PLATE 11 



EXPLANATION OF FIGUUES 



36 The tenth of the series of 40 sections through the same egg of which figure 

 35 represents the 21st section. The thickening of the embryonic area is better 

 shown here. Three cells are in mitosis. At ENT^ the entodermal cells are seen 

 to migrate from the margin of the embryonic area. 



37 and 38 Sections of blastocyst No. 40 (3) shown also in C, text figure 6. 

 The embryonic region {EMB.A) is thick, but limited in superficial area. C, 

 large cell, a retarded blastomere; this cell comes to the surface in a number of 

 sections of the series. TR.ECT, trophoblastic ectoderm. 



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