68 
Proceedings of the Royal Society of Edinburgh. [Sess. 
the boundaries between these areas could be represented by lines drawn 
antero-posteriorly across the ascending frontal convolution, the leg area 
having its lower boundary on the convex surface of the hemisphere in a 
line drawn from the posterior termination of a small sulcus which lies on 
the upper portion of the frontal lobe in the monkey, and which had been 
described and designated X by Schafer,* to the fissure of Rolando. With- 
in the arm area Horsley and Schafer showed that the order of representa- 
tion from above downwards was shoulder, forearm, wrist, and fingers. 
Within the face area which they showed comprised centres not only for 
facial muscles, but also for the whole of the upper part of .the alimentary 
tube, they demonstrated that stimulation at its upper extremity produced 
movements of the upper face muscles, the eyelids and alse nasi moving 
when the electrodes were applied in this position. Ferrier had taken the 
view that retraction of the angle of the mouth was the characteristic 
response of the upper extremity of the face area. Close to the margin 
above the sulcus X a small area was delimited from which, and from the 
adjacent cortex on the mesial aspect, movements of the tail and trunk 
could be obtained. This centre, which the authors denominated the trunk 
area, will be more particularly referred to later. 
In the frontal lobe the authors described a region which they termed the 
head area or area for visual direction. It extended from the margin of 
the hemisphere, round which it dipped for a short distance, outwards and 
somewhat backwards to the upper and anterior limit of the face area. 
Posteriorly it was bounded by the arm area and in front by the non- 
excitable portion of the lobe. Excitation of this area caused movements of 
the head, and from a part of it, as Ferrier had shown, opening of the eyes, 
dilation of the pupils, and turning of the head to the opposite side with 
conjugate deviation of the eyes to that side. 
The localisation of definite movements within the areas was further 
studied by Beevor and Horsley ,j* who found that the succession of movements 
in the joints was similar to that described by Hughlings Jackson as 
occurring in epilepsy. In the earlier part of their work these authors 
assumed a very extensive motor representation of the thumb, considering 
that thumb movements could be obtained by stimulation over a large 
portion of the face area. Later they represented this centre as restricted to 
the lower part of the arm area. 
* Journal of Physiology, vol. iv. p. 316. This sulcus is considered by Cunningham to be 
in all probability a rejDresentative of the sulcus precentralis superior or of the basal part of 
the first frontal sulcus ( Cunningham Memoirs, Royal Irish Academy, 1892, p. 281). 
t Phil. Trans., 1887, 1888, and 1894. 
