22 ELEMENTARY PHYSIOLOGY. 



we may observe the movements of the fingers 

 of a skillful pianist or a rapid type-writer. To help 

 you understand still better how very rapidly the 

 muscles can act, you may remember that in say- 

 ing the one word muscle, the mouth, tongue and 

 voice organs must be pat, in succession, into four 

 different shapes or positions, all of which is done by 

 the proper muscles. We must not get the idea that 

 only the bones are moved by the muscles. Many 

 other parts of the body are moved by their action. 

 For instance, the lips in whistling, the eye -lids in 

 winking, the skin in wrinkling the forehead, or the 

 heart in its ceaseless beating. When a dog pricks 

 up his ears, or a horse drives off the flies by shak- 

 ing his skin, it is done by the action of the muscles. 

 There is another use which the muscles 



Language 



of the serve, which is very interesting. It may 



be called the language of the muscles, 

 and it is remarkable how often they speak for us. 

 A frown on the face is purely the work of the mus- 

 cles; yet everybody understands its meaning. The 

 same is true of a smile. You see two men at a dis- 

 tance standing face to face and near together, with 

 clenched fist and up-raised arm. You do not hear a 

 word they say, but the action of their muscles, which 

 you see, tells you how they feel. You pass near by 

 a vicious horse, as he lays back his ears, or approach 

 a dog whose hair on his neck is drawn up stiff and 

 straight, you hear no sounds, but you understand 

 the warning. It is the silent but expressive lan- 

 guage of the muscles. 



