There is probably no case of fever, however slight, in which the mucous membrane of the bronchi remains in a perfectly sound state. A certain affection of this membrane, the nature of which will be stated hereafter, appears to be peculiar, to fever, and there is reason to believe that the acutest thoracic affection which is at the same time truly febrile, differs from the mildest case of fever, in which there may be no visible sign of any thoracic disease whatever, only in the degree in which this organ is affected. Sometimes it happens, however, that this membrane is implicated in a more than ordinary degree; and when it is so, it gives rise to peculiar symptoms, constituting the case thoracic. The severity of these thoracic, is not always in proportion to the severity of the febrile symptoms, in like manner as there may be the most intense febrile symptoms, without any indication of thoracic disease: but whenever the thoracic symptoms are sufficiently intense to become prominent, and especially when they occur early or attend on the commencement of fever, they invariably and very considerably aggravate the general febrile symptoms. In these prominent thoracic affections, then, two things happen; first, the symptoms properly constituting the febrile train are modified, and, secondly, new symptoms are added to this train, namely, those which indicate derangement in the respiratory organs. The new and peculiar symptoms to which a moderately acute and an early thoracic affection gives rise, are the following; namely— Pain in the chest, sometimes severe, sometimes only slight; sense of stricture or dyspnœa; inability to expand the chest by a full inspiration without pain or uneasiness; cough frequently aggravating the pain; sometimes dry, sometimes accompanied with frothy mucous expectoration. Respiration sometimes slow and heavy, at other times, on the contrary, short and quick; never natural: perhaps the physician may detect thoracic disease in the more obscure, and measure its extent in the more obvious cases, by observing the manner in which the patient breathes, better than by any other single means. The altered respiration is very frequently accompanied with that peculiar noise in breathing which is termed “mucous rattle.”