156 DR. C. E. BEEVOR AND MR. V. HORSLEY ON THE EXCITATION OF THE 
for 5 seconds. In view of the increasing readiness with which epilepsy follows cortical 
excitation as we pass from Apes to the Carnivora this observation is not without 
meaning. 
Conclusion. 
In conclusion we feel obliged to advert once more to the fact that the foregoing 
account is founded upon but one experiment. In view of the difficulty and expense 
of obtaining material we have, however, thought it best to publish the results at once. 
Description of Plates. 
Plates 16, 17 (Figs. 1-5). 
PLATE 16. 
Fig. 1. View of left hemisphere (external surface) which was analysed by excitation, 
and })hotographed directly after the experiment, with the meninges intact. 
Natural size. The photograph has been unavoidably reversed in printing. 
Sy. Fissure of Sylvius. 
G. Fissure of Rolando, placed just behind its genu. 
Pi'.c. Praecentral sulcus. 
S.F.S. Superior frontal sulcus. 
I.F.S. Inferior frontal sulcus. 
F.c. Postcentral sulcus. 
l. I\ Intra-parietal sulcus. 
Fig. 2. View of the same hemisphere after hai’dening in bichromate of ammonia and 
alcohol, and subsequently removing the meninges. Natural size (shrunk in 
hardening). 
The letters are the same as in fig. 1. 
PLATE 17. 
Fig. 3. Photograph of the original drawing of the portion of the cortex examined, 
made at the time of the experiment. The exact size, on paper ruled with 
2 mm. squares, as described on p. 133. 
The letters are the same as in fig. 1, except that the Fissure of Rolando 
is called R. 
The numbers are referred to in the text. 
Fig. 5. Horizontal section of the right hemisphere, showing the level where the 
internal capsule was excited {vide p. 147). 
i.c. Internal capsule. 
jyu. Putamen, or outermost zone of lenticular nucleus. 
m. z. Middle zone of lenticular nucleus. 
o.th. Optic thalamus. 
sJ. Septum lucidum. 
