PHYSICS OF THE BRAIN. 
421 
caloric it is quite possible, by using a fine ether jet and a low 
boiling fluid, to isolate parts with great minuteness. Thus we 
can remove the force from the two large front cerebral hemi- 
spheres without removing it from the smaller hemispheres which 
lie behind, and which form the little brain or cerebellum ; it is 
possible again to remove the force from one hemisphere with- 
out removing it from the oth£r, or from the spinal cord without 
interfering either with the large or the small brain. 
In the superior and front part of each hemisphere of the 
cerebrum there lies a mass of nerve matter very distinct in 
form, and, as it would seem, very distinct in function. The 
older anatomists called this the striated body ( corpus striatum ), 
because in section it appears to be marked by faint lines of 
grey and white colour. It is now more correctly called the 
superior cerebral ganglion. With very little difficulty, and 
without pain, we can expose this ganglion in one or both 
hemispheres, and remove the force from one or from both. 
When we have removed the force from both — when, that is to 
say, we have solidified them, and, for the time, destroyed their 
function — there is presented this singular phenomenon: the 
animal falls forward, or sometimes rushes forward with unmean- 
ing impetuosity, and these symptoms will last until the relaxa- 
tion and restoration of the ganglia is complete. 
We change the line of experiment; we turn from these front 
cerebral ganglia to the lower large ganglia which lie at the 
back of the skull, and form the smaller brain or cerebellum. 
We lock up these, by taking from them their force by cold, and 
at once the animal marches backwards, and turns backward sum- 
mersaults, and in the most determinate manner shows that it has 
no control over these movements until its cerebellum is set at 
liberty by the restoration of caloric. 
If the anterior cerebral ganglia, together with the cerebellum, 
be simultaneously deprived of force, there is neither backward 
nor forward movement, but prostration of movement for the 
time, with equal restoration of power consequent on equal 
restoration of force. 
Throughout all these induced changes on the great centres of 
nervous power, it is observed that however much the volition, 
the perception, and the sensibility of the animal are reduced, the 
semi-voluntary and involuntary acts, the acts of respiration and 
the motions of the heart, are not prevented. To say they are 
not affected is not strictly true, for they are rendered slower 
after a time and feebler ; but this is an indirect retardation of 
function, and would occur if any other large surface of the body 
were for a long period deprived of caloric ; but we may say, con- 
fidently, that the removal of force from the large and small 
brain does not seriously interfere with the functions named. 
H H 2 
