tended with the diathesis phlogistica, we conclude, that, in many cases, this is the cause of their continued form.

63. In many fevers, however, there is no evidence of any diathesis phlogistica being present, nor of any other cause of more considerable spasm; and, in such cases, therefore, we must impute the protraction of paroxysms, and the continued form of the fever, to the weakness of reaction. That this cause takes place, we conclude from hence, that, in many cases of fever, wherein the separate paroxysms are the longest protracted, and the most difficultly observed, we find the most considerable symptoms of a general debility; and therefore we infer, that in such cases, the protracted paroxysms, and continued form, depend upon a weaker reaction; owing either to the causes of debility applied having been of a more powerful kind, or from circumstances of the patient's constitution favouring their operation.

64. Upon these principles, we make a step towards explaining in general, with some probability, the difference of fevers; but must own, that there is much doubt and difficulty in applying the doctrine to particular cases. It applies tolerably well to explain the different states of intermittents, as they are more purely such, or as they approach more and more to the continued form: but seve

ral difficulties still remain with respect to many circumstances of intermittents; and more still with respect to the difference of those continued fevers, which we have distinguished in our Nosology as different from inter.nittents, and as more especially entitled to the appellation of continued, (see Syn. Nos. Meth. part 5, ch. 1, sect. 2), and explained more fully above.

65. From the view given (63 and 64), of the causes of the protraction of paroxysms, and therefore of the form of continued fevers, strictly so called, it seems probable, that the remote causes of these operate by occasioning either a phlogistic diathesis, or a weaker reaction; for we can observe, that the most obvious difference of continued fevers depends upon the prevalence of one or other of these states.

66. Continued fevers have been accounted of great diversity; but physicians have not been successful in marking these differences, or in reducing them to any general heads. The distinctions made by the ancients are not well understood; and, so far as either they or the modern nosologists have distinguished continued fevers by a difference of duration, their distinctions are not well founded, and do not apply in such a manner as to be of any use. We think it agreeable to observation, and to the principles above laid down (63, 64), ts

distinguish continued fevers according as they shew either an inflammatory irritation, or a weaker reaction.

67. This distinction is the same with that of fe-" vers into the INFLAMMATORY and NERVOUS; the distinction at present most generally received in Britain. To the first, as a genus, I have given the name of Synochus; to the second, that of Typhus; and little studious whether these names be authorized by the ancient use of the same terms, I depend upon their being understood by the characters annexed to them in our nosology, which I apprehend to be founded on observation.

68. By these characters I think continued fevers may in practice be distinguished; and if that be the case, the principles above laid down will be confirmed.

69. Beside these differences of continued fever, now mentioned, I am not certain of having observed any other that can be considered as fundamental. But the most common form of continued fevers, in this climate, seems to be a combination of these two genera; and I have therefore given such a genus a place in our nosology, under the title of Synochus. At the same time, I think that the limits between the synochus and typhus will be with difficulty assigned; and I am disposed

to believe, that the synochus arises from the same cause as the typhus, and is therefore only a variety of it.

70. The typhus seems to be a genus comprehending several species. These, however, are not yet well ascertained by observation; and in the meantime we can perceive, that many of the different cases observed do not imply any specific difference, but seem to be merely varieties, arising from a different degree of power in the cause, from different circumstances of the climate or season in which they happen, or from different circumstances in the constitution of the persons affected.

71. Some of the effects arising from these circumstances require to be particularly explained.

One is, an unusual quantity of bile appearing in the course of the disease. This abundance of bile may possibly attend some continued fevers, strictly so called; but, for the reasons above explained, it more commonly attends intermittents, and, we believe, it might have been enumerated (29) among the marks distinguishing the latter kind of fevers from the former. But, though an unusual quantity of bile should appear with continued fevers, it is considered in this case, as in that of intermittents, to be a coincidence only, owing to the state of the season, and producing

no different species or fundamental distinction, but merely a variety of the disease. I think it proper to observe here, that it is probable that the most part of the continued fevers named bilious, have been truly such as belong to the section of intermittents.

72. Another effect of the circumstances occasionally varying the appearance of typhus, is a putrescent state of the fluids. The ancients, and likewise the moderns, who are in general much disposed to follow the former, have distinguished fevers as putrid and non-putrid: but the notions of the ancients on this subject were not sufficiently correct to deserve much notice; and it is only of late that the matter has been more accurately observed, and better explained.

From the dissolved state of the blood, as it presents itself when drawn out of the veins, or as it appears from the red blood's being disposed to be effused and run off by various outlets, and from several other symptoms to be hereafter mentioned, I have now no doubt, how much soever it has been disputed by some ingenious men, that a putrescency of the fluids to a certain degree does really take place in many cases of fever. This putrescency, however, often attends intermittent, as well as continued, fevers; and, of the continued kind, both the synochus and typhus, and all of them in