OP INSECTS. 179 



acic ganglia are nearly united into one mass ; and all 

 the nerves furnished by these ganglia to the loco- 

 motive organs, will be seen to have acquired a con- 

 siderable development 



The sympathetic nervous system has been known 

 from the time of Swammerdam, who discovered it in 

 the larva of the rhinoceros-beetle (Oryctes Nasicor- 

 nis,) but its real nature, and the analogy it bears to 

 the great sympathetic nerve of the vertebrata, were 

 not understood till it was made the subject of a 

 special investigation by John Miiller.* It exists 

 more or less distinctly m all articulated animals, but 

 in none is it so complete as in insects. It is con- 

 sidered as forming two divisions ; one of them con- 

 sisting of a single cord, running along the anterior 

 portion of the alimentary canal, and emitting delicate 

 filaments on each side ; the other of a double nervous 

 webj originating on each side by one branch from the 

 posterior portion of the anterior cephalic ganglion, 

 running down the esophagus, and sending forth 

 branches to the single nervous cord. Both these 

 divisions stand in the most intimate relation to each 

 other, and form one continuous system. The first 

 i,s most conspicuous in Coleoptera, Neuroptera, and 

 Lepidoptera. In these it takes its rise in two arched 

 branches from the anterior cephalic ganglion, which 

 unite in the centre and form a small knot, from which 

 a single nerve emanates and runs beneath the cere- 

 brum. From its curved shape, this was called by 



* Nova Acta Phys. Med. Soc. XIV. part 1, p. 73- 



