xii Illustrations 



FIGURE 



31. Transverse Section through the Body of a 



Tadpole at the Time of Hatching. (After 

 Marshall) 84 



32. The Skull of a 12-mm. Tadpole: A — seen from 



the Right Side; B — seen from Dorsal Side; 

 C — seen from the Ventral Surface. (After 

 Marshall) 86 



The Development of the Chick 



33. Semi-Diagrammatic View of the Egg of the 



Fowl, at the Time of Laying. (After Parker 

 and Haswell, slightly altered from Mar- 

 shall) 92 



34. A — Yolk with the Blastoderm in the Centre, 



the Latter Showing the First Two Cleavage 

 Planes. B — The Blastoderm on a Larger 

 Scale and at a Later Stage of Segmentation. 

 (After Duval) 96 



35. Surface View of the Blastoderm at a Later 



Stage of Segmentation than that Shown in 

 Fig. 34, B. (After Duval) ... 98 



36. Longitudinal Section of the Blastoderm after 



the Completion of Segmentation. (After 

 Duval) ...... 104 



37. Series of Diagrams to Illustrate the Formation 



of the Chick Embryo, Especially the Rela- 

 tions of the Embryo, Yolk-Sac, Amnion, 

 and AUantois. (After Foster and Balfour), 



106, 109, 112 



