THE VITAL PROCESSES. 29 



with nerves the simple eyes, the compound eyes, and the 

 antennas. The subcesophageal ganglion sends nerves 

 to the mouth parts, and is itself connected with the brain 

 by a pair of cords between which the oesophagus passes. 

 On back from the subcesophageal ganglion the nerve 

 chain passes into the thorax, where there is one fused 

 ganglion representing several larval segments. This 



FIG. 14. Stages in development of nervous system of a water beetle. 

 Mcilius sulcatus; showing ventral nerve cord in earliest larval stage, and, 7, the 

 system in the adult. (Kellogg, after Brandt; much enlarged.) 



supplies with nerves the wings, the legs, and the many 

 thoracic muscles. In the abdomen there is usually one 

 ganglion for each segment, the nerve chain terminating 

 in several fibrillae in the last segment. (Fig. 14.) 



Lying above the oesophagus, and having its origin in 

 front of the brain, there lies the sympathetic system. 

 This, by means of two pairs of ganglia, controls those 

 activities which are safely automatic respiration, the 

 action of the dorsal heart, and the usual processes of 



