pleasant dreams which perhaps this very shaking may have called forth or interrupted. A patient who is undergoing tooth-extraction is quite aware that the instrument is pressed into his jaw; he feels the tooth loosening from the gum, but the pain is absent, and he has only the indifferent feeling of its being done. A similar condition has been often (and first by Beau) observed in paralysis. A Swiss physician, Vieusseux, who had a disease in the central nervous system, for a long time remarked that he could feel with one hand impressions of touch and the pulse, but compression or pricking of the hand produced no pain."

Schiff then found that he could produce in rabbits a condition similar to that described by a rapid, but moderate bloodletting. This being done, every part of the spinal cord except the posterior white. columns was divided. The sensibility of the parts behind being now tested, it was found that even a slight touch of the tail would cause the animal to raise its head, open its eyes, and move its ears, whilst the breathing, at the same time, became more hurried. If the tail, instead of being merely touched, was pinched until the nails reached the bone, none of these signs of disturbance occurs. From these and similar observations, Schiff concludes that the conductors of tactile sensibility are functionally and structurally distinct from those of sensibility to painful impressions; further, that these conductors reach the brain through the posterior white columns of the spinal cord; lastly, that each white column contains only the nerve-elements which convey the tactile sensibility of the corresponding half of the body, and that in this case the law of isolated conduction holds good, so that partial destruction of the white columns produces a lesion of sensibility in a corresponding part of the body.

The question of a decussation of the conductors of sensitive impressions in the cord is one on which there is still much difference of opinion. The simplest experiment on the question is that of division of one half of the cord. According to Brown-Séquard, the invariable result of this experiment is hyperesthesia behind the section, whilst on the opposite side sensibility is lost, or extremely diminished. He thence inters that there is a decussation of the conductors of sensitive impressions very nearly, if not absolutely, complete (p. 35). In regard to the loss of sensibility on the side opposite the section, Van Deen, Stilling, Valentin, and Schiff, have found that, in many cases, sensibility is not at all diminished, and in none wholly suppressed. Indeed, Brown-Séquard himself has found that sensibility frequently returns or remains on the side opposite the section, but gives as an explanation, that by a reflex action the muscles of the side of the section (which is in a state of hyperesthesia) contract spasmodically, and thus produce pain. To this view Schiff raises objections which it would occupy too much space to enter into. Nor does he agree with Brown-Séquard as to the results of the other experiment on which the latter argues that a decussation of the sensitive conductors takes place. From a very great number of vivisections on all species of animals, as well as from the study of pathological cases, Schiff has come to the conclusion that the principal mass of grey matter serves to conduct sensitive impressions from either one side of the

body or the other. To the extreme right of the grey matter a very small portion exists, which conducts sensitive impressions from the left side of the body only, and vice versa. The grey matter conveys impressions in all directions; and the agents employed in this omnilateral transmission are the ganglionic cells. To meet Schiff's experimental results, anatomy has to show that on either edge of the grey matter to the extreme right and extreme left, a group of cells exists, the process of which is not connected with the sensitive root-fibres of the same, but of the opposite side. As far as we are aware, no observer has yet ascertained whether such a relation holds. Schiff also maintains that pathological cases favour his ideas as to decussations much more than they do those of Brown-Séquard.

Several years ago, Von Bezold made an extended series of experiments on the question of decussation, and the result was equally adverse to Brown-Séquard's views.*

All experiments on the conduction of motory impulses are much more difficult than those on sensation, principally because one must wait until the animal makes a voluntary movement. No irritation, save that of the will, can be relied on. Another source of difficulty lies in the greater delicacy and vulnerability of the parts of the cord which conduct movement, a very slight degree of compression serving to produce a paralysis of motion.

Continuing our analysis of the experiments of Schiff, we find that in agreement with Van Deen, he believes that the anterior and lateral white columns transmit movement in the direction of the long axis of the cord. If in a frog all but the white anterior and lateral columns be divided, voluntary movements are still possible. In consequence of the difficulty of avoiding injury of these columns, the movements are always weaker than normal. In mammals, Schiff has also succeeded in observing voluntary movements when all but these columns were divided. As anatomy would indicate, and as pathology sanctions, these fibres do not go out of the cord through the motor roots, but join the cells in the anterior grey matter, which also serves for the conduction of movement. If the anterior and lateral columns are divided, after a time voluntary movements are strongly and harmoniously produced behind the section, so that the view of Longet, that the white anterior columns are the sole conductors of movement, is thus proved to be false. The question which next arises is-What portions of the grey substance conduct motor impressions? The answer is not such as former notions would lead us to expect, for Schiff found that when all the anterior parts of the cord were divided, and only a thin segment of the posterior grey substance (a segment so small that it could not be seen with the naked eye!) was left, spontaneous movements of the parts behind still took place.

