Page:The Harveian oration - delivered at the Royal College of Physicians, London, June 24, 1870 (IA b22307643).pdf/48

 were not germs of any kind, but broken scraps of vegetable and animal tissues, spiral vessels from dried horse-dung, hairs, wings, and legs of insects, detrita of dress, and the like. The results were, in fact, entirely negative of any peculiar bodies to which the epidemic disease could be referred.

One general result arrived at at that time, however, agrees with the observation of Tyndall in his recent investigation of dust by a beam of light-viz., that the floating particles in the air are chiefly of an organic nature. This we might have been prepared for, from the specific weight of dried organic material, enabling such dust to float, when the heavier inorganic substances would be deposited.

That infectious diseases, as the name im- ports, spread by emanations from the sick, must have been long known, and that such emanations are of a solid nature we may infer from the fact that they may be dried and conveyed from place to place; but in what state, whether as amorphous material or as