LIST OF ILLUSTRATIONS. 



FIG. PAGE 



1. Diagrammatic Section of an Unincubated Fowl's Egg . . . 12 



2. A. Yellow yolk-sphere filled with fine granules. B. White yolk- 



spheres and ^spherules of vaiious sizes and presenting different ap- 

 pearances ... ... 15 



3. Section of a Blastoderm of a Fowl's Egg at the commencement of 



Incubation ... ... .....18 



4. Section through the Germinal Disc of the ripe Ovarian Ovum of a 



Fowl while yet enclosed in its Capsule 19 



5. Surface Views of the early Stages of the Segmentation in a Fowl's 



Egg 22 



6. Surface View of the Germinal Disc of a Hen's Egg during the later 



Stages of Segmentation • ^3 



7. Section of the Germinal Disc of a Fowl during the later Stages of 



Segmentation 24 



8. 4 to iV. A series of purely diagrammatic representations introduced 



to facilitate the comprehension of the manner in which the body of 

 the embryo is formed, and of the various relations of the yolk-sac, 

 amnion and allantois ......•• -9 3- 



9. Diagrammatic Longitudinal Section through the Axis of an Embryo. 33 



10. Section of a Blastoderm at right angles to the long axis of the 



Embrvo after eight hours' Incubation 4^ 



