1

vital manifestations throughout the entire range of creation, that we feel the dilemma of the position of Stahl; for either we must be prepared to show some essential difference in the human vitality from that of the lowest forms of animal life, or else to credit even polypes and animalculi with the possession of a soul-a conclusion from which we shrink. Stahl's theory of animation has been largely accepted, especially in England, where some of the most celebrated writers, such as Darwin (the elder), have pronounced in its favour. Indeed, Darwin's opening sentence in his famous "Zoonomia" seems to have been taken from Stahl:-"The whole of the matter may be supposed to consist of two species or substances; one of which may be termed spirit, and the other matter. The former of these possesses the power to commence or produce motion, and the latter to receive or communicate it." But even if we accept this theory, as Darwin does, as the foundation of the "laws of life," yet it would be difficult to make any use of it in practice. Perfect as a physiological hypothesis, it entirely fails as a pathological one. If all vital healthy action is due to the immediate activity of the intelligent soul, the natural explanation of all morbid action is, the effort of this soul to defend its house against the intrusion of some destructive force. It is thus ingeniously set forth by Dr. Whytt, a celebrated professor of the University of Edinburgh, who died in 1766:-"As the Deity seems to have implanted in our minds a kind of sense respecting morals, whence we approve of some actions, and disapprove of others, almost instantly, and without any previous reasoning about their fitness or unfitness,—a faculty of singular use, if not absolutely necessary, for securing the interests of virtue among such creatures as men !—so methinks the analogy will appear very easy and natural, if we suppose our minds so framed and connected with our

1 Darwin's Zoonomia. 4to. London.

bodies, as that in consequence of a stimulus affecting any organ, or of an uneasy perception in it, they shall immediately excite such motions in this or that organ or part of the body, as may be most proper to remove the irritating cause, and this without any previous natural conviction of such motions being necessary or conducive to this end. Hence, men do not eat, or drink, or propagate their kind, from deliberate views of preserving themselves or their species, but merely in consequence of the uneasy sensations of hunger, thirst, &c." "There seems to be in man one sentient and intelligent principle which is equally the source of life, sense, and motion, as of reason; and which, from the law of its union with the body, exerts more or less of its power and influence, as the different circumstances of the several organs actuated by it may "It operates by the intervention of something in the brain and nerves.'

require."

If the soul pervades all parts of the body, and communicates, by direct radiation to every cell of which it is built, the power of assimilating appropriate nourishment, and of extracting its proper secretion from the blood; if it gives the power of contraction to the muscles, and of secretion to the liver; if, moreover, it so presides over the wellbeing of its living vesture as to repel, with instinctive perception and force, every source of danger; it is manifest that there is hardly a possibility of the body receiving any injury except from mechanical violence. If what is noxious to any tissue or organ, is instantaneously perceived to be so, just as the palate perceives what is bitter or sour; and if every point has the power of preventing the entrance of this mischievous intruder; the great mass of the disorders of the frame could never exist. Surely the soul is supposed to be immortal, and as immortal must be incapable of languor or fatigue; for languor is the beginning

1 Whytt on Vital Motions, p. 288.

of death, and, if prolonged, becomes exhaustion, which, unrestored, goes on to extinction of faculty and structure. This immortal soul, then, if it be the guardian of every part of the body, must be supposed to be a perfect guardian, always equally vigilant and equally powerful. If this be so, how does it happen that, if you withhold food from a body of men for a couple of days, you will find the great majority of them laid up with a fever? The exciting cause of the fever was present, as well when the men were fed as when they were fasting—why did it take no effect upon the well-fed army, and attack only the famished? Can this be explained by the soul-theory? The soul needs neither meat nor drink; it is immaterial, immortal. Then it was not the soul that opened the gates of the citadel over which it is supposed to keep watch: who or what is it that plays traitor on such occasions? The reply to this question is, that the soul does not operate directly upon the animal frame, but, as Whytt expresses it, "through the intervention of something in the brain and nerves." This "something" is what goes by the name of "the animal spirits,” a term preserved in popular language, and still in constant use, as when we say we are in "low spirits," or "out of spirits." Although the term Animal Spirit was by no means new, yet at this period an attempt was made to give it a more rigorous signification; and the writings of the 17th and 18th century abound in definitions of what is to be understood by the expression. "The animal spirits are the quintessence of the blood and other juices; the vehicle of which is lymph and water extremely dessicated and moveable, and extremely attenuated by flowing through vessels which from large become gradually smaller, being rarified by heat with a subtle vapour." "The nervous fluid, or animal spirits, consists of phlegm or water, oil, animal salt, and earth, all highly attenuated and subtilized, and intimately mixed and incor

