Control .of Circulation. 75 



ankle does better rested on a chair, as less blood flows to it. 

 Nearly every one has noted the pain following the pressure 

 of blood when a sore hand, or foot, is suddenly lowered. 



Experiments illustrating the Effect of Gravity on Circulation. Let 

 the pupils stand. Let one arm hang freely by the side. Hold the other 

 arm straight up as far as the clothing will readily permit. Observe : 



1. The difference in the color of the two hands. 



2. The difference in fullness, both in the feeling of fullness and in 

 the projection of the veins. 



3. The difference in temperature; place the backs of the hands 

 against the cheeks. 



The position largely regulates the amount of blood in the hand, and 

 the amount of blood regulates the temperature, the size, and the color. 



Clothing and Circulation. No part of the clothing 

 should be tight enough to interfere with the circulation. 

 Such interference is perhaps most frequent in our foot 

 wear. In cold weather tight shoes keep the feet cold 

 and may result in their freezing, while the same thickness 

 of covering, if loose, would be comfortable. Men often 

 wear hats too tight ; this probably leads to baldness. Tight 

 garters sometimes hinder circulation and cause cold feet. 



Congestion. Congestion is an unnatural collection of 

 blood in any part or organ. This may be merely for a 

 short time, and no serious harm results from it. But if it 

 is long continued, it may do great harm. 



Inflammation. If the congestion becomes permanent, 

 we call it inflammation. That is, it is a permanent over- 

 supply of blood, which may bring many bad results. 

 There is usually redness, pain, and often swelling. We 

 have all seen such a condition around a boil or a wound. 



Use of Mustard Plaster. Mustard applied to the skin 

 causes irritation. It makes the skin red. This means that 

 more blood is drawn into the skin through the action of 



