From the first time I had an opportunity of seeing the yellow fever, I perceived that there existed but a very distant, if any, analogy between it and the fevers I had been in the habit of treating in the West Indies. And this opinion I have ever since entertained, in opposition to the statement of many respectable authorities; but in conjunction with some highly respectable physicians and friends, who, like myself, had had an opportunity of treating both diseases. The points of difference between these fevers will be noticed in a subsequent part of these observations. But although entertaining this sentiment, I very early came to the conclusion, that the yellow fever was the effect of a gastro-duodenic inflammation, somewhat modified by some unknown cause,--requiring the usual remedies for such a complaint, proportioned only to the strength of the patient, and the force of reaction in the system; and all my subsequent experience has only served to confirm me in this belief. Differing from many physicians respecting its bilious character, I have been led to believe, that the liver is very seldom implicated in the disease;--the secretion of bile, in the majority of cases, being very little, if at all altered. This may very readily be discovered by an attentive examination of the symptoms of the disease, as well as by the appearances noticed on dissection; the lining membrane of the stomach and duodenum presenting in almost every case, marks of inflammation, and giving passage to a large quantity of black matter, which I have always been led to regard as altered blood, mixed with mucus. The liver, on the contrary, so rarely showed marks of disease, that when it did, it was natural to regard its alteration as secondary.