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PART II. OF THE MOTION OF THE BRAIN, OF THE CORTICAL SUBSTANCE, AND OF THE HUMAN SOUL.
CHAPTER I. ON THE MOTION OF THE BRAIN; SHOWING THAT ITS ANIMATION IS COINCIDENT WITH THE RESPIRATION OF THE LUNGS.
BEFORE we approach the subject of the moments or intervals of motion observed by the two brains and medullas, which motion we call animation, it will be requisite as a foundation to prove the motion of this viscus by experience. We must not treat of these moments before we have ascertained their existence, nor inquire into quality before we are certain of actuality. For the ancients utterly denied the existence of this motion, as also do certain of the moderns, though it has at last been clearly detected by several great anatomists, such as Ridley, Vieussens, Baglivi, Fantoni, Bellini, Pacchioni, and others; and so clear is the evidence of its existence that whoever doubts it at the present day must doubt the senses of sight and touch. In asserting the existence of this motion, it will be requisite merely to cite the experimental facts recorded by the above illustrious authors; these facts being worth innumerable arguments. Thus Ridley says, that having opened the head of a living dog, "he observed a systalic motion of the dura mater and longitudinal sinus,... analogous to the pulsation of the heart, which was quicker than usual, and exactly corresponding with it in point of time....When one blade of a blunt pair of scissors was cautiously introduced into an aperture made in the membrane, and the latter was slit open, the brain covered with the pia mater protruded through the apertare, its motion 2
still continuing strong to the touch.... On afterwards gently smearing over the dura mater with a few drops of oil of vitriol, no vibration of the membrane, or at least only an insignificant and obscure vibration, was perceived,... though on applying the finger, the pulse of the brain itself was very distinct.... When a probe was driven deeply into the brain, the animal manifested signs of great pain; and when the blade of a knife was passed right through to the opposite side of the skull, horrible spasms were the result.... Lastly, not only the author himself; but others who witnessed the experiment, on thrusting their fingers into the brain, observed that its systole and diastole were carried on in spite of the great resistance thus opposed." (Philosophical Transactions, an. 1703, p. 1481-1483.) And Vieussens says, "We assert that the whole mass of the brain, especially where it is at some distance from the bones of the skull, has a natural motion of intumescence and detumescence, and we prove it by the single fact, that when we open the head of a dog, or of any other animal, traces of the several external convolutions of the brain are found accurately and deeply engraved upon the bones of the skull. Such traces of the exterior figure of the convolutions of the brain could never be imprinted upon the inner surface of the skull, if the brain were entirely destitute of motion; for no one, we presume, will affirm, that the dura mater, as it lies between the skull and the brain, is capable of producing depressions in the skull." (Neurographia Universalis, cap. vi., p. 41; fol., Lyons, 1685.) Baglivi says, "Whosoever wishes to be assured upon this matter, has only to inspect and consider the anterior part of the cranium in a new born child; for the bones being exceedingly soft, by placing the palm of the hand upon them, we shall feel a strong and regular motion of systole and diastole.... But if we wish to perceive still more clearly the systole and diastole of the dura mater in its whole extent, we may do so in wounds of the head which are accompanied by fracture of the skull, and penetrate to the brain, (such as we ourselves have seen in several of the Italian hospitals,) and we shall then find that the entire portion of the dura mater laid bare by the wound, pulsates equably and forcibly, and not only in those channels and furrows that are hollowed out by the little arteries distributed through it: as would be the case if the motion of the dura mater depended upon these little arteries; supposing which, should convulsive motions supervene from the wound, we should be quite at a loss to account for the strong and evident pulsation discernible throughout the dura mater, and distinguished by its own proper intervals and spaces, so that one would really think it was the heart that was pulsating. [This phenomenon the author has witnessed often, and in the presence of others.]" (De Fibra Motrice Specimen, lib. i., cap. iv.) And Fantoni says, "Nothing in the brain is more conspicuous, than its alternate swelling and subsiding, or dilatation and contraction: these motions are visible in cases of wounds of the head, and in the vivisection of brutes.... We find it recorded of Zoroaster, the celebrated King of the Bactrians, ... that on the very day that he was born, his brain palpitated to such a degree as to repel a hand when placed upon it.... It is well known by experiments, that in living animals, when the brain is wounded, and the finger thrust well into it, a very strong diastole and systole of its substance are perceptible To state a general opinion, not a particle of the brain is destitute of this motion: all the glands and all the little tubes enjoy an alternate and regular compression." (Epist. ad Pacchionum, in Pacch. Operibus, p. 171, 172; 4 to. Rome, 1741.) I say nothing of other observations to the same effect, drawn directly from living subjects, and recorded by a great number of celebrated authors, as Pacchioni, Mayow, and particularly Bellini in his Opuscula, [?] where he speaks of the systaltic motion of the brain and the natural contractility of the spinal marrow. For from the citations already given it is sufficiently evident that the brain has an alternate motion of an internal kind; in other words, a motion arising out of its own bosom; also that its entire surface, namely, the surrounding membranes, the blood vessels, and also the septa and sinuses, depend upon the animatory vibration of the subjacent or interjacent brain, and in part also the dura mater, which is the uniting medium between the motions of the brain and heart, as will be seen in the sequel.
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