GEOGRAPHY, MEDICAL. The liability of particular localities to become the centers of special diseases, or groups of diseases, has been observed from the most ancient periods, as we have excellent evidence in the hippocratic treatise. On airs, waters, and places, one of the undoubtedly genuine works of the great Greek physician, and one of those which best sustains his traditional reputation. Now-a-days, medical geography has become a most elaborate and carefully investigated branch of medical science, the details of which, though of considerable popular interest, are far too complicated and too technical to be discussed with advantage here. The reader may be referred to the articles ENDEMIC DISEASE, CLIMATE, AGUE, DYSENTERY, GOITER, LEPROSY, YELLOW FEVER, PLAGUE, REMITTENT FEVER, for incidental illustrations of the subject. Gen erally speaking, the tropics are subject to diarrhocal diseases, with acute affections of the liver, and severe remittent or pestilential fevers, caused by the exalted temperature acting on the soil, and producing, emanations very destructive of health; the like causes in more temperate climates caustno. ague and diarrhoea, especially during the summer
and autumn in low-lying, ill-drained localities. Temperate climates are also subject in a peculiar degree to pulmonary diseases, and to all manner of contagious fevers, the result of overcrowding and confined air. Certain diseases, again, as goiter, leprosy, and some animal parasites (see ENTOZOA), appear to have no relation to climate, but are found to affect, more or less exclusively, certain well-defined districts of country • as in the case of the Guinea-worm, the Egyptian ophthalmia, the pellagra of Lombardy, the beriberi of Ceylon and the Malabar coast, and the elephantiasis of the Indian peninsula generally. The best works on medical geography are those of MiAltry, in Germany, and Boudet, in France, which are remarkably learned and complete treatises on the whole subject. A more recent one still is that of Dr. August Hirsch of Danzig, a work of immense labour and erudition, not yet completed. On tropical diseases generally, the English works of Annesley, Twining, Morehead, and sir Ranald Martin are of confirmed reputation.