§• 331. 



THE INSBCTA. 413 



(Nerviis recurrens) whicli passes over the oesophagus to the stomach, giv- 

 ing off branches right and left. Reaching the stomach, it divides, after 

 having formed a ganglionic enlargement, into two principal branches. 



The double Stomato-gastric nerve consists of one, two, or three pairs of 

 small ganglia, situated behind the brain, on each side of the oesophagus, 

 and communicating with each other, with the posterior extremity of the 

 brain, and with the Nermis recurrens, by delicate filaments. These fila- 

 ments send fine threads to the oesophagus, and, at certain points, anastomose 

 with the single nerves.'^' 



With the Ilemiptera, a single Splanchnic nerve has been observed, and, 

 for the double system, there has been seen, on each side of the oesophagus, 

 two small ganglia, one behind the other.'-' 



With the Diptera, the splanchnic system appears to be present ; at least, 

 there has been observed on the Chyliferous stomach of the Hippoboscidae, 

 a pair of filaments belonging, probably, to the double system.*^' 



The Lepidoptera have a highly-developed Nerviis recurrens, which often 

 forms, with the caterpillars, several small ganglia lying behind each other 

 on each side of the bi-ain, and connected together by a double nervous 

 arch. The double system arises on each side of the oesophagus, from two 

 ganglia, situated one behind the other, which, with the caterpillars and 

 pupae, are often approximated to a blending together, and which send off, 

 beside the filaments anastomosing with the recurrent nerve, threads to the 

 dorsal vessel.'** The Hymenoptera,''' Neuroptera, and Orthoptera, also, 

 have the two kinds of splanchnic systems. The double trunks are highly 

 developed with the Acrididae, and the Gryllotalpida, and have two pairs 

 of ganglia at their upper extremity, beside one or two on their course; 

 while, with the Libellulidae, Blattidae, and especially the Phasmidae, the 

 single nerve is the most developed.'"* 



1 For the Si)lanchiiic nervous system of the In- tems with the imago and larva of Bombyx mort. 

 Becta, of'which Swammerdamm had already ob- The works of Newport (Philos. Trans. 1832, p. 

 served the recurrent nerve, see, beside the gene- 383, PI. XII. XIII., and 1834, p. 389, PI. XIII. 

 ral works of Biirmeister (Handb. &c. I. p. 308), XIV.) on the larva and imago of Sphinx li^ustri, 

 and Lacordaire (Introduct. &c. II. p. 214), espe- are very distinguished. 



cially J. Muller, Nov. Act. Acad. Nat. Cur. XIV. 5 See Treviranus (Verm. Schrift. III. p. 59), 



1828, p. Y3 ; Brandt (Isis, 1831, p. 1103, also his who thinks he has observed the Nervus recur- 



Bemerk. iiberdie Mundmagen-oder Eingeweidenei'- rens with Apis meUiJica ; Brandt, also (Medizin. 



ven d. Everteljr. 1835, p. 16, or Ann. d. Sc. Nat. Zool. II. p. 203, Taf. XXV. fig. 32, and his Be- 



V. 1836, p. 95), and Newport, Cyclop. &c. loo. merk. &c. p. 22), has described the two systems in 



cit. II. p. 957). this species, and m the Bumble-bee {Apis terres- 



2 Meckel (Beitr. z.ur vergleich. Anat. I. p. 4) tris). 



has observed the Nervus recurrens in the com- 6 According to Burmeister (Handb. &c. I. p. 

 mon Cicada, and Brandt (Bemerk. &c. p. 23, Taf. 310, Taf. XVI. fig. 6 (firyUus migratorius)), the 

 II. fig. 1, 2) has observed the same with Lygaeus, recurrent nerve leaving the frontal ganglion, runs 

 and at the same time the ganglia of the double backwards and ends, after a short course, in a 

 system. ganglion which connects by two filaments with the 

 aSeeZ,. Dw/owr, Ann.d.Sc. Nat. III. 1845, p. 67. internal ganglia of the double system. These 

 4 The recurrent nerve was first discovered in the last send off several branches to the oesophagus, 

 silk-worm hy Swammerdamm (Bib. der Nat. p. and connect, through two filaments, with tlie exter- 

 132, Taf. X.XVIII. fig. 3, g.). Subsequently,/,^- nal ganglia of the same system. From these exter- 

 onet (Traite, &c., p. 577, PI. XII. fig. 1, PI. XIII. nal ganglia arise two lateral trunks which run 

 Sg. 1, PI. XVI. fig. 14, PI. XVIII. fig. 1) de- along the oesophagus and are distributed to the 

 scribed with the larva of the Goat-moth, the gizzard, forming a nervous plexus having four 

 double system and its relations with the dorsal ganglia. See, also, for the same species, Brandt, 

 vessel. Since then, the two systems have been ob- in the Isis, 1831, p. 1104, Taf. VII. fig. 5. Accord- 

 served in the larvae, pupae, and imagines of various ing to this last author (Bemerk. &c. ji. 29, Taf. II. 

 Lepidoptera; see Suckow (Anatora. physiol. Unter- fig. 7-9), the double system of GryUotalpa is sim- 

 such. 40, Taf. VII. fig. 33-38, (pupa and imago of ilarly disposed, only the nervous plexus of the giz- 

 Gas<ro;)ac/!a;)m())t who has described the double zard arises from two posterior ganglia of the two 

 system and the cardiac nerve. See, also, J. Mill- trunks. See, also, for that of GryUotalpa, L. 

 ler (Nov. Act. Nat. Cur. loc. cit. p. 97 (the recur- Dufour, Recherch. sur les Orthopt. &c. p. 285, 

 rent nerve of a larva of Sphinx)), and Brandt PI. III. fig. 22. With Phasma ferula, the four 

 (Isis, loc. cit. p. 1104, Taf. VII. fig. 3, 4, and Be- anterior ganglia of the single system are sraiUl, but. 

 merk. &c. p. 20), who has described the two sya- for compensation, the double system is very com. 



35* 



