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xxix] liability to abscess of the liver, confinement to warm climates or the warm season of temperate climates, local endemicity, the presence of Entamœba tetragena * in the stools and implicated tissues. The intestinal lesion consists primarily of small amœbic abscess formations in the submucosa and the subsequent undermining and necrosis of the superjacent mucosa.

According to Rogers this is by much the most common form of dysentery in India, being at least twice as common as the bacillary. Cases occasionally originate in Great Britain, probably from infection brought from abroad.

As a practical point it may be mentioned that amœbic dysentery may concur with bacillary, or with balantidium, or with verminous dysentery. This circumstance must not be overlooked, either in practice or in pathological studies. The amœba.— The discovery of the presence of amœbæ in the stools of dysenteries, originally pointed out by Lösch, naturally created much interest. Although within the last few years a large literature has grown up around the subject, and although some definite conclusions, both as regards the bionomics of the amoeba and its relation to the disease, have been arrived at, some confusion and uncertainty still remain. Originally regarded by pathologists as a single and definite organism, and called Amœba coli, it is now recognized that there are several distinct species of amoebae to be found in the intestinal canal of man, some of which are pathogenic, others possibly harmless; some true parasites, others ordinary saprophytic amœbæ. Schaudinn maintained that there are two well-defined true parasitic species; these he named respectively Entamœba coli and Entamœba histolytica. The former he regarded as non- pathogenic, the latter as the specific germ of amœbic dysentery. Although more recent proto-