DETAILS OF EARLY EMBRYO. 



8l 



B 







Figs. 71 A-E and continued F-I on page 82. Transverse sections of late 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. 



fli Tongue of mesoblast cells representing the urogenital anlage ; &, megaspheres in process of passing through the yolk-entoblast ; be, body cavity; 

 c. points in extra-embryonic region where the ectoderm cells arc being proliferated into the blastoderm ; a, gut cavity ; m, megasphere appearing 

 in peristomial mesoblast. 



