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 : " Poduraa 

 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 Mnooth 



