Florence E. Sabin 



385 



ScV— 



thoracic duct and of the superficial lymphatics. In Fig. 10, from an 

 embryo 4 cm. long, there is a plexus of ducts in the front wall of the 

 aorta just above the diaphragm. 

 Branches have been injected in 

 this stage to the heart, lung, aortic 

 wall, stomach, duodemim, adrenal, 

 Wolffian body and kidney. At the 

 same time ducts are growing along 

 the subclavian and femoral arteries 

 to make the deep lymphatics of the 

 arm and leg. In Fig. 11, from an 

 embryo 5.5 cm. long, there are 

 additional branches to the repro- 

 ductive organs. At the same time 

 the superficial lymphatics have 

 met and anastomosed over the 

 sides of the body. The lymph 

 Iiearts are now much smaller and 

 are no longer definite sacs, but 

 rather wide ducts. 



From a study of the diagrams it 

 will be plain that the superficial 

 lymphatics starting from the veins 

 primarily and from the four lymph 

 hearts secondarily follow in gen- 

 eral the course of the veins; in the 

 neck the anterior cardinal, in the 

 groin the sciatic. On the other 

 hand, from the time the thoracic 

 duct meets the aorta, the deep 

 ducts grow along the arteries. 

 This distinction was noted in the 

 adult as far back as 1836 by 

 Breschet.^ 



The spread of the superficial 

 lymphatics in embryos up to 4 cm. 

 long is shown in Fig. 1. As has 

 been said, all the ducts shown in the picture have been injected from 

 two points, one in the neck marked a, which corresponds to the posi- 



FiG. 11. Diagram of the lymphatic 

 system in an eiuhryo pig 5.5 cm. long. 

 x"2 Alh, anterior lymph heart; arm d, 

 deep lymphatics to the arm; arm s, 

 superficial Ivmphatics to the ann; ao, 

 plexus to the aorta wall; du, ducts to 

 the duodenum; h, ducts to the heart; oe, 

 ducts to the oesophagus; leg d, deep 

 Ivmphatics to the leg; leg s, superficial 

 Ivmphatics to the leg; lu, ducts to the 

 lung: mp, ducts to the mesenteric plex- 

 us; plh. ducts to the posterior lymph 

 heart; ro, ducts to the reproductive 

 organs;. St, ducts to the stomach wall. 



sBreschet: Le Systeme Lymphatique, Paris, 1836. 



