6. Physicians, the most distinguished characters, have agreed, that the pulmonary consumption may be communicated by contagion. Under the influence of this belief, Morgagni informs us, that Valsalva, who was predisposed to the consumption, constantly avoided being present at the dissection of the lungs of persons who had died of that disease. In some parts of Spain and Portugal, its contagious nature is so generally believed, that cases of it are reported to the magistrates of those countries, and the clothes of persons who die of it are burned by their orders. The doctrine of nearly all diseases spreading by contagion, required but a short and simple act of the mind, and favoured the indolence and timidity which characterized the old school of medicine. I adopted this opinion, with respect to the consumption, in the early part of my life; but I have lately been led to call its truth in question, especially in the unqualified manner in which it has been taught. In most of the cases in which the disease has been said to be propagated by contagion, its limits are always confined to the members of a single family. Upon examination, I have found them to depend upon some one or more of the following causes: 1. Mal-conformation of the breast, in all the branches of the diseased family. It is not necessary that this organic predisposition should be hereditary. 2. Upon the debility which is incurred by nursing, and the grief which follows the loss of relations who die of it. 3. Upon some local cause undermining the constitutions of a whole family. This may be exhalations from a foul cellar, a privy, or a neighbouring mill-pond, but of so feeble a nature as to produce debility only, with an acute fever, and thus to render the consumption a kind of family epidemic. I was consulted, in the month of August, 1793, by a Mr. Gale, of Maryland, in a pulmonary complaint. He informed me, that he had lost several brothers and sisters with the consumption, and that none of his ancestors had died of it. The deceased persons, five in number, had lived in a place that had been subject to the intermitting fever. 4. Upon some peculiar and unwholesome article of diet, which exerts slowly debilitating effects upon all the branches of a family. 5. Upon a fearful and debilitating apprehension entertained by the surviving members of a family, in which one or two have died of consumption, that they shall perish by the same disease. The effects of all the passions, and especially of fear, acted upon by a lively imagination, in inducing determinations to particular parts of the body, and subsequent disease, are so numerous, as to leave no doubt of the operation of this cause, in producing a number of successive deaths in the same family, from pulmonary consumption. In favour of its depending upon one or more of the above causes, I shall add two remarks.