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Fic. 26. Main trunk of the liver from an embryo 20 mm. long (No. 22). 
From a reconstruction in wax. X12. Uv, umbilical vein; vp, portal vein; 
ra, ramus arcuatus; ra, ramus angularis; ru, recessus umbilicalis; dv, ductus 
venosus; vs, vena cava; rd, ramus dextra; rm, ramus media; rs, ramus sin- 
istra; rl, left arborization of the recessus umbilicalis. 
Fig. 27. Photograph of a section of the human embryo, 20 mm. long (No. 
22). % 15. Ru, recessus umbilicalis; dv, ductus venosus; rm, ramus media. 
Between the two branches of the ramus media may be seen a branch of the 
ramus acendus cut transversely. These branches are of the second order 
and the terminal branches the beginning of those of the third order. In 
this case the lobules are .5 mm. in diameter. 
