REFLEX ACTION OF THE SPINAL CORD. 307 



Bions may be thus dispersed, there can be no doubt, as we 

 shall see farther on. The phenomena under consideration 

 certainly point to an appreciation by the cord of the locality 

 of a powerful impression, and this could be manifested in an 

 animal only by an apparent muscular effort to reach the irri- 

 tated spot ; but we can hardly reason from this fact, that in 

 man and the higher animals, the spinal cord shares with the 

 brain the power of appreciating what we know as sensation 

 and of generating the stimulus of true voluntary movement. 

 If a sudden and very powerful painful impression be made 

 upon the surface in man under normal conditions, the hand 

 may be instantly applied to the affected part, apparently be- 

 fore we really appreciate the pain or have time to make a 

 distinct effort of the will ; but the connections between the 

 different parts of the cerebro-spinal axis do not permit us to 

 isolate the action of the cord. Certain it is that, in the higher 

 animals, after removal of the encephalon, and in experiments 

 upon decapitated criminals and patients suffering from para- 

 plegia, there is no evidence of true sensation or volition in 

 the spinal cord ; and in man and the higher animals, we 

 must regard all muscular movements which depend solely 

 upon the action of the cord as a nerve-centre as automatic 

 and entirely independent of consciousness and of the will. 



It is easy to determine, by experiments to which we have 

 already incidentally alluded, that the muscular movements 

 dependent upon nervous action, occurring in decapitated 

 animals, are due to the action of the spinal cord as a nerve- 

 centre. In an animal in which the reflex phenomena are 

 very marked, as they are after decapitation, especially if the 

 animal be poisoned with strychnine or opium, all movements 

 cease immediately when the cord is destroyed. That the 

 gray matter of the cord is the part concerned as a centre in 

 the production of these phenomena, is probable, in view of 

 what we know with regard to the general functions and 

 properties of this substance ; and experiments have shown 

 that this is the fact. If, in a decapitated frog, we make a 



