70 Proceedings of the Royal Society of Edinburgh. [Sess. 
Their work on the anthropoid brain led Griinbaum and Sherrington to 
emphasise what had been pointed out by Schafer,* * * § that the fissures in the 
neighbourhood of the Rolandic area, from the inconstancy of their position, 
form unreliable guides to functional regions. They excepted from this 
rule, however, the two genua of the Rolandic fissure. The upper genu, 
termed by Sherrington the cruro-brachial,j* was found to lie opposite the 
space intervening between leg and arm areas and the lower or bracliio- 
facial between arm and face areas. 
Subsequent to these observations upon anthropoids, Rothmann j de- 
scribed experiments which led him to the conclusion that in Macacus the 
motor area extends to the ascending parietal convolution. He found that 
limb movements followed stimulation thereof with weak currents, and that in 
some cases movements of the thumb were produced more readily by stimula- 
tion behind the fissure of Rolando than in front. He further found that, after 
destruction of the excitable precentral cortex, stimulation of the parietal 
convolution still produces movements of the thumb, fingers, and forearm. 
The views of this author were opposed by Brodmann,§ and are not 
supported by the recent work of Vogt nor by our own results. 
In view of the results, obtained by Griinbaum and Sherrington in the 
anthropoid, it appeared to us advisable to attempt more accurately to 
delimit the cortical motor centres in monkeys. We desired to determine 
whether the movements which can be obtained in these animals by stimula- 
tion of the ascending parietal and other convolutions found to be non-motor 
in the anthropoid, warrant the inclusion of these convolutions in the motor 
area, or whether they are to be explained as due to a spread of current to 
the adjacent excitable cortex. With this object we made a number of 
experiments on monkeys, using species of Macacus and Callithrix. The 
method adopted, which was suggested to us by Professor Schafer, was as 
follows : — The animals were ansesthetised throughout the experiment with 
ether. A skin flap was turned down and the skull trephined over the 
fissure of Rolando on the left side. The opening was then enlarged with 
bone forceps, the dura incised, and the convolutions exposed. After ex- 
ploration of the Rolandic area by means of unipolar faradisation, in which 
we employed an electrode kindly given to us by Professor Sherrington, we 
determined the minimum strength of stimulus which produced muscular 
movements on application of the electrode to either side of the fissure of 
* Festschrift zu Karl Ludivig, Leipzig, 1887. 
t The Integrative Action of the Nervous System, London, 1906. 
J Neurologisches Gentralblatt, 1904, No. 14, p. 668. 
§ Ibid., p. 669. 
