INTRODUCTION. 



11 



Al 



\ "^ 



G 



FIG. 9, A, B, AND C. DIAGRAMS ILLUSTRATING THE FORMATION OF THE AMNION. 

 ALLANTOIS, AND YOLK-SAC. A AND B, IN LONGITUDINAL SECTION ; C, IN 

 TRANSVERSE SECTION. 



E, embryo ; Dh, alimentary tract ; Do, yolk-sac ; t, vitello-intestinal duct ; PP, 

 body-cavity; Ah, amniotic cavity; AF, araniotic fold; A, anrnion ; Al, 

 allantois ; a, somatopleure ; b, splanchnopleure ; M, medullary cord ; (7, notochord. 



