“Finally, it is an observation universally made, and which may be regarded as established, ‘that the origin of epidemic diseases may often be referred to the putrefaction of great masses of animal and vegetable matters; that miasmic diseases are found epidemic, where decomposition of organic substances constantly goes on, in marshy and damp districts. These diseases also become epidemic, under the same circumstances, after inundations, and also in places where a large number of persons are crowded together with imperfect ventilation, as in ships, in prisons, and in besieged fortresses.’[40] But in no case may we so securely reckon on the occurrence of epidemic diseases, as when a marshy surface has been dried up by continued heat, or when extensive inundations are followed by intense heat.” [40] Henle, “Untersuchungen,” p. 52; also p. 57. If we admit these facts we shall be less surprised at the ravages committed by fever, when, after great battles, the wounded are placed in the hospitals of large cities, as in Brussels after Waterloo, in Bilboa, Vienna, &c. Hospital gangrene, the scourge and terror of the wounded, soon shows itself, and cannot be arrested by any known surgical means. Much better were it for the wounded that they had been left on the field of battle. An erroneous opinion prevails, that it is to the presence of the infusoria that the evil influences are to be traced; they, on the contrary, whilst alive, act a beneficial part. The excreta of man whilst putrifying never exhibit the presence of microscopic animalculæ, whilst we find abundance of them in the same matters when in a state of decay. “A wise arrangement of nature has assigned to the infusoria the dead bodies of higher orders of beings for their nourishment, and has in these animalculæ created a means of limiting to the shortest possible period the deleterious influence which the products of dissolution and decay exercise upon the life of the higher classes of animals. The recent discoveries which have been made respecting these creatures are so extraordinary and so admirable, that they deserve to be made universally known.”