38 



IRRITABILITY. 



" The foregoing experiments prove, at least, 

 that when the communication of the nerves 

 with the brain is wholly cut oft", they gradually 

 lose the power of exciting the muscles to con- 

 traction, while the muscles lose their irritability. 

 The result would, however, have been still 

 more decisive if, in place of a single pair of 

 plates, a small galvanic battery had been em- 

 ployed to stimulate the nerves and muscles. 

 That, and that alone, would have enabled us 

 to determine with certainty whether all the 

 power of the muscles, in two of the cases, had 

 been lost. The experiments as they were made, 

 however, prove distinctly enough the necessity 

 of communication with the brain for the pre- 

 servation of nervous and muscular power. We 

 may from them conclude also that if, after the 

 division of a nerve, the excitability of the lower 

 portion, and the irritability of the muscles are 

 restored, the nerve has itself been completely 

 reproduced ; and that this has not been- the 

 case if the nerve and muscle do not retain 

 their vital properties." 



I may here observe, that an experiment, si- 

 milar to those of Professor Mailer and Dr. 

 Sticker, in which Sir Astley Cooper assisted 

 the late Dr. Haighton, was made in this coun- 

 try many years ago, but never published. The 

 sciatic nerve was divided in a dog. In a few 

 days the lower portion had lost its power of 

 exciting muscular contraction. 



These statements appear, then, sufficiently 

 opposed to each other ; how shall we explain or 

 reconcile them ? Before I proceed to discuss 

 this question, I must beg the attention of the 

 reader to a third series of observations and 

 experiments, in a certain sense at variance with 

 both those which have been detailed. 



My own attention was first drawn to this 

 interesting point by the fact, well known to 

 physicians, that if we administer strychnine to 

 patients affected with paralysis, it is frequently 

 the paralytic limbs which first manifest the pe- 

 culiar influence of this powerful remedy. M. 

 Fouquier has, I believe, too hastily generalized 

 this effect of strychnine on the muscles of pa- 

 ralytic limbs. And how well do I remember 

 the same remark being made by M. Louis, as, 

 in our visit round his wards at La Pitie, we 

 came to a case in point. From that moment I 

 did not cease to revolve the question in my 

 mind, and to devise modes of observation and 

 experiment to solve it. Certainly the conclu- 

 sion of M. Segalas d'Etchepare, in regard to it, 

 is any thing but satisfactory. M. Segalas ob- 

 serves : 



" Ces experiences reunies autorisent done a 

 conclure que le tetanos produit par la noix vo- 

 mique a pour condition premiere de son deve- 

 loppemeut la presence du poison dans le sang, 

 et que les phenomenes qui 1'accompagnent sont 

 dus a 1'action anormale de ce fluide sur le sys- 

 teme nerveux. 



" Cette maniere de considerer 1'action de la 

 noix vomique donne un moyen simple d'expli- 

 quer les eftets de cette substance chez I'homme, 

 et particulierement ce fait si remarquable de la 

 contraction des muscles paralyses plus prompte 

 et plus energique que celle des muscles sains, 



fait observe d'abord par M. Fouquier,* et con- 

 state depuis par tant de praticiens du premier 

 ordre. 11 est facile, en eftet, de concevoir que 

 les muscles sains, soumis a la fois a 1'empire 

 du cerveau et a 1'action du poison, resistent a 

 cel!e-ci plus que les muscles paralyses, qui, 

 soustraits a 1'inrluence cerebrale, ne sont plus 

 commandes que par le poison." 



Upon these observations of M. Segalas, M. 

 Ollivier remarks "Mais s'il en est amsi, com- 

 ment se rendre raison d'un fait observe depuis 

 long-temps par tous les praticiens, et sur lequel 

 je viens d'appeler 1'attention, c'est que la noix 

 vomique cause souvent de violentes douleurs 

 dans les membres paralyses, sans apporter 

 aucun trouble dans les parties saines ? Pour- 

 quoi cette action speciale sur les seuls organes 

 paralyses ? et, d'un autre cote, la douleur 

 percue ne prouve-t-elle pas que les parties 

 paralysees ne sont point isolees entierement du 

 centre nerveux, et qu'ainsi ce ne peut etre h 

 cette inconstance qu'on doive attribuer la locali- 

 sation singuliere des effets de la strychnine ? " f 



It will soon be seen that this view, like a 

 former one, is far too general, far too indiscri- 

 minate that it is not in every case of paralysis, 

 that the strychnine would first display its in- 

 fluence on the paralytic limbs. Meantime, 

 however, I figured to myself the fact of the 

 strychnine acting on the spinal marrow, and 

 diffusing its power equally along the nerves, to 

 the right hand and to the left, to the muscles to 

 which they proceed respectively: and I asked 

 myself the question Is the difference observed 

 in its ultimate effects on those muscles, the 

 power being obviously the same, owing to a 

 difference in the degree of the irritability of the 

 muscular fibre itself? Is the irritability of that 

 fibre actually augmented ? If so, the pheno- 

 menon would be explained ! 



I waited with anxiety for opportunities of 

 submitting this question to the decision of ex- 

 periment. This I entrusted, in the first in- 

 stance, to my young friend and intelligent 

 pupil, Mr. Dolman. The result was as I an- 

 ticipated. A little child, aged two years, was 

 perfectly paralytic of the left arm. The slight- 

 est shock of galvanism was directed to be ap- 

 plied which should produce an obvious effect. 

 It was uniformly observed that the paralytic 

 limb was agitated by a degree of galvanic 

 energy which produced no effect on the healthy 

 limb. 



A similar patient, with paralysis of one leg, 

 was subjected to the same experiment by my 

 friend and former pupil Mr. W. F. Barlow, and 

 with the same result. 



I repeated the trial on several patients af- 

 fected with hemiplegia, at my own house, uni- 

 formly with the same event: the paralytic limbs 

 were always moved by an influence which was 

 lower than that required to affect the healthy 

 limb, or if both limbs were agitated, it was 

 uniformly the paralytic limb which was more 

 shaken than the other. 



* Memoire sur 1'emploi de la noix vomique dans 

 les paralysies, par M. Fouquier, 1815. 



t Traite de la Moelle Epiniere, 1827, p. 841. 



