CIRCULATION 



399 



cretion of waste from tissues in lungs, skin, and kidneys are also 

 by way of these very important blood vessels. 



FIG. 129. The lymphatic vessels. The thoracic duct occupies the middle 

 of the figure. It lies upon the spinal column, at the sides of which are seen 

 portions of the ribs (1). a, the receptacle of the chyle; b, the trunk of the 

 thoracic duct, opening at c into the junction of the left jugular (/) and sub- 

 clavian (g) veins as they unite into the left innominate vein, which has been 

 cut across to show the thoracic duct running behind it; d, lymphatic glands 

 placed in the lumbar regions; h, the superior vena cava formed by the junc- 

 tion of the right and left innominate veins. From Martin-Fitz. 



Veins. On leaving an organ the capillaries unite to form veins, 

 which grow larger as they approach the heart, and always carry 



