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Full text of "Expression Of The Emotions In Man And Animals"

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CHAP. I.    SERVICEABLE ASSOCIATED HABITS.          37                              \  ^

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and blowing the nose are completely under our com-                              ;v;   \

mand.                                                                                                                       \   »

When we are conscious of the presence of an irritating

particle in our nostrils or windpipe—that is, when the                                   » <•

same sensory nerve-cells are excited, as in the case of
sneezing and coughing—we can voluntarily expel the
particle by forcibly driving air through these passages;                                 ;* •

hut we cannot do this with nearly the same force,                              * •; "

rapidity, and precision, as by a reflex action.    In this                                 ^   \

latter case  the  sensory nerve-cells  apparently  excite                                 ;   t

the motor nerve-cells without any waste of power by
first communicating with the cerebral hemispheres—the                                  , *

seat of   our consciousness and volition.     In all cases                                  '•

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there seems to exist a profound antagonism between the                                  , *..;

same movements, as directed by the will and by a reflex                                 '   -

stimulant, in the force with which they are performed

and in the facility with which they are excited.     As                                   ;';

Claude Bernard asserts, " I7influen.ce du cerveau tend

done & entraver les mouvements reflexes, a limiter leur

force et leur dtcndue." n

The conscious wish to perform a reflex action some-
times stops or interrupts its performance, though the
proper sensory nerves may be   stimulated.     For in-
stance, many years ago I laid a small wager with a dozen                                     <
young men that they would not sneeze if  they took                             !, *
snuff, although they all declared that they invariably                                     7-
did so;   accordingly they all took a pinch, but from
wishing much to succeed, not one sneezed, though their                             ] * •"
eyes watered, and all, without exception, had to pay                           , '. I
me the wager.    Sir II. Holland remarks12 that atten-                             '   *
tion paid to the act of swallowing interferes with the                             [   I
proper movements; from which it probably follows,                             !   '*

11 See tlie very interesting1 discussion on the whole sub-
ject by Claude Bernard, * Tissus Vivants,' 1866, p. 353-356.
13 'Chapters on Mental Physiology/ 1858, p. 85.