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Localisation of Function in the Lemur’s Brain. 
By F. W. Mott, M.D., F.R.S., and W. D. Hauuipurtron, M.D., F.R.S. 
(Received November 14,—Read December 5, 1907.) 
[PLates 2—4.] 
The brain of the Lemur, the lowest of the ape-like animals, does 
not appear to have been subjected previously to a thorough examination. 
Page May and Elhott Smith brought a brief communication on the 
subject before the Cambridge Meeting of the British Association in 1904.* 
Their experiments were apparently limited to stimulation of the cerebral 
cortex, and they have never published a full account of their work. 
Brodmannt has worked out some of the histological details of the structure 
of the cortex cerebri, and Max Volscht has performed a stimulation experiment 
upon one Lemur. The work of these investigators will be referred to again in 
the course of this paper. 
Our own investigation has in the main dealt with the motor centres, and 
the experimental methods adopted have been the usual ones of stimulation 
and extirpation. In animals so low in the scale, stimulation is to be 
regarded as the more decisive of the two methods for the purpose of localisa- 
tion. The extirpation experiments have, however, confirmed the results of 
stimulation, and in these experiments the course of the resulting degeneration 
was followed by histological examination of the brain and spinal cord. The 
results, moreover, agree remarkably closely with those obtained by a study of 
the histological structure of the various regions of the cortex cerebri. 
One of us (W. D. H) is responsible for the experimental part of the investi- 
gation which was carried out at King’s College, London; the other (F. W. M.) 
is responsible for the histological portion. We have to thank Miss Agnes 
Kelley for assistance in the histological work, and also for the drawings which 
accompany this paper.§ _ 
The species of Lemur employed was the Ring-tailed Lemur of Madagascar 
(ZL. catta) except in two experiments where the Black Lemur (LZ. macaco) was 
used. The results obtained in both species were practically identical. 
* British Association Reports, 1904, p. 760. 
+ ‘Journ. f. Psychologie u. Neurologie, vol. 6, p. 272, 1906. 
{ “Ein Rindenreizungsversuch an einem Halbaffen,” ‘Monatsschrift f. Psychiatrie u. 
Neurologie,’ 1906. 
§ A full description of the histology of the cerebral cortex of the Lemur will be 
‘published later by one of us (F. W. M) in conjunction with Miss Kelley. In the present 
paper only the motor area will be considered, 
/ a 
