THE NEKVOUS SYSTEM 315 



profoundly affects the reflex actions which the spinal cord can 

 carry out, and also its capacity as a conductor. Once in his 

 life, perhaps, a man passes a gall-stone ; for generations such 

 a thing may not have happened in his family. Yet the man 

 finds that he is provided with a nervous apparatus which 

 conveys to consciousness intensest pain. 



It is difficult to think of pain as travelling along nerves in 

 the form of rhythmic impulses, similar to those which produce 

 in consciousness the effects which we have distinguished as 

 sensations. A few lines above we stated that no impulses which 

 affect consciousness normally travel up the vagus or the sympa- 

 thetic nerve, limiting the term " impulse," perhaps unjustifi- 

 ably. The vagus conveys an influence which enters our 

 experience, as hunger. Probably other states of feeling for 

 which we have no names, which resemble pain and hunger and 

 their opposites, are set up through the agency of visceral 

 nerves. 



Fifty years ago attention was called to the difficulty of 

 finding pain-paths amongst the white tracts (nerve-fibres) of 

 the spinal cord. It is as difficult to point them out now as 

 it was then ; but the inference that pain travels up the grey 

 matter has given way to the " neurone theory "; under a 

 misapprehension as the writer holds. Pain travels slowly. 

 If one happens to notice a person who unsuspiciously touches 

 a hot surface, one observes that an interval elapses between 

 contact of his finger with the iron and the exclamation with 

 which he " relieves his feelings." It amounts to more than a 

 second if the iron is not very hot, to several seconds whereas 

 the " reaction time " for touch is only one seventh of a second. 

 The slowness of movement of pain through the nervous system 

 can on the neurone theory be explained only on the hypothesis 

 that it travels from link to link along a very long chain of very 

 short neurones. That pain is a state of the grey matter 

 rather than a succession of impulses, and that (within the 

 cerebro-spinal axis) the state is transmitted through an extra- 

 neuronic medium, seems a simpler explanation. 



The state set up in the segment of the cord in which afferent 

 fibres, conveying pain from viscera, embouch affects its con- 

 ductivity. It subdues reflex action through the segment, and 

 at the same time facilitates or reinforces the transmission of 



