CHAPTER VI. 



THE NERVOUS SYSTEM AND SENSE ORGANS. 



SPECIAL REFERENCES. 



NEWPORT. Nervous System of Sphinx Ligustri. Phil. Trans. (1832-4). Todd's 

 Cyclopedia, Art. "Insecta" (1839). 



LEYDIG. Vom Bau des Thierischen Kb'rpers. Bd. I. (1804). Tafeln zur. vergl. 

 Anat. Hft. I. (1864). 



BRANDT (E.). Various memoirs on the Nervous System of Insects in Horse Soc. 

 Entom. Ross., Bd. XIV., XV. (1879). 



MICHELS. Nerveusystem von Oryctes nasicornis im Larven , Puppen , und 

 Kaferzustande. Zeits. f. wiss. Zool., Bd. XXXIV. (1881). 



DlETL. Organisation des Arthropodeugehirns. Zeits. f. wiss. Zool., Bd. XXVII. 

 (187G). 



FLOGEL. Bau des Gehirns der verschiedenen Insektenordnungen. Zeits. f. wiss. 

 Zool., Bd. XXX. Sup. (1878). 



NEWTON. On the Brain of the Cockroach. Q. J. Micr. Sci. (1879). Journ. 

 Quekett Club (1879). 



GRENACBER. Sehorgan der Arthropoden. (1879). [Origin, Structure, and Action 

 of the Compound Eye.] 



CARRIERE. Sehorgane der Thiere, vergl. -anat. dargestellt (1885). [Comparative 

 Structure of various Simple and Compound Eyes.] 



General Anatomy of Nervous Centres. 



THE nervous system of the Cockroach comprises ganglia and 

 connectives,* which extend throughout the body. We have, 

 first, a supra-oesophageal ganglion, or brain, a sub-cesophageal 

 ganglion, and connectives which complete the cesophageal ring. 

 All these lie in the head ; behind them, and extending through 

 the thorax and abdomen, is a gangliated cord, with double 

 connectives. The normal arrangement of the ganglia in 

 Annulosa, one to each somite, becomes more or less modified in 

 Insects by coalescence or suppression, and we find only eleven 

 ganglia in the Cockroach viz., two cephalic, three thoracic, 

 and six abdominal. 



Yung ("Syst. nerveux des Crustacees Decapodes, Arch, de Zool. exp. et gen.," 

 Tom. VII., 1878) proposes to name connectives the longitudinal bundles of nerve-fibres 

 which unite the ganglia, and to reserve the term commissures for the transverse 



communicating branches. 



