80 



Florence E. Sabin. 



consists of the large jugular sac, measuring 5 x 3.6 mm., with its 

 large extension along the ulnar vein to the arm bud. Emptying 

 into the jugular sac on one side is the thoracic duct which connects 

 with a small cisterna chyli. Ventral to the cisterna chyli is the sec- 



.// // // 1 —V ' / i V" ^ J / ' t . .,- — iirp^fe 



Fig. 13. Coronal section through the jugular lymph sacs In a human 

 embryo of 30 mm.. Mall collection, No. 86. x about 11. The level of the 

 section is shown on the reconstruction of Fig. 21. The section shows the 

 complete lymph sac on the right side and is cut to show the valve on the 

 left. S. 1. j., saccus lymphaticus jugularis ; V. i., V. innominata ; V. j. 1., V. 

 jugularis interna; V. 1. s., vasa lymphatica superficialis. 



ond median sac, the retroperitoneal, which is adjacent to the renal 

 veins. At this stage a connection between the cisterna chyli 

 and the mesenteric sac, which has been so well shown by Baetjer 

 for, the pig of the same size, could not be made out. The posterior 

 sac has now become a long narrow sac, along the course of the primi- 



