228 THE LYMPHATIC SYSTEM 



and right lymphatic duct, it is returned to the venous 

 circulation. While the lymph is in the nodes, newly 

 formed lymphocytes attack and destroy any bacteria 

 that are present. 



Lymph nodes are divided into a superficial and 

 deep set, and usually found around bloodvessels and 

 embedded in fat. Occasionally they are single, but, as 

 a rule, are found arranged in chains. Bloodvessels and 

 nerves are plentiful. Besides these nodes, which will 

 be classified and described later, there are structures 

 allied to them tonsils and Peyer's patches of the 

 small intestines. 



The Composition, Production, and Function of Lymph. 

 Lymph is a clear fluid found within the tissue spaces, 

 and termed intracellular lymph; and in the lymphatic 

 vessels called intravascular lymph. It is alkaline in 

 reaction, and has a specific gravity of 1.02 to 1.04. 

 When observed under the microscope, numbers of 

 leukocytes or white blood cells are seen. These consist 

 of a small amount of protoplasm in which can be 

 seen a nucleus. Lymph will clot, but not as actively 

 or as firmly as blood. The clotting is due to the 

 appearance of fibrin. 



The Chemic Composition. This will vary, dependent 

 upon the portion of the body drained; however, 

 lymph obtained from the thoracic duct has been 

 found to contain, after chemic analysis, 34 to 41 

 per cent, of proteins (serum-albumin, fibrinogen), 

 0.046 to 0.13 per cent, of substances soluble in ether 

 (probably fat), 0.1 per cent, of sugar, and from 0.8 

 to 0.9 per cent, of inorganic salts, of which sodium 

 chloride (0.55 per cent.) and sodium carbonate (0.24 

 per cent.) are the most abundant (Munk). Small 

 amounts of calcium, potassium, and magnesium salts 

 are present; also both free oxygen and carbon dioxide; 

 urea in very small quantities. Lymph is similar in 

 composition to the plasma of the blood, only it does 

 not contain any red cells. 



