CHAPTER II. 



MOTION. 



MOTION is the most manifest sign of life. While we are 

 sitting still, as we say, there are frequent slight motions of 

 the head, body, and limbs. Even during sleep the move- 

 ments of breathing may be seen ; the hand laid upon the chest 

 may feel the beating of the heart, and the finger detect the 

 pulse in a number of places. 



When an animal shows no motion whatever we conclude 

 that it is no longer alive. We must move to get our food, 

 or at least to eat and digest it. Motion is necessary for 

 breathing, for circulating the blood, for getting rid of wastes. 

 We often move to avoid injury. 



Motion is necessary for seeing: we must turn the face 

 toward the object and open the eyelids ; we move the eye- 

 balls ; within the eye are motions to regulate the amount of 

 light admitted, and to adapt the eye for seeing at different 

 distances. 



In feeling, we put forth the hand to touch the object. In 

 tasting, we place the object upon the tongue, or touch the 

 tongue to the object. In smelling, we sniff; and sniffing is a 

 respiratory motion. 



In hearing, we usually turn the head, and there is mo- 

 tion in the ear to adjust the parts to accurately distinguish 

 sounds. 



In speech there is motion. There is motion in facial ex- 

 pression ; or we may communicate by signs, as in writing, or 

 talking with the hands. 



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