The atmosphere of contagion it appears is limited, and strict attention to keep up a line of separation generally proves effectual in arresting or checking its progress. Contact appears necessary to extend the malady, and a direct absorption through the skin forms the ordinary means of transmission. When the cutaneous pores are closed by oil, or any other substance of the kind, an exemption from the fatal scourge has been frequently observed. Mr. Baldwin states, that among upwards of a million of inhabitants carried off by the plague in Upper and Lower Egypt during the space of four years, not a single oil-man, or dealer in oil, had suffered. Mr. Jackson made the same observation in the plague of Tunis. Dr. Assalini, an intelligent medical officer of the French army in Egypt, does not attribute this exemption to the stoppage of the pores, but as the result of profuse perspiration which the inunction of oil produces. The _zeit jagghy_ or olive oil, is considered a specific by most of the Asiatics; and my late friend Mr. Tully observed that all the attendants upon patients suffering from the plague, who carefully smeared their persons and their clothes with this substance, were exempt from the infection. The same observation was corroborated by Sir Brooke Faulkener, during the plague of Malta. Various have been the remedial means proposed in this terrific malady, and preservatives against it have been recorded in the following distich: Haec tria labificum tollunt adverbia pestem; Mox, longe, tarde,--cede, recede, redi. The celebrated plague-water was composed of master-wort, angelica, peony, and butter-bur, viper-grass, Virginia snake-root, rue, rosemary, balm, carduus, water-germander, marygold, dragon-blood, goats'-rue, and mint, infused in spirits of wine. It appears manifest from all the evidence adduced by the contending theorists, that we may come to the following corollaries: 1. Plague may generally be considered as arising from contagion. 2. The spread and decline of the disease is influenced by local peculiarities and revolutions in atmospheric constitution. 3. It appears probable, that under peculiar local circumstances, it may have arisen spontaneously, without having been introduced by contagion; but this invasion must be considered of very rare occurrence. 4. Although transmitted by contagion, a certain distance preserves the healthy from the contamination of the diseased. 5. The enforcement of a limit of separation must be considered indispensable in all our sanitary regulations, in the framing of which great attention must be paid to discriminate between contagion and infection--two sources of distemper essentially different from each other.