edging that the brain of which these vessels are a considerable part, is also distended and moved. It is asserted that the brain cannot move, because its motion would cause a vacuum. Now, if motion of the brain every second would cause a vacuum; then motion of the brain continued through hours, days, weeks, however long and slight, would, for identically the same reasons, cause a vacuum. Well, this is physically impossible, say the theorists, and yet, neither they nor any body deny that atrophy and hypertrophy of the brain are well-established pathological facts. How can a brain become larger or smaller without motion in situ? Such brains certainly have moved, therefore, morbid anatomy proves, that, argue as you please about motion in a vacuum, the brain, none the less, can and at times does have a motion of expansion and contraction in the cranial cavity. And if it can move, against logic in weeks, why can't it move every second with equal independence? Very surely this does not prove that the cerebral pulsations do occur, but it does prove that motion of the brain can occur in the air-tight cranial cavity; and that these pulsatory movements are not physically impossible, which is the sole reason why it is contended that there are no such movements. The indication of normal anatomy on this point is very decisive. In the cranial cavity is a serous sac, which in every other cavity is recognized as one of bountiful nature's kindly provisions for favoring locomotion. The significance of this fact can be no more ignored, than could be the presence of a muscle in an organ whose functions were being investigated. Physicists may confuse the intellect beyond the ability to reason; but until they have explained the meaning of that serous sac, and the significance as to motion of atrophied and hypertrophied brains, I shall remain convinced that the brain can and does move in the physiological adult's cranial

cavity. That these movements may be much less when the skull is closed, than when opened, is probable.

In addition to Bourguignon's, another experiment, that of Magendie, (1842), has a direct and interesting bearing on this subject. Both experiments have been often repeated and verified, but whilst the results are not disputed, the conclusions drawn from them are at variance. Magendie, filling a tube with colored water, introduced it into the spinal cavity. At every expiration the fluid mounted, and at every inspiration it fell in the tube. Which, says Longet, proves that in expiration the cerebro-spinal fluid is ascending to, and in inspiration descending from the brain. Whilst Richet says, it proves just the reverse, that in expiration it is desceuding from the brain into the spinal cavity and vicê versâ for inspiration. The conclusion of neither is scientifically accurate, for the only correct inference is, that when the fluid mounts in the tube, there is augmented pressure on it; without indicating in what direction the fluid that makes the pressure, is flowing. But when, to this fact, that pressure is made on the spinal membranes in expiration, is added the facts that have been already given, as to the augmented quantity of blood in the brain and the swelling out of the spinal membranes in expiration, there can be but one conclusion as to the direction from whence this pressure proceeds, it must be from the brain downwards to the spinal cavity. [Whilst writing this article, a vivisection of an alligator, two feet in length, clearly demonstrated that the pressure was downwards in expiration, and that in inspiration the flow was upwards towards the brain.] Bourguignon's experiment (1839) has served more than all other facts and reasonings to establish the no-movement-view. Longet, and others, regard it as triumphantly conclusive that the brain is unvarying in its size and immovable.

Therefore, as they grant that the blood within the cranium is augmented in quantity in expiration and contend (falsely) at the same time that the quantity of cerebrospinal fluid is also augmented, they are forced to a very unsatisfactory explanation as to what becomes of this excess; which is, that the brain is alternately condensed and rarified, that it varies in mass, (weight), but not in its volume or size. Bourguignon filled a glass tube, having a closed extremity, with water purged of air, attached this hermetically to a hole in the skull, placing the contents of the tube in contact with the contents of the cranial cavity and making the tube itself a part of the air-tight cranial cavity. To the tube was attached a stop-cock, by turning which air could be admitted, and the cranial cavity could be thus, at will, placed in the same condition as when accidents or operations in removing part of the skull, expose it to the air and to our observation. All attest, that under these circumstances, there are no movements in the contents of the tube, unless the stop-cock be turned and air is admitted. In the latter case, the cardiac and respiratory pulsations of the brain at once indicate their power by corresponding movements of the water in the tube. Now, these facts are indisputable and the inference therefore seems irresistible, that, in the ordinary air-tight condition of the adult skull, there are no cerebral movements. Therefore, reasons are imperatively demanded, why, whilst admitting these facts, the conclusion is disputed. The maxim so often in the mouth of my old teacher, Claude Bernard, has here its place:

"Theories, explanations and conclusions, may be and often are false, but facts well observed cannot be; accept then the facts, and if they be at variance with theories and conclusions, change these to suit the facts, and not the facts to suit theories." I accept the fact, but I cannot

accept the inference, because it is, in my estimation, contradictory to those facts which have been already cited. The whole question belongs to physics, to whose adepts my own incompetence forces me to leave it; but the explanation, given by Richet, shall be presented in his own words, literally translated: "It then would be necessary, in order that the liquids should oscillate in a tube presenting these physical conditions, that a vacuum should be produced in the cranial cavity, which is physically impossible. The very ingenious experiment of Bourguignon demonstrates this positively, but nothing more. To conclude from it, that in the cranial cavity no displacement of fluid is affected, and that the brain remains perfectly immovable in its bony box, would be an unjustifiable inference." Repeating and confirming Bourguignon's experiment, he says that, though all oscillation in the tube was absent; there, nevertheless, seemed to be cerebral movements synchronous with respiration. But though this explanation should need explanation and were far more unsatisfactory, I should still remain convinced that the cerebral movements can and do take place. That in these movements the spinal cavity plays the part of an escape pipe to the cranial cavity and that the cerebrospinal fluid is a compensating balance to the intra-cranial blood and the cerebral movements caused by this blood. Therefore, I believe that there is an antagonistic connection between the capacity of the ventricles and the quantity of blood which, by expiration, is detained in the cranial cavity, and that these ventricles and the cerebrospinal fluid passing and repassing from them to the spinal, rather than to the cranial cavity, have thus a far more important physiological significance than is generally assigned them. A comparison between the amount of blood detained in the cranial cavity, by expiration, and the amount of fluid which the ventricles can contain,

tends rather to sustain than refute this view. True, the estimates of both can be but approximative, yet even these may serve to give at least "a smell at the truth." Say the left ventricle discharges at each contraction four ounces of blood and that one-fifth of this goes to the brain. Then, since when expiration is not exerting its influence the blood flows out as freely as it enters, there could be no notable accummulation of blood in the brain, (not enough to produce the respiratory pulse,) except during the time of expiration one to two heart's beats. This one to two heart's beats would add from less than one to one-half tablespoonful of blood to the quantity in the cranial cavity.

The capacity of the ventricles is certainly equal to this and nature has provided, at the posterior part of the fourth ventricle, a small but adequate hole of communication with the spinal cavity for the passage and repassage of this amount of fluid, and has also provided the necessary quantity of fluid. From the facts and views stated, it follows that one at least of the functions of the ventricular cavities is to furnish space for movements of the brain, providing means for the entrance and exit of a fluid which, by its passage out, relieves the brain of that pressure which the blood at its maximum expiration would otherwise exercise upon it; and by its passage back and into these cavities responds to the suction force produced by that effort to cause a vacuum, which a minimum quantity of blood in inspiration tends to produce.

ART. III.-APHASIA. BY PROF. S. M. BEMISS, M.D., New Orleans, Louisiana.

The discussion as to the propriety of applying the term aphasia to designate a distinctive disease, rather than a mere symptom, is now pretty well settled in the affirm