MEMOIR OF MAGENDIE. 121 



the operation, I at length proceeded to open the cavity of the spine in a rabbit, 

 and I cut the posterior roots of the nerves of the inferior extremity ; the animal 

 could still move itself, but the cruelty of this dissection prevented me from re- 

 peating the experiment. I thought it would suffice to make it on an animal 

 newly stunned and insensible. I therefore struck a rabbit behind the ear, so as 

 to deprive it of sensibility by the shock, and then laid bare the marrow of the 

 spine. On irritating the posterior roots of the nerve, I could perceive no con- 

 sequent movement in the muscular tissue ; but when I proceeded to irritate the 

 anterior roots, there ensued, whenever the instrument touched them, a corre- 

 sponding movement in the muscles to which the nerve was distributed. These 

 experiments proved that the different roots, and the different columns whence 

 those roots proceed, are destined to different functions, and that the indications 

 furnished by anatomy were correct." 



It Avould be puerile and unworthy to dwell too much upon the faults of this 

 experiment, ever memorable as it is, as being the first. The author says that 

 " the cruelty of the experiment prevented him from repeating it." If he had 

 observed more closely what took place when he cut the posterior root, (and he 

 might have confined himself to irritating it, which would have been still less 

 cruel than cutting it,) he would have seen the animal give signs of distress ; 

 the indications of sensibility, of pain, would have manifested themselves, as they 

 always do in such cases, and, in this respect, everything would have been de- 

 termined. In the second place, to begin by stupefying the animal, by render- 

 ing it insensible, when sensibility was precisely one of the phenomena to be 

 verified, was no doubt the way to render the experiment less painful, but it was 

 also, with deliberate purpose, to render it insufficient and incomplete. It was 

 to instigate more complete ones, which would be made by others, and in effect 

 to multiply the chances of cruelty in place of diminishing them. 



And this was, in fact, what happened. The experiments of M. Bell were 

 everywhere repeated, and no one was more gratified thereat than himself. " I 

 have only to add," said he in 1825, (fifteen years after his first Essay,) "that 

 it has redounded to the satisfaction of all Europe, that these opinions and ex- 

 periments have been followed up. It has been recognized that the anterior 

 roots of tbe nerves of the spine excite muscular movement, and the posterior 

 roots sensibility. When, in an experiment, the anterior roots of the nerves of 

 the leg are cut, the animal loses all power over the leg, although the member 

 preserves its sensibility. But if, on the other hand, the posterior roots are cut, 

 the fiiculty of movement will still exist, although the sensibility be lost. If the 

 posterior column of the spinal marrow in an animal be irritated, it appears sen- 

 (sitive to the pain, but no similar effect is observed when the anterior column is 

 touched." 



Secoi\d epoch. — System or classification of the nerves. — In 1821 M. Bell 

 read to the Royal Society his first memoir on what he calls the natural system 

 of the nerves. His Essay of 1811 had passed almost without notice, as has 

 been just said. The present memoir produced a profound impression. It was 

 because the author at last addressed himself to the true judges, to a learned 

 company, and because by the very reading of his work he stimulated it to re- 

 flection. It was, besides, the first time that the light of physiology had pene- 

 trated into the study, until then purely anatomical, and until then wholly sterile 

 also, of the nerves properly so called. What had the anatomists of all countries 

 been doing, before M. Bell, in their researches on the different nerves ? They 

 had been emulously striving who should find some new ganglion or some un- 

 known nervous filament, without, however, attaching the least idea to that 

 ganglion or that filament. 



"As long as it is supposed," says M. Bell, "that the nerves proceed from a 

 common centre, that they have the same structure and the same functions, that they 

 are all sensitive, and that they all contribute to convey what is vaguely called 



