THE EMBRYOLOGY OF THE HONEY BEE 



33 



similar numerical relation occurs (see p. 16 and Figs. II and III). 

 Figure 14 represents a sagittal section of a stage a trifle older 



FIG. 14. Anterior end of a sagittal section of an egg about 16 hours 

 old. The point of junction of the future ventral blastoderm with the 

 thin dorsal blastoderm is designated by a star, x 243. 



than those of the two figures preceding. Here the difference in 

 thickness between the dorsal and ventral blastoderm is more 

 marked. Moreover the thicker blastoderm of the ventral side 

 is continued over the anterior pole, being at this point even 

 thicker than the ventral blastoderm itself. At the point on the 

 dorsal surface where the thickened area joins the thinner and 

 somewhat flattened cells of the mid-dorsal area (marked in the 

 figure by a star) the cells of the latter have an irregular amoe- 

 boid form, and separated by short intervals, as though pulled 

 apart. The existence of this area of scattered cells was first 

 noticed in the bee by Dickel (1904) who has made much of it 

 in his endeavor to construct an original interpretation of the 

 origin of the germ layers in insects. A discussion of Dickel's 

 view of the relation of this area to the germ layers will be given 

 later. 



About the time that the nuclei enter the germ layers they un- 

 dergo mitotic division (Fig. nG and H). This may occur either 

 during the migration (Fig. nH) or immediately after (Fig. 



