The entomologist's text book : an introduction to the natural history, structure, physiology and classification of insects, including the Crustacea and Arachnida . ing 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 CVC
The entomologist's text book : an introduction to the natural history, structure, physiology and classification of insects, including the Crustacea and Arachnida . ing 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 terminal chamber is filled,the blood which it contains causes the lateral valves to close,and the blood to be propelled into the next chamber, which,at the same time, also receives a flow of blood from its ownlateral openings. In this manner the blood is forcedtowards the prothoracic chamber, where it terminates, ac-cording to Strauss-Diirckheim, in a single artery, without E E. current of the fluid being^ indicated by arrows (frMr. Bowerbank)—149, Lateral view of the dorsalvessel of Melolontha. 314 PTILOTA : INTERNAL ANATOMY. branches, which carries the blood into the head, where it ispoured out, and thence flows back into the cavity of the body(in distinct arteries, according to Mr. Bowerbank), to beagain taken into the heart, which consists of two membranes,the external one of which is furnished with numerous rami-fications of the air-tubes. The various air-tubes, also, whichare distributed throughout the body, communicate with theblood as it is discharged from the prothoracic chamber, andthus it receives a supply of oxygen. The number of cham-bers in an imago appears to be smaller than in a larva; wehave also seen that the number of segments in the latter aremore numerous than in the former.
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Keywords: ., bookau, bookcentury1800, booksubjectcrustacea, booksubjectinsects
