. Public health and preventive medicine. e ducts of the sheep and ox, and issometimes found in man. It is a leaf-shaped herm-aphrodite worm from ^ to f in. in length, and about^ to -3- in. in breadth (Fig. 16). It produces eggs(Fig. 17) which are voided in the faeces, and therebyreach water or damp soil. After a varying time aciliated embryo escapes from the ovum and makes itsway into a small mollusc, in the pulmonary cavityof which it undergoes further development. At thisstage it may pass with the mollusc into sheep orBattle, or it may leave its intermediate host, and, whilefree in water, or
. Public health and preventive medicine. e ducts of the sheep and ox, and issometimes found in man. It is a leaf-shaped herm-aphrodite worm from ^ to f in. in length, and about^ to -3- in. in breadth (Fig. 16). It produces eggs(Fig. 17) which are voided in the faeces, and therebyreach water or damp soil. After a varying time aciliated embryo escapes from the ovum and makes itsway into a small mollusc, in the pulmonary cavityof which it undergoes further development. At thisstage it may pass with the mollusc into sheep orBattle, or it may leave its intermediate host, and, whilefree in water, or encysted on a water plant, gainentrance to the stomach of its host, be it sheep,cattle, or man, hence one of the dangers of eatinguncleaned water-cress. It causes liver enlargementand its usual sequela3, diarrhoea, sometimes vomiting,fever, marasmus, and often death. In sheep thedisease is known as rot. Other liver trematodes occasionally occur in man,such as D. lanceolatum, D. conjunctum, D. sinense, , D. ringeri (see p. 95).. CESTODA. Fig. 16.—Distomum h< pati-chiii, liver fluke, x 3diameters. Taenia echinocOCCUS.—This is a hermaphro-dite worm whose natural host is the dog, but whose intermediate host maybe man, and many other animals, including the sheep, ox, or pig. The para-site lives in the intestine of the dog, and is a short worm of three or four segments, the terminal one containing the ova(Fig. 18, a). When ripe the terminal proglottisis extruded with the faeces, and, its walls decaying,the eggs are set free. These have now to reach their intermediatehost. They are absorbed along with drinking-water, herbage, etc. From the stomach of theintermediate host the embryo, having developed sixbooklets, bores its way into various tissues of thebody, especially the liver, and becomes resulting cyst (Fig. 18, b) is the hydatid, and its fluid is cyst is lined by a germinal layer, on which small elevations appear,which become holl
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectprevent, bookyear1902
