170 Ley ton and Sherrington 



inferius, which contains representation of the neck. The eyeball move- 

 ment has always been conjugate deviation of both eyes to the opposite 

 side. It has, in our experience, almost always been accompanied by eyes- 

 opening. Our inference from our experience of it is, that in the anthropoid 

 cortex there is no focus in the precentralis motor field which represents 

 eyeball movements in the same relatively direct way as do foci therein 

 represent movements such as those of hand, face, neck, etc., regularly 

 elicitable from the precentralia. We regard the eyeball -turning movement 

 occasionally elicitable from the inferior genual portion of precentralis as 

 secondary to the neck-turning foci, in the same way as we regard the eye- 

 opening elicitable from the same portion as secondarily associated with the 

 neck-turning foci. 



As regards the eyeball-turning movement obtainable from the frontal 

 region, this may be unaccompanied by eye-opening, especially so in the 

 upper part of the region, in our experience. The eyeball-turning is easily 

 detectable although the lids remain closed, the movement of the balls being 

 obvious under the shut lids. 



We are disposed to regard the neck-turning elicitable from precentralis 

 motor region as a protective movement mainly associated with closure of 

 the eyes. The neck-turning movement elicitable from frontal region and 

 from occipital region seems connected with the management of the direc- 

 tion of the gaze. 



2. Neck Area. 

 The area in which neck movements as primary or isolated responses 

 are elicitable is, in our experience, small. The movements are closely 

 associated with that of closure of opposite eye, and the movement is almost 

 invariably one which turns the face away from the side to which the 

 stimulated hemisphere belongs. We have not met with indubitable "re- 

 traction " of the neck, although in an orang in which tetanus had been 

 induced by inoculation wnth tetanus toxin, H. E. Roaf (36) and one of us 

 observed " retraction," which suggests that the observed retraction in that 

 case was a deviated response due to the disease, and probably sj^mptomatic 

 of tetanus. To the small neck field lying on the free surface of the cen- 

 tralis anterior, our observations show that, at least in some specimens, a 

 part of the cortex buried in sulcus post-centralis has to be added. Neck 

 field lies between arm area and face area, and seems to mingle more with 

 the latter than with the former. Occasionally the turning of neck is to- 

 wards ipsilateral side. 



3. Arm Area. 



Thumb. — Movements of thumb are among the movements obtained 

 from the lowest part of arm area, and usually the predominant ones there. 

 Their field abuts on, but mingles relatively little with, eyelids, neck, and 

 " pinna of ear " fields. 



Index Finger. — The field for primary movements of this digit appeared 



