Figs. 1 to 22. — Drawings from tweuty-two serial sections of the embryo 

 (Sections Nos. 164-143 of the entire ovum). 

 O. A. — Cavity of amnion. 



C. M. — Chorion mesoderm. 



D. A. — Duct of allantois. 

 Em. S. — Embryonic shield. 

 Exo. — Exocoelom. 



Mes. — Mesoderm. 



P. A.— Allantoic stalk. 



S. v.— Yolk sac. 



V. — Aiilage of blood vessels. 



