Of such are tetanus and diphtheria, now known to be due to the establishment from without of a local microbic infection, from which focus a toxin is diffused to the nervous matter.
The terrible nervous sequels of some forms of inflammation of the membranes of the brain, again, are due primarily to microbic invasion rather of the membranes than of their nervous contents; and many other diseases may be added to this list.
Of late years enormous impulse has been given to our knowledge of the causation of disease by microbes, through the works of Gaspard, who injected putrid matter into the veins of a living animal; by Villemin, who discovered that tuberculosis is infective; by Davaine; and especially by Pasteur, Koch and others too numerous to mention, who have worked, and are still working, at the microbic causation of disease with marvellous success.
Moreover, the products of microbic secretion tend to produce fever.
Even what are known as common colds are probably due chiefly to microbic infection aided by a chill, just as in the case of pneumonia.