NERVE 



109 



It must be remembered that the nerve ribres of the 

 spinal cord do not regenerate, since they have no neuro- 

 lemma! sheath. 



Fig. 47 shows where the degenerated fibres are found 

 in each case. 



1. Section of the posterior roots leads to degeneration 

 extending up in the posterior columns. 



ToCeribeuuh 



Fig. 48. — To show Redistribution of Impulses in the Cord and the general 

 course of impulses of different kinds. 



2. Section of the cord leads to this, and, in addition, to 

 a zone of defeneration round the lateral and anterior 

 columns. 



The conclusions to be drawn are — (1) that the fibres of 

 the posterior columns are a direct continuation of the 



