416 



Dr. C. S. Sherrington. Note on the [May 4, 



flexor was attended with, a descent of the weight, which indicated 

 the relaxation of the extensor. To establish this connection between 

 two classes of ranscles whether they be grouped near together, as in 

 the limbs, or scattered widely as the muscles of respiration, there 

 must be particular and appropriate nerves to form this double bond, 

 to cause them to conspire in relaxation as well as to combine in con- 

 traction. If such a relationship be established, through the distribu- 

 tion of the nerves, between the muscles of the eyelids and the 

 superior oblique muscles of the eyeball, the one will relax while the 

 other contracts." 



My experiments described above show the correctness of Bell's 

 supposition, at least as regards the external straight muscles, and 

 that the phenomenon of inhibition of activity under volition and under 

 appropriate cortical faradisation is not confined among the ocular 

 group of muscles to the recti externi, the observations made seem to 

 prove. For instance, I have divided the 6th cranial nerve of the left 

 side at its origin from the brain, and then examined the behaviour of 

 the eyeballs under suitable experimental conditions. The position 

 immediately assumed by the eyeballs was that of slight convergence 

 even when under aneesthesia (not very deep). Subsequently the 

 internal strabismus increased somewhat, to disappear, or almost dis- 

 appear, when the gaze was voluntarily turned to the right, but to be 

 greatly increased (i.e., the angle at which the optic axes crossed 

 becoming great) when the gaze was directed to the left. The left 

 eye under volitional movement frequently rotated from the inner 

 canthus outward conjugately with the right, but never passed beyond 

 the primary (median, straight-forward) position. On the gaze being 

 directed from the median primary position toward the right, the left 

 eye rotated conjugately with the right eye usually with an apparently 

 perfect symmetry of motion, but not unfrequently with a movement 

 slower and less ample than the right. On the gaze being directed 

 from the median primary position toward the left, the left eye did 

 not move at all, while the right eye moved of course normally. It 

 was frequently seen that the eyes remained turned to the right, 

 apparently resting in that direction ; it was so generally when the 

 animal was sleepy or dozing. When the gaze was directed from 

 that position over to the left, the movement of the left eye was not 

 unfrequently, so far as could be seen, perfectly conjugated and sym- 

 metrical with that of the right eye, as far as up to the middle line of 

 the palpebral fissure; there it stopped short, while the right eye 

 went a variable distance further. 



On excitation of the appropriate part of the frontal cortex of the 

 right side, both eyes being in the primary position or with a slight 

 degree of convergence at the commencement of the excitation, the 

 right eye swept sharply to the left, and the left either did not move 



