drink, the disinfection of their hands, etc., we doubt whether protective inoculations will ever come into general use as a measure of prophylaxis against this disease. Certainly they can not take the place of those sanitary measures which have been proved to be sufficient for the prevention of epidemics namely, exclusion by a proper inspection service at ports of entry ("quarantine"), isolation of the sick, disinfection of excreta, general sanitary police of exposed towns and cities, boiling the water used for drinking purposes, etc.
But it must be remembered that these measures of prophylaxis, which have undoubtedly resulted in the saving of thousands of lives, are based upon exact knowledge obtained as a result of bacteriological researches. Since the discovery of the cholera spirillum by Koch in 1884, a very large number of skilled investigators have devoted themselves to researches relating to it, and especially to questions relating to its resistance to various destructive agencies. These researches show that it is quickly destroyed by a comparatively low temperature (60° C), by desiccation, and by all known germicidal agents. It is especially susceptible to the action of acids, in comparatively dilute solutions. Our measures of sanitary prophylaxis are therefore established upon a sound experimental basis, and the extension of the disease in civilized countries is the result of a failure to apply well-known means of prevention. As a matter of fact, these measures have been successful in excluding the disease from this country during the last two widespread epidemics in Europe, and have enabled sanitarians to greatly restrict the epidemic spread of the disease in those countries into which it has recently been introduced.
The prevalence of typhoid fever has also been greatly restricted by measures based upon an exact knowledge of the biological characters of the typhoid bacillus, and if the recommendations of sanitarians were fully complied with there is reason to believe that it would be practically banished from our cities and towns.
The bacteriological examination of the water supply of towns and cities is now generally recognized as an important matter, as indicating the sanitary purity of the supply. The detection of the dangerous pathogenic species should lead to the disuse of a water for drinking purposes, or to the recommendation that it be boiled before it is used. The presence of certain other bacteria indicates sewage contamination and consequent danger to those drinking the water without proper precautions as to filtration or sterilization. In Berlin, where the water supply is taken from a river known to be contaminated by sewage, it is passed through carefully constructed "filter beds," and expert bacteriologists
