popular adage of facts being stubborn things. It would be well if all alleged facts were real truths; but it is far otherwise. Medical facts, at least, have not sustained this high character. On the contrary, they have, somehow, fallen into particular disrepute, and it has been sarcastically remarked, that nothing can be less deserving of credit than medical theories, except medical facts. By this sarcasm, however, no moral imputation is intended, nor should it be construed otherwise than as implying the difficulties of the subject, and the imperfection of human intellect.
Facts, then, being the foundation of medical science, the first requisite in all attempts to improve it, is to ensure all alleged facts being real truths. Medical facts are principally derived from the observation of phenomena during life, and the examination of structure after death. In both, many sources of fallacy exist, against which the medical enquirer should be on his guard. It will be convenient to consider, in the first place, those which regard the latter subject.
No facts in medicine are relied on with more confidence than those which dissection displays. Yet the results of necroscopic examination are fraught with fallacies, which it requires great familiarity with the aspects of natural and morbid structure, and intimate knowledge of the changes which take place in them, to detect and avoid. Organic lesions, when far advanced, are sufficiently obvious; but the changes induced by acute disease, and the vascular derangements consequent on inflammatory action are oftentimes equivocal, and very liable to be confounded
