514 
PROFESSORS D. FERR1ER AND G. F. YEO ON THE EFFECTS OF 
length of the pyramidal tiact which connects the region of the cortex with the spinal 
region whence the motor roots of the limb emerge. 
It was noted that for several days subsequent to the operation a spasmodic 
tendency was observable in the right arm, especially as regards the shoulder move¬ 
ments and when the animal extended the right arm forwards. 
This receives a satisfactory explanation in the inflammatory adhesion of the mem¬ 
branes and superficial erosion of the cortex in the region of the upper extremity of 
the ascending frontral convolution and base of the first frontal. The region specially 
implicated was centre 5 (Ferrier), electrical irritation of which causes extension 
forwards of the arm. 
The adhesion was probably caused by the use of styptics to still haemorrhage, which 
occurred to a considerable extent daring the operative procedure: 
But as the irritation subsided the right arm ceased to be affected by spasm, and no 
permanent abnormality was created. 
Experiment 17* (Plates 23 and 24, figs. 45-51). 
In this animal, a large Monkey of the Oynocephalic type, the right hemisphere was 
exposed over the upper half of the ascending frontal and ascending parietal convolu¬ 
tions, and this region was destroyed by the galvanic cautery, as close up to the longi¬ 
tudinal fissure as could be reached without exposing this to view. 
It was observed that as the animal was regaining consciousness during the dressing 
of the wound, it used not only the right arm and leg, but also made some flexion and 
extension movements of the left thigh ; the left arm was not moved. 
Half an hour after the operation it was found that pricking the sole of the right 
foot caused the animal to struggle and withdraw the foot, whereas pricking the left 
foot caused the animal to struggle and express uneasiness, but the foot was not 
moved. 
A similar observation was made as regards the right and left hand. The animal 
evidently from its gestures felt the stimulus as well on the left as right, but it could 
not withdraw the left hand. 
Next day the animal seemed in capital health, but was hemiplegic on the left side. 
The face was not affected. In grinning the two sides of the face acted equally. The 
animal was able to flex and extend the left thigh feebly, and also extend the left leg, 
so that it could raise itself when it wished to take a piece of apple offered it at some 
height above the head. This it took with the right hand. The left arm was kept 
at the side in a state of semiflexion. It was observed in struggling to make also 
some flexion of the fingers of the left hand. Heat applied to either hand or foot 
excited the same grimaces indicative of sensation. 
On the fourth day the condition was similar. In walking the left arm was kept 
in the semiflexed position and the left leg was dragged, the toes catching on a ledge 
which the animal was crossing. 
