Hence the signal failure of quarantine as a means of prevention, with reference at least to the most prevalent epidemics, in all the nations of Europe in which it has been tried in modern times; and hence the general relaxation, and in some instances the total abandonment, of the system of quarantine, with reference to several diseases against which it was formerly rigidly enforced, and the growing distrust in the supposition that measures of this kind really afford protection against the introduction of any epidemic disease into any country. The influence of great epidemics is not limited to human beings; it extends to all classes of domestic animals. It is stated by Dr Thomas Lesslie Gregson, who was at Alexandria during the prevalence of the great plague of 1836, on duty there as surgeon-in-chief to the Naval, Military, and Civil Hospital, that cattle were attacked with decided symptoms of plague some time before the disease broke out among the human species. “Before the disease broke out,” he says, “a number of the Pacha’s oxen were seized with a malady, of which above one hundred died in a few days. I was sent to investigate and report on this epidemic. On examination I found gastroenterite in the most intense degree; so much so, that I have found extensive gangrene in oxen that have only been observed ill twelve hours. They had also large buboes. This I reported plague, and caused them to be interred deeply.” Quarantine is based on the assumption that epidemic diseases depend upon a specific contagion; but the question of contagion has no necessary connection with that of quarantine. The real question is whether quarantine can prevent the extension of epidemic diseases, whatever may be their nature, whether contagious or not. If it can, it is valuable beyond price; if it cannot, it is a barbarous encumbrance, interrupting commerce, obstructing international intercourse, periling life, and wasting, and worse than wasting, large sums of the public money. But if the power of protecting the country from the introduction and spread of disease, whether contagious or otherwise, claimed by quarantine, be really possessed by it, this must be proved by other considerations than those which establish the contagiousness of disease; it is a mere matter of evidence and experience, and consequently the disputed point of contagion should be placed entirely out of view in this discussion, and the whole question should be argued on the broad ground whether or not quarantine is a public security, or is capable of affording practically any useful result.