DISEASES OF THE HEART AND BLOOD-VESSELS. 83 



ANASTOMOSES. 



The branches of certain arteries in different parts unite again after 

 subdividing. This reuniting is called anastomosing, and assures a 

 quota of blood to the part if one of the anastomosing arteries should be 

 tied in case of hemorrhage, or should be destroyed by accident or oper- 

 ation. In such cases the blood is supplied by the collateral vessels of 

 the anastomoses, which gradually enlarge, because the increased quan- 

 tity of blood they are forced to carry distends their walls, and even- 

 tually the part receives all the blood it requires. Were it not for these 

 anastomoses, certain parts would be deprived of blood in certain cases 

 of accident and disease, and mortification would ensue. 



Anastomoses are effected when two branches, after traversing a cer- 

 tain length, reunite to form a vessel larger than either of the branches; 

 others are formed by transverse communications through smaller arter- 

 ies between two larger ones running in the same direction; and they 

 may be formed by a combination of both the foregoing methods. Veins 

 also form anastomoses, and they are even more numerous than those 



of the arteries. 







BLOOD. 



The various kinds of food, after being digested in the alimentary 

 ranal, arc absorbed and carried into the blood by the lymphatics, and 

 by tin 1 blood to the places where nutrition is required. The blood 

 takes fnm all parts of the body all that is useless and no longer 

 required, ami carries it to the different organs where it is eliminated 

 from the body. It contains within itself all the elements which nour- 

 ish the body. 



The blood may be considered a fluid holding in solution certain inor- 

 ganic elements and having certain bodies suspended in it. Authorities 

 differ as to the exact amount of each constituent of the blood, but the 

 following is a fair estimate: In 1,000 parts there are: water, 790 parts; 

 corpuscles, 120 parts; albumen, GO parts; salts and extractive matters, 

 iiii hiding the elements of fibrin, 30 parts. To facilitate description, 

 the bl<xxl may be considered as being made up of the corpuscles and 

 tho liquor sanguinis. The corpuscles are of two kinds, the red and the 

 white, the red being the most numerous. The color of the blood is duo 

 to the coloring matter in the red corpuscles. The red corpuscles are 

 the oxygen carriers. Roth kinds are very minute bodies, which re- 

 quire the aid of the microscope to recognize them. The liquor san 

 guinis is composed principally of water, salts, albumen, and the 

 elements of fibrin. The most abundant salts are the chloride and the 

 carbonate of soda, with a less quantity of the phosphate and sulphate 

 of potassium and lime. The albumen very much resembles the white 

 of an egg in its composition. Fatty matters exist in the liquor san- 

 guiuis iu extremely small particles, and also in combination with soda. 



