2fi6 ANATOMY. 



second somewhat larger ganglion lies some little distance beyond the 

 first, exactly between the sexual organs, and gives off branches to this 

 as well as to the colon. This description has been sketched from the 

 Eristalis lenax of Meigen ; in Musca vomitoria I found precisely the 

 same structure. 



189. 



III. THE SYMPATHIC SYSTEM. 



A peculiar nervous system, which hung connected with the cerebrum 

 by means of fine branches, and in its course spread itself about the 

 anterior portion of the intestinal canal, was formerly discovered by 

 Swammerdam in the larvae of the rhinoceros-beetle (Oryctes nasi- 

 cornis*), and by Lyonet in the larva of the large Cossus^. Subse- 

 quent anatomists took no further heed of this discovery ; and until 

 Cuvier, who described some of the forms of these nerves, it was not 

 again thought of. Since then J. F. Meckel, Treviranus, and Marcel 

 de Serres have described this system in individual insects ; but Joh. 

 Miiller claims the greatest merit for giving the details of this system 

 in a distinct treatise J, having proved these nerves to be peculiar to 

 many insects, and for having represented them in several orders. 

 J. Brandt has likewise completed the observations of Mailer, and 

 has given a well-executed representation of the various relations of the 

 nerves in the caterpillar and imago of the silkworm. From these 

 earlier contributions, and from my own individual observations, I 

 deduce the following results : 



190. 



The sympathic system is peculiar to all insects, but in the several 

 orders it takes a different form : we may distinguish in it two main 

 divisions. A single cord, which runs upon the surface of the oeso- 

 phagus and stomach, giving off delicate branches on all sides, and where 

 the oesophagus passes through the brain running with the oesophagus 

 beneath the cerebrum : and a double nervous web, consisting of ganglia, 



* Biblia Natura, PI. XXVIII. f. 2 and 3. 

 t Lyonet, PI. XII. f. 1 . h. 



+ Nova Acta Phys. Med. Soc., torn. xiv. part i. p. 73, &c. 



J. J. Brandt, Beobachtungen iiber die Systeme der Eingeweidcnerven. Isis. 1831, 

 p. 2003. 



