362 GENERAL BIOLOGY 



The eggs are bluish-white and oblong in shape. They are fertilized 

 just before leaving the queen's body. The eggs are deposited at the base 

 of the cells and then fastened into position in the cells by a secretion. 

 Fertilized eggs are laid in cells that have already been arranged to re- 

 ceive them, some being in queen cells, and some in worker cells, while 

 unfertilized eggs are placed in drone cells. But there seems to be evi- 

 dence that mistakes are made, and the right type of egg is not always 

 placed in the right cell. 



EMBRYOLOGY 



After the nuclei of the sperm and egg have united into a single 

 nucleus a. chitinous covering, the chorion, surrounds the entire egg. As 

 cleavage takes place, no definite cell walls appear. This means that a 

 great mass of protoplasm is present with many nuclei. These nuclei 



migrate to the periphery to form a 

 single layer of cells, called the blas- 

 toderm, while the remaining portion 

 of the yolk remains as yolk-sub- 

 stance until it is converted either 

 into food for the developing em- 

 Fig. 237. bryo, or into further cellular sub- 

 Cross section of germ-band of Clytra at 

 gastrulation. g., germ-band; i., inner layer. Stance. 



A germ-band or primitive streak 



(Fig. 237) now forms on one side of the egg where the blastoderm be- 

 comes thickened. This is to become the ventral side pf the bee. The 

 brain develops separately. A median groove arises in the germ-band, 

 and so two germ layers are formed, an outer layer called the ectoderm, 

 and an inner known as the entomesoderm. It is the latter layer from 

 which both entoderm and mesoderm arise. Now the germ-band grows 

 around the entire egg. 



It is of interest to know that while the antennae and four pair of 

 appendages can be seen near the anterior end of the embryo, one pair 

 of the anterior appendages disappear and the others become mouth 

 parts. Then, three pair of appendages develop on the thorax, all of 

 which disappear before hatching. 



METAMORPHOSIS 



The life-history of the bee is divided into four periods : egg, larva, 

 pupa, and adult or imago. 



Queens, workers, and drones remain in the egg three days, but the 

 queens remain in the larval stage five and a half days, and in the pupal 

 stage seven days, while the workers remain in the larval stage five days, 

 and in the pupal stage thirteen. The drones remain in the larval stage 

 six days, and in the pupal stage fifteen days. 



