CHAPTER XIV. 



HYGIENE OF THE CIRCULATORY ORGANS. 



1. To Ensure a Healthy and Regular Circulation of the 

 blood, the skin must be kept warm. Cold, we have 

 learned (p. 72), contracts its blood-vessels and drives 

 the blood elsewhere. This does no harm if it be only 

 for a short time; indeed often does good. But a pro- 

 longed chill of the surface is very apt to cause disease of 

 some internal organ, by keeping it overfilled with blood, 

 or congested. 



A blush is a brief healthy congestion of the skin of the 

 face. It may be compared to the flushing of the mucous 

 membrane of the stomach when gastric juice is being 

 secreted. In each case, the temporary rush of blood to 

 the part nourishes it. But continued overfulness of 

 blood has an opposite effect. Too much liquid from 

 the blood soaks through the walls of the capillaries, 

 and the organ in which they lie becomes puffy and 

 swollen. 



2. Taking Cold. Congestion produced by a chill of 

 the surface oftenest shows itself on some mucous mem- 

 brane. If that lining the nose be attacked, it becomes 



1. What effect has the temperature of the skin on the circulation of 

 the blood ? What is apt to result from a prolonged chill of the sur- 

 face ? What is a blush ? To what compared ? Results of prolonged 

 overfulness of blood ? 



2. Where do congestions due to cold most often occur? Describe 



