ii THE BLOOD AND THE LYMPH 15 



Clotting is of great value as a means of preventing 

 bleeding to death from wounds. The clot forms a plug 

 that closes the opening of a blood vessel. 



Get a tumbler half full of fresh blood and leave it exposed to the 

 air for a short time. Watch it carefully and describe the formation 

 of the blood clot. The yellowish liquid that is squeezed out is 

 the serum. 



17. Anaemia. Blood may contain red corpuscles so 

 poorly made or so few in number that they are unable to 

 carry a sufficient amount of oxygen to the cells of the 

 body. Such a condition is known as ancemia. A per- 

 son who is anaemic is languid, pale in the face, lips, and 

 under the finger nails. He complains that he is tired 

 after the slightest exercise, and suffers much from head- 

 ache and drowsiness. 



18. How to keep the Blood Pure and Wholesome. 



1. Eat an abundance of good, wholesome food daily. 



2. Work and sleep in rooms thoroughly ventilated. 



3. Take a sufficient amount of outdoor exercise in 

 the sunshine each day. 



4. Keep the clothing loose, so as not to interfere with 

 the circulation of the blood or with the action of the 

 lungs. 



5. Keep the skin clean by frequent baths. 



6. Never drink beverages that contain alcohol, whether 

 in large or small quantities. 



7. Get enough sleep every night so that the waste 

 products may be removed from the blood daily. 



8. Remember that health depends largely upon the 

 condition and quantity of the blood. 



