462 On the Nerve Roots of the Lumbosacral Plexus. [May 18, 



the nerve fibres so as to exclude the possibility of diffusion of the 

 current. 



The same muscle is represented in more than one nerve root, 

 usually two, and to an unequal extent in these. And when variation 

 is met with it is a rule that one of the nerve roots in which the 

 muscle is represented is different, rather than that it is represented in 

 more nerve roots. 



When the same muscle is represented in two nerve roots, the 

 muscle fibres innervated by one root are not innervated by the other, 

 so that only part of the muscle contracts when a single root is 

 excited. 



A b lation Experim ents. 



Division of any given nerve root produces paresis of the group of 

 muscles supplied by it, which paresis is temporary, nearly all of it 

 being recovered from. The amount of paresis or paralysis produced 

 is proportional to the number of nerve roots divided ; and this again 

 varies according to whether the roots divided are consecutive or 

 alternate ones, the effect being much greater in the former than in 

 the latter case. Such division of one or more nerve roots does not 

 result in incoordination of the remaining muscular combinations 

 represented in other nerve roots ; the remaining movements are 

 merely more feeble. 



Exclusion of a certain Root or Eoots during an Epileptic Convulsion in 



the Limb. 



Division of one or more nerve roots produces alteration of the 

 position of a limb daring an epileptic convulsion, which altered 

 position depends on the muscular combinations that have been thus 

 thrown out of action. And the effect is identical when the root or 

 roots are divided at the time when the convulsions are evoked and 

 when they have been divided some weeks previously. No incoordina- 

 tion is produced in the remaining muscular combinations ; and there 

 is no evidence of overflow of the impulses which ought to travel 

 down the divided root, into other channels through the spinal centres, 

 so as to reach the muscles by new paths. 



