Forest entomology . to maintain asupply, and again open for ex-pulsion. The act of breathing,therefore, is somewhat after thenature of a bellows, inasmuch asair is received at a special open-ing and driven throughout thetubes. In addition to the func-tion of breathing, it is obviousthat the inflating of the tubesis associated with the machineryof flight. Fig. 17 is a photo-graphic representation of atrachea from a butterfly. The organs concerned withfeeding and digestion occupy aconsiderable space in the body-cavity of many insects. Fromactual specimens this can onlybe understood by careful di
Forest entomology . to maintain asupply, and again open for ex-pulsion. The act of breathing,therefore, is somewhat after thenature of a bellows, inasmuch asair is received at a special open-ing and driven throughout thetubes. In addition to the func-tion of breathing, it is obviousthat the inflating of the tubesis associated with the machineryof flight. Fig. 17 is a photo-graphic representation of atrachea from a butterfly. The organs concerned withfeeding and digestion occupy aconsiderable space in the body-cavity of many insects. Fromactual specimens this can onlybe understood by careful dis-section and microscopical man-ipulation. The accompanyingfigure, however (fig. 18), takenfrom Miall and Denny, will con-vey a very good idea of theseinternal organs. In the centre of the figurethe food - canal is s we have the salivary glands and reservoir which contain thesaliva, which is not only beneficial in digesting the food withinthe canal, but in some sucking insects is mixed with the crude. Fig. 16.—Diagram of the ch icftru nks of the trachealsyst, hi of an insect; the central nervous system isalso shown. a, antennae ; o, eye; st, anterior stigma; I, longi-tudinal trunk. — After Kolbe. (From Text-Book of Zoology, by Dr J. E. V. Boas.) 14 FOREST ENTOMOLOGY. sap of the plant before the juice is taken up by the c we have the long crop, and below this we have the gizzard,which organism in some species is a favourite object for the micro-scope. Then we have a stellate arrangement of the csecal tubes orblind tubes; and proceeding from this there is the stomach, whichis simply a tube. At k we have the kidney tubes, and then thesmall and large intestine, ending in the rectum and anus. In fig. 19 M t<
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