r 331 ] 
VIII. On the Descending Degeneralions which fodoie Lesions of the (Ljcus Margined is 
and Gynis Fornicaius in Monkeys. 
By E. P. Feance. With an Introduction hy Professor Schafer, F.R.S. 
{From the Physiologiccd Laboratory, University College, London.) 
Received March 9,—Read March 28, 1889. 
[Plates 27-29.] 
INTRODUCTION. 
The following paper contains the record of an investigation into the degenerations 
which follow lesions of the gyrus marginalis and gyrus fornicaius in Monkeys. The 
work has been carried on under my direction by Mr. Feance, with the aid of a grant 
from the Government Grant Fund, and represents part of a long investigtition into 
the degenerations which follow artificially produced cerebral lesions, the material for 
which has been furnished by cases operated upon in conjunction respectively with 
Professor V. Hoesley and Dr. Sangee Beown. These cases and the physiological 
results of the operalions have already been published in the ‘ Philosophical Trans¬ 
actions.’* The experiments here dealt with, twelve in number, comprise only the 
lesions of the gyrus marginalis and gyrus fornicatus, and, with one exception 
(case 12), are taken from the series of experiments performed in conjunction with 
Mr. Hoesley. t 
Of the twelve cases, six were of removal, or attempted removal, of the gyrus mar¬ 
ginalis, and six of removal, or attempted removal, of the gyrus fornicatus. But in 
only one or two instances was the lesion, as determined by post-mortem examination, 
exactly limited,to the convolution which it was attempted to remove, for in most 
cases the adjacent gyrus was to a certain extent involved in the injury. This was 
especially the case when removal of the gyrus fornicatus had been attempted, on 
account of its deep situation, and the difficulty of getting at it without some 
manipulation of the superjacent gyrus. Nevertheless, the removal of one or the other 
* V. Horsley and E. A. Schafer, “ A Recoid of Experiments on the Functions of the Cerebral 
Cortex,” ‘Phil. Trans,’ B, 1888, pp. 1-45 ; and Sanger Brown and E. A. Schafer, ‘ Phil. Trans.,’ B, 1888, 
pp. 303-.327. 
t In an Appendix, which has been added subsequently, lesions of the external motor cortex are dealt 
with by Mr. France. 
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