THE EMBRYOLOGY OF THE HONEY BEE 121 



the frontal ganglion (Figs. 39 and 40, FtGng) lying between 

 them, by short thick cords of nerve fibres covered on the exterior 

 by a layer of ganglion cells, the frontal nerves (Fig. 40, FtNv). 

 The two nerves composing this commissure arise on each side 

 from the anterior face of the tritocerebrum and at their point 

 of origin from the latter is the root of a nerve which passes 

 cephalad to the labrum, the labral nerve (Figs. 39 and 40 LmNv). 



The histological structure of the brain is simple and essentially 

 similar to that of the ganglia. Each lateral half consists of a 

 mass of ganglion cells covered by the neurolemma and surrounding 

 a central mass of nerve fibres continuous with that of the cir- 

 cumoesophageal commissures. 



The stomato gastric system of the newly hatched larva consists 

 of the following parts: the frontal ganglion, the stomatogastric 



. iBr 



Fig. 43. 'Coronal (horizontal) section through the right half of the 

 protocerebrum of a newly hatched larva (Stage XV), x 337. 



