484 Prof. C. S. Sherrington. [Jan. 31, 



of the action of exciting stimuli during the period of inhibition. It is a 

 "successive spinal induction" following upon inhibition, just as in the 

 instance previously given. 



Fig. 3. — Knee-jerks. The knee-jerks were elicited by taps of equal intensity delivered at intervals 

 signalled by a metronome. During the time marked by the signal the afferent nerve of a 

 flexor muscle of the knee was weakly faradised. This inhibitory stimulus depressed the 

 knee-jerk. After the inhibitory stimulus was discontinued the jerks increased to beyond their 

 amplitude prior to the inhibition ; this increase is accompanied by a tonic after-action following 

 each jerk. Time registered above in seconds. 



In the " scratch-reflex," after its inhibition by the crossed extension-reflex, 

 or the homonymous flexion-reflex, a similar after-exaltation is sometimes 

 seen. Fig. 4 exemplifies such an occurrence. But the time of interruption 

 of the reflex has usually in my records been too short to allow much scope 

 for the development of successive spinal induction, and the quick tiring of 

 the scratch-reflex under electric excitation is unfavourable to examining it 

 there. 



