Text-book of comparative anatomy . r vesicular appendages enter its anterior portion. The hind-gut is lined with a delicate chitinous intima and has a muscular wallwhich, at the terminal portion ending in the anus, is of considerable thickness. Itslength varies, it is often very long and coiled. The limit between the mid- and hind-guts is often difficult to define, since themid-gut also may have an intima, and its ontogenetic development is not sufficientlyworked out. It is assumed, somewhat arbitrarily, that the hind-gut begins at thepoint where the Malpighian vessels enter. A
Text-book of comparative anatomy . r vesicular appendages enter its anterior portion. The hind-gut is lined with a delicate chitinous intima and has a muscular wallwhich, at the terminal portion ending in the anus, is of considerable thickness. Itslength varies, it is often very long and coiled. The limit between the mid- and hind-guts is often difficult to define, since themid-gut also may have an intima, and its ontogenetic development is not sufficientlyworked out. It is assumed, somewhat arbitrarily, that the hind-gut begins at thepoint where the Malpighian vessels enter. Although these are undoubtedly forma-tions of the hind-gut, they do not necessarily always appear at its anterior hind-gut is often further subdivided. Its last division sometimes carries anunpaired crecum. Paired anal glands (stink glands) may also enter it. The analpapilke, etc. classed as glands have already been mentioned. The intestine of certain(, Psyllirfa*, and Cicadcc is peculiarly constituted. The mid-gut and part. FIG. 31P.—Digestive apparatusof Caratms auratus (after Dufour).7:, Head with mouth parts ; oc, ceso-phagus; in, crop (hifduvies); j/c,masticatory stomach ; cd, chyle stom-ach covered with villi; r7ii,Mfilpi^hianvessels; ed, hind-gut with rectum 462 COMPARATIVE ANATOMY CHAP. of the hind-gut form a loop (Fig. 322). The 2 limbs of the loop grow togetherfor a certain distance, and wind round each other at this part. In the larvre of some Hymenoptera, Neuroptera, Myrmekon, and Dipt/ r«(Pupipara) the mid-gut ends blindly and is not yet connected with the hind-gut, thelatter performing exclusively excretory functions (Fig. 321). The Malpighian Vessels.—These are long, generally filamentous appendages,which begin to form as imaginations of the proctodteum. Their large epithelial
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
