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SECT. XVIII. PHYSIOLOGY. 153 
intestinal canal, the brain, and all the cerebral 
nerves reciprocally influence each other; no one 
can deny this position, except those who have 
confined their studies to the dead body. Emotions 
of the mind have powerful influence on the intes- 
tinal irritability; severe grief is frequently the 
cause of violent diarrhoea, and the effects of fear 
-have not even escaped the notice of the populace. 
cccLxx1x. The irritability of the intestinal 
canal is generally involuntary ; the task which it 
has to accomplish is too important to be intrusted 
to the caprices of volition, and its functions 
proceed without interruption, while the mental 
faculties are suspended by repose. In some few 
individuals there is a trifling degree of voluntary 
contraction in the stomach; but, in the course of 
my life, I have only met with one person who 
could at pleasure eject the contents of his stomach. 
Even the sight and smell of disagreeable objects 
sometimes convulse the stomach. 
cccLxxx. A morbid state of the intestinal canal 
readily influences the brain ; the presence of worms 
in any part of it, and acrid or corrosive poisons, 
readily induce delirium and coma; and even 
excessive repletion may bring on a state resem- 
bling ebriety. The inhabitants of Australia, 
whose subsistence is extremely precarious, commit 
enormous excesses of gluttony, if plenty be 
within their reach. When a whale is accidentally 
U 
