BODY SIZE AND CELL SIZE 



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Figs. 11, 12 Corresponding stages in the eggs of C. fornicata and C. adunca, 

 drawn to the same scale. In the former there are present 62 ectoderm, 10 meso- 

 derm and 7 endoderm cells; in the latter 66 ectoderm, 10 mesoderm, and 7 

 endoderm cells. The 4 additional ectoderm cells in C. adunca are 2 additional 

 posterior turret cells and 2 posterior basal cells, shaded by transverse lines. 



