entirely contained in the pyramidal bodies and in the grey matter associated with them, the olivary columns as well as the restiform being excluded by the fact that they certainly do not decussate in that region. A striking confirmation of the truth of this view is furnished by a class of cases (of which several are now on record) in which there has existed atrophy of one half of the brain and of the corresponding anterior pyramid, with paralysis and atrophy of both limbs on the opposite side, and also atrophy of the opposite half of the spinal cord, the restiform and olivary bodies remaining unaltered.

M. Brown-Séquard has collected fourteen examples of that curious class of cases of paralysis, in which the loss of power has existed on the same side with the encephalic lesion : and he states that all of them were characterized by the same features-namely, incomplete paralysis, no anæsthesia (save in a single case), and frequent fits of vertigo; and that the lesion was of the same nature in all,

having been the result of the existence of a tumour pressing upon the anterior surface of one of the crura cerebelli and the insertion of the trigeminal nerve. This paralysis may be explained in two modes; either by the supposition that it is the result of the destruction of some of the conductors of volitional power; or by the hypothesis that it proceeds from the irritation of certain of the nerve-fibres in the peduncle, in the same way as a reflex paralysis is often occasioned by irritation of centripetal nerve-fibres in any viscus, in any membrane, or in any nerve-trunk that contains them. The former explanation requires the hypothesis that there are motor fibres that do not decussate, which is rendered improbable by the limitation of the paralysis to one side; and it seems to be disproved by cases in which the effect of the destruction of a large part of one of the crura has been muscuJar paralysis of the opposite side. The latter is favoured by the fact that reflex paralysis more frequently proceeds from irritation of the peripheric branches of the fifth pair, than from the like irritation of the branches of any other nerve; and that it usually affects the side of the body on which the irritation exists. The question is one of great interest; and the phenomena of every case in which this form of paralysis presents itself should be carefully observed and recorded, for the sake of the aid which a comparison of its symptoms and of its post-mortem appearances may afford to the determination of their real relation.

Some very interesting suggestions are offered by M. Brown-Séquard in the latter part of his course, in regard to the functional relations of the encephalic portion of the motor apparatus, as manifested in the effects of lesions in producing vertigo, convulsions, rotatory and rolling movements, &c. His views on these points, however, are so far from being completely stated, that we think it better to abstain at present from the discussion of them; merely mentioning that he thinks he bas evidence that there is much nervous matter in the pons varolii, in the olivary tract, and in other parts about the base of the encephalon, which is not employed in the transmission either of sensory impressions, or of the orders of the will to muscles, but which is endowed with the singular property of producing, after even a slight irritation, persistent spasms or clonic convulsions in various parts of the muscular apparatus. It is through this part of the nervous apparatus, according to him, that the movements of rolling and rotation are produced ; their source being sometimes a lesion or irritation acting directly on the tract in question, sometimes a change in its circulation produced by contraction either of its bloodvessels or of those of some other part of the encephalon, but very frequently a reflex irritation conveyed through some other nerve, especially the auditoryas in the well-known experiments of Flourens on section of the semicircular canals. This idea harmonizes well with the results of various pathological phenomena, especially the occurrence of convulsions on one side and of paralysis on the other from the same lesion, the convulsions being on the same side with the lesion, owing to the nondecussation of the olivary columns. But it cannot be doubted that this set of fibres and nerve-cells, supposing it to exist, must have some important normal or physiological function; and to the nature of this, M. Brown-Séquard at present gives us no clue whatever.

V. Although it cannot be said that M. Brown-Séquard's researches into the actions of the Sympathetic System have established any principle that is new to Physiologists,

a

yet we are disposed to regard them as among the most practically-important of all his contributions to Neurology. For if they have not dispersed all the cloud of uncertainty that hung over this subject, they bave made such openings through it as to afford us clear and definite glimpses of what was previously so misty and obscure as to present scarcely any appreciable form; and whilst they have thus given a character of reality to much that was before so vague and speculative that it could lay no claim to be accounted scientific truth, they offer many suggestions of the highest value in the interpretation of pathological phenomena, and in the selection and application of remedial means. Amongst the Physiologists, of our own country at least, who have most philosophically studied the functions of the Sympathetic system of nerves, we believe that those views had come generally to prevail which were formally taught by Dr. Alison, and explicitly set forth by him in the pages of one of our predecessors* _namely, that its special purpose is to bring the functions of Organic Life into harmony with those of Animal life, in virtue of the guiding and restraining influence which it possesses over the former; but that whilst it can either excite, modify, or retard the acts of Nutrition, Secretion, &c., those acts are in themselves independent of it, in the same sense that the actions of horse are independent of those of the rider upon his back, who nevertheless controls and directs them at his own will. The evidence obtained by Valentin and other experimenters as to the power of the Sympathetic to excite contractions in the heart, the muscular coat of the alimentary canal, the walls of the great vessels, and other muscular organs immediately concerned in the maintenance of the organic functions, and as to the derivation of this power from the Spinal Cord, was generally accepted as rendering it probable that a part of its influence was exerted through its regulation of the calibre of the bloodvessels; a modus operandi which was specially indicated on the one hand by the distribution of the Sympathetic upon their muscular walls, and on the other by the phenomena of blushing and other kinds of vascular turgescence arising from mental emotion. But although this regulation of the supply of blood accounted for much,

