Fright may produce a wild beating of the heart, a death-like pallor, a gasping motion of the lips, an uncovering or protruding of the eye-balls, a sudden rigidity of the body as if “rooted” to the spot.

Grief may cause profuse secretion of tears, swollen, reddened face, red eyes and other familiar symptoms.

Shame may cause that sudden dilation of the capillary blood-vessels of the face known as “blushing.”

[Sidenote:  Bodily Effects of Perception]

The sight of others laughing or yawning makes us laugh or yawn.  The sound of one man coughing will become epidemic in an audience.  The thought of a sizzling porter-house steak with mushrooms, baked potatoes and rich gravy makes the mouth of a hungry man “water.”

Suppose I show you a lemon cut in half and tell you with a wry face and puckered mouth that I am going to suck the juice of this exceedingly sour lemon.  As you merely read these lines you may observe that the glands in your mouth have begun to secrete saliva.  There is a story of a man who wagered with a friend that he could stop a band that was playing in front of his office.  He got three lemons and gave half of a lemon to each of a number of street urchins.  He then had these boys walk round and round the band, sucking the lemons and making puckered faces at the musicians.  That soon ended the music.

[Sidenote:  Experiments of Pavlov]

A distinguished German scientist, named Pavlov, has recently demonstrated in a series of experiments with dogs that the sight of the plate that ordinarily bears their food, or the sight of the chair upon which the plate ordinarily stands, or even the sight of the person who commonly brings the plate, may cause the saliva to flow from their salivary glands just as effectively as the food itself would do if placed in their mouths.

[Sidenote:  Taste and digestion]

There was a time, and that not long ago, when the contact of food with the lining of the stomach was supposed to be the immediate cause of the secretion of the digestive fluids.  Yet recent observation of the interior of the stomach through an incision in the body, has shown that just as soon as the food is tasted in the mouth, a purely mental process, the stomach begins to well forth those fluids that are suitable for digestion.

[Sidenote:  Bodily Effects of Sensations]

The press recently contained an account of a motorcycle race in Newark, New Jersey.  The scene was a great bowl-shaped motor-drome.  In the midst of cheering thousands, when riding at the blinding speed of ninety-two miles an hour, the motorcycle of one of the contestants went wrong.  It climbed the twenty-eight-foot incline, hurled its rider to instant death and crashed into the packed grandstand.  Before the whirling mass of steel was halted by a deep-set iron pillar four men lay dead and twenty-two others unconscious and severely injured.  Then the twisted engine of death rebounded from the post and rolled down the saucer-rim of the track.