426 
POPULAR SCIENCE REVIEW. 
which all act in the same manner as cold, pressure, or exhaus- 
tion, affect differently sections of the brain matter, producing 
various phenomena analogous to dreams. 
Lastly, some other external influences, by causing concentration 
of force on one particular part of brain, may so reduce other parts 
to rest as to cause that inertia which Carmichael calls reverie. 
This is a disturbance of the equilibrium of force in the brain 
which can be intensified by practice; and there is no difficulty in 
tracing the phenomena of mesmerism, such as they are, to their 
physical source when the nature of reverie, or waking dream, is 
explained and understood. 
Balance of Power in the Brain. 
One more fact relating to the physics of the brain, as taught 
by experiment, and I have done. We have seen that when 
the anterior cerebral ganglia are destroyed for a time, an animal 
moves impulsively forward, and that, when the cerebellum is 
destroyed, the animal moves impulsively backwards. This in- 
dicates the existence of a balance of power between these centres 
— a balance which is also detectable between other centres. It is 
therefore a fair inference, that every centre of power in the 
brain is, during healthy states, physically balanced, and that 
what is called a well-balanced mind is really a properly ba- 
lanced brain. By this reading we explain many phenomena of 
living action otherwise inexplicable. 
By constant overaction one centre of the brain may gain 
undue power, which shall be so persistent as to distinguish the 
man throughout life. Or a centre of power may be suddenly 
prostrated, and the balancing centre, no longer controlled, may 
overcome all for the moment, and produce phenomena not 
before observed in the same organism. Impulses — sudden, 
vehement, propulsive, onward, under the influence of any im- 
pression which for a moment paralyses the cerebrum, are thus ex- 
plained. Whenever the cerebrum alone is overcome with sudden 
shock, it fails in power the same as when its structure is de- 
prived of force by the direct action of cold or by pressure: 
then the propulsive cerebellum unaffected shows its force un- 
checked, and there is forward rush. In some stages of disease of 
the cerebrum and specially of disease induced by alcohol, there is 
this break of balance. I lately pulled out from under a railway 
train the headless trunk of a man. Passing into a tunnel out of 
which the train had emerged, I found the brain of this man entire, 
and while the servants of the company were fetching the police, 
I read in the brain his physical history, and interpreted it to the 
Inspector by my side. I discovered that while the cerebellum was 
quite sound the anterior lobes of the cerebrum were intensely con- 
