THE CANADIAN ENTOMOLOGIST. 



species ; occasionally the spiracles are of great interest, though but little 

 studied, while the sculpture and mai kings of the elytra are sometimes 

 beautifully brought out by rendering them transparent and examining by 

 transmitted light. It is well worth the time of any entomologist to study 

 closely under higher powers the mouth-parts and other appendages of even 

 the larger beetles, as he gains in this way a familiarity with the normal 

 appearance of these structures in various groups, and the interpretation of 

 generic and specific characters in more obscure types becomes a matter 

 of less difficulty. If one has dissected a large number of insects and 

 studied them carefully, he is the better qualified for understanding the 

 visible portions of those forms that are too rare to be cut up or whose 

 integuments are so thick and clumsy as to be unavailable for balsam 

 mounts. 



For dissection, alcoholic specimens are usually preferable to dry ones, 

 but the latter may be prepared readily by relaxing in the ordinary manner 

 in a softening dish or by soaking for a few minutes in hot water. The 

 principal objection to the use of dried specimens is that such material is 

 more likely to be dusty and to give trouble in getting clean mounts, or 

 else to contain so much air as to make extra work in getting rid of the 

 resultant bubbles. 



The tools needed are few. A pair of fine forceps, a slender-pointed 

 scalpel, and a pair of small scissors with sharp, delicate blades are 

 required, and may be obtained from any dealer in microscopical supplies. 

 These may be supplemented by a couple of dissecting needles, made by 

 cutting oft the heads of two insect pins and forcing the blunt ends into 

 handles of soft wood, about the size of ordinary penholders. The needles 

 are useful in holding specimens while cutting. A block of clean soft 

 wood, against which to cut when separating the insect members, will be 

 found convenient and will preserve the edge of the scalpel. 



The chemicals required are: (i) a small bottle of 15% aqueous 

 solution of caustic potash; (2) a quantity of commercial alcohol, which 

 runs about 90% ; (3) some absolute alcohol ; (4) clearing fluid, which may 

 be oil of cloves, or, if preferred, a mixture made by adding pure spirits of 

 turpentine to an equal quantity of liquefied crystals of carbolic acid ; (5) 

 some hard (dried) Canada balsam dissolved in enough pure benzole to make 

 a freely-flowing fluid. This should be kept in the special balsam bottle 

 sold for the purpose, and may be thinned with more benzole as it becomes 

 thicker with age. The dishes in which the chemical treatments are 



