THE VITAL PROCESSES. 



29 



With nerves the simple eyes, the compound eyes, and the 

 antennae. The suboesophageal gangKon 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 suboesophageal gangHon the nerve 

 Cham 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 fibrilke in the last segment. (Fig. 14.) 



Ljdng above the oesophagus, and having its origin in 

 front of the brain, there lies the S5niipathetic 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 



