CHAP, v.] THE SPINAL CORD. 607 



an inhibitory action on the generation of sensory impulses, more 

 particularly of those more complex impulses which we have 

 supposed to arise in the local mechanism of grey matter with 

 which the posterior roots are connected. In other words, this 

 one-sided exaltation of sensation may be compared to the general 

 increase of reflex action which occurs in the spinal cord after 

 removal of the brain. But we cannot enter into the full discussion 

 of this matter here. 



Much discussion has arisen on the question whether the spinal 

 cord itself is irritable towards stimuli other than nervous, that 

 is whether it can be excited by electric and other stimuli applied 

 directly to it. Undoubtedly, the cord, as a whole, is irritable ; 

 if two electrodes be plunged into it, and a current sent through 

 it, muscular movements, arterial constriction, and other results, 

 follow. But in such a case, the current may fall into nerve- 

 roots, which are as irritable, at least, as the nerve-trunks. But 

 even if the nerve-roots be eliminated, the white matter at 

 least is irritable; for it has been found that movements result 

 when the anterior columns are isolated for some way down and 

 stimulated with an electric current. With regard to the grey 

 matter it has been maintained that though it will convey both 

 motor and sensory impulses, it cannot originate them. It has 

 accordingly been spoken of as kinesodic and cesthesodic, as simply 

 affording paths for motor and sensory impulses. But the argu- 

 ments urged in support of this view cannot be regarded as 

 conclusive. 



