CH. XVIII.] 



THE THORACIC DUCT 



223 



the lymphatic system of vessels will be seen to pass through a com- 

 paratively large trunk called the thoracic duct, which finally empties 

 its contents into the blood-stream, at the junction of the internal 

 jugular and subclavian veins of the left) side. There is a smaller 

 duct on the right side. The lymphatic vessels of the intestinal canal 

 are called lacteals, because during digestion (especially of a meal con- 

 taining fat) the fluid contained in them resembles milk in appear- 



Lympliatics of head and 

 neck, right. 



Right internal jugular 



vein. 

 Right subclavian vein. 



Lymphatics of right arm. 



Ileceptaculum chyli. 



Lymphatics of lower ex- 

 tremities. 



Lymphatics of head an 1 

 neck, left. 



Thoracic duct. 



Left subclavian vein. 



Th )racic duct. 



Lacteals. 



Lymphatics of lower ex- 

 tremities. 



FIG. 235. Diagram of the principal groups of lymphatic vessels. (From Quain.) 



ance ; and the lymph in the lacteals during the period of digestion 

 is called chyle. Chyle is lymph containing finely divided fat-globules. 

 In some parts of its course the lymph-stream passes through lym- 

 phatic glands, to be described later on. 



Origin of Lymph Capillaries. The lymphatic capillaries com- 

 mence most commonly either (a) in closely-meshed networks, or (&) 

 in irregular lacunar spaces between the various structures of which 

 the different organs are composed. In serous membranes, such as the 



