the action of the heart and arteries, and of the respiratory organs, and of inducing coldness of the surface of the body, languor, disposition to syncope, and other symptoms of general debility; in short, of producing all the effects of sedative or debilitating, as contradistinguished from those of stimulant, powers.

The only argument which Dr Brown advances in support of his proposition, that no such substances as Sedatives exist, is a reference to several instances in which a sedative effect is produced by the diminution or abstraction of the ordinary exciting powers. (Elements, § 21, d, e, %, n.) That a sedative effect may be produced in this manner has been long known to physicians, and forms the basis of what is familiarly known by the name of the Antiphlogistic Regimen. But this obviously affords no proof of the non-existence of a class of substances possessing actually sedative or positively debilitating powers; an inference which would require to be founded on an examination of the effects of all the different substances that are capable, when applied to, or introduced into, the system, of affecting the propelling power of the heart and

arteries.

VI. "The excitement of living systems varies according to the degree of excitability which has been assigned to each, and according, also, to the number and degrees of the stimuli which have been applied. Health and disease are the same state, depending on the same cause, that is Excitement, varying only in degree.' (Elements, §23, 65; Outlines, § 10, 13, 53, 55.)

That the effect of a stimulus must be in a ratio com

pounded of its force and of the more or less excitable state of the part to which it is applied, is a proposition which is not likely to be contested. It was stated generally by Dr Cullen in the following terms:

"The effect of every machine will be as the power applied and the nature of the machine, taken together."-And again, more particularly: "Every action, every motion, that occurs in the human body, may have a comprehended cause, and the exact state of it is almost always as the stimulus applied, and the mobility of the system, taken together. Increased motion, therefore, may be considered as arising either from the power of stimuli that are unusual, or from the usual stimuli being increased; or, the stimulus being given, it may arise from increased tone and vigour, or from increased mobility."

In affirming that health and disease are the same state, depending on the same cause, that is, excitement,-varying only in degree, it is obvious that Dr Brown merely expressed that they are both living states; that where there is no life, there can be no disease, any more than there can be health,-a proposition of undeniable truth, but which certainly does not add much to the stock of our medical knowledge.

VII. "Predisposition to disease is a middle state of Excitement between perfect health and disease, produced by the same exciting powers that give rise to these two states, and always precedes universal, but never local, diseases." (Elements, § 6; Outlines, § 65, 52.)

In regarding Predisposition as the middle state of Excitement between perfect health and disease, and in assigning to that state a certain range on each side of

perfect health, Dr Brown seems merely to have adopted the common opinion of physicians, first very accurately expressed by Galen, and of which Dr Cullen was accustomed to give the following account in his lectures on Pathology :—“We can imagine a standard of health; but that perfect standard exists nowhere in any one person. Physicians have been long sensible of this, and therefore they have invented a term, Latitude of health. They suppose that health may deviate, on either side, from the standard without passing to the opposite state, that of disease. If I were to attempt to establish a standard of health, it would consist in a certain conformation of the body, in a certain vigour of actions affixed to a certain time of life, &c.; and young persons not arrived at that period, or old persons who have gone from it, though they cannot rightly perform all their actions, are still considered as not under disease."

That predisposition may be produced by the same causes that give rise to the states of health and disease, is another opinion which certainly did not originate with Dr Brown, but one which has been maintained by pathologists in every age, in relation to the operation both of the common supporters of life, and of several of the ordinary exciting causes of diseases. Abundant proofs of this are to be found in every medical work which treats of the exciting and predisposing causes of diseases.

It is not easy to conceive by what train of observation or reasoning Dr Brown was led to conclude that Universal diseases are always, and Local diseases never, preceded by Predisposition; for both parts of the affirmation seem to be equally erroneous. That Universal diseases may arise without any peculiar liability to their attacks having been previously engen

dered by the operation of their exciting causes, we have every day proofs, in the production of intermittent and of contagious fevers of all sorts, from temporary and occasional exposure to the operation of their respective causes. And, on the other hand, there can be no question that many individuals are more disposed than others to particular local diseases, such as scrofulous and cancerous tumours and ulcers; or that the same individual may be more disposed to such diseases in one period of his life than in another.

VIII. "Debility may be the consequence either of the excess or of the deficiency of stimuli; the debility which is occasioned by an excess of stimuli is termed Indirect; and that which arises from a deficiency of stimuli, is denominated Direct debility. Death, therefore, may occur either as the consequence of an excess of stimulant power exhausting the excitability irreparably, or in consequence of a diminution of the excitement from a deficiency of stimuli, and the accumulation of Excitability." (Elements, § 35 and 45. Outlines, § 22 and 29; 18 and 26.)

The distinction made by Dr Brown between the debility arising from a deficiency of stimuli, which he denominates Direct, and that which is induced by the excessive use of stimuli, termed by him Indirect Debility, has by many been regarded as the most original part of his Theory of Medicine. That Dr Cullen, however, had recognized and distinctly pointed out the two kinds of causes from which debility may proceed, is evident from the account formerly given (vol. i. p. 371.) of the various circumstances which he

enumerated as capable of producing that state; on the one hand, exercise carried to fatigue, excessive heat, every unusual degree of excitement, and repeated excitements, at length wearing out the system-the causes of the state which Dr Brown denominated indirect debility and on the other hand, indolence, cold, the withdrawing of blood from the vessels of the brain, want of nourishment, copious evacuations, and the absence of habitual stimulants,-the sources, obviously, of Dr Brown's direct debility.

With regard to the debility arising from excess of stimulant powers, denominated Indirect by Dr Brown, Dr Cullen had remarked in his lectures on Pathology, that "such is the constitution of the nervous system, that every unusual degree of excitement is followed with a proportional degree of collapse."-"Any power," he remarks, in his lectures on Therapeutics, "exciting the nervous system in a very considerable degree, is followed by a proportional degree of collapse; and when the excitement is to a certain degree, the collapse may be fatal."-" The excess of stimulant power," he observes in another place (Works, i. 563), may be dangerous, merely by the repeated and violent excitement, and the state of debility that necessarily follows."

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With regard, again, to the debility produced by the abstraction of stimuli-denominated Direct by Dr Brown, Dr Cullen, in his lectures on Pathology, has made the following observation. "Another occasional cause of debility is the withdrawing of blood from the vessels of the brain; and as the vigour of the brain depends upon the state of tension in the whole of the system, debility