68 THE VITAL PROCESSES 



not drained by the right lymphatic duct, and empties it 

 into the left subclavian vein. Connection is made with the 

 subclavian vein on the upper side at the place where it 

 is joined by the left jugular vein. The thoracic duct has 

 a length of from sixteen to eighteen inches, and is about 

 as large around as a goose quill. The lower end terminates 

 in an enlargement in the abdominal cavity, called the re- 

 ceptacle of the chyle. It is provided with valves through- 

 out its course, in addition to one of considerable size which 

 guards the opening into the blood vessel. 



The lymphatics which join the thoracic duct from the 

 small intestine are called the lacteals (Fig. 28). These do 

 not differ in structure from the lymphatics in other parts of 

 the body, but they perform a special work in absorbing the 

 digested fat (Chapter XI). 



Lymphatic Glands. The lymphatic glands, sometimes 

 called lymph nodes, are small and somewhat rounded 

 bodies situated along the course of the lymphatic tubes. 

 They vary in size, some of them being an inch or more in 

 length. The lymph vessels generally open into them on 

 one side and leave them on the other (Figs. 28 and 30). 

 They are not glands in function, but are so called because 

 of their having the general form of glands. They provide 

 favorable conditions for the development of white corpus- 

 cles (page 29). They also separate harmful germs and 

 poisonous wastes from the lymph, thereby preventing their 

 entrance into the blood. 



Relations of the Lymph, the Blood, and the Cells. - 

 While the blood is necessary as a carrying, or transporting, 

 agent in the body, the lymph is necessary for transferring 

 materials from the blood to the cells and vice versa. 

 Serving as a physiological "go between," or medium of 

 exchange, the lymph enables the blood to minister to the 



