countenance and cold extremities are all taken as so many conditional integrals of the complex idea conveyed to the mind by the term concussion. All of these symptoms are but results of the molecular vibrations to which the brain has been subjected. So that the term conveys a definite and uniform meaning to all, it will answer the purposes of professional convenience, and is therefore unobjectionable. Concussion, then, as an objective condition, we will consider to imply a sudden agitation of the corpuscles of the brain among themselves, without laceration or structural lesion of the delicate, tenuous tissues which maintain them in that intimate anatomical relation to each other that constitutes the aggregate organism of the normal brain; without rupturing any of its blood vessels, however minute, and with all the catenation of symptoms above enumerated as consequences of this mechanical commotion. This we regard as having been the true condition of our patient. Immediately after striking the ground she was insensible and thought to be lifeless. Consciousness returned after a short time, and with some assistance she walked a part of the way to a house near by. This locomotion, however, was rather an instinctive than a voluntary and intellectual act directed and controlled by the judgment.

The disturbance of innervation, intellection and the circulation was instantaneous and the direct effect of the concussion. The functions of the brain were enfeebled, not entirely suspended. Shortly after receiving the blow evidences of compression were exhibited in an increasing tendency to coma and more complete obliteration of intellect, with deep stertorous breathing. A rational explanation of this condition would seem to be that the capillary blood vessels of the brain were partially paralyzed by the shock, and dilating to the ingress of blood, permitted an intravascular congestion, which produced the symptoms of compression that were so manifestly present. Had these symptoms been caused by extravasation of blood they would have been more persistent and permanent.

In cases where the violence dealt has been a little greater, the injury to the capillaries may permit a very slight exudation of the coloring matter of the blood, giving a reddish tint to the neighboring portions of the cerebral substance. By some this con

dition is denominated a contusion of the brain; but the application of this distinctive term to designate such special lesion has by no means been sustained by the endorsement of the profession, and it involves a seeming inconsistency that will always render it an objectionable term. A contusion implies a bruise or injury inflicted by some blunt substance upon the soft parts, and may be of varying degrees of intensity, from a slight rupture of blood-vessels, producing ecchymosis and discoloration of the part, to that in which the tissues are reduced to shreds and pulp. In the milder cases the injury is of but little note. The functions of the part being but slightly disturbed, soon recover their normal activity, while in the more severe cases they are wholly destroyed. The lesion in the cerebral capillaries is not the result of the direct contact of the solid substance producing it, but of the agitation of the particles among themselves, without affecting the consistency or solidity of the brain in the least. Without further discussion of this subject we may remark that any injury to the brain amounting to a real contusion, without destruction of its organism, would be a very refined and delicately executed work, not often to be met with in the list of casualties to which this organ is exposed. Contusion, therefore, as a probable condition, is equivalent to a disintegration of the organism of the brain, and a total and permanent obliteration of the functions of the contused parts, and for all practical purposes might be eliminated from the nomenclature of brain injuries without the least damage to surgical terminology.

Our case also presents the pathological condition of compression of the brain, not only from vascular turgescence, but from depression of a portion of fractured bone. It is not within the scope of this paper to give the differential diagnosis between concussion and compression, nor the kindred manifestations of compression and contusion, or mechanical destruction of the brain. Every grade of derangement, from the slightest deflection of normal function up to the total obliteration of all the functions of the brain, may mark the progress of compression from expansion of blood. Its progress will be more or less prolonged; while in compression from a depressed portion of fractured bone, the symptoms, on the contrary, will be sudden and instantaneous. In the case reported the functional symptoms of compression resulting from the depressed bone

