THE EMBRYOLOGY OF THE HONEY BEE 



39 



of the significance of this change will be deferred to the end of 

 the section. 



Twenty-eight to thirty hours. At this stage (Fig. 17) a cross 



FIG. 17. Transverse section through the anterior half of an egg about 

 28-30 hours old. All of the cells of the blastoderm, including those of the 

 dorsal side, have assumed a columnar form, x 243. 



section through any portion of the egg shows the blastoderm of 

 nearly equal thickness over the entire circumference, the dorsal 

 thin strip of the stage preceding having regained a thickness 

 equivalent to the remainder of the blastoderm; its cells neverthe- 

 less are distinguishable from those of the remainder of the blasto- 

 derm by their irregular form. In general the blastoderm cells are 

 regularly prismatic, much shorter and more compact in structure 

 than in the preceding stage, and slightly constricted near their 

 bases (Fig. I2F). The latter are, as before, fused to form a 

 continuous layer, but this is now thin, dark and granular, ap- 

 parently composed of material derived from the inner cortical 

 layer. Each cell still possesses an elliptical vacuole lying centrad 



