CIRCULATION 



49 



Function. — The lymph fluid is essentially the blood minus the 

 red blood corpuscles. The general fluid movement is from blood 

 capillaries into lymph spaces, then lymph vessels, and, finally, 

 back to the blood of the anterior vena cava. The lymph fluid 

 distributes nourishment by osmosis directly to the body tissues, 

 and removes waste materials by the same process. For example, 

 in the lymph fluid held by the lymph spaces of the cows ' udder 

 and very close to the milk-gland cells, are the food materials 

 from which the gland cells may manu- 

 facture the casein, fat, sugar, and 

 other ingredients of milk. The nutri- 

 tious materials are as a rule taken into 

 the lymph from the blood, and waste 

 materials which the lymph receives 

 from the tissues are poured into the 

 blood through the thoracic duct and 

 the right lymphatic duct. 



Practical application. — The student 

 should see in the circulation something 

 more than a collection of technical 

 terms and abstract theories concern- 

 ing the physics of circulation. 



The blood serves, in a general 

 way, as a wholesale distributor of 

 needed materials to the tissues, and 

 as a wholesale collector of waste and 

 poisonous substance from the tissues. 

 The lymph fluid is, in a general way, 

 the retail distributor and collector; 

 and the two, after all, constitute one 



circulation system, the lymph being the watery portion of the 

 blood, plus white corpuscles. It comes into the tiny lymph spaces 

 from the capillaries and returns to the large vein (anterior vena 

 cava) through two large lymph vessels, the right lymphatic and 

 the thoracic. The entire circulatory system has an intimate and 

 important part in all disease processes, such as congestion, inflam- 

 mation, tissue degeneration, and restoration after inflammation. 

 An abundant circulation through the dairy cow's udder makes 

 possible the production of a large quantity of milk. A disturb- 

 ance in the circulation of a human brain causes a person to 

 faint and fall. 



Fig. 27.- 



-A Lymph Node. 

 {Eddy.) 



