PLATE 5 



EXPLANATION OF FIGURES 



61 Late cleavage, dorsal view, showing the preparation of E^ for division. 



62 A little later than preceding, showing three large entodermal cells; the 

 embryo is considerably contracted and is more spherical. , 



63 Two-hundred-and-fifty-cell stage, dorsal view. 



64 Same as preceding, in a contracted condition. 



65 Embryo with the dorsal ectoderm not represented, to show E and its 

 derivatives; the two posterior cells are in preparation for cleavage. 



66 Stage little later than last; shows the five large interior cells; e'-- not 

 represented. 



67 Embryo viewed from the right side, the ectoderm not shown; the interior 

 cells are slightly rounded and do not completely fill the space; the dorsal side is 

 to the right of figure; the blastopore is closed. 



68 Dorsal view of embryo with overlying ectoderm not shown; ten large 

 entodermal cells are present, five upper and five lower; the cavity represented is 

 the future body cavity. 



69 Same as the preceding, contracted, with the ectoderm represented. 



70 An embryo showing the division of the five upper and five lower large 

 entodermal cells; a few of the spindles are shown. 



71 Late embryo from the right side showing the early formation of the 

 stomodaeum and the temporary foot. 



72 An optical section of embryo little later than last. 



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