While the system of Boerhaave prevailed in the south of Germany, different views arose in the north. The patient and industrious Hoffman thought he saw in fevers a change in the state of motion, and an inaction, which he styled a spasm (spasmus periphcricus), in the extreme vessels. His colleague and rival, rather than his enemy, Stahl, carried the idea further; and gave some sufficiently distinct views of altered determination as the cause of many disorders. The former, however, deeply immersed in the chemical pathology, though he decidedly referred all diseases to altered motions and the state of the nerves, gave no fixed determinate tern of pathology on this foundation, but intermixed these ideas with the different kinds of chemical acrimony; and the latter involved it so deeply in a logical form, and mixed it so intimately with his peculiar me-taphysicaldoctrines, that they have hitherto escaped notice, and will not probably again engage the pathologist's attention.

As the symptoms of fever are so exclusively nervous, and as the vital power is so particularly affected, it is singular that they should not have been at once referred to the nervous system, and its peculiar animating principle. Dr. Cullen, taking the hint certainly from Hoffman, started, as usual, into a track at once bold, comprehensive, and original. The cold stage he considers as the source of the subsequent phenomena; and this he supposes owing to debility. A state of debility is evident, he thinks, from the previous symptoms of languor and lassitude; and occasioned by some sedative powers, which are the more remote causes of fevers. These diminish the energy of the brain and the whole system, particularly of the extreme vessels in every part, inducing the symptoms of the cold fit, and a spasm on these vessels. This spasm excites the action of the sanguiferous system by the intervention of the vires medicatrices naturae, thus restoring the energy of the brain, and overcoming its cause. The discharge of sweat, and the relaxation of all the excretory vessels, are the consequence.

One great defect in this system, which we shall first notice, is, that the return of the paroxysms is not accounted for. Debility confessedly precedes; but, according to this doctrine, the debility is conquered. The return can only be explained then by the cause continuing to act. When this is a material one, as marsh miasmata or contagion, the reason may be admitted; though it militates against a succeeding opinion of Dr. Cullen, that, when once the disease is produced, the influence of the remote cause ceases. When, however, the cause is not material, when the fever is excited by emotions or passions, the explanation will not avail; but this subject we shall resume.

In this system the production of spasm by debility is an isolated fact, without a support; and the introduction of the vires medicatrices naturae is the interposition of a divinity in an epic, when no probable resource is at hand. Yet each may be perhaps easily reconciled by a little change.

Dr. Darwin's explanation of fever is less distinct. He considers the causes as producing a quiescence of the arteries, and the subsequent heat as an exertion of the sensorial power, in consequence of accumulated irritability. We have admitted this author's principle of accumulated irritability; but have some doubts whether it is applicable to this purpose. From the language and the illustrations we can expect no further increase than we have found of previous diminution; no more can be collected than has been lost: but what proportion does the very few hours shivering bear to the burning heat of seven days, during which the shortest inflammatory fever continues? Added to this, at the end of fever we find every symptom of exhausted irritability, as if not only the accumulation was expended, but the former stock diminished. Again, in every case of accumulated irritability, some time is required for the temporary repression. In the human body it is accumulated, but in no extraordinary degree, after some hoars sleep; in some animals after the torpor of a whole winter; on captain Bligh's crew, after weeks of abstinence and confinement. These facts bear no proportion to the shortness of the cold fit, compared with the continuation of the heat; and, though it be admitted in a certain degree, it must be with some modifications and explanations.

We have often hinted that we differed in some respects from Dr. Cullen, and shall now state what we think a more probable view of the subject, connecting, in some measure, both the opinions just stated. Not the slightest doubt can exist but that the first symptoms of fever are those of debility - of a debility of the sensorial power, in other words, of the energy of the brain. This may arise from actual or from partial debility, occasioning an unequal excitement in different parts of the brain, which seems to produce the same effects. Under the article Convulsions, and other places, we have endeavoured to show that either real debility or unequal excitement is the cause of irregular action of the muscles; and this appears in the tremors and rigors, and in the spasm of the capillaries, not only of the surface and glands, but of every other organ. The irritability thus accumulated may occasion the exertion of the sensorial power; but the heat, for the reasons assigned, is not wholly owing to this exertion. In fact, the greater activity of this power, or of the vires medicatrices, implies increased energy; but through the whole course of fever we see only debility, and its consequence, irregular action. Even the boasted sensorial power is weakened, or irregularly exerted; and while the sanguiferous system acts with vigour, the voluntary muscles and the brain show every mark of diminished energy. There is then no contest between these rivals, the spasm and the vires medicatrices; but the debility continues, though varied in its form.