If it be true that epidemic diseases, such, for example, as influenza and cholera, traverse the globe in determinate courses or zones, and often spread from country to country, and through the vast populations of their great cities, in single weeks, and even days, it must be futile to array such a machinery as that of quarantine, that is to say, a vessel placed at the entrance of one or two seaport towns, a line of soldiers guarding a few miles of the frontier, of a particular country against morbific agents, which pursue their course like the blight that destroys the vegetation of a country in a night, and which extend their influence over the greater part of the habitable globe.

If it be true that the epidemic influence precedes the actual outbreak of epidemic disease—that that epidemic influence is present in a country, creating a predisposition or susceptibility to disease before the epidemic appears in its true and recognized form,—quarantine must be futile, because, before it takes its precautions or erects its barriers, such as they are, the epidemic is already in the country busy in action, vitiating the blood of the most susceptible of the population, and preparing the way for its general attack.

If it be true, as ancient and modern authorities are agreed, that, without the essential preliminary of an epidemic atmosphere on the spot, foreign contagion is inert, and that, unless both concur, no pestilence ensues, quarantine under any circumstances must be useless; for in the absence of an epidemic atmosphere it must be useless, because then no disease will spread beyond the individual affected; and with the presence of an epidemic atmosphere it must be useless, because then the disease will spread wherever the infected atmosphere goes and finds favouring conditions.

If the preceding principle be true, it must be futile to place vessels coming from infected countries in quarantine, unless those vessels are capable of bringing with them an epidemic atmosphere, and unless quarantine can control such an atmosphere when imported; and the uselessness of this procedure will be placed in a still stronger light when recent experience as to the comparative insusceptibility of Europeans, though resident on the spot, to plague itself is considered.[[28]]

[28]. Dr W. H. Burrell, Deputy Inspector-general of Hospitals, who was three years Principal Medical Officer at Malta, presented, in 1852, to the General Board of Health, an elaborate examination on the plague which had formerly raged in that island. The following are the conclusions to which he had arrived:—

“1. There is no evidence to prove, or even to render it probable, that the plague was introduced either into Malta in 1813 or into Gozo in 1814 by importation.

“2. There is every reason to believe that the plague existed in Malta at the time of the arrival of the ship supposed to have introduced the disease; and that in Gozo the first case (a stranger) contracted the disease from local causes, which enhanced by quarantine, produced it in others.

“3. The lower orders, and those occupying the lowest, most crowded, and worst ventilated dwellings, furnished the great majority of cases; which decreased in proportion with improvement in these respects.

“4. As this discriminative preference of the disease to attack certain classes, living in certain localities, never obtains to the same extent with diseases arising from a specific contagion, it is more than probable that the causes engaged in the generation of the plague are not constant, but variable and accidental; its initial cause, the peculiar atmospheric constitution, having no power to develop the disease, unassisted by season and local conditions.

“5. The transmissibility of plague from person to person out of the noxious atmosphere in which it originated—the only certain test of such a power—has not been proved by the four instances, during thirty-eight years, in which it is alleged to have been communicated to persons employed by the Quarantine Department of Malta, carbuncular affections being endemic among the population of this island.