THE LYMPHATICS. 303 



accumulates under the skin, and forms blisters when you get 

 badly sun-burned. 



What the Lymph does. 



Well now, a most marvellous thing occurs within our bodies. 

 This lymph which saturates the body like water in a bog, sucks 

 from the blood its oxygen and digested nourishment through 

 the walls of the blood vessels, and so feeds the cells of our 

 bodies. Our bodies are burning all the time. We are con- 

 stantly using up the cells of our bodies. They burn away in 

 countless millions every instant of time, and are replaced by 

 new cells created from the nourishment supplied indirectly by 

 the blood, and directly by the lymph. The dead cells, when 

 burned up within the body, take the form of carbonic acid. 

 This gas is sucked up by the lymph, and through the walls of 

 the tiny capillary blood vessels. The latter carry it away in- 

 stantly to the larger veins which in turn pour into yet larger 

 ones still, until the poison-laden blood reaches the heart. This 

 human pump then forces it up into the lungs where it is changed 

 by the oxygen gas we inhale. The poisons are thus breathed 

 out and escape from the body. 



The Lymphatics. 



You wonder, perchance, how the watery lymph, laden with 

 impurities, is drained away. Like a thick network, countless 

 numbers of tiny tubes spread out under the skin, and amongst 

 the tissues. These are known as lymphatic vessels, because 

 they carry lymph. The blood vessels are unending. They pro- 

 ceed from the heart, divide and sub-divide until they form a 

 fine network of tiny tubes. These small blood vessels have no 

 blind or open endings. When their work is done in supplying 

 the lymph with their load of nourishment, and when they have 

 sucked up as much poisonous dead matter as they can from 

 the lymph, they begin to run together, forming larger and yet 

 larger channels which conduct the blood back to the heart to 

 be once again pumped into the lungs. On the contrary, the 

 lymphatics have open mouths. The lymph, which saturates 

 the tissues, is drained off by these httle lymphatic tubes, the 

 open mouths of which suck it up and hurry it along into larger 



