218 THE MICROSCOPE AND ITS REVELATIONS. 



CHAPTER XIX. 

 INSECTS AND ARACHNIDA. 



616. THERE is no Class in the whole Animal Kingdom which affords 

 to the Microscopist such a wonderful variety of interesting objects, and 

 such facilities for obtaining an almost endless succession of novelties, as 

 that of Insects. For, in the first place, the number of different kinds 

 that may be brought together (at the proper time) with extremely little 

 trouble, far surpasses that which any other group of animals can supply 

 to the most painstaking collector; then again, each specimen will afford, 

 to him who knows how to employ his materials, a considerable number 

 of Microscopic objects of very different kinds; and thirdly, although some 

 of these objects require much care and dexterity in their preparation, a 

 large proportion may be got out, examined, and mounted, with very little 

 skill or trouble. Take, for example, the common House-fly: its eyes 

 may be easily mounted, one as a transparent, the other as an opaque object 

 ( 626); its attennce, although not such beautiful objects as those of 

 many other Diptera, are still well worth examination ( 628); its tongue 

 or 'proboscis' ( 629) is a peculiarly interesting object, though requiring 

 some care in its preparation ; its spiracles, which may be easily cut off 

 from the sides of its body, have a very curious structure ( 635); its ali- 

 mentary canal affords a very good example of the minute distribution of 

 the trachece ( 634); its wing, examined in a living specimen newly come 

 forth from the pupa state, exhibits the circulation of the blood in the 

 'nervules' ( 633), and when dead shows a most beautiful play of iri- 

 descent colors, and a remarkable areolation of surface, when examined 

 by light reflected from its surface at a particular angle ( 638); its foot 

 has a very peculiar conformation, which is doubtless connected with its 

 singular power of walking over smooth surfaces in direct opposition to 

 the force of gravity, and on the action of which additional light has 

 lately been thrown ( 640); while the structure and physiology of its 

 sexual apparatus, with the history of its development and metamorphoses, 

 would of itself suffice to occupy the whole time of an observer who should 

 desire thoroughly to work it out, not only for months but for years. 1 

 Hence, in treating of this department in such a work as the present, the 

 Author labors under the embarras des richesses; for to enter into such a 

 description of the parts of the structure of Insects most interesting to 

 the Microscopist, as should be at all comparable in fulness with the 

 accounts which it has been thought desirable to give of other Classes, 

 would swell out the volume to an inconvenient bulk; and no course 

 seems open, but to limit the treatment of the subject to a notice of the 



1 See Mr. Lowne's valuable Treatise on " The Anatomy and Physiology of the 

 Blow-fly," 1870. 