Other experiments showed that the central grey substance, as well as the posterior, conducts motory impulse, whilst experiments instituted to ascertain the direction in which conduction of motor impulse

* Ueber die Gekreuzten Wirkungen des Rückenmarks : Zeitschr. für wissensch. Zoologie, ix. p. 307.

could occur, showed that in transmission of motion the grey substance effects this in every direction. We have seen that with sensitive impressions, the same law holds. How and why two such different elements as white and grey matter should both serve to conduct motor impulses we know not; nor do we know how the isolated transference of the impulse of the will is conveyed to determinate muscles. Equally ignorant are we, whether the cell processes which transmit motion are also capable of transmitting sensation.

Betwixt the sensitive and motory properties of the cord, analogy would appear to exist on more points than one. Thus, as in the case of sensation, the elements which conduct motion, white as well as grey, are in themselves not motory. To distinguish this property, Schiff proposes to term these elements "kinesodic." The experiment of Longet, in which it was supposed that galvanic irritation of the white columns produces motion in the parts behind, shows nothing beyond the fact that the muscles supplied by the nerve-roots going from the point when the excitation is applied, may be excited to action. The only motory parts of the cord are fibres of the anterior roots, which traverse obliquely, or at right angles, the anterior white columns. As already indicated, the fibres of the latter are not prolongations of the anterior roots, but originate in the cells of the grey matter.

On dividing one-half of the spinal cord, it is found that although there is no complete paralysis of motion, certain groups of muscles have their action weakened, and some are paralyzed. Amongst the latter are the muscles of respiration on the same side, and if the section is made above the origin of the phrenic nerve, the respiratory moveinents on that side are wholly suspended; but if the section is lowersay opposite the last cervical vertebra-the paralysis is confined to the external respiratory muscles. This result is specially due to division of the lateral columns.

Space forbids us entering upon the causes of the hyperesthesia which is observed after section of parts of the spinal cord, and we can do no more than remind the reader of the remarkable proneness to convulsive movements which Brown-Séquard found to follow certain lesions of this

organ.

In concluding this exposition of the views of Schiff, it may be of interest and service to the practical reader to put here verbatim the pathological corollaries which that physiologist deduces from his researches in the laboratory, so that by comparative observations at the bedside, and in the post-mortem theatre, the truth of these conclusions, as well as their diagnostic value, may be tested :

"1. Although, contrary to a common supposition, a limited disorganization of the posterior columns does not produce insensibility to pain in the parts behind, and a corresponding limited lesion of the anterior columns does not produce loss of movement, a total disorganization of these columns produces in the former case anesthesia, in the latter paralysis.

"2. When perfect anesthesia is the result of an injury which affects the spinal cord at a limited spot only, somewhere in the neighbourhood of only one or of some dorsal or cervical vertebræ, not only the posterior columns, but the

whole of the æsthesodic substance (including the anterior horns) must be affected at the injured part.

"3. Complete paralysis in all parts of the body behind a diseased portion of the cord in the long direction may occur―

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a. Without any lesion of sensibility, save only constricting pain at the level of the diseased part, in cases of mere compression of the cord through dilatation of the vessels, with effusion, exudation or affection of the sheath. "b. Without lesion of sensibility, and without any pain, perfect paralysis must occur in disease of the antero-lateral columns and of the total kinesodic substance, if one may suppose this substance to be affected independent of the æsthesodic.

"c. Should it be certainly proved that the central parts of the grey substance contain no kinesodic elements which conduct longitudinally, one would expect perfect paralysis of the posterior parts of the body, if anywhere, in the long direction, the antero-lateral columns, the four grey cornua and gelatinous substance of Rolando are affected, spontaneous pain is absent, sensibility to pain remains, but on account of the simultaneous limitation of the transverse extent of the asthesodic substance, perception of pain is retarded.

"d. Paralysis occurs in disease of the anterior column and the whole grey substance; in this case sensibility to pain is lost, but sensibility to touch remains.

e. Disease of the kinesodic substance, and of some parts of the anterior column, is accompanied with paralysis affecting certain parts and passing by others.

