decisively that the decussation of nerve-fibres (at least of the majority of them) devoted to the conduction of sensory impressions, does not at any rate take place, as some have held, at a point higher up in the cerebro-spinal axis than the pons Varolii; for here we have a loss of sensibility of the skin on the "left" side of the body (the same side on which power of motion was destroyed) produced by disease on the "right" side of the pons Varolii (the left side being unaffected). Had it been otherwise-that is, had the bulk of the sensory fibres coming from the left side of the body (that affected with contactile anæsthesia) passed through the pons Varolii prior to their crossing or decussation -then they must have penetrated the uninjured left portion of the pons Varolii, and in this way escaped all implication; and we should not have had any anesthesia of the limbs on the left side of the body. In like manner, this case also shows that the nerve-fibres addicted to the conduction of voluntary power passing downwards from the brain to the right side of the body, intercross at a point below the lower margin of the pons Varolii.

CASE V.-Extravasation of blood on one side of the median line of the pons Varolii. Complete loss of power of movement in the muscles of the right arm and leg, and also of sensibility, as regards pinching and pricking, of the integument on the same side of the body.

This case, which I venture to quote from the Transactions of the Pathological Society,' was brought before the notice of that Society* by my late friend, Mr. W. Barlow, formerly resident officer at the Westminster Hospital. It was that of a woman, aged thirty-four, who, after falling down suddenly, was found to have lost all power of motion in the right arm and leg, and also to have anæsthesia, as regards the impressions of pricking or pinching, of the paralysed limbs. There was, moreover, paralysis of the muscles of the left side of the face, the left eyelids not being capable of closure, and the mouth being greatly drawn to the right. Reflex action of the affected limbs could easily be excited. Consciousness was unimpaired, and even intelligence remained until within a few hours of death, which occurred five days after the accident.

Post-mortem examination.-A coagulum of blood as large as a filbert, which had ruptured into the fourth ventricle, was found so situated in the pons Varolii that a section of this organ in the mesial line passed almost, “but not quite," through the centre of the effused blood. The brain and cerebellum were otherwise natural.

Remarks. Here I would premise, that if the description of this case by Mr. Barlow had been somewhat more precise and fuller of detail, it would have been, for the purpose to which I am applying it, more available; but it is nevertheless most useful. The post-mortem record certainly implies that blood-clot was located more on one side than the other of the pous Varolii, but fails to state on which side it preponderated. The probabilities are, and I think it must, from the symptoms, be assumed, that the blood-clot was situated more on the left side of the median line than on the right, and that it involved the left part of the pons more especially-along, no doubt, with a considerable portion of the right part of this organ. Thus we have

* Transactions of the Pathological Society of London, 1852-3, p. 28.

loss of power of motion, and loss of a certain form of sensibility, on the right side especially, of the body; although, considering that the lesion was not confined to one side of the pons, there may have been, in addition, a certain degree of, or even very considerable interference with, the power of motion or sensibility on the opposite side. This latter might have been comparatively so insignificant that the right side attracted by far the most attention.

The assumption just entertained as to the left side of the pons Varolii being chiefly the seat of the effused blood, becomes materially fortified, and the gap in the documentary evidence greatly filled up, by the fact of the existence of facial paralysis (so termed) on the "left" side, and absence of it on the right side. The blood-clot was no doubt altogether out of the way of the source of the portio dura of the seventh pair on the right side, but was evidently placed so much on the opposite (the "left" side) as to involve the portio dura on that side. Had the clot been quite central, and not more on one side than the other, we should either have had no facial paralysis at all, or have had it on the two sides to an equal degree. Again, had it been quite central, we should doubtless have had an equal degree of loss of voluntary power and sensibility on both the sides of the body.

CASE VI.-Large masses of scrofulous deposit in the right portion of the pons Varolii and medulla oblongata; general loss of muscular power; great numbness and "coldness" of the left arm and hand.

Fig. 3. The illustration exhibits masses of scrofulous deposit in the right portions of the medulla oblongata and pons Varolii,

The patient, a girl, aged eighteen years, was brought into St. George's Hospital with headache, and great numbness and " COLDNESS" of the left arm and hand, which she had experienced for about a year. There was also a peculiar oscillating movement of both eyeballs, but especially of the right one. The patient for two or three years had been subject to double vision. General loss of voluntary muscular power and semi-stupor, with a difficulty in swallowing and articulating her words, preceded death.

