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secondly, because, in almost all the cases in which an effort is made by the vis medicatrix naturve, a cold fit and a spasm of the extreme vessels are almost always the beginning of such an effort. See Gaub. Pathol. Medicin. art. 750.
43. It is therefore presumed, that such a cold fit and spasm at the beginning of fever, is a part of the operation of the vis medicatrix ; but, at the same time, it seems to me probable, that during the whole course of the fever, there is an atony subsisting in the extreme vessels, and that the relaxation of the spasm requires the restoring of the tone and action of these,
44. This it may be difficult to explain ; but I think it may be ascertained as a fact, by the cone sideration of the symptoms which take place with respect to the functions of the stomach in fevers, such as the anorexia, nausea, and vomiting, (14).
From many circumstances it is sufficiently cer. tain, that there is a consent between the stomach and surface of the body; and in all cases of the consent of distant parts, it is presumed to be by the connection of the nervous system, and that the consent which appears between the sentient and moving fibres of the one part with those of the other, is such, that a certain condition prevailing in the one part occasions a similar condition in the other,
In the case of the stomach and surface of the body, the consent particularly appears by the con, nection which is observed between the state of the perspiration, and the state of the appetite in healthy persons; and if it may be presumed that the appetite depends upon the state of tone in the muscular fibres of the stomach, it will follow, that the connection of appetite and perspiration depends upon a consent between the muscular fibres of the stomach, and the muscular fibres of the extreme vessels, or of the organ of perspiration on the sur, face of the body,
It is further in proof of the connection between the appetite and perspiration, and at the same time of the circumstances on which it depends, that cold applied to the surface of the body, when it does not stop perspiration, but proves a stimulus to it, is always a powerful means of exciting appetite.
Having thus established the connection or consent mentioned, we argue, that as the symptoms of anorexia, nausea, and vomiting in many cases, manifestly depend upon a state of debility or loss of tone in the muscular fibres of the stomach ; sọ it may be presumed, that these symptoms in the beginning of fever, depend upon an atony communicated to the muscular fibres of the stomach from the muscular fibres of the extreme vessels on the surface of the body.
That the debility of the stomach which produced vomiting in the beginning of fevers actually de.
pends upon an atony of the extreme vessels on the surface of the body, appears particularly from a fact observed by Dr. Sydenham. In the attack of the plague, a vomiting happens, which prevents any medicine from remaining on the stomach: and Dr. Sydenham tells us, that in such cases he could not overcome this vomiting but by external means applied to produce a sweat; that is, to excite the action of the vessels on the surface of the body,
The same connection between the state of the stomach and that of the extreme vessels on the sur. face of the body, appears from this also, that the vomiting, which so frequently happens in the cold stage of fevers, commonly ceases upon the coming on of the hot, and very certainly upon any sweat's coming out, (14). It is indeed probable, that the vomiting in the cold stage of fevers, is one of the means employed by nature for restoring the determination to the surface of the body; and it is a circumstance affording proof, both of this, and of
the general connection between the stomach and - surface of the body, that emetics thrown into the stomach, and operating there, in the time of the cold stage, commonly put an end to it, and bring on the hot stage.
It also affords a proof of the same connection, that cold water taken into the stomach produces an increase of heat on the surface of the body, and is very often a convenient and effectual means of producing sweat.
From the whole we have now said on this subject, I think it is sufficiently probable, that the symptoms of anorexia, nausea, and vomiting, de. pend upon, and are a proof of, an atony subsisting in the extreme vessels on the surface of the body; and that this atony, therefore now ascertained as a matter of fact, may be considered as a principal circumstance in the proximate cause of fever.
45. This atony we suppose to depend upon a diminution of the energy of the brain; and that this diminution takes place in fevers, we conclude, not only from the debility prevailing in so many of the functions of the body, mentioned above, (35), but particularly from symptoms which are peculiar to the brain itself. Delirium is a frequent symptom of fever: and as from the physiology and pathology we learn, that this symptom commonly depends upon some inequality in the excitement of the brain or intellectual organ; we hence conclude, that, in fever, it denotes some diminution in the energy of the brain. Delirium, indeed, seems often to depend upon an increased impetus of the blood in the vessels of the brain, and there. fore attends phrenitis. It frequently appears also in the hot stage of fevers, accompanied with a headach and throbbing of the temples. But as the impetus of the blood in the vessels of the head is often considerably increased by exercise, external heat, passions, and other causes, without occa. sioning any delirium; so, supposing that the same impetus, in the case of fever, produces delirium, the reason must be, that at the same time there is some cause which diminishes the energy of the brain, and prevents a free communication between the parts concerned in the intellectual functions. Upon the same principles, also, I suppose there is another species of delirium, depending more entirely on the diminished energy of the brain, and which may therefore arise when there is no una usual increase of the impetus of the blood in the vessels of the brain. Such seems to be the delirium occurring at the beginning of the cold stage of fevers, or in the hot stage of such fevers as shew strong marks of debility in the whole system.
46. Upon the whole, our doctrine of fever is explicitly this: the remote causes (36), are certain sedative powers applied to the nervous system, which, diminishing the energy of the brain, thereby produce a debility in the whole of the functions (35), and particularly in the action of the extreme vessels, (43, 44). Such, however, is at the same time, the nature of the animal economy (38), that this debility proves an indirect stimulus to the san. guiferous system ; whence, by the intervention of the cold stage, and spasm connected with it (39, 40), the action of the heart and larger arteries is increased (40), and continues so (41), till it has had the effect of restoring the energy of the brain,