. there have seemed to be residual phenomena which indicate that the Sympathetic system has some direct relation with the operations of nutrition and secretion; in virtue of which it can excite, modify, or repress them, not by altering the supply of blood, in the first instance at least

, but by affecting the uses to which the blood is put in its passage through the capillaries, and thus consecutively augmenting or diminishing the demand for blood in any particular organ. And it has been thought that this agency might uot unreasonably be attributed to the system of fibres which has its central terminations in the vesicular matter of the ganglia of the Sympathetic itself

, and which may be considered to constitute the essential part of that system, as distinguished from the portion which is directly derived from the Cerebro-spinal.

Such having been, as we believe, the doctrines currently taught, in this country at least, previously to the commencement of M. Brown-Séquard's researches upon this subject, we shall now inquire how far they have been corrected, modified, or substantiated by the results of his investigations. The first point which he has established is the influence of the Sympathetic nerve upon the calibre of the ordinary bloodvessels, by the contraction it has the power of exciting in their muscular walls. In the latter part of 1851 and the commencement of 1852, M. Claude Bernard made public the results of his experiments on the effects of section of the cervical sympathetic; the most marked of these effects being—besides the permanent contraction of the pupil

, which had long previously been noticed by Pourfour du Petit, John Reid, and others an increased affilux of blood to the head, manifested in turgescence of the vessels of the inside of the ear, elevation of temperature, and augmented sensibility. Impressed, like many other physiologists, with the belief that these results (which might in some degree be likened to a state of persistent blushing) were all due to the paralysis of the muscular walls of the bloodvessels, M. Brown-Séquard considered that the normal state of things would be brought back if galvanisın were employed to make them contract; and on making the experiment he found that the results were what he anticipated. These results, having been published in the ‘Philadelphia Medical Examiner for August, 1852, of course take precedence of those of similar experiments communicated a few months

later by M. Claude Bernard to the “Société de Biologie,” and of those obtained about the same date by Dr. Waller, whose experiments we had ourselves the opportunity of witnessing; and they obviously afforded the first decisive evidence of the influence exerted by the sympathetic system over the calibre of the bloodvessels. Putting aside its action on the pupil, the principal results of section of the cervical sympathetic are clearly traceable to the increased afflux of blood to the head; and they may be

very closely imitated by holding an animal suspended by its hind-legs for a short time, so as to produce congestion in the head. The chief antagonistic effects of section and of galvanization of the nerve may be thus contrasted :

Section of the Nerve.
1. Dilatation of Blood-vessels.
2. Aflux of Blood.
3. Increase of Vital Properties.

Galvanization of the Nerve.
1. Contraction of Blood vessels.
2. Diminution of Blood.
3. Decrease of Vital Properties.

The source of what M. Brown-Séquard appropriately terms the vaso-motor fibres of the Syınpathetic, distinctly lies (as does that of the fibres which dilate the pupil) in the Spinal Cord. Those proceeding to the vessels of the head come forth, according to him, by the roots of the last cervical and first and second dorsal nerves ; but their place of real origin he believes to be partly the upper part of the spinal cord, but chiefly the medulla oblongata and the neighbouring parts of the encephalon, their connexion with which explains the readiness with which they are affected by emotional states. In other parts of the body, the nerves of the bloodvessels seem to come partly from the cervical sympathetic, but chiefly from the cerebro-spinal axis; so that if the spinal cord be transversely divided on one side in the dorsal region, we find in the lower limbs of that side the dilatation of bloodvessels, the elevation of temperature, the hyperæsthesia, and the increased muscular contractility, which in the head follow the section of the cervical sympathetic.

