The signs, symptoms, and consequences of inflammation—and amongst others, heat—are modified by the distance of the affected part from the centre of circulation. All actions, healthy as well as morbid, proceed with more vigour in the superior extremities—in the head, the neck, and the trunk, than in the more remote parts of the body; for to the former the blood is transmitted more speedily, if not in greater quantity, and is not so liable to be impeded in its return. Hence an arm may bear up under a severe injury, which, to an inferior extremity, would prove inevitable destruction. The heat, however, of an inflamed part, is generally supposed to be much greater than it really is. The sensation of heat is considerable to the patient, as well as to any observer, whilst the absolute increase of temperature is very slight indeed. It has been proved by the most decided experiments of Mr. Hunter, on the mucous canals of animals, first when in health, and again after violent inflammation had been excited, that little or no variation of temperature can be observed. The elevation of temperature is probably constant, though only amounting to a degree, or even less. As the blood is the source of heat, wherever an increased quantity is circulated, there should, to some extent, be increased heat. The effects of an incited action of the vessels on the system at large must now be adverted to; or, in other words, that general disturbance in the system which attends inflammatory incitation, and which occurs in a degree proportioned to the power of the exciting cause, and the kind of texture primarily affected. The functions both of the sanguiferous and nervous systems are deranged, producing a state termed Symptomatic or Sympathetic Inflammatory Fever. From some observations of my friend Mr. Gulliver, it is probable that this state is frequently, if not generally, dependent on changes in the blood consequent on inflammation. A sort of decomposition of part of the fluid and vitiation of the remainder; the fibrin being separated and effused into the injured part for the purposes of reparation, while the blood globules are converted into pus in the capillaries, and mixed with the circulating fluid. Thus the presence of pus in the blood may become the proximate cause of fever; but if an outlet to the matter be established, if it be discharged by the occurrence of suppuration in a cavity or on a surface, the case is benefited and the constitution relieved. This points to an important principle in practice. Nature puts it in operation in small-pox, for example—how favourable it is for the pustules to come out, and to what danger is not the patient exposed if they are repelled.