Post-mortem examination.-Two large rounded masses of firm scrofulous material were found occupying, one the centre and posterior part of the right portion of the medulla oblongata, and projecting into the fourth cerebral ventricle, the other the upper and right portion of the pons Varolii (fig. 3).* The posterior parts of the crura cerebri were also softened, and one or two small scrofulous deposits were met with in the posterior parts of the cerebral hemispheres.

Remarks. The particulars of immediate interest in this case, as regards the question for which I here introduce it, are the following:

*This specimen in now in the St. George's Hospital Pathological Museum, as Preparation No. 10 a, Sub-series iv., Series xx.

(a) The conjunction of the disease of the "right" part of the pons Varolii and medulla oblongata with the disorder of sensibility on the "left" (the opposite) side of the body.

(b) The fact that sensibility on one side was affected, whilst the scrofulous deposit was situated so low down as it proved to be on the opposite (the right) part of the medulla oblongata, demonstrating that the decussation of such up going or centripetal nerve-fibres as form the medium of communication for sensory impressions, decussate, to a great extent at least, at some part or parts below the medulla oblongata.

(c) The complaint of "coldness" of the arm and hand (of long duration) on the side opposite to the lesion of the pons Varolii, &c. This point is of great interest in connexion with the subject of the conduction of reflex phenomena (as regards blood vessels) in the pons Varolii-a subject treated of by Dr. Brown-Séquard at p. 525 of vol. i. of his Journal de la Physiologie.'

CASE VII.-Laceration of the cervical part of the spinal cord, the left side being mainly affected, in connexion with dislocation of the vertebra; contactile sensibility of the skin interfered with, chiefly on the opposite (the right) part of the body.

· History.-The case was that of a man, aged twenty-eight, who was brought into St. George's Hospital in a state of collapse, but conscious, after a fall and blow. At the first he was quite able to move his legs, but not his arms, and two hours subsequently he lost all power over both his legs. At a later period the lower part of the body and the legs, as well as the lower part of the right arm (as high up as the elbow), were found to have completely lost sensibility to the impressions of touch or pinching; the upper part of the right arm still, however, perfectly retaining sensibility to these tactile impressions. The legs and arms continued immovable, and the triceps muscle of the left arm became affected by repeated spasms. Priapism also existed. The patient died seventy-two hours after the injury.

Post-mortem examination.-Dislocation of the fourth and fifth cervical vertebræ was found. There was considerable laceration of the corresponding portion of the spinal cord, the left part of its substance being chiefly implicated in the injury, and the central parts being much more affected than the outer ones. The parts injured were greatly softened, and infiltrated with

effused blood. The anterior root also of one of the nerves near the mutilated part of the spinal cord was torn off, with the exception of a few of its lower fibres.

Remarks. The above case seems to illustrate the fact that afferent sensory fibres actually decussate in the spinal cord, and that also in various parts. This is exemplified by the circumstance that whilst we have injury chiefly to the "left side" of the cord at the lower part of the cervical region, we have the contactile sensibility of the skin mainly affected on the "right" (the opposite) side, the whole of the right arm below the elbow being totally deprived of this form of sensibility. If decussation of such sensory fibres as pertain to the lower parts of the arms had not existed at some part below the injury of the spinal cord, this injury, so much the more extensive as it was on the left side of the cord, would of course have been followed by greater loss of sensibility on the same or corresponding side of the body.

48-XXIV.

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Such are the clinical cases, obtained, with one exception, from the experience supplied by St. George's Hospital, which I would adduce as bearing upon several important propositions newly advanced by Brown-Séquard touching the functions of the spinal cord, and indicative especially of the anatomical routes along which communication is established between the central nervous masses and the peripheric portions of the frame.

I might have proffered other cases also from the same source, but as none appeared to afford such manifest illustrations, or to be so free from subordinate phenomena calculated perhaps in the minds of some to cloud or complicate the main subject which those clinical cases are intended to elucidate, I have desisted from any multiplication of their number. Had all the instances of disease or injury of the cerebral and spinal centres been at the time of their occurrence carefully examined with reference to the special views promulgated by Brown-Séquard, there can, I think, be no doubt that the pathological experience of a field so wide as that which a hospital like St. George's presents (whether furnished by facts accumulated under the "curatorship" of so many accurate and scientific observers as were my predecessors, or during the period-one of between six and seven years in which the charge of the pathological department fell to my lot), would have afforded a vastly additional number of cases which would have proved highly available for such an occasion as the present

one.

