LIST OF ILLUSTRATIONS. XVli 



FIG. PAGE 



29. Diagrammatic representation of the Eye of the Chick of about the 



Third Day as seen when the head is viewed from underneath as a 

 transparent object ......... 99 



30. D, E, F. Diagrammatic Sections of the Eye of the Chick of about 



the Third Day . . . . . . . . . .100 



31. Section of the Eye of Chick at the Eourth Day .... 104 



32. Section through the Hind-Brain of a Chick at the end of the Third 



Day of Incubation . . . . . . . . . 1 io 



33. Two Yiews of the membranous Labyrinth of Columba domestica. 



A from the exterior, B from the interior . . . . .112 



34. Transverse Section of the Head of a Foetal Sheep (16 mm. in 



length) in the region of the Hind-Brain . . . . . 113 



35. Section of the Head of a Foetal Sheep (20 mm. in length) . . 114 



36. Section through the internal Ear of an Embryonic Sheep (28 mm. 



in length) . . ... . . . . . . .116 



37. Head of an Embryo Chick of the Third Day viewed sideways as an 



Opaque Object . . . . . . . . . .118 



3S. The same Head as shewn in Fig. 37, seen from the Front . 121 



39 A. Diagram of the Arterial Circulation on the Third Day . . 122 



39 B. Diagram of the Venous Circulation on the Third Day . .124 



40. Section of the Tail-end of an Embryo (Chick) of the Third Day . 125 



41. Section through the Dorsal Region of an Embryo at the commence- 



ment of the Third Day . .126 



42. Diagram of a portion of the Digestive Tract of a Chick upon the 



Fourth Day. . . . . . . . . . .128 



43. Four diagrams illustrating the Formation of the Lungs . . .129 



44. Section through the Dorsal Region of an Embryo at the end of 



the Third Day .......... 135 



45. Head of an Embryo Chick of the Third Day (seventy-five hours) 



viewed sideways as a transparent object . . . . .137 



46. Embryo at the end of the Fourth Day seen as a transparent 



object . . . . . . . . . , . .142 



