28 





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FIG. ii. A series of stages to illustrate the entrance of a cleavage cell 

 into the cortical layer during the formation of the blastoderm. In A the 

 cleavage cell has just come into contact with the lighter tinted cortical 

 layer. In F the external portion of the cleavage cell has entered the 

 cortical layer and has produced a well marked elevation on the surface of 

 the egg. In G and H the cleavage nucleus is dividing, x 1107. 



