The falling off in the number of patients at the Paris Institute is related to the establishment of similar Institutes at Lyon, Marseilles, Bordeaux, Lille, and Montpellier. But is it not possible that a patient, after treatment at the Paris Institute, should die at home of rabies, and his death not be notified to the Institute? The answer is, that the Institute is very careful, so far as possible, to keep in touch with its old patients. For instance, in 1903, it recorded the case of a carpenter in a Welsh village, who had died of rabies nearly two years after treatment. And, of course, an Institute patient, wherever he was, would be of interest to his neighbours: and a death from rabies would excite attention, and would hardly fail to be reported. It is not impossible that some sort of intensive modification of Pasteur's treatment may be found, not for the prevention, but for the cure of hydrophobia; and two successful cases of this kind have been reported in the _Annales_ of the Paris Institute. Apart from this faint hope, the _cure_ of hydrophobia is where it was in the days of the "Tonquin medicine" and the "Tanjore pills." VII CHOLERA The study of cholera was the hardest of all the hard labours of bacteriology; it took years of work in all parts of the world, and the difficulty and disappointments over it are past all telling. Koch's discovery of the comma-bacillus (1883) raised a thousand questions that were solved only by infinite patience, international unity for science, and incessant research; and the Hamburg epidemic (1892) marks the time when the comma-bacillus was at last recognised as the cause of cholera. A mere list of the men who did the work would fill page after page; it was bacteriology _in excelsis_, often dangerous,[26] and always laborious. [26] "In order to prove that this _vibrio_ is the cause of Asiatic cholera, several tests upon themselves have been voluntarily made by investigators in laboratories. These were carried out in Munich and in Paris. The results to the experimenters were sufficiently severe to indicate positively the pathogenic character of the spirillum, and its capacity to produce cholera-like infections. Such experimentation is, of course, to be deprecated; indeed, the occurrence of accidental laboratory infections, one of which ended fatally, furnished the necessary final proof of the specificity of the cholera _vibrio_, and rendered unnecessary any exposure to the risks belonging to voluntary inoculation." (Dr. Flexner, Stedman's _Twentieth Century Practice_, vol. xix., 1900.)