868 



INSECT. 



knows with what pertinacity the blow-fly discovers 

 meat, even when concealed under napkins, in sates, 

 &c. That butterflies will fly down to flowers from a 

 considerable height, may be accounted for by the 

 action of their eyes, indeed we have seen butterflies 

 fluttering on the outside of windows, within which 

 were coloured bits of paper, which they evidently 

 mistook for flowers. In the two preceding senses 

 we have seen that their existence might be presumed 

 from the existence of luminous properties in certain 

 species, or by the emission of sounds by others. In 

 like manner the discharge of numerous and varied 

 ecents by many insects, induces us to admit the 

 sense of scent in insects, although the organ of this 

 sense is as little ascertained as that of hearing. Thus 

 the disgusting odour of the bug, the cock-roach, or 

 the lady-bird ; the rose-like scent of the cicindela; the 

 inusk-like scent of the musk beetle; the garlic scent of 

 many andrenae ; the goat-like scent of the caterpillar 

 of the goat moth ; or the strong acid smell of many of 

 the ants, sufficiently prove a keen perception of effluvia 

 in insect*. As to the organ of this sense the majority 

 of naturalists, Baster, Lehmann, Cuvier, Dumeril, 

 Audnuin, Strauss-DUrckheim, and to an extent Bur- 

 meister, from analogy with the vertebrated animals, 

 regard the lining of the spiracles as exercising this 

 function ; whilst Christian, Reaumur, Lyonnet, De 

 Blaiuville, and Latreille, consider the antennae in this 

 light. Marcel de Serres and Bonnsdorf, as well as 

 Christian, conceive the palpi to be smelling organs. 

 Comparetti described various cavities and cells in the 

 front of the head, which he regarded as performing 

 the office of a nose ; but his assertions have never 

 been confirmed. Treviranus considered the entire 

 mucous lining of the mouth as the organ of smell; 

 whilst Kirby and Spence give the name of rhinarium, 

 or nostril piece, to the membrane connecting the 

 skull and the clypeus (which they call the nose), and 

 have described a pair of circular pulpy cushions 

 under the clypeus and rhinarium, covered by a mem- 

 brane transversely streaked with beautifully fine stride, 

 as the organs of smell, which they discovered in the 

 burying-beetle (Nccrophagus vetpeUo) and some others. 

 But these discoveries are not confirmed by other and 

 more elaborate insect anatomists, who have discovered 

 no similar organ, nor do Kirby and Spence indicate 

 bow scents can pass through the rhinarium. 



d. Tkc Sense of Taste. II we have noticed the 

 flesh-fly, as affording a proof of the existence of scent 

 of insects, the same insect may be again cited to 

 prove that insects are not deficient in the sense of 

 taste ; indeed, to suppose that animals, having such a 

 beautifully constructed and complicated oral appa- 

 ratus as is exhibited by the mouths of insects, which 

 also exhibit such discrimination and fastidiousness in 

 the choice of their food, should be deficient in this 

 sense, seems not to be very philosophical, although 

 such has been asserted by Rudolphi and some other 

 physiologists. That this sense is seated in some part 

 of the mouth or digestive organs is, however, gene- 

 rally admitted. Some authors, however, have sun- 

 posed it to exist in the palpi, whilst others regard it 

 s seated in the pharynx, or at the commencement of 

 the throat. The tongue, however, is more generally 

 regarded as its real seat, this being a fleshy organ 

 in many insects and provided with a great abundance 

 of nerves, and furnished with saliva from the mouths 

 of the ducts of the glands lying beneath this organ, 

 ft must, however, be admitted, that there are many 



insects in which the analogue of the tongue is not de- 

 veloped, or exists merely as a horny seta. 



e. The Sense of Touch. In the higher animals the 

 outer envelope of the body is, from its peculiar con- 

 struction, generally, and in all parts, adapted to 

 receive impressions by this sense ; but in insects, the 

 hard scaly texture of the external covering neces- 

 sarily prevents such a general system of touch, and 

 we are therefore compelled to search for organs 

 which may in an especial manner be regarded as the 

 organs of this sense. Here, too, however, we find 

 difficulties similar to those which have met us in our 

 researches relative to the other senses : thus the an- 

 tennae, palpi, wings, and tarsi, and particularly the 

 anterior tarsi, have been regarded as the organs of 

 this sense ; and, indeed, the opinion, that the first- 

 named organs constituted the real feelers, has been 

 maintained by some writers with so much zeal, that 

 even violent abuse has been heaped upon persons 

 professing a different view of the subject. It is true, 

 that the antennae have been generally termed feelers, 

 and the proceedings of some of the IchneumonidtB 

 have been adduced as instances in support of these 

 organs being capable of feeling (as detailed in our 

 article ICHNEUMONID/E) ; but here, as Kirby and 

 Speuce observe, either by means of its antenna?, it 

 hears a slight noise made by the latent grub, perhaps 

 by the action of its mandibles, or else that, by its mo- 

 tions, it generates a motion in the atmosphere of its 

 habitation, which, striking upon the antennas of the 

 parasitic ichneumon, are by them communicated to 

 its sensorium. Moreover, the ovipositor of these in- 

 sects is much longer (in Fceniis and Pimpla) than the 

 antennae ; so that, by inserting the latter into the 

 holes in walls, posts, &c., it is impossible that they 

 can reach the latent grub. Strauss-Durckheim, and 

 some others, on the contrary, regard the articulated 

 tarsi as the organs of touch ; Kirby and Spence con- 

 sidering them also as organs of active touch, whilst 

 the same authors, together with Knoch, Lehmann, 

 Cuvier, and Burmeister, regard the palpi as the 

 organs of touch, these parts being, without intermis- 

 sion, applied to every surface, and being terminated 

 by a minute transparent membrane, which is sup- 

 posed to be the precise seat of this sense ; although 

 Strauss-Diirckheim, who carefully examined it, con- 

 sidered it as the organ of a distinct double kind of 

 sense, partaking both of touch and taste. In some 

 bees which we are at present experimenting upon, 

 and which thrive upon moistened white sugar, we 

 notice the maxillary palui applied to the surface of 

 the sugar all the time that the insect continues to 

 feed. 



B. The Digestive System. 



After the food has been taken into the mouth and 

 been submitted to the action of the trophi, it passes 

 into the pharynx or entrance to the stomach. The 

 digestive organs are opened at each end, extending 

 from the mouth to the anus; sometimes they are 

 straight, and at others bent or twisted together ; 

 and, as in the higher animals, they are short in the 

 predaceous species, but elongated in those which 

 feed upon plants : sometimes they are of an equal dia- 

 meter throughout, but at other times variously con- 

 stricted. Where the number of these constrictions 

 is the greatest, the digestive tube consists of, 1st, the 

 pharynx ; 2nd, the oasophagus or gullet ; 3rd, the 

 craw or jabot ; 4th, the gizzard or ventriculus ; 5th, 

 the stomach or duodenum ; and 6th, the intestines, 



