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THE SNAKES OF SOUTH AFRICA. 



The Elixir of Life. 



Connected with the heart is an endless system of tubes, 

 which carry the blood all over the body. 



The blood is the elixir of life. The stomach, with the aid 

 of the liver, pancreas, bowels, and lungs, changes the food 

 which we eat into blood, in a most marvellous way. The blood 

 is composed of tiny bodies, known as corpuscles and a watery 

 fluid known as the Plasma. There are red, and there are 



Fig. 124. — Exterior view of the human heart and the great 

 blood vessels. The heart has four chambers — two auricles 

 and two ventricles. (From Blackie's Physiology .) 



white corpuscles. The red corpuscles are those which make 

 the blood appear red. They and the Plasma carry food to 

 every cell of the body. In fact, they are living food— the 

 elixir of life. They renew the wasted cells. They are the 

 builders. As quickly as the cells of the body are broken down, 

 so they build up more. The white blood corpuscles are also 

 known as Phagocytes or Leucocytes. They attack and eat up 

 disease microbes, and repair wounds. 



