226 HENRY K. DAVIS 



indistinct. Cases 14 and 18 represent such a plexus. In all 

 the other cases of this type, the right and left lumbar trunks are 

 distinct. The intestinal trunk joins the caudal extremity of 

 the thoracic duct in 6. instances (figs. 16, 17, 19, 20, 24, 28); 

 the right lumbar lymphatics in 3 instances (figs. 18, 25, 29); 

 the left lumbar lymphatics in 4 instances (figs. 22, 23, 26, 27) ; 

 and in both the right and left lumbar lymphatics in 1 instance 

 (fig. 21). 



The caudal extremity of the thoracic duct in 9 instances 

 (figs. 16, 17, 18, 20, 22, 24, 26, 28, 29) presents an ampulliform 

 dilatation, the cisterna chyli. This is absent in 5 instances, 

 and in its place in 4 instances (figs. 21, 23, 25, 27) there is a 

 lymphatic plexus. In 1 instance (fig. 19), there is neither a 

 cisterna chyli nor lymphatic plexus. 



In addition to the right and left lumbar and intestinal branches, 

 the thoracic duct may receive the following branches: (1) col- 

 laterals which drain the intercostal spaces (present in all cases) ; 

 (2) efferent vessels which drain the posterior mediastinal lymph 

 nodes; (3) the left internal jugular trunk in all cases; and (4) 

 the left subclavian trunk in cases 14, 15 and 16. The collaterals 

 mentioned above drain, as a rule, more than one intercostal 

 space. There is not, however, a collateral for each intercostal 

 space. The trunks draining the posterior mediastinal nodes 

 had been destroyed in most of the cases. 



Lymph glands are associated with the thoracic duct in 11 

 instances (figs. 16, 19, 20, 21, 23, 24, 25, 26, 27, 28, 29). In 

 9 instances (figs. 17, 18, 19, 21, 24, 25, 26, 28, 29) the duct 

 divides into two branches which unite again after a short distance 

 to form a single trunk. These were called 'insulae' by Haller 

 ('75). In case 20 (fig. 29) there is a bifurcation of the terminal 

 portion of the duct and each branch presents an ampulliform 

 dilatation, similar to a cisterna chyli. 



In the abdominal portion, the thoracic ducts of this group lie 

 ventral to the bodies of the first 2 lumbar and 12th thoracic 

 vertebrae and between the crura of the diaphragm or under cover 

 of the right crus. Ventrad they are in relation with the right 

 side of the abdominal aorta. 



