THE EMBRYOLOGY OF THE HONEY BEE 



37 



inner surfaces are regular and smooth in contour. On the inner 

 surface the inner cortical layer is evident, but this is also more 

 uniform as well as thinner than before. Moreover the processes 

 on its inner surface are no longer so strikingly apparent, although 

 they still exist. 



Twenty-four to twenty-six hours. This stage is represented 

 by a sagittal section, figure 16. The blastoderm at this stage 



FIG. 16. Anterior portion of a sagittal section of an egg about 24-26 

 hours old. The contrast between the thick ventral blastoderm (ventral 

 plate) and the thin dorsal strip is very marked. The point of junction 

 between them is marked by a star, x 243. 



differs from that of the preceding stage in several particulars. 

 The contrast between the blastoderm on the dorsal surface and 

 that over the remainder of the egg is very marked, since there is 

 now evident, along the dorsal mid-line, a fairly well developed 

 strip about one-third of the diameter of the egg in width, and ex- 

 tending from one pole to the other, composed of flattened cells. 

 On the other hand, the cells of the ventral and lateral surfaces 

 have become elongated and columnar in form, whereby, the thick- 

 ness of the blastoderm in these regions is much increased. In 

 addition the thickened blastoderm over the anterior pole has 

 disappeared, giving way to a thin sheet of cytoplasm containing 



