PHYSIOLOGY OF THE NERVOUS SYSTEM. 



721v 



flex, and these two kinds have an immediate 

 but unknown relation to each other, so that 



each afferent nerve has its proper efferent one, 

 the former being excitor, the latter motor. 



before the Royal Society on February the 16th and 

 23d, and March the 2d, 1837, but was not pub- 

 lished in the Transactions. This paper is entitled, 

 " On the true Spinal Marrow and the Excito- 

 motory System of Nerves." 



The object of this paper the author states to be 

 the developement of a great principle in physio- 

 logy that of the special function of the true spinal 

 marrow and of a system of excito-motory nerves. 



" It is this principle," he continues, " which 

 operates in all those actions which have been de- 

 signated sympathetic, which regulates the func- 

 tions of ingcstion and expulsion in the animal 

 economy, and which guards the orifices and sphinc- 

 ters of the animal frame." 



" The principle to which I allude," he proceeds, 

 " has been confounded with sensation, and vo- 

 luntary, and what has been designated instinctive, 

 motion, by all (sic) physiologists, with one single 

 exception (Sir Gilbert Blane). It has been sup- 

 posed to be a function of the rational (Stahl) or 

 irrational (Whytt) soul. It has been considered 

 by some (Haller, &c.) as attached to the brain; 

 by others (Whytt, Soemmering, Alison, Muller,) 

 as attached to the brain and spinal marrow ; by 

 others (Le Gallois, Flourens, Mayo,) as peculiarly 

 attached to segments of the spinal marrow ; it has 

 been viewed by others as the function of the sym- 

 pathetic (Tiedemann, Lobstein,) or of the pneu- 

 mogastiic nerve (Bell, Shaw) ; and, lastly, by 

 others as operating through identity of origin or 

 anastomoses of nerves (Mayo)." 



How very strange it is that amidst all the re- 

 search displayed in this paragraph, no mention 

 should have been made of Unzer and Prochaska, 

 the only authors who really had clearly stated the 

 correct doctrine respecting nervous phenomena in- 

 dependent of the mind ! ! 



In this paper Dr. Hali falls into the curious error 

 of affirming that the power which is developed in 

 the nervous system in connection with sensation 

 and volition, is different from that through which 

 the reflex actions are produced. To the latter he 

 limits the term vis nervosa, and, having quoted 

 Haller's very correct description of the course 

 which it takes in motor nerves, he affirms that his 

 researches have disclosed a series of phenomena 

 " directly at variance with the conclusions of 

 Haller." 



I confess myself quite unable to discover in what 

 respect Dr. Hall's results are at variance with the 

 laws of the vis nervosa as laid down by Haller. All 

 that the latter physiologist affirmed was that the 

 nervous force travelled from trunk to branches in 

 motor nerves, and that irritation of the spinal cord 

 caused convulsions of the limbs which derived their 

 nerves from below the point of stimulation. Now 

 these facts are strictly true by whatever stimulus 

 the nervous force is excited in motor nerves it travels 

 from trunk to branches ; and the statement made 

 by Haller respecting the spinal cord is equally true, 

 namely, that the motor force travels downwards, 

 and that irritation of the cord affects only the 

 limbs below the irritated point. All that Dr. Hall 

 has made out which is at variance with this pro- 

 position is, that sometimes the anterior extremities 

 may be thrown into action by stimulating that seg- 

 ment of the cord from which the posterior extre- 

 mities derive their nerves, from whence he con- 

 cludes that " the motor power in the spinal mar- 

 row will act in a retrograde direction." 



This conclusion, however, does not follow from 

 the experiments adduced in support of it. If the 

 spinal cord of a turtle be irritated in the segment 

 from which the nerves to the hinder extremities 

 spring, and all four extremities are thrown into 

 action by that stimulus, we are not authorized to 

 conclude that the motor power will act in the spinal 



marrow in a retrograde direction; all that we are 

 justified in affirming is that the same change which 

 would excite the nerves of the irritated part of it 

 may be propagated from its lower to its upper part. 

 How this takes place is uncertain, whether by sen- 

 sitive fibres or by commissural fibres, or by vesicular 

 matter, most probably by the last. 



It may, however, be stated that such phenomena 

 as those described take place chiufly in an excited 

 state of the cord, as when the animal is under 

 the influence of strychnine or in tetanus and 

 their occurrence is far from being in accordance 

 with a normal state of action of the spinal cord. 

 I have frequently irritated the cord in healthy 

 animals without producing any movements save 

 in parts below the point stimulated. (Vide supra, 

 p. 721G.) 



Dr. Hall in this paper draws the same conclusions 

 as in his work last referred to as to the existence of 

 a " true spinal marrow physiologically distinct from 

 the chord of mtra-spinal nerves ; of a system of 

 excito-motory nerves, physiologically distinct from 

 that of the sentient and voluntary nerves ; and of a 

 nervous influence the excito-motory power ope- 

 rating in directions incident, upwards, downwaids, 

 and reflex, with regard to the true spinal marrow, 

 the centre of this excito-motory system." When 

 Dr. Hall uses the term physiologically distinct, of 

 course he means, likewise, anatomically distinct. 

 One part cannot be physiologically distinct from 

 another without being anatomically so also. 



In the second section of this paper Dr. Hall gives 

 " a slight sketch of the opinions of physiologists 

 upon, the subject of this memoir." He alludes to 

 the views of Haller, Monro, Whytt, Blane, Le Gal- 

 lois, and the Reporters of the Institute upon Le 

 Gallois' Essay, Mayo, Flourens, Alison, and Mul- 

 ler, but makes no allusion to either Unzer or Pro- 

 chaska. 



I pass over the third, fourth, fifth, and sixth sec- 

 tions, and proceed to the seventh. Here the laws 

 of the excito-motory system are stated, and those 

 extravagant powers are attributed to it, which I 

 have in the text endeavoured to show it cannot 

 exercise. But, in addition, this system is made to 

 be the nervous agent of the appetites and passions ! 

 What strange confusion! that a system, devised as 

 the special centre of nervous actions independent 

 of the mind, should be the seat of phenomena 

 preeminently mental, and intimately connected 

 with sensation. 



The remainder of this essay consists of further 

 remarks on the anatomy, physiology, pathology, 

 and therapeutics of the excito-motor system, and 

 concludes with some observations on the ganglionic 

 system of nerves. 



In 1841 Dr. Hall published his work on the Dis- 

 eases and Derangements of the Nervous System. 

 In this work I am not a%vare that any new or addi- 

 tional fact has been stated not mentioned in those 

 already quoted. It includes a reprint of several 

 memoirs read to the Medico-Chirurgical Society. 



In 1843 a " New Memoir on the Nervous System" 

 appeared, dedicated to Professor Flourens as to 

 one " who has in his responsible office displayed 

 the most candid, impartial, and generous judgment 

 of the works of others." 



I find it necessary to notice an assertion con- 

 tained in a note to the advertisement of this work 

 Dr. Hall observes : 



" My first memoir was entitled, ' On the Reflex 

 Function of the Medulla Oblongata and Medulla 

 Spinalis.' This important function as the nervous 

 agent in all the acts of ingestion and of egestion in 

 the animal economy was previously unknown. It 

 is not mentioned by Whytt, or Prochaska, or any 

 other author ; who, however they may cite the 

 term reflex, or detail experiments, or treat of syni- 



