PLATE 3 
EXPLANATION OF FIGURES 
Median plane reconstructions from sagittal sections of the chick embryo, 
head region only. The notochord is indicated by cross-barring, the neural plate 
stippled, entoderm and preaxial mesoderm (prechordal plate) stippled; the 
ectoderm shown in black. All figures at the same magnification, X 50. 
Sted 
~ 
28 
29 
30 
31 
32 
33 
Series 139, 6-7 somites. 
Series 106, 10 somites. 
Series 119, 14 somites. 
Series 109, 16 somites. 
Series 127, 22 somites. 
Series Gage 54s, 30 + somites. 
Ventral view of a model of the head of a chick, eight to nine somites, 
anterior portion, X 67. To illustrate the ventral end of the ‘sutura terminalis’ 
marking the anterior end of the brain-plate. Back of it is the ‘hypophyseal area’ 
and a shallow Seessel’s pocket continuous caudally with a dorsal pharyngeal 
groove. 
490 
