204 HUMAN PHYSIOLOGY CHAP. 



ous rubbing with the hands. A good vigorous rubbing 

 of the entire body with the hands or with a rough, dry 

 towel is an excellent form of exercise for anybody. 



144. Alcohol and Tobacco. It is a fact of common 

 observation that alcohol acts upon the nerves in such a 

 way as to make it difficult and impossible to control 

 the muscles. The unsteady and staggering gait of 

 the drunkard is an illustration. The young men on the 

 baseball, football, track teams, and rowing crews in 

 the best universities of this country are not allowed 

 to drink alcoholic beverages of any kind, or to smoke 

 cigars or cigarettes at any time. The reason for this is 

 apparent. 



The effect of stimulants and narcotics is most marked 

 upon the nervous system. They act upon the muscles 

 chiefly in an indirect way. But the presence of these 

 drugs in the blood may affect the nutrition of the mus- 

 cles, causing them to become weak and flabby, and there- 

 fore sluggish and irresponsive to all commands sent to 

 them over the nerves. They lose their natural strength 

 and power of endurance. 



SUMMARY OF THE MAIN POINTS 



i. The muscles cover the bony framework, making the form 

 round and full, cause all movements, and form walls for some 

 important organs. 



'2. There are about five hundred voluntary muscles in the 

 body and a large number of involuntary muscles. Muscles 

 differ widely in size and shape. 



3. A muscle has an origin, an insertion, and a fleshy part 



