472 



MALL. 



[Vol. V. 



strate that the origin of this vessel is constantly shifting as the 

 following table shows : — 



His's embryo M 

 Dog embryo . . 

 His's embryo B 2 

 Dog embryo . . 

 Human embryo . 

 His's embryo A~ . 

 Cat embryo . . 

 Dog embryo . . 

 Adult, human . . 



" cat . . . 



" dog . . . 



1 Omphalo-mesenteric vein. Atlas. Replace Fig. 15, PI. VI., into M 4 , PI. VII. 



2 Atlas. Replace Fig. 35, PI. II., into Fig. 1, PI. I. 



3 Atlas. Replace Figs. 79 and 86, PI. V., into Fig. 4, PI. I. 



It is only left for us to conclude that the stomach, liver, 

 and pancreas receive their artery while they lie dorsal to the 

 heart, and as their organs move backward the origin of the cce- 

 liac axis is gradually shifted in the same direction. 



In these cases the omphalo-mesenteric artery is also shifted 

 with the cceliac axis. In our embryo this vessel has a double 

 origin, which indicates that this movement may be brought 

 about by an anastomosis forming and then occlusion of the old 

 origin. There is no twig from the omphalo-mesenteric to the 

 mesentery. 



The twigs which arise from the lumbar aorta at once break 

 up into a capillary network which extends to and encircles 

 the intestine, finally communicating with a vein which empties 

 into the omphalo-mesenteric vein. 



Veins. 



The veins which I have followed out are the jugular, cardinal, 

 subclavian, omphalo-mesenteric, and umbilical. Their general 

 course is shown in the reconstruction. It will be noticed that 



