EMBRYO WITH EIGHT SEGMENTS. 



195 



he embryo-region no trace of a coelomatic fissure. Over the area pellucida there 

 is no angioblast between the mesoderm and entoderm, it not having yet penetrated 

 from the area opaca. 



Figure 147 represents, under a considerably higher magnification, three sec- 



Seg 



EC. 



mes 



En 



FIG. 147. CHICK EMBRYO WITH SEVEN SEGMENTS. TRANSVERSE SERIES 510, SECTIONS 311, 212, 172. 

 Three transverse sections across the caudal end of the medullary groove. A, Section through one of the segments. 

 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. 



