Page:The Harveian oration - delivered at the Royal College of Physicians, London, June 24, 1870 (IA b22307643).pdf/49

 germs, we know no more to-day than was known a thousand years past.

No new fact bearing upon the propaga- tion of contagious diseases has been reached by the recent investigations on dust. We cannot infer that summer catarrlı is due to infusoria, because the nasal mucus formed in the disease, and at no other time (?), was found peopled by vibriones, since de- composing mucus is generally populous with these infusorial creatures.

The phenomena of fermentation and pu- trefaction in dead and decomposing sub- stances afford no explanation of the changes. observed in a living body in a fever process. The purulent matter produced in small-pox is not in any way comparable to the yeast plant, growing in fermenting fluids. The microscope shows no forms in variolous pus, which are not contained in other purulent innocuous exudations. It is to be regretted that a confusion in terins has been made. Instead of dust and disease, it should rather have been dust and putrefaction,