ON THE FUNCTIONS OF THE CEREBRAL CORTEX. 35 
are mainly of interest as showing the connpleteness of removal of the frontal and 
occipital lobes, and the limits of the lesion upon the under-siii-face of the hemisphere. 
25. 
Lesion 1. — Left occipital lobe removed. The heraiopi'a (imperfect visual perception 
of objects on right of mesial plane) which resulted was accompanied by partial 
hemiplegia and oedema of the opposite foot (so that there was probably some 
haemorrhage into the ventricle). The paralysis was, however, in great part gradually 
recovered from, but the hemiopia persisted, although in a diminished form, until three 
weeks after, when {Lesion 2) the right occipital lobe was removed. This was also 
followed by imperfect visual perception (of objects on left of mesial plane), bat the 
animal was attacked by gangrenous cellulitis of the feet, and had to be killed sixteen 
days after the second lesion. In this interval of time there was little or no recovery 
from the visual imperfection. 
The brain is represented in fig. 25. From this it will be seen that the removal of 
the occipital lobes has not been quite complete, especially upon the right side, not 
more than half of which has been excised. 
26. 
Lesions ] and 2.— In this Monkey both occipital lobes (external and posterior 
surfaces and a part of the under-surface) were removed, with an interval of fourteen 
days between the two operations. A little of the external surface was, how^ever, left 
intact. 
Result. — The first lesion (on the right side) was followed by left hemiopia, which 
had not been recovered from when the second (on the left side) was established. The 
immediate i-esult of the double lesion was to produce almost complete blindness. This 
was gradually recovered from to a certain extent, so that, although small objects did 
not appear to be distinctly discerned, larger ones were seen and obstacles were 
avoided. There seemed after a time to remain a general impairmennt of visual percep- 
tions, without, so far as could be made out, absolute blindness in any part of the field 
of vision, but of this we cannot speak with any certainty. 
Lesion 3. — Two months after the removal of the left occipital lobe, and with the 
animal in the condition just described, the angular gyrus uf the right side was cut 
away. 
Mesult. — This operation was followed by complete hemiopia, the right side of both 
retinae being perfectly blind. A threatened blow coming from the left side was not 
avoided, no objects appeared to be seen, nor was any food picked up if placed on the 
left side of the mesial plane of vision. This condition lasted without recovery until 
the animal's death (from dysentery) three n]onths Inter. 
The brain, viewed from behind and somewhat from above, is shown in fig. 26. 
F 2 
