. The animal kingdom : arranged after its organization; forming a natural history of animals, and an introduction to comparative anatomy. Zoology. The Leeches {Hirudo, Linn.)— Ifave an oblong body, sometimes depressed, and wrinkled transversely; the mouth encircled by a lip, and the posterior extremity furnished with a flattened disk, both ends being adapted to fix upon bodies by a kind of suction, by means of which these animals move, for. having fixed their anterior extremity, they draw the other up to it and fix that, and then readvance the first, [besides which, they swim with facility]. S
. The animal kingdom : arranged after its organization; forming a natural history of animals, and an introduction to comparative anatomy. Zoology. The Leeches {Hirudo, Linn.)— Ifave an oblong body, sometimes depressed, and wrinkled transversely; the mouth encircled by a lip, and the posterior extremity furnished with a flattened disk, both ends being adapted to fix upon bodies by a kind of suction, by means of which these animals move, for. having fixed their anterior extremity, they draw the other up to it and fix that, and then readvance the first, [besides which, they swim with facility]. Several have a double series of Fig. 207.—HirudoofEcinalis; «, its anterior extremity, shewing the sucker. pores underneath the body, which are the orifices of little internal pouches, considered by some natu- ralists as organs of respiration, although they are generally filled with a mucous fluid. The intestinal canal is straight and swoln at intervals, extending for two thirds the length of the body, where there are true cceca. The blood they swallow continues red, and without alteration, for several weeks. The ganglia of their nervous system are much more separated than those of the Earthworms. They are hermaphrodite, and have a large penis about the anterior third of the body, and a vulva a little behind it. Several accumulate their eggs into cocoons enveloped by a fibrous excretion. [On opening the Leech shortly after it has gorged itself with the blood of its prey, it will be found that none of the blood has passed into the intestines. The operation of digestion is extremely slow, notwithstanding the rapid and excessive manner in which the Leech fills its stomach: a single meal of blood will suffice for many months, nay, more than a year will sometimes elapse before the blood has passed through the intestines in the ordinary manner, during all which period so much of the blood as remains undigested in the stomach continues in a fluid state, and as if just taken in, no
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Keywords: ., bookauthorwe, bookcentury1800, bookdecade1860, booksubjectzoology
