. Public health and preventive medicine. tum is the larval form of an arachnoid whose adult form is known. It occurs encysted in the liver. Geographical Distribution.—Egypt, the Soudan, and the West Coastof Africa. (d) INTESTINAL. INFUSORIA. Trichomonas intestinale is sometimes found in diarrhoeic forms are common and unimportant. VERMES, CESTODA. Taenia mediocanellata.—This hermaphrodite tapeworm is a commonparasite of man, who forms its host,its cyst stage being passed usually inthe ox, which therefore forms its inter-mediate host. There is usually only a single
. Public health and preventive medicine. tum is the larval form of an arachnoid whose adult form is known. It occurs encysted in the liver. Geographical Distribution.—Egypt, the Soudan, and the West Coastof Africa. (d) INTESTINAL. INFUSORIA. Trichomonas intestinale is sometimes found in diarrhoeic forms are common and unimportant. VERMES, CESTODA. Taenia mediocanellata.—This hermaphrodite tapeworm is a commonparasite of man, who forms its host,its cyst stage being passed usually inthe ox, which therefore forms its inter-mediate host. There is usually only a single present in the humanintestine at one time. The worm isvery long, from 12 to 24 ft., and itssmall head, though unadorned bybooklets or a rostellum, possesses fourwell-marked suckers (Fig. 19). Theproglottides vary in shape and sizefrom the head towards the tail, thesmallest being towards the cephalicends, and the broadest in the segments contain the many-branched uterus and the ova, thoseat the distal end being the most. Fig. 19.— Head and immature segments ofTaenia, mediocanellata, ? 12 diameters. mature (Fig. 20, a). Whenripe, they are cast off, and escapefrom the hosts body by theirown movements, or are expelledalong with the faeces. Theymay then discharge their eggseither through the marginal poreby a rupture in the fore part ofthe uterus, or as a result ofgeneral decomposition, or theova may not be set free till thesegments have been ingested bythe intermediate host. Eachoval egg (Fig. 20, b) contains anembryo, and the egg-shell has tobe dissolved by the digestivejuices before the six-hooked em-bryo is liberated. By aid of its hooks the embryo bores its way through thetissues till it reaches muscular substance, where it promptly discards its hooks,6
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectprevent, bookyear1902
