PHYLUM ARTHROPOD A 321 



ganglion innervates the mandibles, labium, and other mouth 

 parts. From the subcesophageal ganglion a ventral chain of 

 ganglia (Fig. 241, g) extends posteriorly through the thorax and 

 into the abdomen. Small stomato- gastric ganglia are connected 

 with the organs of digestion, circulation, and respiration, and a 

 delicate, sympathetic nervous system is also present. 



SENSE ORGANS. The compound eyes are constructed on a 

 plan similar to those of the crayfish (p. 285, Fig. 203) and are 

 especially adapted for seeing moving objects. The ocelli are 

 less complex than the compound eyes, and are probably of use 



FIG. 244. Longitudinal section through part of an antenna of a worker 

 honey-bee, c, conoid hairs; /, tactile hairs; ho, auditory pits; n, nerves; 

 s, smell hollows. (From Cheshire.) 







only to distinguish light from darkness, although they may per- 

 ceive form at very short distances. 



The principal organs of smell are situated on the antennae. 

 They are hollows in the cuticle~(Fig. 244, s), connected with a 

 cell supplied with nerve- fibers (n). The queen possesses about 

 1600 smell hollows on each antenna, the worker 2400, and the 

 drone 37,800. The sense of smell is considered of great impor- 

 tance in the life activities of bees. 



Pits near the mouth of the bee have been identified as toste_ 

 organs. Taste setae are present near the end of the ligula (Fig. 



237^)- 



Certain pits on the antennae are supposed to be end organs 

 of hearing (Fig. 244, ho). Sounds are produced by the vibra- 



Y 



