THE BLOOD AND ITS CIRCULATION 



317 



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LYMPH 



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1 



Function of Lymph. — The tissues and organs of the body 

 are traversed by a network of tubes which carry the blood. Inside 

 these tubes is the blood proper, consisting of a fluid plasma, the 

 colorless corpuscles, and the red corpuscles. Outside the blood 

 tubes, in spaces between the cells which form tissues, is found 

 another fluid, which is in chemical composition very much like 

 plasma of the blood. This is the lymph. It is, in fact, fluid food 

 in which some colorless amoeboid corpuscles are found Blood 

 gives up its food material to the lymph. This it does by passing it 

 through the walls of the 

 capillaries. The food is in "^^ 

 turn given up to the tissue SLoS)^ 

 cells, which are bathed by YmE^ 

 the lymph. 



Some of the amoeboid 

 corpuscles from the blood 

 make their way between 

 the cells forming the walls 

 of the capillaries. Lymph, 

 then, is practically hlood 

 plasma plus some colorless 

 corpuscles. It acts as the 

 medium of exchange between 

 the hlood proper and the cells 

 in the tissues of the body. 

 By means of the food sup- 



ply thus brought, the cells ^^^^ exchange between blood and the cells of 



of the body are able to grow, the body. 



the fluid food being changed 



to the protoplasm of the cells. By means of the oxygon passed 



over by the lymph, oxidation may take place within the cells. 



Lymph not only gives food to the cells of the body, ])ut also takes 



away carbon dioxide and otherwaste materials, which are ultimately 



passed out of the body by means of the lungs, skin, and kidneys. 



Internal Secretions. — In addition to all the functions given 

 above, the blood has recently been shown to carry the secretions of 

 a number of glands through which it passes, although tliese glands 



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