But it is universally felt that in matters of scientific research rich and important details may be brought together indicating most praiseworthy diligence and to a considerable extent philosophical precision, and nevertheless they may be deficient when called into requisition in aid of any special general question, and this merely from the want of the existence of some paramount intention or guiding purpose in the mind of the investigator at the moment of observation. The mind's eye not being illumined from any particular source, the experimenter or observer very frequently not only fails to a certain extent in constructing or giving unity and coherence to the edifice for which each individual fact might be most fitted, but also records the phenomena presented to his notice in such a way that when employed by future artificers, they are found to be just wanting in that single element or characteristic which alone is required to render them fully useful for his specific purpose. This must, I imagine, have been found to be the case with all who in any department of the intellect have set themselves with a particular or newly-acquired insight to utilize disjointed material, whether amassed by themselves on any previous occasion, or by others; and in like manner I have found it to obtain with regard to the varied subject-matter which our hospital has at its disposal (the valuable aggregate of a period now extending over nearly twenty years),* in reference to Dr. Brown-Séquard's theories on the nervous system.

This appears to be a fitting opportunity for making known the fact that we are originally indebted to the energy and practical industry of my friend Professor Hewett (whom as curator at a long interval I had the honour of succeeding), for the superior arrangements at St. George's Hospital which we possess as respects the systematic recording of post

As their consideration may in a measure explain past deficiencies, and also prove in some degree serviceable for future guidance, I will here venture to enumerate some of the particulars which, had they been in past years attended to by observers in our profession in the registration of clinical histories and in the record of post-mortem appearances, would have greatly heightened the intrinsic value of such recorded facts as are to be met with in many of our medical publications. These particulars naturally arrange themselves under the separate headings of Clinical or Life Histories and Post-mortem Pathological Appearances.

As regards the Life Histories, in the first place, an oversight with respect to the following items may frequently be noticed as having occurred- -an oversight which, let it be remembered, was in many cases positively quite inevitable at the time, owing to defect in our then existing physiological knowledge, resting upon which alone as a basis, pathological statements or speculations can possess any true or constructive philosophical character.

Firstly. The frequent observations as respects any diminution or loss of power recorded baldly as "paralysis," without any qualification whatever that is to say, without any approximative statement as to the degree of deficiency of muscular power, or as to the method of its access, whether gradual or rapid; whether the paralysis followed a so-called "fit" or not, and if so, whether it was attended by pain at the onset (i.e., at the exact period when the supposed lesion of the nervous structures took place). Again, it is noticeable that "hemiplegia" is often stated to have occurred, whilst very frequently, indeed, no mention is made as to the existence or absence of any degree of facial paralysis, or of divergence in the movements or alteration in the form and appearance of the tongue; or if such mention does exist, there is not infrequently a total want of allusion to the side of the face or tongue affected. Still further, in connexion with this subject, there is, judging from the mention of certain collateral symptoms, a frequent want of diagnosis between the opposite states of "paralysis" and " spasm" of the facial muscles (two conditions which, it is important to notice, may pass into each other, and which if only slightly marked, may without difficulty be mistaken for each other).

Secondly. We often find reference made to diminution, or entire loss of power of voluntary movement, along with evident and total omission as to whether or not the condition of the muscular or various forms of tactile cutaneous sensibility were in any manuer implicated.

Thirdly. There is often a mention of diminution or loss of cutaneous sensibility, but no accompanying particularization of the special form of anesthesia which exists-whether, that is to say, it was an interference with the perception of mere contactile impressions, or an insensibility to the various other cutaneous impressions, as of differences in temperature, of pinching, pricking, &c.

mortem observations accompanied by their clinical life-symptoms. The excellency of the plan to which I allude, will be, I trust, more widely made known ere long, as we are about to print and publish the Catalogue of the Hospital Pathological Collection, revised and remodelled by Mr. Gray and myself, under the sanction of the Medical School Committee.