LOCOMOTION. 



fao 3 



3. Observe the thin layer of Cartilage over the ends of the 

 bones. Feel it. Cut off a thin slice. Consider how its 

 smoothness and elasticity give ease 



of motion, and diminish the shocks 

 that the body receives. 



4. Thoroughly clean one of the 

 long bones, and study its form and 

 parts. Its tough covering is the Peri- 

 osteum. 



Locomotion. By continuing 

 such observations as we made when 

 we began to study our motions, we 

 can analyze and understand many of 

 the common movements which we 

 habitually make. 



Although we are not ordinarily 

 conscious of the fact, when we are 

 standing still we are using many mus- 

 cles. The accompanying figure illus- 

 trates how some of the muscles act in 

 keeping the body upright. Our weight, 

 or, we would better say, the force of 

 gravity, is continually trying to pull 

 us down to the ground. The joints 

 are all freely movable, and hence as 

 soon as the muscles cease to act prop- 

 erly, in balancing against each other, 

 we lose our equilibrium, and fall if 

 we do not quickly regain it. 



In walking, we lean forward, and 

 if we take no further action we fall, 

 on the ground, pushing the body forward, while the other leg 

 is flexed, and carried forward to save us from the fall. We 



\ 



Fig. 8. 



Action of the Muscles 

 in Standing. 



But we keep one foot 



