516 REPORT— 1897. 



III. The Activity of the Nervous Centres ivhich correlate Antagonistic Mii^s- 

 cles in the Limhs. By Professor C. S. Sherrington, M.D., F.R.S. 



The recent results of histology in regard to the nervous system have 

 brought with them the view that the physiological continuity between 

 nerve cell and nerve cell does not involve anatomical continuity of the 

 nerve cells. The theory of cellular contact put forward by Forel and 

 Golgi has received a large amount of confirmation from subsequent 

 Avorkers, as Cajal and KoUiker. The place of linkage between nerve cell 

 and nerve cell — the synapsis as it is termed by Professor Foster — is a 

 place where the conduction of nervous impulses is supposed to occur 

 across an intervening substance. This character in the construction of 

 the chain of conductors has given rise to speculation as to possibility of 

 increase or decrease of difficulty for conduction along a given line due to 

 alteration at the gap between adjacent links in the chain. 



Various histologists (Renaut, Demoor, Duval, Solvay, Lepine, <fec.) 

 assert that the cells of the nervous system possess, to a certain degree, the 

 power of contractility of their processes. Cajal thinks that the neuroglia 

 cells are certainly contractile, probably more so than the nerve cells 

 proper. These authors speak of the expansion and retraction of the 

 branches of the nerve cell. Certain drugs which depress nervous action, 

 such as chloroform and chloral, and certain conditions such as fatigue 

 and sleep, are described as producing or being accompanied by retraction 

 of cell branches in the nerve cells of cortex cerebri, cerebellum, and 

 elsewhere. The retraction of the cell processes is supposed to withdraw 

 the cell from its connections with its neighbours. Interruptions in the 

 chains of conduction for impulses can thus be brought about. There is 

 much that is at any rate simple in this view, and I have attempted to 

 apply a test to it in the case of a certain place of linkage in the spinal 

 cord. 



A place of linkage as well known perhaps as any in the central 

 nervous system is that between the afferent fibre of the sensory spinal 

 root and the motor nerve cell of the ventral horn of the spinal cord. I 

 have attempted to examine what happens when the conduction across this 

 link becomes under certain circumstances difficult. It is well known that 

 to judge by their reflex effects afferent nerve fibres are more easily 

 excitable through their end organs than from their cut ends ; in other 

 woi'ds, reflexes are more easily elicitable from the surfaces of the skin 

 than from the cut ends of cutaneous nerves. The depression of function 

 in this case seems to occur at the synapsis between the spinal end of the 

 afferent fibre and the motor cell of the ventral horn with which it is 

 .usually in facile connection. It may be because the severance of the 

 nerve fibre breaks that tonic action (postulated in it as the basis of 

 muscular tonus) which streams along it inwards from its peripheral 

 vsensifacient endings. Some peculiar depression of conductivity does seem 

 to be produced between it and the motor horn cells, for the section of 

 the afferent roots to a spinal region renders extremely difficult the obtain- 

 ing of a reflex from the ascending stem of the root-fibres that have been 

 transected — that is, the connection between the afferent spinal fibre and 

 the motor spinal cell becomes more difficult in consequence of mere sever- 

 ance of the afferent spinal fibre from its own parent cell. The question I 



