Among these distinctions, based upon the course of the F., one demands particular notice, as involving an important law of febrile diseases generally, and of a large class of fevers of warm climates in particular. Periodic increase and diminution, or paroxysms of longer or shorter duration, with intervals of more or less perfect relief from all the symptoms, are characteristic of most diseases of this kind, but especially of those aris ing from malaria, i.e., emanations from the soil, educed under the influence of solar heat. The duration of the paroxysms and of the intervals, the complete intermission, or more partial remission, of symptoms, become in such cases the characteristic facts that mark the type, as it is called, of the F., which is accordingly distinguished as inter mittent, remittent, or continued; and, according to the length of the periods, Tertian, Quartan, Quotidian, etc. (q.v.).
The true pathology, or ultimate essence of the febrile state, is still a subject open to question; but it is in accordance with modern physiology to regard F. as connected with some complex derangement of the functions on which the animal heat is known to depend—viz., the nutrition of the textures, or the vital changes constantly in operation
between the blood, on the one hand, and the ultimate atoms of .solid texture, on the other. Recent observations have shown that, in the paroxysm of ague, the waste of the nitrogenous tissues is in excess; and further, the curious result appears to be arrived at, that for almost every grain of excretion representing this excess of waste in a given time, there is a proportional increase of the temperature of the blood, according to accurate thermometric observations. If such observations are corroborated and extended, it will probably appear that the cause of F. is to be found in an increased destructive decomposition of the atoms of texture through the oxygen absorbed at the lungs and circulated with the blood; perhaps under the influence of a derangement of nervous system; which has been shown by experiment to have a very marked control over the generation of animal heat.
The treatment of F. will be considered under the separate forms already referred to.