These vaso-motor nerves are not only called into activity by direct excitation, but are susceptible of being made to call forth contractions in bloodvessels by reflex action, This conclusion, the value of which we estimate very highly, was first decisively evidenced several years since by experiments performed by M. Brown-Séquard in conjunction with Dr. Tholozan, on the effect of the application of cold to one band in producing a marked reduction in the temperature of the other.* They found that when one hand was held in water cooled down nearly to the freezing point, the other gave all the evidence of contraction of its vessels, both in its general aspect, and in its rapid loss of heat, which in some instances was such as to reduce the thermometer held in it as much as 32° Fahr. That this reduction was not due to a loss of heat from the body and members generally, was made clear by the fact that the thermometer placed in either axilla showed scarcely any depression; so that no doubt can be reasonably felt that the stimulus of cold, which produced direct contraction in the vessels of one band, also operated to call forth reflex contraction in those of the other. If

any

confirmation were wanting, it is afforded by experiments more recently made; which show that after section of the cervical sympathetic, the distended vessels of the ear may be made to contract by irritation of the cutaneous branches of some of the spinal nerves. This reflex contraction of the muscular walls of the bloodvessels may proceed to the extent of spasm, so complete as scarcely admit of the passage of blood through their tubes; and it is not a little remarkable that transverse section of a lateral half of the spinal cord near the medulla oblongata, whilst it produces paralysis and dilatation of the bloodvessels of one side of the body, should call forth such a spasm in those of the other, that scarcely a drop of blood follows the division of the skin upon that side, and the temperature falls rapidly, often to that of the atmosphere. It might of course be suggested that this diminished circulation on one side might be fairly laid to the account of the increased circulation on the other; and this explanation receives due consideration from M. Brown-Séquard, who put its value to the test by the ingenious. experiment of forcing the blood into the vessels of the opposite side by putting a ligature round the dilated trunk on the side on which the section bas been made, the result of which was that the temperature rose so slowly as to make it obvious that the circulation was obstructed ; and be further states that injections of blood through the femoral artery in the limbs thus affected are made with far more difficulty than in the limbs of healthy dogs.

The facts thus experimentally ascertained give the fullest confirmation to the doctrine which had been previously taught by various physiologists, ourselves among the rest, that the sudden stoppage of the heart's action in many cases of shock, is due to a reflex influence transmitted throngh sympathetic. It is well known that persons bave fallen dead on the spot from drinking cold water on a warm day, or from blows on the epigastrium, especially when the stomach is distended with food; whilst a rapid prostration, if not immediate syncope, is an almost pathognomonic sign of the perforation or rupture of any of the principal abdominal or pelvic viscera, quite irrespective of the hæmorrhage which may result from such an accident. The same result, moreover, is well known to follow extensive lesions of the peripheral expansions of the cerebrospinal nerves, as by burns, crushing of joints, and the like; the syncope induced by them being exactly like that which is produced by concussion or other sudden and extensive injury of the cerebro-spinal centres themselves. The like result has been obtained by the sudden application of severe cold to an extensive surface peculiarly susceptible of it; thus when shaved rabbits are plunged into ice-chilled water, they die immediately with spasm of the heart. In all these cases, the par vagum

has probably a considerable share in the transmission of the reflex influence to the heart. It is well known that a sudden stoppage of the heart's action may be produced by the application of the magneto-electric current either to the par vagum, or to the medulla oblongata near its origin.; and that this effect cannot be produced if the par vagum or its cardiac branches have been previously divided. So it is shown to be probable by M. Brown-Séquard, that in those rare cases in which death from the inhalation of chloroform takes place by the stoppage of the heart's action before the suspension of respiration, the effect is due to the impression made by the chloroform upon the pulmonic branches of the par vagum, and transmitted by reflexion to the cardiac; for he has found that in dogs, which seem to be more frequently affected in this way than are other animals, life may sometimes be restored by mechanically exciting the heart to renewed contraction by pressure on the chest; whilst this mode of death has not occurred in any dog in which the par vagum had been divided previously to the administration of chloroform. Still it cannot be reasonably doubted that the Sympathetic, not the par vagum, is the channel of this influence to the vascular system generally; and the existtence of such a condition as spasm of the extreme vessels,” to use the phrase of the sagacious Cullen, may henceforth be considered a capital fact in biological science, its insecure foundation of vague hypothesis having now been strengthened by the solid supports of experimental proof.

