228 



THE MICROSCOPE AND ITS REVELATIONS. 



FIG. 422. 



in each whorl; the highest of these whorls is composed of mere knobby 

 spines: and the hair is surmounted by a curious circle of six or seven large 

 filaments, attached by their pointed ends to its shaft, whilst at their free 

 extremities they dilate into knobs. An approach to this structure is seen 

 in the hairs of certain Myriapods (centipedes, gaily- worms, etc.), of 

 which an example is shown in Fig. 422, A; and some minute forms of this 

 class are most beautiful objects under the Binocular Microscope, on ac- 

 count of the remarkable structure and regular arrangement of their hairs. 

 625. In examining the Integument of Insects, and its appendages, 

 parts of the surface maybe viewed either by reflected or transmitted light, 

 according to their degree of transparence and the nature of their cover- 

 ing. The Beetle and Butterfly tribes furnish the greater number of the 

 specimens suitable to be viewed as opaque objects: and nothing is easier 

 than to mount portions of the elytra, of the former 

 (which are usually the most showy parts of their 

 bodies), or of the wings of the latter, in the manner 

 described in 175. The tribe of Curculionidce, in 

 which the surface of the body is beset with scales hav- 

 ing the most varied and lustrous hues, is distinguished 

 among Coleoptera for the brilliancy of the objects 

 it affords; the most remarkable in this respect being 

 the well-known Curculio wiperialis, or * diamond- 

 beetle' of South America, parts of whose elytra, 

 when properly illuminated and looked-at with a low 

 power, show like clusters of jewels flashing against 

 a dark velvet ground. In many of the British Cur- 

 culionidae, which are smaller and less brilliant, the 

 scales lie at the bottom of little depressions of the 

 surface; and if the elytra of the ' diamond beetle ' be 

 carefully examined, it will be found that each of the 

 clusters of scales which are arranged upon it in rows, 

 seems to rise out of a deep pit which sinks-in by its 

 side. The transition from Scales to Hairs is" ex- 

 tremely well seen by comparing the different parts 

 of the surface of the diamond-beetle with each other. 

 The beauty and brilliancy of many objects of this 

 kind are increased by mounting them in cells in 

 Canada balsam, even though they are to be viewed 

 with reflected light; other objects, however, are ren- 

 B; lair of jKS?. dercd less attractive by this treatment; and in order 

 to ascertain whether it is likely to improve or to 

 deteriorate the specimen, it is a good plan first to test some other portion 

 of the body having scales of the same kind, by touching it with turpen- 

 tine, and then to mount the part selected as an object, either in balsam 

 or dry, according as the turpentine increases or diminishes the brilliancy 

 of the scales on the spot to which it was applied. Portions of the wings 

 of Lepidoptera are best mounted as opaque objects, without any other 

 preparation then gumming them flat down to the disk of the wooden 

 slide ( 175); care being taken to avoid disturbing the arrangement of the 

 scales, and to keep the objects, when mounted, as secluded as possible 

 from dust. In selecting such portions, it is well to choose those which 

 have the brightest and the most contrasted colors, exotic butterflies being 

 in this respect usually preferable to British; and before attaching them to 

 slides, care should be taken to ascertain in what position, with 



