Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct - for the use of schools and colleges (1870) (14596085559)

Identifier: outlinesofcompar00agas (find matches)

Title: Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges

Year: 1870 (1870s)

Authors: Agassiz, Louis, 1807-1873 Gould, Augustus A. (Augustus Addison), 1805-1866 Wright, Thomas, 1809-1884

Subjects: Physiology, Comparative Zoology

Publisher: London : Bell & Daldy

Contributing Library: MBLWHOI Library

Digitizing Sponsor: MBLWHOI Library

Text Appearing Before Image:

s,after a time, becomes the chry-salis, which finally developsthe perfect insect. The jaws ofinsects (figs. 195 to 199) areconstructed after the type wehave already described in an-nelida, Crustacea, and arach-nida, that is to say, they areplaced laterally, and moved bypowerful muscles; we recog-nize two pair, an external pair,or mandibulse (fig. 195, m\and an internal pair, or maxil-Ise (j); the mouth is furnishedwith a superior lip, or labrum,and an inferior lip, or labium.The development of the jawsis in strict relation with thenatural food of the insect. Thesuctorial apparatus of the hy-menoptera, that of the commonbee (fig. 1 9G), for example, isvery singular; projecting frombetween the jaws we observe asucker (/), composed of nume-rous rings ; this organ, calledby Treviranus the fleshytongue, is situated at the com-mencement of the esophagus,in a horny sheath, formed bya prolongation of the labise,into which it can be with-drawn at pleasure. The canalof the sucker is very incon-

Text Appearing After Image:

Fig. 179.—Digestive Organs of aBeetle. a, the head which supports thejaws; b, the crop and gizzard ; d,the chylific stomach; c, the biliaryvessels; d, the intestine; e, secretingorgans ; /, the anus. 176 ORGANS OF DIGESTION. siderable, opening into a bag situated before the esophagus,into which it leads ; the function of this bag appears, ac-cording to Burmeister, to be simply the rarefaction of itscontained air, by which fluids in the proboscis and esopha-gus are pumped up into the first stomach. Insects pro-vided with organs of mastication are deprived of this suck-ing apparatus; so that the development of maxillae and suc-torial instruments stand in an inverse ratio to one another.Burmeister is of opinion that, in insects deprived of a pro-boscis, the sucking bag is converted into a crop. Thedigestive organs of coleopterous insects present considerablevariety in their structure; two sections of the order areformed on this difference alone; to the one section belongsthose which ha

Umrisse der vergleichenden Physiologie, die die Struktur und Entwicklung der lebenden und ausgestorbenen Tierrassen berühren, für den Gebrauch von Schulen und Hochschulen 1870 Buchillustrationen Medizin Physiologie Zoologie Insekten Medizin Bilder aus dem Internetarchiv

1870

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