64 
Proceedings of the Royal Society of Edinburgh. [Sess. 
X. — The Functions of the Rolandic Cortex in Monkeys. By W. A. 
Jolly, M.B., and Sutherland Simpson, M.D., D.Sc. {From the 
Physiological Laboratory, University of Edinburgh .) Communi- 
cated by Professor E. A. Schafer, F.R.S. 
(MS. received March 1, 1907. Read March 18, 1907.) 
The Rolandic cortex is discussed in the following paper, and an account 
is given of experiments on monkeys, performed with the object of mapping 
out this region more accurately and of delimiting in it the areas concerned 
with movements of different parts of the body. The method employed is 
a new one, and will be described in detail. 
The theory that the functions of the brain reside in distinct areas in its 
substance was advanced in early times. Proof that this theory is correct 
has only been obtained comparatively recently. 
It was known to the Greek physicians that each hemisphere of 
the brain presides functionally over the opposite side of the body. 
This was evident to them from the situation of paralysis and the 
nature of convulsions which follow upon injuries to a hemisphere. 
Further, they believed, from the study of monoplegias, that the move- 
ments of different groups of muscles have their source in different regions 
of the brain. 
The sensibility of the cerebral cortex to excitation was not known to 
the Greeks, and remained unknown until our own time. 
During mediaeval times localisation of function in distinct parts of the 
brain was accepted as a fact on the authority of the Greeks, and support 
was lent to the belief by clinical observations on the effects of injuries in 
producing loss of speech or of memory. 
Willis, in the year 1682, writing in terms of the theory current at that 
time, that namely of the production and distribution of animal spirits, 
located in the cortex of the brain the function of initiating voluntary 
muscular movements, and regarded the central part of the cerebrum, the 
spinal cord, and the nerves as the pathway through which the cortex 
exercises its function upon the muscles. 
Attempts which were made in the dawn of the era of physiological 
experiment to elucidate the facts were unsuccessful. 
Haller (1776) came to the conclusion that the function of producing 
