THORACIC DUCT IN MAN 239 



of 22, or in 9.09 per cent (figs. 30, 31) ; and into the thoracic duct 

 in 2 cases out of the 22, or in 9.09 per cent (figs. 10, 19) . 



The point at which the thoracic duct lying on the right side of 

 the aorta begins to incline to the left is subject to some variation. 

 The incUnation begins opposite the body of the 3rd thoracic 

 vertebra in 1 case out of 22, or in 4.545 per cent (fig. 22) ; opposite 

 the body of the 4th thoracic vertebra in 5 cases out of 22, or in 

 22.725 per cent (figs. 14, 18, 19, 24, 25) ; opposite the body of the 

 5th thoracic vertebra in 12 cases out of 22, or in 54.54 per cent 

 (figs. 10-13, 16, 17, 20, 21, 23, 26, 27, 29) ; and opposite the body 

 of the 6th thoracic vertebra in 2 cases out of 22, or in 9.09 per cent 

 (figs. 15, 18). In 1 case out of 22, or in 4.545 per cent the duct 

 lying on the right side of the aorta did not cross over to the left 

 side (fig. 30) and in 1 case out of 22, or in 4.545 per cent there was 

 no duct on the right side of the aorta (fig. 31). 



There is a divisiq^n of the thoracic duct into two branches which 

 unite again to form a single trunk. This has been termed an 

 'insula' by Haller. One or more insulae occurred in 13 cases 

 out of the 22, or in 59.085 per cent (figs. 10, 12, 13, 15, 17, 18, 20, 

 21,25,26,28,29,30). 



In 10 cases out of the 22, or in 45.45 per cent (figs. 10, 12, 13, 

 14, 19, 20, 23, 24, 28, 29) lymph glands are situated along the thoracic 

 portion of the thoracic duct. According to Sabin ('12) lymph 

 glands develop from a lymphatic plexus and as Pensa ('08-'09) 

 remarks, lymph glands may occur anjrwhere along the course 

 of the thoracic duct. This one may expect, I think, if he recall 

 the early embryonic plexiform arrangement of the thoracic duct. 



I have observed among my cases the forms of terminations 

 shown in table 1. Terminations of the thoracic duct similar 

 to those described in my cases have been reported by Parsons 

 and Sargent ('09), Wendel ('98), and Verneuil ('53), who cites 

 Boullard's cases (tables 2 and 3). 



Table 4 is a comparison of the percentages of the different 

 modes of termination of the thoracic duct as given in tables 1 

 to 3. From table 4, it will be seen that my results agree quite 

 closely with those of Boullard and with those of Parsons and 

 Sargent. 



