force and violence unequalled in fever, and yet no fever be in- vomiting, and loathing of food, no sickness takes place, and the 44. Thus also the action of the heart and arteries may be diminished by abstinence, by disease, and by old age, far below that degree which occurs in the ordinary state of fever; and yet the body will be entirely free from fever; and for the obvious reason that no degree of debility or diminution of natural action can constitute the morbid action of fever. 45. Notwithstanding the difficulty, nay, even the impossibility of accounting for the symptoms and appearances of fever on the principle of natural action in the sanguiferous system, yet this seems to have been the universal error of medical philosophers. This principle pervades all the most celebrated European systems and theories-It is taught in their universitiesIt is promulgated in books-It is handed down from one to another, and no one takes the trouble to inquire whether it bears on its front the marks of truth. Although it is evidently insufficient to explain the morbid appearances of fever, yet no one has extended his views to the discovery of another, and a better principle, on which to found the doctrine of the disorder. The theories of Cullen, of Brown, and of Darwin, are all equally founded on the supposition that a mere increase or diminution of natural action in the heart and arteries constitutes the essence of fever. They endeavour to account for a pre ternatural disturbance in the circulation, on the principle of natural motion; and to explain a morbid condition of the body, as consistent with healthy action-The disorder of the arterial system is not distinguished from the natural order of motion-And sickness, according to them, is produced by the same manner of action in the blood-vessels as health. They have, consequently, all failed in their attempts to investigate the proximate cause of fever, or to give a rational explanation of its phenomena. And although theory after theory, and system after system have fallen into ruin as fast as they were reared, still every succeeding writer has continued to build on the same insufficient foundation. This, I have said, appears to have been the universal error of European pathologists, because they have all embraced it. But in this country the science of Medicine has been emancipated from that error by the genius and talents of Dr. Rush. His penetrating mind early discovered the imperfections of the prevailing doctrine, and the fallacy of the principle on which it rested. He was accordingly led to conceive the idea of a preternatural kind of action ex isting in fever, essentially different from the natural action of the arterial system; and from the supposed analogy between the disordered state of the blood-vessels in this complaint, and the irregular action of the muscles of the body in convulsion, he has erroneously placed the proximate cause of fever in a convulsive action of the arteries. Although he is evidently correct in the general principles of preternatural or morbid action, still he has erred, as I conceive, in the application of that principle to the manner of action in the arterial system. But, notwithstanding he may not have arrived at the truth, yet he has opened the way for its discovery, by dissipating the prejudices of error, and pointing out the true path of investigation. 46. This leads me to remark in the next place, that as fever does not consist in the natural action of the arterial system, so neither does it consist in the convulsed action of that system. This doctrine of convulsion in the blood-vessels is attempted to be supported by a pretended analogy between fever and convul sions in the nervous or muscular system in general. But there is no such particular and characteristic analogy existing, as is competent to establish the identity of action in the two dis orders. On the contrary, the analogies which do occur are, for the most part, such as are common to most diseases, and such as are not sufficiently specific to distinguish one disease from another. Thus, for example: Are convulsions preceded by debility? So is fever, and so also are most other diseases. Do convulsions, under certain circumstances, affect the brain? So undoubtedly do certain states of fever-so do certain other dis eases-so do certain medicines and so do many other causes. Are there certain convulsions which do not affect the brain? So neither do certain fevers, and so neither do most other disAre there local convulsions? So also there are numer ous local disorders. Are there certain grades in convulsions? So there are necessarily in all diseases. Are convulsions most apt to occur in infancy? So also are a variety of other complaints. In this way we might go on and enumerate circumstances and symptoms which are common to a vast number of disordered states of the body. But these considerations could have no weight in establishing the sameness of the proximate cause in all those disorders; and they do by no means prove the similarity of febrile and convulsive action. eases. 47. If there be any appearances of convulsive action in the muscles during fever, as the tremors in the cold state of intermittents, and the occasional supervention of general convulsion in other fevers, it is to be remembered that the seats of the two disorders are in different systems of the body, which are subject to different kinds of morbid action from the same exciting causes. Accordingly, while convulsive action in the muscles of locomotion happens, a very different kind of action may at the same time occur in the arteries in fever: For we know that those muscles admit of no other morbid action than convulsive; but the arteries are capable of reversed action, which is more easily induced, and by less powerful causes than convulsive action. It is, therefore, no argument in favour of fever being a convulsion of the arterial system, that convulsion is induced in another system of muscles. 48. I shall readily admit, that in certain states of fever the irregularity of action in the pulse is such as to resemble, in some measure, convulsive motion in other parts of the muscu lar system. But I do not thence concede that it constitutes the proximate cause of the disorder; for although it be granted, that the sanguiferous system, and particularly the heart, is, like all other muscular parts, capable of convulsive action, and that this convulsive action does sometimes take place in the highest grades and last stages of fever, yet it does by no means follow, that therefore convulsive action always exists in fever, and operates as its immediate cause. On the contrary, in the ordinary states of fever, and particularly in the mild grades of it, where the morbid action of the heart and arteries is not irregular, and is scarcely to be distinguished from the healthy action, there is no resemblance, in the movements of the sanguiferous system, to convulsive action. If, therefore, convulsion of the heart and arteries at any time happen, it is rather to be considered as an accidental circumstance, or a consequence of fever, than as its cause; for it cannot be supposed to be its cause unless it occurs always, in all fevers. But in the greatest number of febrile cases the action of the heart and arteries is as uniform and regular as in health. To say, therefore, that in such cases of mild and almost imperceptible fever, there is a convulsion of the blood-vessels, would be like saying, that nausea is a convulsion of the stomach. 49. It now only remains for me to show that the proximate cause of fever is the reversed action of a part of the arterial system. Here I cannot avoid noticing an important observation of Dr. Rush, which is strictly applicable to this part of our subject, and tends to confirm the truth of my doctrine. It is, that the essence of all diseases" consists in irregular action, or in "the absence of the natural order of motion, produced or invited "by predisposing debility." Agreeably to this fundamental principle, which I consider as having been misapplied in the case of morbid action in the arterial system, I shall contend, that in all those organs of the body, whose natural action consists in a simultaneous contraction of their fibres, as in the individual muscles of locomotion, disorder consists in their irregularity of action, and that hence proceed .convulsions. But that in all those organs whose natural action consists in a successive ordet of contractions, as in the vascular system, disorder consists most commonly in the absence, or change of the natural order of motion; and that from thence proceed vomiting in the alimentary canal, and fever in the arterial system. The truth of this position is to be inferred from all those considerations which I have already mentioned, as well as from all the symptoms of fever, which are next to be considered. 50. The most conspicuous phenomena of fever, and those which always occur in the disorder, are, First, A languor, or sense of debility, a sluggishness in motion, and some uneasiness in exerting it, with frequent yawning and stretching. Secondly, A paleness and sallowness of the skin, a shrinking of the fea tures, and a diminution of the bulk of every external part, as if sudden emaciation had taken place; a disappearance of the fulness of the blood-vessels on the surface, and an apparent retrocession of the blood to the internal parts of the body. Thirdly, A sense of oppression at the præcordia, a laborious respiration, and an unusual excitement of the heart and large arteries, manifested most commonly by a preternatural frequency, and sometimes by an oppression of the pulse. 51. The first of these symptoms are universally admitted to denote debility, which always precedes fever, and constitutes its predisposing cause. The second have been variously interpreted. Dr. Boerhaave ascribed them to a lentor or viscidity of the blood, and this he supposed to be the proximate cause of fever. Dr. Hoffman and Dr. Cullen conjectured them to deVOL. 1. 5 |
