A text-book of entomology, including the anatomy, physiology, embryology and metamorphoses of insects, for use in agricultural and technical schools and colleges as well as by the working entomologist . directions, but only by sections, showing the membra- . nous intersegmental as seen in Fig. 16, which represents the thickened folds, g.— After Gra- bcr. integument divided into segments, and folded inwardbetween each segment, this thin portion of the skin being the inter-segmental fold. Each segment corresponds to a special zone of the subdivided muscular tube(m), the fascia extendinglongitudi
A text-book of entomology, including the anatomy, physiology, embryology and metamorphoses of insects, for use in agricultural and technical schools and colleges as well as by the working entomologist . directions, but only by sections, showing the membra- . nous intersegmental as seen in Fig. 16, which represents the thickened folds, g.— After Gra- bcr. integument divided into segments, and folded inwardbetween each segment, this thin portion of the skin being the inter-segmental fold. Each segment corresponds to a special zone of the subdivided muscular tube(m), the fascia extendinglongitudinally. The figureshows the mode of attach-ment of the fascia of themuscle-tube to the seg-ment. The anterior edgeis inserted on the stiff, un-yielding, inner surface ofeach segment: the hinderedge of the muscle is at-tached to the thin, flex-ible, intersegmental fold,which thus acts as a ten-don on which the musclecan exert its force. (Gra-ber.) Fig. 17 makes this still clearer. The muscles (m) extend betweentwo segments immediately succeeding each other. Supposing theanterior oue (^1) to be stationary, what do we then see when themuscle contracts ? Does it also become shorter ? The interseg-. Fio. 17. — Diagram of the internment and arrangementof the segments! muscles: A, relaxed; m, muscle; g,membranous articulation ; r, chitinous ring. B, the samecontracted on both sides. C, on one side. — After Graber. 32 TEXT-BOOK OF ENTOMOLOGY segmental again mental fold is drawn forwards, and hence the entire hinder segmentmoves forward and is shoved into the front one, and so on with theothers, as at B. Afterwards, if the strain of the muscle is relieved by the diminishing action ofthe tensely stretched, inter-membrane, itreturns to a state ofrest. (Graber.) While we look upon thedermal tube of worms as asingle but flexible lever, thebody of the arthropods, asGraber states, is a linearsystem of stiff levers. Wehave here a series of stiff,solid rings, or hooks, unitedby the interse
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectinsects
