NERVOUS SYSTEM OF INSECTS. 



319 



the antennal nerves (Fig. 276, at}. The simple brain of the 

 locust may be compared with the more complicated brain of 

 a,n ant, as seen in Fig. 279. 



The infra-oesophageal ganglion (Fig. 278, ?/), as its name 

 implies, lies under the oesophagus at the base of the head, un- 



Fig. 279. Right half of an ant's-brain: uG, infra-oesophageal ganglion ; Or, brain; 

 "7, central connective portions ; W, semi-circuLir bodies of the small-celled portion 

 of tne brain lyin.r next to the basal portion of the brain, from which the nerves to the 

 simple eyes (an) arise ; Au, optic lobes ; An, anteunal lobes (the bodies appearing 

 like cells are rounded mass of the network of the substance of the cord ; r, cellu- 

 lar cortical substance of the brain ; ko. twofold body of the commissure connecting 

 the brain wi.h the itifra-cesoph-igeal ganglion. After Leydig, from Graber. 



der a bridge of chitine, and directly behind the tongue. It ia 

 connected with the supra-oesophageal ganglion by two com- 

 missures passing up each side of the oesophagus. From the 

 ander side of the infra-cesophageal ganglion arise three' 

 pairs of nerves, which are distributed to the mandibles. 



