THE NERVOUS SYSTEM AND THE EYES. 



125 



two large antennal lobes, from which are given off the antennal 

 nerves. The third innervates the lower part of the face and the 

 labrum, while it gives off also a pair of nerves which unite in a small 

 swelling, the frontal ganglion, that lies between the pharynx and the 

 front of the head. A nerve runs posteriorly from this on the dorsal 

 side of the pharynx or oesophagus to behind the brain, where it 

 divides into several branches, some of which bear small ganglia while 

 others extend backward on the cesophagus to the stomach. These 

 nerves, originating in the frontal ganglion, constitute the stomato- 

 gastric system, sometimes called also the " sympathetic system." 



— AntNv 



Fig. 53. — Brain and subcesophageal ganglion of worker and their principal nerves, 



anterior view. 



The subcesophageal ganglion consists of at most four ganglia which 

 innervate the mandibles, the hypopharynx, the first maxillae, and the 

 labium or second maxillas. In adult insects the body ganglia also 

 very commonly fuse with one another in varying combinations, for 

 the number present is always less than the number of segments, vary- 

 ing from eleven to one. 



The brain of the bee (fig. 53, Br) is distinctly composed of two 

 parts, the protocerebrum [IBr), carrying tlie large optic lobes {OfL), 

 and the deutocerebrum {'BBr) , which consists principally of the con- 



