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Rh metabolism and excretion incident to high temperature and muscular inactivity, that a very large and unusual amount of physiological work is thrown on the liver. With this large amount of work there is a corresponding hyperæmia. This may be considered the first stage of tropical liver hyperæmia from functional activity; up to this point it is a purely physiological condition.

Pushed a step farther, this physiological hyperæmia passes into congestion with blood stasis, and a consequent diminution of functional activity. Hyperæmia of a physiological character will be evidenced by increase of functional activity, and there will be a copious flow of bile, sometimes causing diarrhœa of a bilious character, particularly morning diarrhœa. But when the limits of physiological hyperæmia are passed, and congestion of a pathological character sets in, the consequent arrest of function will be evidenced by pale stools, perhaps diarrhœa of a pale, watery, frothy, fermenting character in the last case the diarrhœa doubtless depending, in part at least, on fermentative processes set up in the contents of an alimentary canal no longer kept relatively aseptic by an adequate supply of healthy bile. Other symptoms of this condition are headache; furred tongue; scanty, high-coloured, loaded urine; a feeling of weight or fullness, or even of pain, in the region of the liver, and probably enlargement of the percussion area and other physical signs of enlargement of that organ. One step farther, and such a condition may pass into actual hepatitis attended with fever, smart pain in the liver, tenderness on percussion, and still more marked increase of the hepatic area.

A functionally very active hyperæmic organ is prone to inflammation, even on slight cause. In the case of the hyperæmic liver a common cause of inflammation is chill, such as may arise from a cold bath, a wetting, or from lying uncovered on a warm night in a current of air. The experienced resident knows this very well, and is at great pains to guard against such an occurrence. He very likely wears what is known as a cholera belt; he sleeps, even on the warmest night,