THE MUSCLES 137 



them to fill up anew. This pumping is done by the pres- 

 sure of the thickened muscle fibers on the veins, the flow 

 being controlled by the valves. It has been actually ob- 

 served that the quantity of blood flowing through one of a 

 horse's muscles used in eating, was three times as great 

 when the animal was engaged in chewing oats as when the 

 muscle was at rest. This powerful effect upon the circula- 

 tion causes renewed nutriment to reach every neighboring 

 organ and tissue, and the waste material to be removed. 

 Through the effects of exercise upon the circulation, the 

 body is thus purified and made sound and strong (Fig. 128). 



233. An Aid to the Memory. In tracing the effect of 

 muscular work upon the different organs, let us take them 

 in the order in which the organs are located in the body. 

 Let us go in order from the outer organs to the deeper ones, 

 viz : skin, fat, muscles, skeleton, viscera. The viscera will 

 then be taken in order, beginning with the highest, viz : 

 brain, lungs, heart, digestive organs, and lastly, general 

 effects. By using this fixed order, all can be called to mind 

 without omission. It is recommended to the pupil that he 

 group other series of topics in his memory in the same way, , 

 thus keeping the mental eye upon the body instead of upon 

 the pages of the book. 



234. The Nine Effects of Muscular Exercise enumerated 

 in order are as follows : 



1. The Skin. It opens the pores of the skin with 

 perspiration, fills the capillaries with fresh blood, and 

 improves the complexion by making the skin fresh, pink, 

 and smooth. 



2. The Fat. In cases of undue accumulation of fat, the 

 fat is burned up, and in cases of too great leanness, muscu- 

 lar exercise, by means of improved digestion and circulation 

 causes the fat to increase to the proper amount. 



3. The Muscles. Muscles affect themselves through 

 the improved circulation, and even the weakest and 



