CHAPTER XV. 

 TRANSUDATIONS RELATED TO THE BLOOD. 



THE LYMPH. 



The capillary vessels convey the arterial blood with its store 

 of nutriment to the various tissues, which by transudation 

 receive the required amount of nourishing matter. The 

 transuded liquid is the lymph which serves the double purpose 

 of nourishing the tissues and draining them also, since this 

 liquid not only gives up large molecules of absorbable matter, 

 but takes up at the same time various products of metabolism. 

 What is left over after this contact with the tissues collects in 

 the minute lymph capillaries and then into the larger lymphatic 

 circulation proper. 



Composition. Being thus related to the blood the lymph 

 must have a composition not greatly different from that of 

 the plasma. The normal lymph is a nearly clear fluid with a 

 specific gravity somewhat less than that of the serum as a rule. 

 It contains salts and organic substances as does the serum of 

 the blood, but is naturally poorer in protein elements since a 

 portion of these has been taken up to nourish the neighboring 

 cells. Very few red corpuscles are present, but as the forma- 

 tion of leucocytes or white corpuscles takes place in the so- 

 called lymphatic glands these form elements are abundant in 

 the final flow. 



It has been already shown that potassium salts are common 

 to the corpuscles of the blood, while the salts of sodium are 

 abundant in the plasma. We naturally find the same thing in 

 the lymph which contains, in addition to proteins, fat, sugar, 

 cholesterol, etc., inorganic salts, having about the following- 

 composition, according to some old analyses by Schmidt : 



Sodium chloride 5.67 per 1000 



Sodium oxide 1.27 



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