The entomologist's text book : an introduction to the natural history, structure, physiology and classification of insects, including the Crustacea and Arachnida . heart, yet this name has been ordinarily given toa series of large reservoirs forming a longitudinal tube, ex-tending throughout the entirelength of the body (commencingat the first thoracic segment) be-neath the dorsal integuments andmuscles, and which is easily dis-tinguished by its alternate con-tractions and dilatations, similarto those of the heart in the higheranimals, which may be constantlyobserved in the silkworm and othern
The entomologist's text book : an introduction to the natural history, structure, physiology and classification of insects, including the Crustacea and Arachnida . heart, yet this name has been ordinarily given toa series of large reservoirs forming a longitudinal tube, ex-tending throughout the entirelength of the body (commencingat the first thoracic segment) be-neath the dorsal integuments andmuscles, and which is easily dis-tinguished by its alternate con-tractions and dilatations, similarto those of the heart in the higheranimals, which may be constantlyobserved in the silkworm and othernaked caterpillars. In this dorsalvessel, as it has been called bysome physiologists, the blood iscontained, and which, unlike thatof the vertebrata, is cold, trans-parent, and often entirely colour-less. It was, however, consider-ed, that as no outlet had beendiscovered, there could be no cir-culation, and yet it was supposedthat the fluid in some way or other made its escape, andwas disseminated amongst the various internal organs, whichit penetrated by imbibition. Strauss-Diirckheim, however,discovered that there exists in the cockchafer a series of ori-. Muscular system of the Caterpillarof the Goat-moth {Cosstii ligni-perda). CIRCULATORY SYSTEM. 313 fices opening into each side of the dorsal vessel, and fur-nished with valves. The dorsal vesselconsists, according toStrauss-Diirckheim, ofeight successive cham-bers in the cockcha-fer. Mr. Bowerbanksays, they are aboutequal in number tothe sections of thebody in the larva ofan Ephemera, sepa-rated by convergingvalves, which allowthe blood to be pro-pelled forward towardsthe head, but preventits retm-ning. Theblood abounds in veryminute oat-shaped par-ticles, and is seen cir- Figs. 148, Larva of Ephemera, showing the central Culatinff iu CVCrV Part of the body, fromwhence, upon eachpulsation and opening of the lateral apertures, it rushesinto the dorsal vessel, and is conveyed into the anteriorpart of the body. When the termina
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