226 



THE REASON WHY. 



" And he took him by the right iiand, and lifted him up ; and immediately hii 

 feet and ancle bones received strength." ACTS in. 



enced by impulses directed to them 

 through the nervous system by the 

 mind, which is the governing power. 



948. Why does the heart beat 

 without any effort of the will? 



Because the muscles of the heart are 

 involutary muscles that is, they are 

 independent of the will, and receive a 

 continuous nervous stimulus which is not 

 under the controul of the mind. 



Fig. 58 MUSCLES AND VES- 

 SELS OP THE LEG AND 

 FOOT. 



A. A large ligament, which covers the kneo 

 pan, or inoveable bone of the knee, by which 

 the ends of the bones of the thigh and leg are 

 kept from slipping over each other. 



B. A muscle which passes underneath the 

 cartilages of the ankle, and gives off four ten- 

 dons, which are distributed to the toes, and by 

 which they are extended in elongating the foot, 

 walking, &c. 



C. Part of the muscle which forms the fleshy 

 bulb of the calf of the leg, and which terminates 

 in the large tendon attached to the heel, called 

 the tendon of Achilles. 



D. One of the ligaments which bind the 

 tendons and the bones of the ankle. 



E. Arteries proceeding from the large vessel 

 descending the leg, by which the toes are sup- 

 plied. 



949. Why are the muscles of the 

 arms, <$fc., made subject to the con' 

 troul of the icill ? 



Because, as they supply the mechanism through which we adapt 

 ourselves to our varying wants and circumstances, it was necessary 

 that they should be placed under the controul of the mental poweCj 

 and be moved only in accordance with wans necessities. 



