588 NERVOUS SYSTEM. 



that an authorized reprint can be so readily consulted, it is only necessary to refer to 

 this to show that Bell did not at that time regard the anterior roots as motor and the 

 posterior roots as sensory, hut that he thought that the anterior roots were for both 

 motion and sensation and the posterior roots presided over " the secret operations of 

 the bodily frame, or the connections which unite the parts of the body into a system." 



In August, 1822, Magendie published his first experiments upon the functions of the 

 roots of the nerves. Unlike any of the observations made by Charles Bell upon the 

 spinal nerves, these were made upon living animals. The spinal canal was opened, and 

 the cord, with the roots of the nerves, was exposed. The posterior roots of the lumbar 

 and sacral nerves were then divided upon one side and the wound was united with 

 sutures. The result of this observation was as follows : 



u I thought at first that the limb corresponding to the divided nerves was entirely 

 paralyzed ; it was insensible to pricking and to the most severe pinching, it also appeared 

 to me to be motionless ; but soon, to my great surprise, I saw it move in a very marked 

 manner, although the sensibility was still entirely extinct. A second, a third experi- 

 ment, gave me exactly the same result ; I commenced to regard it as probable that the 

 posterior roots of the spinal nerves might have functions different from the anterior roots, 

 and that they were more particularly devoted to sensibility." 



The experiments in which the anterior roots were divided were no less striking : 



" As in the preceding experiments, I only made the division upon one side, in order 

 to have a term of comparison. One can conceive with what curiosity I followed the 

 effects of this division ; they were not at all doubtful, the limb was completely motion- 

 less and flaccid, while it preserved a marked sensibility. Finally, that nothing should be 

 neglected, I divided at the same time the anterior and the posterior roots ; then followed 

 absolute loss of sensation and of motion." 



From these experiments Magendie drew the following conclusions : 



" I am following out my researches, and shall give a more detailed account of them in 

 the following number ; it is sufficient for me to be able to announce at present as positive, 

 that the anterior and the posterior roots of the nerves which arise from the spinal cord 

 have different functions, that the posterior seem more particularly devoted to sensibility, 

 while the anterior seem more especially connected with motion." 



In the second note, published in the same volume of the Journal de physiologic 

 (1822), Magendie exposed and irritated the two roots of the nerves, with the following 

 results : 



" I commenced by examining in this regard the posterior roots, or the. nerves of sen- 

 sation. The following is the result which I observed : on pinching, pulling, or pricking 

 these roots, the animal manifested pain ; but this was not to be compared as regards 

 intensity with that which was developed if the spinal cord were touched, even lightly, 

 at the point of origin of the roots. Nearly every time that the posterior roots were thus 

 stimulated, contractions were produced in the muscles to which the nerves were distrib- 

 uted ; these contractions, however, are not well marked, and are infinitely more feeble 

 than when the cord itself is touched. When, at the same time, a bundle of the posterior 

 root is cut, there is produced a movement in totality in the limb to which the bundle is 

 distributed. 



" I repeated the same experiments on the anterior roots, and I obtained analogous 

 results, but in an opposite sense ; for the contractions excited by the contusion, the prick- 

 ing, etc., are very forcible, and even convulsive, while the signs of sensibility are hardly 

 visible. These facts are, then, confirmatory of those which I have announced ; only they 

 seem to establish that sensation is not exclusively in the posterior roots, any more than 

 motion in the anterior roots. Nevertheless, a difficulty may arise. When, in the pre- 

 ceding experiments, the roots had been cut, they were attached to the spinal cord. Might 

 not the disturbance communicated to the cord be the real cause either of the contrac- 

 tions or of the pain which the animals experienced ? To remove this doubt, I repeated 



