. Elementary text-book of zoology. Zoology. ALIMENTARY CANAL. X the simple narrower portion which follows it. Larger ca?ca, too, after the manner of Itejxific </?<nit/x, may be inserted at the com- mencement of the chylitic ventricle (Orthoptera). The commencement of the hind gut or posterior portion of the alimentary canal is indicated by the opening of filiform ctecal tubes, the M<tljii<ilii<oi vessels. It is divided into two or more rarely three regions, which are distinguished as the small intestine, the lanje. intestine and the rectum. The last region is provided with a str
. Elementary text-book of zoology. Zoology. ALIMENTARY CANAL. X the simple narrower portion which follows it. Larger ca?ca, too, after the manner of Itejxific </?<nit/x, may be inserted at the com- mencement of the chylitic ventricle (Orthoptera). The commencement of the hind gut or posterior portion of the alimentary canal is indicated by the opening of filiform ctecal tubes, the M<tljii<ilii<oi vessels. It is divided into two or more rarely three regions, which are distinguished as the small intestine, the lanje. intestine and the rectum. The last region is provided with a strong layer of muscles, and contains in its walls four, six or more longitudinal ridges, the so-called rectal ijlamls (fig. 439, R}. Sometimes two glands, the so-called anal glands (, Ad], open into the rectum immediately in front of the anus. Their secretion, on account of its irritating qualities and dis- agreeable smell, seems to serve as a pro- tection to the animal. In exceptional cases the larva alone takes up nutriment, the sexually mature apterous form being without a mouth (Ephemera). Finally the stomach of the larva in a few cases ends blindly, and does not communicate with the hind gut (larva? of Htjinenojytera, Pupipara, Ant-lion). The Malpighian vessels already men- tioned, which were formerly erroneously held to be bile organs, undoubtedly func- tion as urinary organs. Their contents, secreted by the large nucleated cells of their walls, are usually of a brownish yellow or white colour, and consist of an aggregation of small granules and con- cretions, which, for the most part, consist of uric acid. Crystals of oxalate of lime and faurin have also been found. The numbers and grouping of these filiform tubes, which are usually very long and wound round about the chy- lific ventricle, varies very much. As a rule there are four or six, or more rarely eight of them opening into the intestine, but in the Hymenopterct and Orthoptera the number is much larger: in the l
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
