2l8 



TEXT-BOOK OF PHYSIOLOGY. 



lymph through this complicated system of passages is aided by the 

 contraction of the muscle-fibers in the capsule of tKe'gTand. 



j^ie lymph-corpuscles or lymphocytes originate for the most part 

 in the ^land substance of the cortical alveoli. , In this situation there 



FIG. 91. DIAGRAM SHOWING THE COURSE OF THE MAIN TRUNKS OF THE ABSORBENT 

 SYSTEM. The lymphatics of lower extremities (D) meet the lacteals of intestines 

 (LAC) at the receptaculum chyli (RC), where the thoracic duct begins. The 

 superficial vessels are shown in the diagram on the right arm and leg (S), and 

 the deeper ones on the arm to the left (D). The glands are here and there shown 

 in groups. The small right duct opens into the veins on the right side. The 

 thoracic duct opens into the union of the great veins of the left side of the neck 

 (T). (Yeo's "Text-book 0} Physiology."} 



are groups of cells, so-called germ centers, which divide very rapidly 

 by jtritosis^and give rise constantly to groups of young cells which 

 soorTrindTheir way into the lymph stream. 



The Thoracic Duct. The thoracic duct is the general trunk of 



