532 
PROFESSORS D. FERRIER AND G. F. YEO OX THE EFFECTS OF 
ments of the head wei'e seen, and also extension of the trunk. In this case also in 
addition to the frontal regions, portions of the head of the corpus striatum was removed 
on both sides, more on the left than right. 
The facts of Experiment 23 show that extensive lesion of the prefrontal lobes, subse¬ 
quent to the time when all effects of destructive lesions at the base of the frontal 
convolutions had disappeared, caused for a time disorders in the movements of the 
head—shown in lateral oscillation of the head, and apparent inability to turn the 
head and eyes. 
There was also in this case a phenomenon not observed in any other case, viz.:— 
ptosis of the right eyelid. There was no local injury perceptible to account for this, 
but whether it was the direct result of the prefrontal lesions is a point that may be 
questionable. The facts of this experiment taken with those of Experiments 19 and 
20 render it probable that the prefrontal lobes have essentially the same physiological 
relations as the electrically effective postfrontal centres. 
In Experiments 19 and 20, notwithstanding the extensive destruction of the post¬ 
frontal centres, the paralysis of the lateral movements of the head and eyes was very 
transitory, and in Experiment 23 the destruction of the prefrontal regions subsequent 
to the recovery from the lesions of the post-frontal centres re-induced similar 
symptoms. Hence it would appear that so long as portions of the frontal centres 
remain intact, the movements of the head and eyes are not permanently paralysed. 
The prefrontal and postfrontal regions are shown by the secondary degenerative 
changes demonstrated in Experiments 22 and 23, to be anatomically related to the 
same tracts of the internal capsule and crus cerebri. This fact also would indicate 
community in their physiological relationships. Though the prefrontal regions did 
not react, or very doubtfully, to electrical stimulation, yet this would not militate 
against their being considered part of the same physiological centre as the postfrontal 
regions. For it was found that the occipital lobes did not respond like the angular 
gyri to electrical stimulation, and yet formed an integral portion of the visual centres. 
As to the psychical effects of the frontal lesions it is difficult to speak at all definitely. 
In some cases there was no very marked change, yet in others, as in Experiment 2, 
previously carefully studied, there was a very manifest alteration in the character of 
the animal. 
On the whole there seemed mental deterioration, characterised by general apathetic 
indifference or purposeless unrest : effects which, in comparison with those of other 
lesions, appear to have special relation with lesions of the frontal lobes as such. 
SECTION Y. 
Lesions of the Hippocamfal .Region. 
In none of the experiments recorded in the preceding sections relating to lesions in 
the occipital, parietal, frontal, and external convolutions of the temporo-sphenoidal 
