1909.] 



Innervation of Antagonistic Muscles. 



267 



old prominence. Finally, the contralateral stimulus is withdrawn and the 

 extensor's contraction gradually passes away. After a minute's pause the 

 observation was repeated with unaltered intensity of the stimuli, but with 

 reversal of their sequence. The ipselateral stimulus precedes and produces 

 its unopposed effect ; this stimulus still remaining in operation, the contra- 

 lateral stimulus is now combined with it and remains without visible 

 influence on the myogram, although what its unopposed effect would be 

 is guaranteed by the just preceding observation. This comparatively easier 

 suppression of the contralateral reflex by the ipselateral than of the 

 ipselateral by the contralateral explains how it is that when similar afferent 

 nerves of both hind limbs or similar points of skin in the limbs are 

 simultaneously and similarly stimulated extension occurs in neither limb and 

 flexion occurs in both.* 



The effect of fairly strong and equal concurrent stimulation of symmetrica] 

 afferents of the two limbs in giving flexor effect at both knees, whereas 

 stimulation of one of the afferents gives flexion at ipselateral knee and 

 extension at contralateral, recalls strikingly a result obtained by Mott 

 and Schaferf on the eyeball movements under concurrent stimulation of 

 balanced points of the two cerebral hemispheres right with left. Stimulation 

 of the cortex of one hemisphere gives lateral deviation of both globi to the 

 opposite side. It has been shownf that in this movement reciprocal inner- 

 vation is at work producing inhibition of one muscle with excitation of its 

 antagonist. Mott and Schafer found concurrent stimulation of points in the 

 two hemispheres produce, when appropriately graded, a convergence of the 

 two globi. Here, obviously, of the two antagonistic influences, that on the 

 ipselateral globus preponderates over that on the contralateral, just as in the 

 case of the limbs the ipselateral reflex preponderates over its antagonistic 

 contralateral. And in the eyeball result, just as in the result on the limbs, I 

 imagine that appropriate analysis would reveal in this case an algebraic 

 summation of excitation and inhibition just as with the flexor and extensor 

 knee muscles. In short, in both cases antagonistic reactions are adding them- 

 selves with plus and minus signs. 



VI. — It will be noted that the ipselateral afferent, just as it is prepotent in 

 excitation, so also is prepotent in inhibition. This supports the view put forward 

 in these Notes§ that the inhibition and the excitation are complemental 



* Sherrington, article " Spinal Cord," ' Schafer's Text-book of Physiology,' vol. 2, p. 840, 

 1899 ; also ' Integrative Action of Nervous System,' p. 225, 1906. 

 t 'Brain,' vol. 13, p. 170, 1894. 



\ Sherrington, ' Eoy. Soc. Proc.,' Note II, vol. 53, p. 411, 1893. 



§ Sherrington, ' Eoy. Soc. Proc.,' Note VIII, vol. B 76, p. 277, 1905. 



U 2 



