262 . Mr. J. 8. R. Russell. On the Nerve Roots of 



general convulsions were evoked is attended with the same results as 

 when the section is done at the time when the convulsions are 

 induced. I accordingly divided the 4th and 6th lumbar roots . on 

 one side, ten days before the day on which I proposed to excite the 

 cortical discharge ; and I divided the same roots on the opposite side 

 at the time when the general convulsions were evoked. The result 

 was that the positions of the two limbs were identical during the 

 convulsions. The result of this experiment was confirmed by similar 

 experiments with different combinations of nerve roots. 



This method of experimentation was first employed by me in the 

 investigation of the nerve roots which enter into the formation of the 

 brachial plexus of the dog ; and, as I have before pointed out, it 

 serves the double purpose of being a means of checking the results of 

 direct stimulation experiments, and of affording us the power of 

 ascertaining whether elimination of a root does or does not result 

 in incoordination of the remaining combination of movements. The 

 results obtained by its use have abundantly confirmed those obtained 

 by stimulating the individual nerve roots ; and also prove that the 

 coordination of the movement produced by the remaining roots is 

 not in the slightest degree affected by the elimination of one or more 

 of them. They also make it clear that there cannot be overflow of 

 nerve impulses through the spinal centres, at any rate to any great 

 extent, i.e., impulses which should reach the muscle through the 

 nerve root that has been divided do not under these circumstances 

 reach them by other commissural channels. 



Discussion of Results. Conclusions. 



Stimulation Experiments. A comparison of the results obtained by 

 Ferrier and Yeo, those by Sherrington, and my own, shows that there 

 is considerable difference of opinion as to which is the highest nerve 

 root in the lumbar series excitation of which produces movement in 

 the posterior extremity of the monkey. We are all agreed that 

 flexion at the hip is the first movement of the limb evoked as we 

 excite the lumbar roots from above downwards, but Ferrier and Yeo 

 regarded the 4th lumbar as the first in the series from above down 

 excitation of which caused this movement, whilst Sherrington states 

 that in both types of plexus which he has described this movement 

 was produced by excitation of the 2nd lumbar root, though it was 

 feeble in the case of the " postfixed " class of plexus. In no instance 

 have I observed this movement when the 2nd lumbar root was 

 stimulated, the 3rd lumbar being the first root in the series from 

 above down in which I have observed this movement to be repre- 

 sented. 



Extension at the hip Ferrier and Yeo found represented in the 5th 



