Plate X. 

 Entire Embryos of Cynthia partita; Gastrula to Tadpole. 



Muscle cells shaded by vertical lines, mesenchyme by transverse line*, nerve plate and tube by fine 



stipples, chorda by coarse stipples. 



Figs. 148-151. Four view? of the same embryo; fig. 14.8 dorsal, 149 ventral -posterior, 150 same view 

 but deeper level, showing mesoderm and endoderm, 151 right side. Many of the ecto- 

 derm cells are passing into the 10th generation. 



Figs. 152-154. Three views of : embryo ; fig. 152 dorsal, showing closure of the blastopore from in 



front, 153 same view but deeper level, showing cells beneath the ectoderm, 154 ventral 

 view of mesoderm and endoderm below ectoderm. 



Figs. 155 and 156. Two ventral views of an advanced gastrula, the first showing the superficial ecto- 

 derm, the latter the endoderm and mesoderm lying beneath the ectoderm. 



Fig. 157. Left side of embryo, showing, in optical section, muscle cells, mesenchyme, chorda and nerve 

 plate. 



Figs. 158 and 159. Two optical sections of the same embryo, the former (158) through the open blas- 

 topore at the posterior end of the embryo, the latter (159) through the region anterior to 

 the blastopore. 



Figs. 160-162. Three views of the same embryo from the ventral side but drawn at different levels; 

 160 surface view showing ectoderm ; 161 same view deeper level, showing mesoderm and 

 endoderm : 162 same view still deeper level, showing chorda, mesoderm and endoderm. 



Fig. 163. Dorsal view of embryo of same stage as preceding showing nerve plate and tube, mesoderm 

 and chorda. 



Figs. 164 and 165. Two views of same embryo from right side ; fig. 164 median optical section show- 

 ing chorda, nerve tube and endoderm ; 165 more superficial view showing muscle cells 

 and mesenchyme. 



Fig. 166. Older embryo from right side, showing in optical section nerve tube, chorda, mesoderm and 

 endoderm. 



Fig. 167. Young tadpole from left side showing in optical section nerve tube, chorda and mesoderm. 



