90 F. W. THYNG 



The sub-ureteral channel (Urnierenvene of Hochstetter) has 

 been obUterated caudally. The supra-ureteral channel is not 

 only much smaller than its companion on the right, but is sub- 

 divided caudally by numerous mesenchymal septa, indicative of 

 commencing atrophy. 



The left subcardinal vein, caudad of the renal anastomosis 

 has degenerated, but its cephalic extremity is connected with the 

 suprarenal sinusoids as on the right. It will ultimately form the 

 left suprarenal vein, a tributary to the left renal. 



The vena hemiazygos still opens into the left common cardinal. 

 It is connected with the azygos by the anastomosis at the level 

 of the 10th thoracic spinal nerve, mentioned above. 



Portal system. The left umbilical vein {V.um.s.) is repre- 

 sented in plate 4. In the liver it communicates with the hepatic 

 sinusoids, its blood passing chiefly through an especially large 

 sinusoid, the ductus venosus (D.v.) which joins the left side of the 

 common hepatic vein (vena cava inf erioris) . 



The trunk (V.vit.) fomned by the fused vitelline veins (Begg '12) 

 passes through the coelom in a separate strand of mesentery 

 (plate 2). In the dorsal mesentery of the duodenum it is joined 

 by the superior mesenteric vein (V.mes.s.) of which only thestump 

 is here shown. The trunk formed by this union, the vena 

 omphalo-mesenterica {V.07np.-mes.), now bends cephalad, and 

 passes dorsal to the anastomosis of the dorsal and ventral pan- 

 creatic outgrowths. After receiving the lienal vein {V.li.) it 

 becomes the vena portae (V.P.) which enters the liver where it 

 joins the hepatic sinusoids, and, by means of a considerable 

 channel, the right side of the ductus venosus. 



The hepatic sinusoids discharge into the vena cava inferior 

 (common hepatic segment) by way of the hepatic veins (Vv.hep.). 



Lymphatics 



The jugular lymph sacs {S.jug.), comparable to those dis- 

 covered by Sabin ('02) are seen in plate 6. The left also appears 

 in plate 5. They are large, nearly syimnetrical sacs somewhat 

 constricted into segments, and are situated one on either side, 



