DR. D. FERRIER ON THE BRAIN OE MONKEYS. 
441 
any interest in aught beyond their own immediate sensations, paid no attention to, or 
looked vacantly and indifferently at, what formerly would have excited intense curiosity, 
sat stupidly quiet or went to sleep, varying this with restless and purposeless wanderings 
to and fro, and generally appeared to have lost the faculty of intelligent and attentive 
observation. 
Perhaps this condition may be attributed to the constitutional disturbance excited by 
the operative procedure alone ; but the effects of this are capable in a great degree of 
elimination ; and in the record of subsequent experiments it will be seen that after 
operations of equal severity marked differences are observable according to the part of 
the brain which was destroyed. The animals seem to bear the operation with com- 
paratively little constitutional disturbance ; and this is testified by the fact that they 
continue to eat and drink heartily within a few hours, and often less, after a large 
portion of the brain has been removed. 
The phenomena occurring towards the latter end of the periods of observation are 
more to be regarded as signs of constitutional disturbance, and as indications of the 
advance of inflammatory softening or morbid process into other cerebral regions. The 
spasmodic motor affections, as well as the paretic condition seen in regard to certain 
movements, are to be explained by the implication of motor centres, the nature and 
position of which will be illustrated in the next series of experiments. 
Destruction of Motor Areas— Begions of the Fissure of Bolando. 
In my former Memoir I have related the results of electrical irritation of regions 
situated in the immediate neighbourhood of the fissure of Kolando, which show that 
certain definite and purposive movements of the hand, foot, arm, leg, face, and mouth 
result from the electrical stimulus applied to individual areas capable of more or less 
exact localization. The experiments next to be related have reference to the effect of 
destruction of these centres, collectively and individually, on the power of voluntary 
motion. 
Experiment IV. 
June 18 th, 1873. — The right hemisphere of a monkey had been partially exposed and 
experimented on for the purpose of localizing the regions of electric stimulation. 
The part exposed included the ascending parietal and postero-parietal convolutions, 
the ascending frontal, and the posterior extremities of the three frontal convolutions. 
After having been under experimentation for eight hours the animal recovered 
sufficiently to sit up and take food. The wound was sewn up, and the animal placed in 
its cage. 
June 19 th. — The animal is apparently as well as ever, eating and drinking heartily, 
and as lively and intelligent as before. No change was perceptible during the whole 
of this day. 
June 20 th — The wound was oozing, and the animal was less active ; but there was 
MDCCCLXXV. 3 N 
