264 Mr. J. S. R. Russell. On the Nerve Roots of 



whom I have divided the 2nd sacral nerve roots have, up to the pre- 

 sent, had plexuses resembling the " prefixed " class. I have great 

 difficulty in understanding how Sherrington finds any given muscle 

 represented in so many more nerve roots, as a rule, than I do, and y 

 conversely, how he finds so many more muscles, and, in consequence, 

 movements, represented in certain roots. As an instance, the tibialis 

 anticus is stated to be represented in the 5tb, 6th, and 7th lumbar 

 nerve roots, while I have only found it represented in the 5th and 6th 

 lumbar roots. Then, again, the 1st sacral nerve root in the " pre- 

 fixed " class of plexus, which corresponds most closely to the type of 

 plexus I have most commonly met with, is said to produce extension 

 at the hip with slight rotation outward of the thigh, flexion at the 

 knee, extension at the ankle, strong flexion and abduction of the 

 hallux and flexion of the digits in " interosseous " position ; whereas, 

 like Ferrier and Yeo, the only movements I have found most con- 

 stantly represented in this root have been interosseal flexion of the 

 digits, with flexion and adduction of the hallux. 



The only way in which I can account for these very great differences 

 in our results is by supposing that while I have only included those 

 roots in which a given muscle is most commonly met with, and those 

 movements, or muscles, most commonly met with in any given root, 

 Sherrington has included every variation ; for, as an example, all the 

 movements mentioned by him as represented in the 1st sacral root, I 

 have found represented in that root in rare instances, but never all 

 represented together in any single animal. The movements most 

 commonly met with in any single animal were those already men- 

 tioned, and when variation occurred it consisted in one or other of 

 the other movements being added to these. 



If I am correct in my interpretation of Sherrington's classification 

 of results, I cannot help feeling that that which I have adopted is 

 more instructive and less likely to lead to confusion. 



With regard to the question whether the limb plexuses have an 

 anatomical or physiological significance, I find it difficult to believe 

 that the developmental processes which bring about these arrangements 

 of nerve fibres do so on a purely anatomical basis without regard for 

 physiological combination. Because excitation of a given nerve root 

 with the induced current evokes a movement which may not resemble 

 a natural one is to me no argument against the possibility that in 

 this nerve root nerve fibres destined for the supply of certain groups 

 of muscles are combined in such proportions as they are likely to 

 be required in certain natural movements. The point is one which is 

 exceedingly difficult to test by experiment, and those instituted by 

 Sherrington with a view to solving this problem do not appear to me 

 to be conclusive. 



The facts that muscles or groups of muscles are represented in such 



