ON THE FUNCTIONS OF THE CEREBRAL CORTEX. 
3 
having usually been given). This has the great advantage of causing the animal to 
remain perfectly quiet for several hours after the operation, and of permitting it, 
during the slow process of recovery from the effects of the morphia, to become 
accustomed to the collodion dressing, which would otherwise be irksome, and this 
would lead to attempts at removal. 
It has, however, the disadvantage that observations cannot be at once made upon the 
disturbance of function produced ,by the lesion, on account of the condition of stupor 
which is caused by the morphia. This disadvantage is not so great as it may at first 
sight seem, for such immediate observations are of less value than later ones, 
especially when the lesion is an extensive one, on account of the very considerable 
disturbance which must be temporarily produced upon the remainder of the hemi- 
sphere, partly by the blocking of the vessels of the ablated portion, and partly by 
the loss of support experienced by the neighbouring portions when a large piece has 
been removed at one operation. 
We may conveniently arrange our general results according to the regions to which 
they respectively relate, and they will therefore be grouped under the following heads, 
viz. : — I. Prefrontal ; II. Central or Motor ; III. Occipital ; IV. Temporo-sphenoidal 
and Limbic. 
I. — Results of Experiments upon the Prefrontal Region of the 
Hemisphere. 
Results of excitation. — Electrical excitation of the anterior end of the frontal 
lobes has invariably yielded negative results in our hands. But behind the anterior 
end of the sagittal limb of the precentral sulcus the lateral movement of the head 
and eyes described by FERRiERt begins to be evident. 
Result of ablation. — In three cases we have completely removed at one operation 
the anterior third or fourth of both frontal lobes, including all that part which we 
had found electrically inexcitable. In two of these the animals rapidly recovered 
without showing any sign of motor paralysis,^ nor could any deficiency of general or 
special sensibility be detected. One of the two Monkeys was a very tame animal, 
which had acquired certain tricks before the operation ; these were exhibited equally 
well afterwards ; nor was the Monkey rendered any less tame or intelligent, so far as 
could be detected, as the result of the lesion. In both cases the animals were under 
* The moi'phia has also appeared to us to diminish the hasmorrhage from the cut cerebral sui'face. 
This is in any case easily stayed by the application of gentle pressure, 
t Febeier, ' Functions of the Brain,' 2nd edition, p. 242. 
X After lesions of the anterior part of the frontal lobes the animals for the first few days always 
assume a characteristic attitude, sitting with the head bent downwards between the arms, and they 
appear more lethargic than is usual after operations involving other parts of the brain. But after a 
few days all these symptoms pass completely away, and the normal attitude and disposition are resumed. 
B 2 
