Expression Of The Emotions In Man And Animals

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.