were strictly negative. And, it may be asked, why were they such? When a portion of the skull is driven in so as to encroach upon the intra-cranial cavity, how can it be that the brain is not injuriously compressed by it? And will not any and every compression of the brain disturb its functions? While we may be unable to render a satisfactory and logical answer to these questions, we can have no difficulty in sustaining the proposition that such facts as above intimated do have a real existence, for they have repeatedly come under our personal observation, and we know they do occur. But to what extent such intrusion upon the capacity of the cranium may be made without deleterious interference with the functions of its viscera we may not be able to say. Nature seems to have foreseen the liability to the occurrence of these accidents, and wisely to have provided a protection against them in the diffusion of the cerebrospinal lymph in the cavity of the cranium and its ready exit through the lymph channels when the space it might occupy should be demanded to compensate the condition of an accident. Physiologists estimate the amount of this fluid at several ounces; and scientific observers are of opinion that nearly an equal amount of reduction of the capacity of the cranium may take place before the functions of the brain will be suspended. Hence a considerable amount of depression or effusion may exist without necessarily resulting in fatal consequences. In this case the depression did not materially interfere with the healthy functions of the brain, and was, therefore, not interfered with; but where grave cerebral symptoms show themselves the safety of the patient requires that the depressed bone be elevated, an operation that usually calls for the employment of the trephine. But in a few cases we have obtained the most perfect and satisfactory results from pneumatic force improvised through the medium of an air-pump and cupping glass. And had we been able to procure them we should have given the treatment a trial in this case, and probably with a fair prospect of success. The remedy is so simple, safe, and, in suitable cases, so efficient, that it should always be resorted to where not contraindicated. In all compound fractures, where pneumatic force is liable to exude brain substance, the treatment would manifestly be improper.

In all cases of injury of the brain not resulting in immediate, or very early death, the conditions to be combated will invariably be

consecutive inflammation, or effusion, or possibly both. The latter is the more grave condition of the two. But the only treatment which can promise the least benefit in this case is also that which is eminently suited to the former. Soon as the perilous depression has passed away, the most energetic efforts should be made to anticipate and control these formidable conditions. All means calculated to allay excitement and prevent an undue flow of blood to the brain should be promptly put in requisition. Indeed, the circulation of the brain should be limited to the minimum of vital safety. The depressed, feeble cerebral activity resulting from the shock should be utilized as a valuable therapeutic condition. Taking advantage of this, excessive reaction may be prevented and the safety of the patient greatly promoted. Perfect quietude, with the head elevated and kept cold by the free application of ice and ice-water, while normal temperature of the extremities was steadily maintained, exclusion of light and noise from the room, thorough evacuation of the bowels by a drastic cholagogue cathartic, the energetic employment of arterial sedatives and of diuretics, with a bland, unirritating diet and regimen, carried our patient over without excessive excitement ever becoming established. This plan of treatment was adopted early, before reaction ran up to the normal standard, and was persevered in steadily so as to effectually control all tendency to inflammation; and the gratifying result most fully and clearly vindicated the correctness of the principle upon which the treatment was conducted. It goes to show that the depressant or sedative treatment, early adopted and judiciously tempered to the force and energies of the circulatory system, may repress excitement and effectually cut off the incoming dangers of a destructive inflammation before the condition is fully developed, thereby making the patient's condition one of much greater safety, while the duties of the physician are rendered more clear and intelligible, and his services, in the preservation of human life, invested with an infinitely greater value.

EXPERT EVIDENCE: WHAT IT IS.

F. J. VAN VORHIS, M. D., B. L., INDIANAPOLIS, IND.

The great advancement in scientific knowledge, the additions that are each day being made to the number of known facts, the constant changing of hypothetical into positive knowledge, the becoming a matter of common information of that which but yesterday, though based upon the most advanced scientific knowledge, was but an intelligent opinion, and the multiform ways in which the facts of science and the opinions of scientific men are related to the affairs of society, make the question as to the relation of the facts of science and the experts in the sciences and professions to courts and legal investigations one of no little importance. It is a question to the importance of which the medical profession of this State has been for several years fully alive.

Our esteemed friend, Dr. Wilson Hobbs, has read two valuable papers before this society upon "The Medical Witness," the first of which appears in the Transactions of 1877, the other in the Transactions of 1878.

After two such exhaustive papers I present this paper with some diffidence, and the more so because I find myself compelled to differ somewhat from some of the views expressed in the papers of Dr. Hobbs; not so much as to what is the law in regard to the compensation of expert witnesses, but more particularly in regard to what constitutes an expert witness, and as to what is expert evidence.

The general meaning of the word expert is well understood, and I need not consume time or space by repeating it, but just