of entire security is not positively determined, but it has been approximated as follows: in Italy, 400 to 500 feet; in California, 1,000 feet; along the Appalachian chain of the United States, 3,000 feet; in the West Indies, 1,400 to 1,800 feet; in India, 2,000 feet. In any of such regions, however, malaria may drift up ravines to an indefinite height. The agency of winds in transporting malaria for considerable distances cannot be questioned. Lancisi, author of the famous work "De Noxiis Paludum Effluviis," published in Rome in 1717, attributes to such influence the fact of the Roman Campagna having become unhealthy after the removal of the sacred groves exposed it to the currents of wind blowing from the Pontine Marshes. In later years, Barat accounts in the same manner for an epidemic of malarial disease which arose in 1869 on the island of Réunion, believing the poison to have been transported by the wind from Mauritius, where such affections were then alarmingly prevalent. In this instance none of the ordinary local causes could account for the outbreak. In four months, over 4,000 cases occurred in a population of 23,000. Salvagnoli and other observers affirm that malarial diseases increase in intensity, and penetrate farther inland on the island of Sicily and in South Italy during the sirocco laden with African miasm.
With regard to the question, "Can drinking-water act as a vehicle for the introduction of malaria into the animal system?" a priori it seems reasonable to suppose that such may be the case. If malaria, be it a gaseous substance or an accumulation of minute organisms, cannot pollute water, it differs essentially from other materials of similar form with which we are better acquainted. But, in fact, we have positive proof that malarial fevers may be due to drinking impure water. Mr. Bettington, of the Madras Civil Service, states that in that country it is notorious that the water may produce miasmatic fever and affections of the spleen. He mentions villages placed under similar conditions as to marsh-air, in some of which fevers are prevalent and in others not—the difference resulting from the former drinking marsh-water and the latter pure water. In one village there were two sources of supply—a tank fed by surface and marsh water, and a pure spring; only those who used the tank-water contracted fever. The celebrated instance related by Boudin is still more conclusive on this point. In 1834 there returned to Marseilles from Bona in the ship Argo 120 soldiers, of whom 103 were seized with various forms of malarial fever after drinking marsh-water taken on board at Bona. On the other hand, the sailors of the same vessel, who had pure water, and 780 men embarked on two other vessels, remained well. The few soldiers on the Argo not attacked had purchased their drinking-water from the sailors. Against such positive evidence as this the statement of Finke that in Hungary and Holland marsh-water is drunk without injury is of little value.