Again, while according to this received arrangement a train of symptoms, every one of which is found in acute inflammation, is made a distinct genus of fever, numerous diseases, each forming an exquisite specimen of fever, are totally excluded from the order, and placed at a considerable distance in the nosology. Because scarlatina is a fever attended with a peculiar eruption on the skin; because rubeola is a fever attended with an eruption on the skin also peculiar; because variola is a fever attended with another peculiar eruption, and urticaria with another, these diseases are not made varieties of fever, but, designated by the term exanthemata, are formed into a separate order: while, on the other hand, fevers attended with petechiæ, with papulæ, with aphthæ, with vesicles, are accounted fevers, and accordingly are termed petechial, miliary, aphthous, erysipelatous, vesicular fevers; whence synochus petechialis, synochus miliaris, synochus aphthosus, &c. Without doubt is right that these varieties of disease should be discriminated and named; but this mode of classifying them has a necessary tendency to divert the mind from dwelling on those essential circumstances which make all of them mere varieties of one great disease; and to fix it upon those comparatively unimportant though obvious circumstances which simply modify the malady without in the least affecting its identity. It has already been stated that the grouping of the symptoms, or, in other words, the formation of the species of fever cannot be scientifically or usefully accomplished until we have arrived at a perfect knowledge of the condition of the organs upon which the trains depend; and that our knowledge of these conditions is so imperfect, especially with regard to many of the species, that this classification cannot possibly be made at present. It is not even known whether the condition of the organs in intermittent be the same as it is in continued fever. The mere periodicity in the recurrence of the febrile paroxysms by which this class of disease is at present characterised, is an exceedingly unsatisfactory principle of distinction, unless we at the same time knew the state of the system upon which that periodicity depends. The alternate transition of intermittent into remittent and continued, and of continued and remittent into intermittent fever, of which the history of epidemics affords so many striking examples, and of which Sydenham, Pringle, and all the older writers have recorded so many interesting accounts, as events which they themselves daily witnessed, seems to shew that there can be nothing amounting to a generic difference between these several diseases. The type, as far as we have the means of judging, appears to be determined entirely by the intensity of the disease. An intermittent increasing in violence and malignity changes into a remittent or a continued fever, and a continued or