. An introduction to zoology, with directions for practical work (invertebrates). INTRODUCTION TO ZOOLOGY alimentary canal. Its oval body is about half an inch long, and is pointed at both ends. It lives in the water, gliding over the water-weeds in search of the small worms and insect larvae on which it feeds. The Trematoda are Flatworms which, unlike Li^CT-flukes Tiirbellaria, are parasitic, and are not usually ciliated. The body is provided with suckers with which the Trematod clings to its prey. The Liver- fluke of the sheep {Distomum kepaticum) is one of these. It has an extraordinary lif
. An introduction to zoology, with directions for practical work (invertebrates). INTRODUCTION TO ZOOLOGY alimentary canal. Its oval body is about half an inch long, and is pointed at both ends. It lives in the water, gliding over the water-weeds in search of the small worms and insect larvae on which it feeds. The Trematoda are Flatworms which, unlike Li^CT-flukes Tiirbellaria, are parasitic, and are not usually ciliated. The body is provided with suckers with which the Trematod clings to its prey. The Liver- fluke of the sheep {Distomum kepaticum) is one of these. It has an extraordinary life-history, living part of its life inside the liver of a sheep, and the other part within the body of a water-snail (Limnaea truncatula), or of a land-snail (Helix). It passes out from the snail on to the grass, and is then swallowed by the sheep when it eats the grass. ^ The Tapeworms are also parasitic; they have Tapeworms. * ^°"S' ribbon-like, segmented body with no ali- mentary canal. The segments are very little dependent on each other; each is capable of reproduction, and separates from the rest when ripe, leaving the body of its host, and passing the second stage of its life in another host. Taenia solium, the tapeworm para- sitic in man, passes the second stage of its life in the pig as the " bladder worm," and then again infects man if the pig's flesh is eaten without having been previously cooked sufficiently to kill the bladder worms.^ Nemertinea. The Nemertine worms Ribbon- are long, soft-bodied, unseg- worms. mented forms, probably nearly related to the whirl-worms. Like them, they have no body-cavity, and they have a covering of fine cilia. Fig. 50.âIdneus marinus. \yxxt in some other ways they are more ^NMuralHist^^S^'^' !»ig^V developed ; specially character- . ^ . , , ^ . istic of them is the long muscular pro- a, Anterior end; 6, posterior . nir â , end. boscis which can be protruded from the front end of the body just above the mouth. I
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherlondo, bookyear1913
