67 
1906-7.] Functions of the Eolandic Cortex in Monkeys. 
opening o£ the eyes, dilation of the pupils, and movements of the head and 
eyes to the opposite side. 
Subsequent to Ferrier’s work, Hitzig * also investigated the monkey’s 
brain by electrical stimulation. He differed from Ferrier in that he 
restricted the area governing the movements of limbs and face to the 
ascending frontal convolution. Within this gyrus Hitzig described motor 
centres for the lower and upper extremities, the face and the mouth, tongue 
and jaws. The position of these centres was only approximately correct. 
Thus Hitzig placed a centre concerned with movements of the ear and 
closure of the eyes above the inferior genu of the Eolandic fissure, and the 
highest point of the precentral fissure in an area of the cortex which was 
afterwards clearly shown by Horsley and Schafer f to be embraced in the 
centre for the upper extremity. 
Ferrier’s results were confirmed by, among others, Luciani and 
Tambourini,! who came to the conclusion that the excitable areas for the 
limbs and face in monkeys are not limited to the ascending frontal convolu- 
tion, as maintained by Hitzig, but that Ferrier was right in considering that 
they extend also to the ascending parietal and angular gyri. This view of 
Ferrier, that the motor areas extend behind the fissure of Eolando, which, 
as we now know, does not hold good, was generally accepted and greatly 
influenced subsequent work. 
The next advance in motor localisation in the monkey was made by 
Horsley and Schafer, § who established the fact that the excitable area 
extends to the mesial face of the hemisphere. Ferrier had found in one 
case that irritation of the fronto-parietal portion of the marginal gyrus 
gave rise to muscular movements. Horsley and Schafer, using interrupted 
induction shocks with the coil fitted with Helmholtz’s side wire, showed 
that minimal stimuli elicited from part of the convolution “ contraction of 
perfectly definite groups of muscles, or in some cases of single muscles, 
producing more or less co-ordinated movements,” thus proving that the 
marginal gyrus contributes to the true motor area. They supported their 
conclusion by extirpating the excitable area in this convolution. The out- 
standing result of this experiment was distinct paralysis of the leg. The 
animal was able to assume and maintain a nearly normal attitude and to 
employ its arm for the purpose of progression. 
The motor areas in the ascending frontal convolution were also for the 
first time correctly delimited by the same observers. They showed that 
* Untersuchungen iiber das Gehirn, Berlin, 1874. t Phil. Trans., 1887. 
X Ricerche sperimentali sui centri psico-motori corticali, 1878. See also Brain, London, 
1879, vol. i. p. 529. 
§ Proc. Roy. Soc., London, 1884, vol. xxxvi. p. 437. Phil. Trans., 1887. 
