126 THE ANATOMY OF THE HONEY BEE. 



spicuous antennal lobes {AntL) that give off the large antennal 

 nerves (AntNv). The tritocerebrum is not present as a distinct brain 

 division, and its nerves, the labral {LmNv) and the frontal {FtCom), 

 appear to arise from the deutocerebrum at the base of the antennal 

 lobes. The frontal ganglion {FtGng), formed at the union of the 

 two frontal nerves, gives off a very small, anterior, median nerve and 

 a much larger, posterior, stomatogastric trunk {StgNv, represented 

 in the drawing as cut off a short distance behind the frontal ganglion) 

 which goes backward on the dorsal side of the pharynx beneath the 

 brain. Behind the latter, and just where the pharynx contracts to 

 the tubular oesophagus, the stomatogastric nerve bears a pair of small 

 ganglia which are connected by short nerves with the brain, and 

 then it breaks up into branches that go posteriorly along the oesopha- 

 gus but have not been traced. 



The circumoesophageal commissures are so short in the bee that 

 the suboesophageal ganglion appears to be attached directly to the 

 lower ends of the brain, while the oesophagus appears to penetrate 

 the latter between the antennal lobes. The three principal pairs of 

 nerves from the lower ganglion {3/dNv, MxNv, and LhNv) go to the 

 mouth parts. 



A most thorough study of the internal structure of the brain of 

 the bee has been made by Kenyon (1896), to whose paper the reader 

 is referred if interested in this subject. Kenyon 's descriptions have 

 never been verified, but his work has an appearance of thoroughness 

 and carefulness. He applies the term " brain " to both of the nerve 

 masses of the head, distinguishing the upper as the " dorsocerebrum " 

 and the lower as the " ventrocerebrum," being led to do this from 

 physiological considerations, the separation of the two being merely 

 incidental to the passage of the oesophagus. 



In the thorax of the bee (figs. 1 and 52) there are two large ganglia 

 {IGng and 2Gng). The first is prothoracic, being situated above 

 the prosternum, in front of the entosternum (fig. 52, Fu.^), and it 

 innervates the prothorax and the first pair of legs. The second, 

 vrhich is situated in front of the middle legs and is protected above 

 by the arch of the common entosternum of the mesothorax and meta- 

 thorax (fig. 52, Fu^+s), is a combination of the mesothoracic and 

 metathoracic ganglia and the first two abdominal ganglia. This 

 composite structure is evident from the fact that it innervates both 

 the middle and the hind legs, the bases of both pairs of wings, the 

 mesothorax, the metathorax, the propodeum, and the first abdominal 

 segment behind the constriction (the true second segment) . The first 

 and second ganglia of the abdomen (fig. 52, SGng and ^Gng) lie in 

 the first two segments (// and ///) behind the constriction, which 

 are the true second and third segments. But since the nerve trunks 

 of these ganglia go, in each case, to the segments behind them, we 



