Common Earthworm. 123 



glandular follicle secreting them to be considerably enlarged in re- 

 lation to their function as accessory generative organs. 



In the anterior fifteen segments in the interval between the inner row 

 of setae and the nerve cord, a white muscular fascicle is seen passing 

 forwards and finally upwards alongside of the commissural cords of the 

 nei-ve collar, and dorsally to the nerves given off from the first ventral 

 ganglion, to be inserted partly in the capsule of the cephalic ganglia, and 

 partly in the muscular and tegumentary tissues above them. No mus- 

 cular fibres are developed upon the commissural cords connecting the 

 ventral chain with the supra-oesophageal ganglia, as there are upon the 

 ventral coi'd itself; and the function of retracting the supra-oesophageal 

 ganglia, together with the structures above them, is performed by the 

 muscle here described, which from its origin and course acts at great 

 advantage. These two muscular bands have at first sight an appearance 

 closely similar to that presented by the two somewhat widely separated 

 halves of the ventral cord of the Tubicolar Annelids, and of Peripatus, or 

 to that of the accessory nerve-chains, developed in the Amphinomidae in 

 relation with the locomotor organs. 



For an excellent account of the nerve system of the Earthworm, 

 see Lockhart Clark, Royal Society's Proceedings, 1857, pp. 



344-351- 



For figures of the general arrangement of the nerve system, see 

 pi. viii., and Description. Quatrefages, Regne Animal An- 

 neles, pi. i. e, fig. 2a, and Ann. Sci. Nat., Ser. iii., tom. viii., 

 1847, p. ^6, for discovery of sympathetic system in Lumbricus. 

 See also D'Ukedem, I. c, pi. iii. fig. 4. 



For the histology, see Leydig, Tafeln zur Vergleich. Anat., iv., 

 fig. 8, and the various authors cited in the letter-press of 

 that work at pp. 138 seqq., 168 seqq. 



For figures of the nerve cord as existing in two separated halves, 

 see Grube, in Miiller's Archiv. for 1 853, Taf. x., 14. Quatre- 

 fages, ' Suites a Buffon,' Anneles, pi. iii., figs. 7 and 8 ; in 

 Peripatus Edwardsii, and Sabella and Scrpula. 



