ON THE

IRRITABILITY OF THE MUSCULAR FIBRE

IN

PARALYTIC LIMBS.

BY MARSHALL HALL, M.D., F.R.S. L. & E.

FELLOW OF THE ROYAL college of PHYSICIANS OF LONDON; "ACADÉMIE ROYALE DE MÉDECINE FOREIGN ASSOCIATE OF THE

MÉDECINE" OF PARIS;

&c. &c. &c.

Received March 13th-Read March 28th, 1848.

THE Society did me the honour to publish a paper on the subject of the present communication in the Twenty-second volume of its Transactions.

In the last volume, or the Twelfth of the New Series, a paper on the same question is published, from the pen of Dr. Todd.

The conclusions to which Dr. Todd has arrived are at va

riance with my own. On first discovering this, I hastened to ascertain what could be the cause of the discrepancy between us, confident as I felt that my experiments and observations had been conducted with extreme care. I soon perceived that Dr. Todd had not employed the same kind of apparatus; and a few comparative trials established the fact, that in the difference of apparatus consisted the difference between our results.

I.-The Instrument employed.

My object was to select such an apparatus as, being of the very mildest operation, should really be a test of the irritability of the muscular fibre of those muscles subjected to its

influence, and present the least complicated results. It was essential to avoid violence-to avoid all effects of timidity, surprise, sudden sensation, &c., evinced in starting, wincing, &c. I chose the well-known Cruikshank's battery or trough, the commonest, the simplest, the mildest, the most easily adjusted, of all. By means of this instrument I could apply a gentle galvanic influence, proceeding from ten, twenty, thirty or more plates, consisting of a simple current of low intensity; I could, in a word, apply the precise power required; viz. the lowest which would produce an obvious effect.

Dr. Todd has used the electro-dynamic or the magnetoelectric apparatus. Now these are machines of great intensity; and instead of affording a simple current, inflict currents rapidly interrupted, repeated and even alternated; events, each of which presents its own peculiar effects on the muscle or on the nervous and muscular fibre.

But waiving the mere à priori objections, that the same instrument was not employed by Dr. Todd as by myself, it was impossible to conclude, without experiment, that the effects of instruments so different would be the same. I may now add, as the result of experiment, that, so far from being identical, the results afforded by the two instruments are diametrically opposite. We have, in this simple fact, the entire explanation of the discrepancies between Dr. Todd's statements and my own.

In effect, as my friend Mr. Henry Smith, to whom I am indebted for his most able assistance in all these experiments, early and acutely observed, the galvanic trough is, from its simplicity of operation and its low intensity, really a test of the irritability of the muscular fibre; whilst the electrodynamic apparatus, from its extreme intensity and mode of action, displays the power of the muscular mass.

It may also be surmised, that whilst the simple current of low intensity acts principally on the superficial fibres, the rapidly-repeated galvanic agency, in its intense form, may penetrate to the deeper-seated nerve, and so display a degree of energy not observed in the other case.

And I beg here to lay before the Society an interesting fact, illustrating the effect, even upon nerves of sensation and volition, of disuse :-A frog had lost its inferior extremity, probably by some voracious fish; the divided thigh presented a stump perfectly healed. On examining and comparing the two lumbar nerves, I observed that that nerve which proceeded to the amputated limb had become atrophied. Doubtless this occurs in cases of disuse from paralysis; and, consequently, that nerve may lose more or less of its excitor power.

That Mr. Smith's view of this question is the correct one, is proved by an experiment which I have repeatedly made.

If the hands of a healthy person be subjected to the action of the electro-dynamic apparatus, they are energetically closed: the flexors muscles being more massive and powerful than the extensors, the former are more forcibly contracted than the latter; it is their power not their irritability which is tested.

But it is to an actual case in point that we must appeal; and I beg here to introduce an experiment, made to determine the question before us, viz. that of the results obtained by the two kinds of apparatus to which I have adverted. I give it in the words of Mr. Smith. It was made on the 10th of November 1847.

"In a case of hemiplegia of three years and a quarter's duration, in a man aged 28, the arm being slightly wasted and the hand contracted, the leg only a little enfeebled, we first applied the current from the common Cruikshank's battery, the hands being placed in salt water in one basin, the feet in another: on using a small number of plates, the muscles of the paralysed arm were found to be slightly affected by a current which did not influence those of the unaffected arm; on augmenting the number of plates, both arms were moved, but the paralytic arm more than the other.

"We now substituted Hearder's electro-dynamic apparatus for the Cruikshank's battery: both arms were moved, but the

unaffected more than the paralytic arm, the muscles being more powerfully contracted, as observed both by the sight and touch; a difference which became still more obvious as the power of the apparatus was augmented."

Having thus pointed out the source of the discrepancy between the results obtained by Dr. Todd and myself, I need not proceed any further. Still there are so many and such important questions involved in this inquiry, that I am anxious to be allowed to adduce fresh evidence of the statements made in my former paper. Most of all, I would call the attention of the Society to the great physiological principles involved in this inquiry-viz. that, whilst volition is an exhauster of the irritability of the muscular fibre, this irritability is essentially dependent on the influence of the spinal marrow; and to the important application of galvanism as a test of that irritability, and as a diagnostic between the cases of paralysis, in which, first, the influence of the cerebrum, or, secondly, the influence of the spinal marrow, is severally removed; for both these doctrines remain in their full force.

II. The Terms employed.

Before I proceed, I must also take this opportunity of defining the medical terms employed by me in this discussion.

In the first place, by cerebral paralysis, I mean any disease which severs the influence of the cerebrum, and consequently the acts of volition, from the paralysed limbs.

In the second place, by the expression spinal paralysis, I mean any disease which severs the influence of the spinal marrow from those limbs.

In my former memoir, I speak expressly of "the cases of paralysis arising from the severed influence of the spinal marrow, as distinguished from those arising from the severed influence of the cerebrum merely."

Cerebral paralysis usually depends on disease of the cerebrum, but spinal paralysis may depend on disease situated in any locality, even in the cerebrum, so as to sever