122 THE EMBRYOLOGY OF THE HONEY BEE 



,Br- 'Br,(OpL> 



2Br(AntL) 



LbNv- 



SoeGng 



Fig. 44. Sagittal section of the head of a newly hatched embryo 

 (Stage XV), passing laterad of the median plane and intersecting the 

 right half of the brain (Br), the circumoesophageal commissure (OeCom) 

 and the suboesophageal ganglion (SoeGng), x 337. 



nerve or nervus recurrens, and a pair of ganglion lying against 

 the sides of the posterior region of the oesophagus, the pharyngeal 

 ganglia. To these may be added, for the sake of convenience, the 

 so-called ganglia or corpora allata of Heymons, which in fact are 

 probably not ganglia at all, according to Heymon's own state- 

 ment (1897), (Figs. 39 and 42, Cor All). 



The frontal ganglion (Figs. 39, 40 and 45, FtGng) is a large and 

 conspicuous pyriform ganglion with its blunt end directed ceph- 

 alad, lying in the median plane at the base of the lab rum and just 

 above the oesophagus. It consists of a compact mass of ganglion 

 cells surrounding a core of nerve fibres. From its anterior end 

 nerve fibres, accompanied by a few scattered ganglion cells, run 

 to the tip of the labrum. At its posterior end the frontal ganglion 

 becomes continuous with the stomatogastric or recurrent nerve 

 (Figs. 41, 42 and 45, StgNv) which runs backward in the median 



