24 THE EMBRYOLOGY OF THE HONEY BEE 



strands composing the network present the same appearance as 

 in the unsegmented egg ; within the zone they are scarcely visible. 

 On examination of the interior region with high powers it is 

 seen that the network has now all but disappeared, of it there 

 remains only a cobweb-like remnant, with tiny polyhedral thick- 

 enings marking the nodes (Fig. 10). Since the network periphe- 





FIG. 10. Protoplasmic reticulum from center of egg, Stage II, showing 

 diminution of reticulum subsequent to the peripheral migration of cleav- 

 age cells, x 1107. 



rad of the zone of cells is not altered, it is evident that what was 

 lost from the interior of the egg has been drawn into the 

 cleavage cells. This process of absorption continues as the cells 

 advance until they reach the cortical layer, when the condition 

 formerly seen only within the line of cleavage cells now prevails- 

 throughout the entire egg, except in the immediate neighborhood 

 of the yolk cells. By far the greater portion of the protoplasm 

 originally present in the ovum is drawn to its surface to furnish 

 material for the building up of the future embryo. A similar 

 process of absorption of protoplasm by the cleavage cells doubt- 

 less exists in most insect eggs, but is much more strikingly evi- 

 dent in certain of the Hymenoptera than elsewhere. Carriere 

 and Burger have described and figured it for both Chalicodoma 

 and Anthophora; in both of these forms it is identical with that 

 seen in the honey bee. Grassi and Dickel have also represented 



