472 
DR. D. EERRIER ON THE BRAIN OE MONKEYS. 
Destruction of the Optic Thalamus. 
Experiment XIX. 
February 12th, 1875. — The left hemisphere was exposed by a trephine^opening in the 
region of the pli de passage from the posterior division of the angular gyrus to the occi- 
pital lobe. 
With a small trocar and cannula (after the method adopted by Nothnagel in his 
experiments on rabbits) the anterior extremity of the annectent gyrus was perforated 
horizontally in the direction which experiments on the dead brain had taught me to 
reach and destroy the optic thalamus. 
After withdrawal of the trocar, a stilette with expanding wings was passed through 
the cannula, and rotated so as to break up the parts with which it should come in 
contact. 
There was some haemorrhage from the cannula. 
The operation was completed at 5.30 p.m. 
5.50 p.m. The animal now is sitting up, leaning towards the right side. Makes some 
movements with its left limbs. 
7 p.m. The animal looks quite active and intelligent. Can move about pretty freely, 
but seems weak on the right side. Does not use the right hand in taking hold of any 
thing presented to it. A hot iron applied to the right hand caused the animal to wince 
and rub the part touched. 
8 p.m. Animal can move about. Took a piece of apple offered to it in its left hand, 
and held it to its mouth with both hands. Sight and other senses do not seem affected. 
8.45 p.m. A bandage was placed on the left eye in order to ascertain the condition as to 
vision on the right. The bandage could not be maintained, as the animal bounced 
about, knocking its head against furniture, and tearing at the bandage till it got it off. 
Owing to this the condition as to sight could not be definitely tested, though the run- 
ning against obstacles seemed to indicate affection of sight in the right eye. 
February 13 th . — 11 a.m. The animal is much in the same condition as yesterday. 
Uses all four limbs in walking, but the movements of the right are made with caution 
and hesitation ; nor does it use the right hand in grasping, taking every thing offered to 
it with the left. 
3 p.m. Thinking that the optic thalamus had been only partially destroyed, I passed a 
hot wire in the track of the cannula, so as to completely traverse the optic thalamus, 
the distance &c. being carefully calculated from the result of experiments on the 
dead brain. 
Before the animal recovered from chloroform the left eye was bandaged, and the 
animal laid before the fire. 
3.10 p.m. The animal, while lying before the fire, begins to make some movements 
with its left limbs. The right remain motionless. The right eye was open, and the 
pupil dilated. 
