HYDROPHOBIA—IMPORTANT EXPERIMENTS.
M. Pasteur, who has already made so many valuable discoveries in connection with diseases that are propagated by germs, has, in his own name and that of his assistants, MM. Chamberlan and Roux, communicated to the French Academies of Sciences and Medicine the results of his experimental inoculations with the virus of rabies. He finds that the virus may remain in the nervous tissues without manifestation for three weeks, even during the summer months. Virulence is manifested not merely in the nervous tissues, but in the parotid and sub-lingual glands. The granulations observed in the fourth ventricle, when in a state of virulence, are finer than the granulations in the fourth ventricle when in a healthy state, and they can be coloured by means of aniline derivatives. The virus of rabies injected into the veins or beneath the skin produces paralytic rabies, while inoculations into the spinal cord or the brain produce the paroxysmal form. Inoculations with quantities of the virus too small to be effective, have no preservative influence against subsequent inoculations. Whether the virus is propagated by means of the nervous tissues or by absorption through the surfaces of the wound, has not been ascertained. Finally, the experiments have shown that the protective ‘attenuation’ of the virus is possible. The energy or the nature of the virus varies in each species of animals. By passing the virus through different animals, ‘cultures,’ or varying qualities of virus, are obtained, whose precise effects can be predicted. Thus a ‘culture’ has been obtained which certainly kills a rabbit in five or six days, and another which certainly kills a guinea-pig in the same time. Other things being equal, the virulence varies inversely with the duration of the incubation. M. Pasteur and his assistants have good reason to believe that by means of a special culture they have succeeded in making twenty dogs absolutely proof against rabid inoculations. M. Pasteur, with his usual caution, asks for a little longer time before finally pronouncing on the condition of the dogs in question. To devise a means of making the dog proof against rabies is, of course, to devise a means of almost certainly preserving man (including children) from this frightful disorder; for hydrophobia is almost invariably communicated to man and other animals by the bites of rabid dogs.