138 



HISTOLOGY. 



the veins, but they cannot be detected in the rabbit figured; they may be 

 formed later when the lymphatic system is essentially complete, In the 

 adult the lymphatic vessels from the legs follow lire femoral, hypogastric 



and common iliac vessels 

 to the aorta, in front of 

 which they form a net- 

 work. Here they are 

 joined by lymphatics from 

 the viscera, notably from 

 the intestines. The latter 

 vessels were called lac- 

 teals from their milky 

 appearance when filled 

 with fat obtained from 

 the alimentary canal. 

 The net is continued into 

 the thorax as one large 

 vessel, the thoracic duct, 

 which may or may not be 

 enlarged at its origin, 

 forming the cisterna chyli. 

 The thoracic duct 

 receives intercostal 

 branches; in places it 

 may be irregularly re- 

 solved into several small 

 vessels which reunite. 

 Near its termination in 

 the left subclavian vein 

 the thoracic duct receives 



FIG. ^.-LYMPHATIC VESSELS AND VEINS IN A RABBIT OP Subclavian and jugular 



I4 DAYS, is HOURS; 14.5 MM. x 11.5. trun k s from t he left arm 



The lymphatics are heavily shaded, x being along the left vagus 



nerve and y along the aorta. The subclavian vein is formed onrl Ipft ftirlf nf thf> VipaH 



by the union of the primitive ulnar, Pr. Ul., and external d11 



mammary veins, Ex. M. The other veins are: In. J. and rf>;nprtivplv On thf 



Ex. J., internal and external jugulars; Ce., cephalic; Az., respect. ciy. 



azygos; V., vitelline; G., gastric; S. M., superior mesenteric; ; i . J_ fU or - C c 



R. A., renal anastomosis (left renal vein); V. C. I., Tight Side there IS a 



inferior vena cava; Fe., femoral; An. T., anterior tibial; / ,7 , j , 



Pr. Fi., primitive fibular; c. b., branch to connect with lyWlpnatlC UUCt 



the femoral vein. . .. . 



by the union of vessels 



from the right arm, the right side of the head and heart, and the 

 right lung. Sometimes the thoracic duct bifurcates in the thorax sending 

 a branch to the right lymphatic duct, or its main stem may be on the right 

 side. Instead of a single opening of each duct into the vein, there may be 



