274 Mr. Graham Brown and Prof. C. S. Sherrington. [Mar. 16, 



elicited from the pre-central convolution, producing, so to say, an echo of the 

 pre-current response, but this dies out usually after the first repetition. 



VIII. After-Discharge subsequent to the Eesponse of a Cortical 

 Point. 



(a) Tonic After-Discharge. 



Among the forms of after-action (attached to the responses) evoked by 

 cortical stimulations one commonly met with is what may be termed " tonus 

 remainder." This was noted by Bubnoff and Heidenhain in certain degrees 

 of morphia-action in the dog ; they speak of the phenomenon as contracture.* 

 It resembles closely the shortening reaction observable in reflexes evoked 

 during decerebrate rigidity. It differs from that, however, (1) in being less 

 complete, i.e., in less completely maintaining the full amplitude of the con- 

 traction on which it supervenes, and (2) in appending itself to flexor as well 

 as to extensor contractions (figs. 3, a, b ; 4 ; 5 ; 16), whereas in decerebrate 

 rigidity it is only the extensor contractions which exhibit the post-stimulatory 

 continuance. Conversely, just as in decerebrate rigidity a lengthening 

 reaction appends itself to and prolongs a reflex relaxation, so too after 

 cortical inhibitory relaxations a relaxation remainder persists as a common 

 after-effect. Here also the appended remainder does not so nearly equal the 

 full relaxation it follows as it does in decerebrate rigidity. And here too it 

 appends itself in the cortical reactions both to flexor and to extensor effects : 

 whereas in decerebrate rigidity it appends itself to extensor alone. 



The degree of tonus in the antagonistic muscles is reciprocal; and the 

 influence of a cortical point on the tonus as seen in the effect of stimulation 

 of the point is also reciprocal (figs. 2, 3, 4). 



(b) Epileptoid After-Discharge. 

 Epileptoid after- discharge of limited distribution has occurred not 

 infrequently in our experiments. It has been frequently observable that the 

 epileptiform clonic discharge following upon stimulation of an F point or an 

 E point is confined as far as the muscles under examination by the myograph 

 are concerned to one of the antagonists (figs. 6, 8, 11, 14, 16). We have more 

 than once seen that an epileptoid discharge in the flexor muscle following 

 on stimulation of a flexor cortical point is increased by subsequent stimulation 

 of an extension cortical point (fig. 8), while restimulation of the flexion 

 cortical point diminished the epileptoid discharge during the period of the 

 stimulation (fig. 11). 



* 1 Pfluger's Archiv,' 1882, vol. 26, p. 136. 