One of the first fruits of the establishment of this position is a new theory of Epilepsy ; which is propounded by M. Brown-Séquard as a legitimate inference from facts experimentally ascertained by himself as to the artificial production of this disorder in animals; and which is applied by him not only with great ingenuity, but, as it appears to us, with great success, to the explanation of the varied phenomena of this disease as it presents itself in Man. In the course of his experiments upon the effects of various injuries of the spinal cord, he observed that after certain lesions of that organ in its dorsal or its lumbar region, especially in guinea-pigs, fits of epilepsy appear spontaneously at intervals of a few hours or of a day or two. These fits consist in clonic convulsions of almost all the muscles of the head, trunk, and limbs (except such as are paralysed by the lesion of the spinal cord), together with laryngismus and loss of consciousness; and when the fit has lasted long, it leaves behind it a sort of drowsiness or unwillingness to move. By trying various kinds of irritation, M. Brown Séquard found that fits could be artificially induced in these animals by simply pinching a particular part of the skin; that, namely, which covers the angle of the lower jaw, and extends from thence to the eye, the ear, and nearly to the shoulder. It is only the skin

that has the power of receiving the irritation which excites the fit; as the nerves which supply this part may be irritated without the occurrence of convulsions. When the spinal cord has been injured on one side only, it is only on that side that the irritation of the skin will induce the fit; if both sides have been injured, then the fit may

be induced by irritation of the skin on either side. That the cause of the fit does not lie in the mere pain produced by the irritation, would appear from the circumstance that the degree of sensibility of that part of the face and neck is not greater than that of the neighbouring skin, and is far less than that of some parts of the skin in one of the hind limbs; and it must be attributed to some peculiar kind of irritation, which only the cutaneous ramifications of the nerves that convey it have the power of receiving, and which may not even be felt as a sensation. From a careful examination of the sequence of the phenomena presented by the animals thus affected, M. Brown-Séquard has come to the conclusion that the immediate result of the excitation is to produce, through the Cerebro-spinal centres and their nerves, a more or less powerful convulsion of the muscles of the face, whilst through the vaso-motor fibres of the Sympathetic, it induces a spasmodic contraction of the bloodvessels of the Cerebrum and of the face, indicated by the pallor which marks the commencement of the seizure; and it is not a little remarkable that the very same inference has been contemporaneously drawn by two able German experimenters, Kussmaul and Tenner, from researches in many respects different. The following is given by M. Brown-Séquard as the ordinary filiation of the other phenomena of the ordinary epileptic paroxysm :

brain proper:

“ CAUSES.

EFFECTS. 1. Excitation of certain parts of the excito- 1. Contraction of blood vessels of the brain motory side of the nervous centre.

proper and of the face, spasm of some mus

cles of the eye and face. 2. Contraction of the blood vessels of the 2. Loss of consciousness and accumulation

of blood in the base of the encephalon. 3. Extension of the first excitation, partly 3. Tonic contraction of the laryngeal, the due to the accumulation of blood in the base cervical, and the tboracic expiratory muscles. of the encephalon.

(Laryngismus and trachelismus.) 4. Contraction of laryngeal and of thoracic 4. Crying, and stoppage of respiration. expiratory muscles.

5. Farther extension of the first excitation 5. Tonic contraction, extending to most of of the nervous centre.

the muscles of the trunk and limbs. 6. Loss of consciousness, and tonic contrac- 6. Falling. tion in the trunk and limbs.

7. Laryngismus, trachelismus, and the fixed 7. Asphyxia, with obstacles to the return state of the chest.

of venous blood from the head and the spinal

cavity. 8. Asphyxia, and the accumulation of black 8. Clonic Convulsions everywhere; conblood in the encephalon and in the spinal tractions of the bowels, the bladder, the utecord.

rus; erection ; increase of many secretions ;

efforts at inspiration, 9. Exhaustion of nervous power generally, 9. Cessation of the convulsions; coma or and of the reflex faculty especially, except for heavy sleep, after which extreme fatigue and respiration, which gradually becoines normal. headache."

The asphyxia, to which so great a share is due in the phenomena of epilepsy and in its most serious consequences, depends, according to M. Brown-Séquard, not only on the state of the larynx (as Dr. Marshall Hall maintained), but on that of the chest; for not only cannot the blood return easily from the head on account of the trachelismus, but also it cannot enter the chest from either the spinal canal or the head on account of the fixed state of expiration.* Besides, he continues, the bronchial tubes are themselves frequently obstructed; and all these changes co-exist with an increased production of

We have seen a case of one of the strange varieties of hysteric convulsion, in which there was spasmodic closure of the glottis during expiration, with repeated and most violent expiratory efforts, but without any loss of conscious. ness; and this was repeated, time after time, in the course of an hour, the obstruction to the return of the blood from the head, as indicated by lividity of the face and the turgescence of the veins of the neck, being such as to occasion the gravest alarm, until it was relieved by the free expiration permitted by the yielding of the glottis.