"4. Contraction and convulsions in parts of the body behind the injured spot can never be the consequence of an isolated irritative affection of the antero-lateral columns, or of the grey substance, since no motor fibre-i. e., none which upon irritation call forth movement-traverse the spinal cord in the long direction.

5. These symptoms, however, may occur in a transitory form in discase of the anterior columns, exclusively in the muscles supplied by the nerves traversing the diseased portion that is on a level with the injury.

"6. Convulsions of the posterior extremities, with cramp, and generally with contraction, in very great irritability, with extension, also, which makes their free movement impossible, occurs in diseases of the higher divisions of the cord in the dorsal or cervical regions. In such a case, it is from disease of the pos terior columns or the nerves traversing them, which act reflectively on the motory parts. Some change of the reflecting grey matter, analogous to that produced by certain narcotic poisons, might also give rise to contractions of the feet.

7. Contraction may also be produced by slight pressure on the cord. In such a case, the contraction depends on a paralysis of the extensors, and it disappears in sleep, or if the person lies very quiet, and also in the early stages of ether narcotism; whilst in cases of cramp from irritation of the posterior columns, a much higher degree of narcotism is required.

"8. Disease of the posterior columns can also (through the laws of reflexion) call forth convulsion and contracture in parts higher up, towards the head. "9. Disease of one posterior column, which causes slighter reflex contractions, has its effects confined to the limbs of the corresponding side.

"10. Isolated degeneration of the posterior columns, a little way above the cauda equina acts:

a. In an irritative way, by producing pain (spontaneous or on pressure) in those nerves which traverse the diseased part, and often a constricting pain at the part affected, and a little above it. The longitudinal fibres of the posterior columns call forth, in the part of the body behind,

a constant sensation of touch, described as formication with varying sensation of heat and cold. Sense of pain in the parts behind continues, and is even exalted, as long as the posterior columns are hyperemic.

b. When such a lesion acts in a paralysing way, we find at the level of the paralysed roots a circle of the body which is quite anaesthetic, whilst sensation to pain is present above and below this ring. This anesthetic circle is not sharply defined, and appears of different breadth at different times. Below this circle, sense of tickling, touch, and temperature, is absent. Pain or pressure is very well perceived, but is imperfectly localised.

c. When a disease at first acts irritatively (softening, for example), and extends along the cord from below upwards, the painful circle travels with it, leaving an extending anesthetic circle. Below this, objective sense of touch is absent, but instead of it, there is subjective and perverted sense of touch (formication).

"11. When, with motion unaffected, a painful ring is present without alienation of sense of touch, we should find that the nerve-roots alone, outside the cord or within it, were affected.

"12. When, besides the posterior columns, the whole æsthesodic substance is diseased, we shall find behind the diseased spot perverted sensations of touch and no sense of pain.

"13. A disease of the spinal cord which first produces convulsions and then a perfect loss of voluntary movement in the provinces of nerves which go off behind, extends to the anterior and posterior columns and the kinesodic substance; it does not however require to go so far into the parts conducting sensitive impressions in order to produce perfect anesthesia.

"14. A disease of the cervical portion of the cord, which, with paralysis of the extremities and the trunk, permits the respiratory movements to take place, does not affect the lateral columns.

"15. Isolated degeneration of one lateral column suspends the respiration on this side only. If both lateral columns below the fourth vertebra are diseased, the lower ribs are not used in respiration, which becomes strongly abdominal.

"16. When the lower part of the cord is paralysed, the motions in the different muscles of the upper part of the body become more frequent and stronger.

"17. Since only a small bridge of grey matter is sufficient to transfer sensitive or motory impressions, it is possible that in many cases, especially when this grey substance is surrounded by softened parts, softening occurs after death, and the connecting link of grey matter is not observed, and fluid matter fills up the gap.

18. The above physiological experience may be applied to cases of wounds which scarcely disturbed the function of the cord (a bridge of grey matter being left?).

"19. It is rare to find that after a lesion of the spinal cord, feeling or motion is permanently lost on one side only."

Space does not permit our alluding to the influence which the spinal cord exerts on the functions of respiration, circulation, nutrition, heat, and digestion. We have been principally anxious to expose the views of our German brethren on the structure and functions of the cord, and must offer this as a reason for having made but slight refe rence to writings which can be readily found in the English literature of the subject.

65-XXXIII.

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