STRUCTURE OF FOUR-DAY CHICKS 



129 



dorsal mesentery 

 tnesonephric duct 



omphalomesenteric vein 

 liver 



dorsal ganglion 

 neural tube 



lateral t^lencephalic vesicle 



ectoderm of head 



planchnic 



mesoderm 



vitelline vessels 



allantoic artery 

 coelom 

 post, appendage bud 



Fig. 46, — Diagrams of transverse secthansjol ar fbur-day chick. The location of 

 the sections is indicated on a small outline sketch of the entire embryo. 



