In man this species was first found by Winogradoff in Tomsk (nine cases), then by Kholodkowsky in a peasant from the neighbourhood of Petrograd who had travelled a great deal in Siberia, and finally by Askanazy in five persons who were natives of the East Prussian district of Heydekrug. In Tomsk, _Opisthorchis felineus_ is the most frequent parasite of man that comes under observation at _post mortem_ (6·45 per cent.), whereas _Tænia saginata_ has only been found in 3·2 per cent., Echinococcus in 2·4 per cent., _Ascaris lumbricoides_ in 1·6 per cent., and _Oxyuris vermicularis_ in 0·8 per cent. of the autopsies. In the district of Heydekrug, however, the species in question is also frequent, as in a few years five cases came to our knowledge (of which three were diagnosed by the discovery of the eggs in the fæces). [Illustration: FIG. 152.--Egg of _Opisthorchis felineus_, Riv. 830/1.] [Illustration: FIG. 153.--_Opisthorchis felineus_: from the cat. _m._, mouth; _p.b._, pharynx; _i._, gut; _g.p._, genital pore; _ac._, ventral sucker; _ut._, uterus; _v.g._, vitellarium; _ov._, ovary; _s.g._, shell gland; _r.s._, receptaculum seminis; _t._ testes; _ex. p._, excretory pore. (After Stiles and Hassall.)] In none of Winogradoff’s nine cases had the death of the patient been caused direct by the parasites, yet more or less extensive changes in the liver were found in all of them; such as dilatation of the bile-ducts with inflammation and thickening of their walls, and foci of inflammation or atrophy in the liver substance; icterus was present five times and atrophy of the liver an equal number of times; ascites was observed three times, and in two cases, probably of recent date, the organ was enlarged. The number of parasites found fluctuated between a few and several hundreds. In two of Askanazy’s cases, which he examined more closely, carcinoma which had developed at the places most invaded by flukes was found at the _post-mortem_, so that perhaps there may be grounds for the connection which the author seeks to establish between cancer of the liver and the changes induced by the parasites; these changes consist of numerous and even ramified proliferations of the epithelium of the biliary duct into the connective tissue, which is likewise proliferated. The number of worms found in one case amounted to over 100; in a second case, in which the parasites had also invaded the pancreatic duct, their number was even larger. Winogradoff as well as Askanazy found isolated flukes in the intestine also.