\ 



PLATE 3 



Q.s. 



' 





w.d. 



x. 



Fig. 6. Section of an injected embryo pig 9.5 mm. long passing through the lower half of the 

 Wolfnan body. 



Fig. 7. Dissection of an injected embryo pig 1 4 mm. long, to show the capillary plexus which 



precedes the azygos veins. 

 Fig. 8. Section of an injected embryo pig I 3.5 mm. long showing the capillary plexus which 



precedes the azygos veins. 



