414 



THE INSECTA. 



<^332. 



The Colcoptcra have, in both their larval and their perfect states, a 

 fcobly-developcd double nervous system arising from two pairs of ganglia, 

 and a highly-developed Nervus recurrens which, with a few species, forms, 

 directly behind the Gaiiglion frontale, a second ganglion. It runs along 

 the oesophagus, and usually forms, posteriorly, still another ganglion, and 

 then divides dicLotomously.*'^^ 



A great number of the Insecta have, in all their states, another system 

 of nerves, called Respiratory nerves, which, in view of their functions, 

 ought very properly to be classed among the mixed nerves, for they con- 

 tain not only motor, but also vegetative fibres. This system arises by 

 several single roots from the longitudinal commissures of the ventral cord. 

 Each of these roots divides into two Nervi transversa which deviate from 

 each other at right angles, and anastomose with the ganglia of the ventral 

 chain and with its peripheric nerves, receiving at the same time organic 

 fibres from the ganglia of the double splanchnic system. These respiratory 

 nerves are distributed to the large trachean trunks, and especially to the 

 muscles of the stigmata. The respiratory movements of Insecta cannot, 

 therefore, be regarded as properly of a voluntary nature.® 



CHAPTER IV, 



ORGANS OF SENSE. 



§ 332. 



The sense of Touch appears to be seated, with Insecta, in very difierent 

 parts of the body.'^' It is chiefly located in the palpi of the mouth, 

 which, for this purpose, are usually terminated by a soft surface.'^' The 

 antennae, also, serve as tactile organs, but in a very variable manner, ac- 

 cording to their forms, the degree of their development, and the habits of 



plete ; see Brandt, Bemerk. &c. p. 27, Taf. III. 

 fig. 1-5, and J. Mxiller, Nov. Act. Nat. Cur. loc. 

 cit. p. 85, Tab. VIII. fig. 1, 3. These two anato- 

 mists have given, moreover, details with figures on 

 the splanchnic nerves of Libellula, Blatta, Man- 

 tis and Gryllus. 



7 Swammerdamm (Bib. der Nat. p. 132, Taf. 

 XXVIII. fig. 2) has observed the Nervus recur- 

 rens in the larva of Oryctes nasicornis. Milller 

 (Nov. Act. Nat. Cur. loc. cit. p. 94, Tab. VII. fig. 

 4, 5) has figured it with Lucanus and Dijliscus. 

 Straus (Consid. &c. p. 406, 391, PI. IX.) has ob- 

 served with Melolontha, not only the single 

 nerve, but also the double system which, however, 

 he mistook for the accessory ganglia of the brain ; 

 Brandt (Mediz. Zool. II. p. 103, 118, Taf. XVII. 

 fig. 3, 4, Taf. XIX. fig. 20) was the first to under- 

 stand the true nature of this system with Meloe and 

 Lytta. See, moreover, Burmeister (Ilandb. &c. 

 Taf. XVI. fig. 8 (a larva of Ca/osoma)), Newport 

 (Philos. Trans. 1834, PI. XIII. fig. 4, 5 (imago and 

 larva of Timarcha tenebriosa), and Cyclopaed. 

 &c. fig. 405, 412, 416-418 (Tii.iarc/ia, Mcloe and 

 Lucanus)) ; also Sckiiidte, in KrOyerKs Naturh. 

 Tidskrift. IV. p. 104, PI. I. Acilius. 



a Although /.(/one«(rrait6,&c., p. 98, 201, PI. 



IV. fig. 5, PI. XX. fig. 1) had already described this 

 respiratory system with the larva of the goat- 

 moth, under the name of brides epiniires, it is 

 Newport who has recently called the attention of 

 anatomists to this subject, by furnisliing, with ad- 

 mirable details, the disposition of this respiratory 

 plexus, in the larva, pupa and imago of Sphinx 

 li^ustri (Philos. Trans. 1832, PI. XII. fig. 4, 

 1834, PI. XIII. &c., and 1836, PI. XXXVI., also 

 Cyclopaed. loc. cit. p. 947, fig. 400). See, also, 

 Milller's ideas (Archiv, 1835, p. 82) on the nature 

 of this nervous system. With various Coleoptera 

 and Orthoptera, with Locusta, Gry/lotalpa, and 

 Carabus, the single roots arise, according to New- 

 port, from small ganglia, at the points where are 

 given off the Nervi transversi. 



1 For the senses of the Insecta in general, be- 

 side the works of Spence and Kirby, Burmeister 

 and Lacordaire, see Schclver^s Versuch einer 

 Naturgesch. d. Sinneswerkz. bei d. Insckten u. 

 Wurmern, 1798, a work in which are related the 

 opinions of the older naturalists on this subject. 



■•i The tactile sense of the palpi is of great service 

 to Insecta when they eat; for these organs are used 

 not only to feel the food but also to retain, and con- 

 vey it between the jaws. 



