Pneumonia is not unfrequently an exciting cause of Phthisis. Like catarrh, its frequent repetition is more dangerous than a single attack. Pneumonia may indeed act merely as a predisposing cause of Consumption, by leaving the lungs in a debilitated and irritable condition, favourable to the production of that disease; but it is an exciting cause, when in consequence of inflammation of the lungs, suppuration follows, and vomica or empyema is the consequence. This shews the close analogy between Phthisis Pulmonalis and ordinary Pneumonia. In the first, the inflammation being seated in the cellular and comparatively insensible portion of the lungs, is slow and gradual, and the consequent suppuration forms in the same manner; while in Pneumonia, the membranous as well as cellular portion of the lungs being involved in the disease, the inflammation is rapid and violent, and must soon terminate in either resolution or suppuration. Hence Phthisis Pulmonalis was appropriately called by Dr. Rush a “_Pneumonicula_.” No word could more accurately describe the nature of the disease. That acute observer has drawn an excellent parallel between the two diseases, and concludes with observing, “In short the pneumony and Consumption are alike in so many particulars, that they appear to resemble shadows of the same substance. They differ only as the protracted shadow of the evening does from that of the noon-day sun.” It is remarked, however, that all cases of Pneumonia terminating in suppuration are not necessarily fatal. If a predisposition to Phthisis do not exist, or the constitution be not too much debilitated, a vomica may burst and be discharged, and the patient recover. A third exciting cause of Phthisis, is the suppression of accustomed evacuations. These evacuations are the menses, the lochiae, the discharges in Leucorrhæa, and from ulcers, fistulæ and issues. Retention of the menses producing Chlorosis, being a consequence of debility, does not excite primary Phthisis Pulmonalis, but the secondary form of the disease. Suppression of the menses, however, not unfrequently excites a Consumption, bearing all the characters and requiring the treatment of primary Phthisis. The plethora, consequent on the cessation of the menses, has often the same effect. Asthma, by the constant irritation to which it subjects the lungs, becomes an exciting cause of Consumption. Several eruptive diseases, as Scarlatina, Small-Pox and measles, often produce the same disease. Morton also enumerates stone in the kidneys and bladder, gout and rheumatism, as causes of Consumption. By the same author, contagion is supposed to communicate this disease. Morgagni, Van Swieten, Home and Heberden all hold this opinion. And Morgagni relates that Valsalva, who was predisposed to Consumption, was so satisfied of its contagious nature, that he constantly avoided being present at the dissection of the lungs of persons who had died of that disorder.