G. C. Davenpokt. — Primitive Streak. 



PLATE IX. 



Fig. 45. Transverse section of the notocliordal canal of embryo shown in 

 Figures i and i', Plate I. The section here figured falls just 

 posterior to the anterior end of the floor seen in Fig. i', Plate I. 



X 73- 

 Fig. 46. Transverse section of the same embryo passing through the anterior 



lip of the dorsal notochordal opening. X 73- 

 Fig. 47. Transverse section (the third behind the notochordal opening) through 



the streak region of Figs. 2, 2', Plate I. X 240. 

 Fig. 48. Transverse section, the sixth behind the dorsal notochordal opening 



of the embryo shown in Fig. 2, Plate I. X 240. 



