DETAILS OF EARLY EMBRYO. 



8l 



(\ 



/^f 



B 



H 



n 



be 



■w^. 



Figs. 71 A-E and continued F-I on page 82.— Transverse seclions of lale gastrula shown in Plate V, fig. 36. The sections pass 



forward ; the first of the series. A, traverses the tail folds; the last, I, the head region of the early embryo. 



«i ToDgue of mesoblast cells representing the urogenilal anlage ; f>, megaspheres in process of passing through ihe yolk-entoblast ; oc, body cavity ; 

 C, points in extra-embryonic region where the ectoderm cells are being proliferated into the blastoderm ; i/. gul cavity ; "'t megasphcre appearing 

 in peristomial mesoblast. 



