460 Mr. J. S. R. Russell. On the Nerve Boots of [May 18, 



merits led to the observation of the alteration in the action of the 

 posterior extremity in progression, in cjimbing or in standing, evoked 

 by section of one or more nerve roots. A second method of control 

 consisted in the observation of the influence of section of a root or 

 roots in excluding part of an epileptic spasm induced in the limb by 

 intravenous injection of absinthe. As a qorollary to this, the question 

 as to whether the results differed in any way when the section of the 

 root or roots was made some time previously, or at the time when 

 the general convulsions were evoked, was tested. Special attention is 

 called to the advantages of this method of experimentation, made use 

 of by the author in a former research, but otherwise not yet adopted 

 by other investigators. 



Excitation Experiments. 



In discussing the results obtained by this method of experimenta- 

 tion the discrepancies which exist between the results obtained by 

 Ferrier and Teo, by Sherrington, and by the author respectively, are 

 pointed opt. With regard to the upper limit at which nerve fibres 

 leave the spinal cord for the supply of the lower limb, the first of 

 these observers are held to have placed the limit too low, while 

 Sherrington has placed it too high, the author finding that the 3rd 

 lumbar root is the highest which supplies nerve fibres to muscles 

 acting directly on the limb. The author agrees with Ferrier and Yeo 

 in considering the 1st sacral' nerve root the lowest of the series 

 which contributes nerve fibres to the limb, and he has never found 

 the 2nd sacral nerve root supplying the limb even in that class of 

 plexus designated "postfixed" by Sherrington, in which, according 

 to this observer, the 2nd sacral sends a branch to the sciatic nerve. 



Great difficulty is experienced in attempting to reconcile Sherring- 

 ton's results with those obtained by the author, as regards the 

 number of nerve roots in which a given muscle is represented, and, 

 conversely, the number of muscles and, in consequence, movements 

 represented in certain roots ; unless it be that Sherrington has in- 

 cluded every variation, while the author has only included those 

 roots in which a given muscle is most commonly represented and 

 those movements or muscles most commonly found represented in any 

 given nerve root. 



The author does not think that the developmental processes which 

 bring about the arrangement of nerve fibres do so on a purely 

 anatomical basis, without regard for physiological combination ; and 

 arguments in support of this view are adduced. 



Contrary to the observations of Sherrington, who found that each 

 bundle of nerve fibres which contributes to the formation of a nerve 

 root represents, as it were, a miniature root, containing nerve fibres 



