MEMOIR OF MAGENDIE. 123 



be guided,) there are three classes of nerves ; nerves purely motive, nerves purely 

 sensitive, and nerves at once motive and sensitive ; the first with a single and 

 anterior root, the second with a single and posterior root, the third Avith roots 

 both anterior and posterior. Never had a more vivid light been shed upon a 

 subject more obscure, confused, and, to use the received term, more inextricable. 



The nerves, then, are at length classified, and their classification may be called, 

 as M. Bell in fact calls it, .a natural classification ; for it is given at once by the 

 origin and the function — that is to say, by the two characters which are the 

 most sure, whether regarded in the light of anatomy or physiology. 



I have counted but three classes of nerves ; M. Bell makes four : it is because 

 I deliberately omit the great sympathetic, upon which he has bestowed too 

 little attention to make it worth mentioning here.* It has been seen, moreover, 

 that, besides the two columns of the spinal marrow, the anterior and posterior, 

 M. Bell admits a third, which he calls the lateral column. This third column, 

 which appeared to him so important, is at present, and with reason, regarded as 

 being at least very problematical. Of the five nerves which M. Bell considers 

 as springing from it, and which are the five respiratory nerves — the 2^(t.thetic, 

 thcyacial, the spinal, the 2)neu?nogastric and the glaso-p/iaryngian — the first 

 three spring from the anterior column and are exclusively motors ; the fourth 

 springs from two roots and is motive and sensitive ; the fifth springs from the 

 posterior column and is exclusively sensitive. 



To consider, then, only what is clear, established, and will be permanent in 

 the researches of M. Bell : the spinal marrow (and I do not here separate from 

 it the medulla oblongata) is composed of two columns, the one sensitive, the 

 other motive. All the nerves which spring from the sensitive cohimn are sensitive ; 

 all those which spring from the motive column are motors. From the origin 

 may always be inferred the Junction ; from the function may always be inferred 

 the origin ; and M. Bell was not deceived when, from the simple anatomical 

 diversity of origin, he had foreseen the physiological diversity oi function. 



Thikd epoch. — Discussion of M. Bell with M. Magcndie. — This discussion 

 relates to two points : first, the discovery of the proper functions of the roots ol 

 the nerves; and, secondly, the discrimination of the special functions of the 

 seventh and fifth pairs. 



In reference to the first point, M. Magendie read to the Academy, July, 1822, 

 a memoir in which he announced that having cut the posterior root of a nerve 

 in an animal, he had only abolished sensatio?i, and that having cut the anterior 

 root, he had only abolished movement. This result was received with the ad- 

 miration merited ; but some months later M. Magendie read a second memoir, 

 in which he retracted all that he had said and discredited all that he had done. 

 Each root was no longer exclusively sensitive or motive ; each was both one and 

 the other : only, the anterior root was more motive than sensitive, and the pos- 

 terior more sensitive than motive. 



There could scarcely have been a greater advantage offered to j\I. Bell. 

 Hence, in a note which he attributes to a pupil, a pretence which could not but 

 render recrimination more easy and acrimonious, ]M. Bell incessantly presses his 

 adversary with this dilemma : Either, he says to him, you adhere to your former 

 memoir, and then I have over you a priority of at least ten years ; or you abide 

 by the second, and there is then nothing in common between us, no longer any 

 subject of debate ; I maintain the exclusiveness of action of each root, and you 

 return to the old idea of the accumulation ot two actions in each. What reply 

 could there be to this reasoning ? As a man of sense, M. Magendie did not 

 reply at all ; he did much better ; he made a new discovery, and one fully as 

 difficult at least as the first : he discovered the recurrent sensibility. 



* He regaidecl it as the lien " which seems to iiuite the three other orders of nerves (those 

 of sejisation, those oi voluntary movement, and those of the respiratory movement) and the 

 body itself in one whole." {Natural System, &c., p. 5.) 



