DE. D. EEEBIEB ON THE BEAIN OE MONKEYS. 
487 
With the exception of the injection of the vessels of the pia mater behind the frontal 
section, the rest of the brain had a normal aspect. 
The most important fact demonstrated by this experiment is that the conjoint removal 
of the frontal and occipital lobes exercises no effect on the powers of voluntary motion 
or of sensory perception. 
The results of the post mortem examination indicate that the phenomena of the second 
day are not to be regarded as the effect of the removal of the frontal lobes as such, but 
as due to the inflammatory complications which resulted in death. 
But the fact that for many hours after the operation the animal continued to retain 
its powers of sensation and of volition, proves that these faculties are independent of 
the frontal and occipital lobes, and that they are associated with those parts of the brain 
which, by other experiments, I have shown to be specially related to sensation and 
motion. 
What the positive effects were, as distinguished from the merely negative, it would 
be difficult to state in exact terms. They are quite in accordance with experiments 
already related as to the effect of destruction of the frontal lobes. 
Without entering further into the psychological aspects of these results, I would sum 
up the conclusions which seem to me to be legitimately deducible from them as follows: — 
(1) Ablation of the frontal regions of the brain which give no reaction to electrical 
irritation is without effect on the powers of sensation or voluntary motion, but causes 
marked impairment of intelligence and of the faculty of attentive observation. 
(2) Destruction of the grey matter of the convolutions bounding the fissure of Rolando 
causes paralysis of voluntary motion on the opposite side of the body, sensation remaining 
unaffected, while lesions circumscribed to special areas in these convolutions, previously 
localized by the author, cause paralysis of voluntary motion limited to the muscular actions 
excited by electrical stimulation of the same parts. 
(3) Destruction of the angular gyrus (pli courbe) causes blindness of the opposite eye, 
the other senses and voluntary motion remaining unaffected. This blindness is only of 
temporary duration, provided the angular gyrus of the other hemisphere remains intact. 
When both are destroyed the loss of visual perception is total and permanent. 
(4) The effects of electrical stimulation and the results of destruction of the superior 
temporo-sphenoidal convolution indicate that this region is the centre of auditory per- 
ception. 
(5) Destruction of the hippocampus major and hippocampal convolution abolishes 
the sense of touch on the opposite side of the body. 
(6) The sense of smell has its centre in the subiculum cornu ammonis or tip of the 
uncinate convolution on the same side. 
(7) The sense of taste is localized in a region in close anatomical relation to the 
centre of smell, and is abolished by lesion of the lower part of the temporo-sphenoidal 
lobe. 
(8) Destruction of the optic thalamus causes complete ansesthesia of the opposite side 
of the body. 
