“The condition under which cholera infantum appears, and the _only_ condition essential to its development, is continued high temperature day and night—a mean thermometer above 75°, with small daily range. This high and slightly varying temperature continued from six to ten days, will invariably, in our climate, bring cholera infantum (together with the bowel trouble symptomatically more or less distinct, but pathologically akin to cholera infantum), and the longer this condition of things continues the more numerous and the more intractable the cases become. This is as true in the country as in the city, though we are led to think, as we read the books, that this is a disease of the city especially. Deaths are registered, to be sure, and the books are made in the cities, but if the conditions above mentioned exist in the country, the disease appears there—of course, not a great many cases, for the susceptible bodies furnished by a single block in the city would outnumber those of two or three square miles in the country—yet I am glad to admit that the _conditions_ for obvious reasons are not so likely to be present in the country; the contrast, in point of green grass, shade, cool water, and moving air, is no less marked than is the percentage of mortality, and it is _no more_ marked. “Few, if any, recoveries take place until the temperature falls; this fall is usually attended by rain; but this does not seem to be essential, the fall of temperature alone being sufficient to bring about a better state of things. When the temperature falls, cases improve and new cases cease to appear. Sewer emanations do not seem to have anything directly to do with the production of disease, except so far as they tend to impair the general health, and thus diminish the power of the system to resist any disease producing influence, and sewer poisons are no less abundant and deadly at other times than they are when cholera infantum cases are most numerous, and this is the time of year above others when the sewers are abundantly ‘flushed.’” Filth he does not consider is any more abundant in the summer, and the disease declines with the increase of the very rains that favor increased decomposition. He does not attach much importance to unripe fruits as a causative element. “For whoever saw a youngster who would not exchange all his earthly possessions for a green apple, and whoever saw a child in good health injured by an unripe apple or by any quantity not altogether unreasonable?” And then the sufferers from cholera infantum are all under two years, and hence have not arrived at the green-fruit eating stage of their existence. Nine tables are constructed, showing the weekly mortality from cholera infantum in Philadelphia, New York, Boston, Baltimore, Cincinnati and Chicago, and also as far as possible the record of thermometric range. An analysis of the table bears out the author’s views as regards the causative influence of continued high temperature.