BLOOD TBMPEKAT0EE 171 



are an abundance of fresh air to secure sufficient oxygen 

 supply, plenty of sleep to prevent too great a drain by 

 the tissues upon the food and oxygen it carries, exercise 

 to allow the proper' distribution of food and oxygen to all 

 parts of the body and the removal of waste, and mitri- 

 tious food for diet to maintain the proper food content 

 of the plasma. This latter condition also affects the red 

 corpuscles as well as the plasma, as without iron it is 

 impossible to form hsemoglobin. 



Amount of blood in the body. — We might expect that the 

 constant giving up of food and oxygen by the blood would cause 

 its quantity to vary. So far as known, however, the loss of these 

 substances and the acquiring of wastes is so balanced that the 

 quantity is fairly constant, an'd in a healthy person amounts to 

 about one thirteenth of the total weight of the body. The amounts 

 in different parts of the body, however, vary. Roughly, it is 

 distributed in the following proportions : ' 



Heart and Limgs 25% 



Liver 25% 



The Skeletal Muscles 25% 



The Other Organs 25% 



Blood Temperature. — Heat is constantly being pro- 

 duced in all of the animal tissues of the body, and at the 

 same time heat is being given off to the outside air from the 

 surface of the body. The amounts produced and lost 

 vary in different parts of the body. Now, the blood is 

 passing constantly from one part of the body to the other, 

 and hence necessarily carries warmth from the parts where 

 greater amounts of heat are produced to places where 

 there is less. In this way it tends to equalize the tempera- 

 ture in all parts of the body, and the temperature of the 

 ' Foster, Physiology. 



