6y8 



A MANUAL OF PHYSIOLOGY 



the first to make the decisive experiment necessary to show 

 that they are the conductors of sensory impulses. 



When the posterior roots are divided, loss of sensation 



b ral 



Corte 



of Pur am* 



Filrt of Direct_ 

 Pyramidal track. 



Nerve- Cells 





I j Medulla 

 fl/ Oblong at a 



srF ^Rtcrcsse dFi Ire ?\ 



\ ______ '_'.'.. j Uncrossed Fibre. ] 



\ /' Spinal 



J' Ccrd 



Anterior 

 \Rool- 



ctroundCell of 

 Ant. Horn 



Par/is 



FIG. 253. SOME POSSIBLE PATHS OF EFFERENT IMPULSES IN THE CENTRAL 

 NERVOUS SYSTEM (SCHEMATIC). 



Details are omitted from the scheme. For instance, each pyramidal fibre is repre- 

 sented as arborizing around one anterior cornual cell only, and no collaterals are shown. 



occurs in the region to which they are distributed. If only 

 one root is cut, the loss of sensation is never complete in 



