418 



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



Faradisation of the left occipital cortex directed both eyes to 

 the right with a slight downward or slight upward inclination or 

 without any inclination, according to the area excited (Schafer, 

 Munk). Faradisation of the right occipital cortex, if both eyes were 

 approximately in the primary position, caused the right eye to be 

 slowly and steadily turned to the left, and the left eye to be steadily 

 brought fully up to the medium primary position if it were not 

 already in it ; if already fully in the primary position the left eyeball 

 did not move at all. If the left eye moved at all it very generally 

 started its movement distinctly before the right eye and appeared to 

 rotate less slowly than did the right. This difference was best seen 

 if the eyes were previous to the excitation resting in a direction to 

 the right. On then faradising with weak or moderate currents 

 the left occipital cortex the steady slow rotation of the left eye 

 commenced so much before that of the right that sometimes the 

 left had travelled half-way to the primary position before the right 

 eye had well started. Under excitation of the right occipital cortex 

 the movement of the left eye toward the left seemed so clearly 

 stronger, sharper in starting, and even quicker and steadier than 

 under excitation of the right frontal cortex, that I attempted to 

 balance it against the movement to the right produced from the left 

 frontal cortex. On each occasion, when tested, I found that, the two 

 eyes being kept directed to the right by moderate excitation of the left 

 frontal cortex, they could be sent over to the left again by moderate 

 or strong excitation of the right occipital cortex, and in each instance 

 the left or paralysed eye was again the first to start travelling. Three 

 similar experiments gave results quite similar to the above in the 

 points mentioned here. 



In two experiments, one on a small Rhesus and one on a large 

 Sinicus, I have combined with section of the left 6th nerve section of 

 the left 4th nerve at its exit from the brain. The results obtained 

 agreed in many respects with those obtained when the 6th nerve 

 alone was severed. Points of difference were the following : — In the 

 median position of rest the left eye was turned slightly upward as 

 well as inward. On excitation of the right frontal cortex, the eyes 

 starting in the primary position, the right eye was turned to the left 

 side and the left eye was turned upward, more or less amply, rarely 

 not at all ; the left eye was never observed to rotate to the left beyond 

 the primary median position. When particular points in the right 

 frontal cortex had been found which directed the eyes not merely to 

 the left but upwards also, on stimulation being applied the left eye was 

 turned upward to a greater degree than was the right. When places 

 were found in the right frontal cortex which directed the right eyeball 

 downward as well as to the left, occasionally the left eye moved a little 

 downwards ; more usually it moved distinctly upwards, so that there 