porated together." We may observe that the terms animal spirits and nervous fluid are used as 'synonomous. "It is evident," says Dr. Barry,2 "from the structure of the nerves, and from their being deprived of their influence when obstructed by a ligature or diseases, that the exercise of their function depends upon the motion of a nervous fluid or animal spirits through them." "This nervous fluid seems to be formed for more extensive uses than sensation and motion."

The celebrated Dr. Mead writes:-"This fluid, so far as we can discover by its effects, is a thin volatile liquor, of great force and elasticity; being, indeed, most probably, a quantity of the "mineral elastic matter," incorporated with fine parts of the blood, separated in the brain, and lodged in the fibres of the nerves. This is the instrument of muscular motion and sensation, and a great agent in secretions, and, indeed, in the whole business of the animal economy. By the universal elastic matter I understand the subtle and active substance diffused throughout the universe, which our great philosopher, Sir Isaac Newton, supposes to be the cause of the refraction and reflection of the rays of light, and of the vibrations by which light communicates heat to bodies, and which, readily pervading all bodies, produces many of their actions upon one another. This is the nature of the animal spirits."3 Between the idea that the animal spirits were a quintessence evaporated by the heat of the body from all its parts, and therefore confining, in a spiritual or ghostly form, all the elements which the body contained; and this notion of the animal spirits being a portion of the ether of the universe, the contrast is great, and warns us not to confound all the so-called vitalists in one category.

1 Dr. Malcolm Fleming on the Nature of the Nervous Fluid, p. 24.

2 A Treatise on Digestion, by Dr.

Barry, p. 157.

3 A Mechanical Account of Poisons, by Dr. Mead.

Let us now consider how this hypothesis of Stahl's stands related to pathology and therapeutics. One important fact, well-nigh forgotten by the chemists, was brought into prominence by Stahl, viz., that man was a spirit, and, as such, subject to many disorders from which the lower animals are free; and that, in dealing with man as a subject of experiment or investigation, we shall be led into certain error if we neglect the spiritual elements of his constitution. But, this fact admitted, still we want to know how the spirit acts in deranging the body. We find this question discussed by Stahl's disciples. Perry' tells us, that the whole tribe of nervous diseases arises from what he calls distemperature of the animal spirits. Let us observe that most writers of his school, although they so far accept Stahl's notion of the soul as the chief source of life, yet, when they come to work the problems of pathology, transform the soul, or the immaterial and undying part of man, into a material spirit. Thus Perry speaks of the animal spirits being material, although subtle, and being subject to depravation and alterations of various kinds, and of the great indication for the cure of diseases in which they are implicated being to strengthen them. To strengthen the animal spirits! Here is a new theory of treatment. differs from the doctrine of humours taught by Hippocrates and Galen; it differs from the doctrine of specifics taught by Sydenham, and from the doctrine of the chemists. It is the beginning of a great change in the practice of the art of medicine; for by the term "to strengthen the animal spirits," is really meant to stimulate them; to excite them to make a greater effort to resist or overcome the evil forces in the system. This doctrine is the unavowed parent of subsequent systems. If Stahl is right, that the spiritual principle presiding over every specification of the frame is the source of all vital motions, and if the

A Treatise on Disease, by Dr. C. Perry, Vol. I., p. 50.

It