82 PREPARATION AND MOUNTING 
of lines running from the base to the apex, others reminding 
us of network—bead-like spots only are seen in some— 
indeed, almost endless changes are found amongst them. 
These scales are not confined to butterflies and moths, nor 
indeed to the wings of insects. The different gnats supply 
some most beautiful specimens, not only from the wings, 
but also from the proboscis, &c.; whilst- from still more 
minute insects, as the podura, scales are taken which are 
esteemed as a most delicate test. The gorgeous colours ' 
which the diamond beetles show when under the microscope 
are produced by light reflected from minute scales with 
which the insects are covered. 
In mounting these objects for the microscope it is well to 
have the part of the insect from which the scales are usually 
taken as a separate slide, so that the natural arrangement 
of them-may be seen. This is easily accomplished with the 
wings of butterflies, gnats, &c.; as they require no extra- 
ordinary care. In mounting the scales they may be placed 
upon slides, by passing the wings over the surface, or by 
gently scraping the wing upon the slide, when they must be 
covered with the thin glass. Of course, the extreme tenuity 
of these objects does away with the necessity of any cell 
excepting that formed by the gold-size or other cement used 
to attach the cover. The scales of the podura should be 
placed upon the slide in a somewhat different manner. This 
insect is without wings, and is no longer than the common 
flea. It is often found amongst the sawdust in wine-cellars, 
continually leaping about by the aid of its tail, which is 
bent underneath its body. Dr. Carpenter says :—“ Poduree 
may be obtained by sprinkling a little oatmeal on a piece 
of black paper near their haunts; and after leaving it there 
for a few hours, removing it carefully to a large glazed basin, 
so that, when they leap from the paper (as they will when 
brought to the light), they may fall into the basin, and may 
thus separate themselves from the meal. The best way of 
obtaining their scales, is to confine several of them together 
beneath a wine-glass inverted upon a piece of fine smooth 
