302 



STUDY OF YOUNG CHICK EMBRYOS. 



Fig. 173. — Chicken Embryo with Seven Segments. 

 Three transverse sections across the caudal end of the medullary groove: A, Section through one of the seg- 

 ' ments ; B, Section posterior to the segments ; C, Section just in front of the primitive streak. Md.gr, 

 Medullary groove, nch, Notochord. Ec, Ectoderm, mes. Mesoderm. En, Entoderm. X 230 diams. 



