1912.] Instability of Cortical Points. 



271 



of the nervous system throughout a whole series of centres dealing with the 

 locality whence the excited afferents proceed. 



The mutual influence of the peripheral stimulus (afferent nerve) and 

 cortical point on each other's responses depends largely on the relative 

 intensities of their stimulations. Thus the effect of the cortical E point 

 can be wholly reversed by the stimulation of the afferent nerve with certain 

 intensities of stimulation. But with stronger stimulation of the E point its 

 own usual effect can be made to break through, and for a time wholly 

 suppress that of the afferent nerve. There are intermediate degrees in which 

 the E point's effect, although initially reversed, quickly returns subsequently 

 to its own usual character and subtracts from that of the peripheral nerve 

 and even wholly suppresses it. 



VI. The Effect of Concurrent Stimulation of Two Cortical Points 



In some of the experiments the stimulation apparatus has been so arranged 

 as to allow of faradisation of two cortical points at the same time. We have 



Experiment 15, CaZlothrix, 4.3.12. — In this record a cortical F point (C — D) is stimulated, 

 and during the period of stimulation a cortical E point (E — F) is concurrently stimulated. 

 It will be seen that during the F reaction the E stimulus produces a flexor relaxation and 

 a late extensor contraction. 



Antagonistic to Each Other. 



Fig. 17. 



