. The physiology of the Invertebrata. es, is ejected from theanus. Brachinus displosor will furnish twelve such discharges,but subsequently explosion with noise is replaced by theemission of a yellowish or brownish fluid, which readilyvaporises. These discharges are meant to arrest the onset oflarger predacious beetles. Brachinus crepitans is sometimesgregarious, and when one individual is disturbed the whole PHYSIOLOGY OF THE INVERTEBRATA. 263 discharge in unison, but after about twenty explosions theyonly emit a white fluid. M. P. Pouchet * says:— Linstinct de la dtfense est telle-ment inher
. The physiology of the Invertebrata. es, is ejected from theanus. Brachinus displosor will furnish twelve such discharges,but subsequently explosion with noise is replaced by theemission of a yellowish or brownish fluid, which readilyvaporises. These discharges are meant to arrest the onset oflarger predacious beetles. Brachinus crepitans is sometimesgregarious, and when one individual is disturbed the whole PHYSIOLOGY OF THE INVERTEBRATA. 263 discharge in unison, but after about twenty explosions theyonly emit a white fluid. M. P. Pouchet * says:— Linstinct de la dtfense est telle-ment inherent h, la tribu des Bombardiers, quau seul coup decanon dalarme de Iun deux, tous les autres crdpitent enmSme temps : cest un feu roulant sur toute la ligne. There is something in these insects discharging the fluidin unison which seems to point out that they are guided notmerely by instinct, but by that which is the equivalent of mind. The, chief enemy of B. crepitans, which inhabits GreatBritain, is Calosoma inquisitor (Fig. 48).. Fig. 48.—Bombardier Beetle and its Enemy.(^J/ier F. A. PouCHET.) The secretory glands of the Bugs are situated exterior tothe insertion of the posterior legs, and emit foetid effluvia onseizure. The ground bettles of the genus Carabus, when disturbed,eject a fluid which is caustic if applied to the skin. In conclusion, it may be remarked that a very largenumber of insects eject liquids or vapours as a means of * L Univers, p. 137. 264 PHYSIOLOGY OF THE INVERTEBRATA. protecting themselves, more or less, from the attacks ofvarious enemies.* (6) There are two pairs of salivary glands of the larvalLepidoptera (see Pig. 7). The posterior or second pair secretethe viscous substance, which hardens on exposure to theatmosphere and forms silk. This silk is the material inwhich the larvee or caterpillars invest themselves. The vis-cous substance from these glands is made into threads andspun into cocoons by means of a slender tubular organ calleda spinner
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectinverte, bookyear1892
