of the common fly is often used, 
and is comparatively easy to prepare. By pressing the 
head, the tongue (as it is commonly termed) will be forced 
* See Mr. Hepworth’s interesting articles on the fly’s foot in the 
second and third volumes of the Ma:roscopic Journal. 
