Text-book of comparative anatomy . anglion, :.>thoracic and 8 abdominal ganglia. The last abdominal ganglion comes from threerudimentary ganglia, which are separate in the embryo. The adult bee (Fig. 320,p. 462) possesses a brain, infra-cesophageal ganglion, 2 thoracic and 4 abdominalganglia. The posterior and larger thoracic ganglion consists of the 2d and 3dthoracic ganglia fused together ; the composition of the last abdominal ganglion outof 3 ganglia can still be clearly made out. (3) Where the nervous system in the imago is much concentrated, it is very often( Muscidce] much concen
Text-book of comparative anatomy . anglion, :.>thoracic and 8 abdominal ganglia. The last abdominal ganglion comes from threerudimentary ganglia, which are separate in the embryo. The adult bee (Fig. 320,p. 462) possesses a brain, infra-cesophageal ganglion, 2 thoracic and 4 abdominalganglia. The posterior and larger thoracic ganglion consists of the 2d and 3dthoracic ganglia fused together ; the composition of the last abdominal ganglion outof 3 ganglia can still be clearly made out. (3) Where the nervous system in the imago is much concentrated, it is very often( Muscidce] much concentrated in the larva also, and at the same time slightlydifferentiated. We have here a case of the imaginal characteristics being shiftedback on to the larval stage. (4) The nervous system in the larva is seldom much concentrated when not con- 468 COMPARATIVE ANATOMY CHAP. centrated in the imago. Myrmeleon is, however, a case of adaptation of the nervoussystem to the short compressed form of body of the larva. utt nr d <jf g ttr. FIG. 326.—Median longitudinal section through the head of Blatta orientalis. The nervoussystem of the head is drawn entire, hyp, Hypopharynx ; os, oral cavity ; Ibr, upper lip ; ijf, ganglion frontale ; g, brain ; na, root of the antenual nerve ;?io, root of the optic nerve; g/,, anterior; gp, pos-terior ganglion of the paired visceral nervous system ;oe, oesophagus; c, cesophageal commissure; usg,infra-oesophageal ganglion ; cc, longitudinal commis-sure between this and the first thoracic ganglion ;sg, common duct of the salivary glands; Ib, lowerlip = 2d pair of maxilUe ; nr, nervus recurrens ; d,nerve uniting the frontal ganglion with the commissure ; e, nerve from this commissureto the upper lip ; /, nerve from the infra-oesophagealganglion to the mandible ; g, to the anterior max-illae ; h, to the lower lip (after Bruno Hofer). (5) In many cases where in the larvathere is an apparently concentrated ventralchord, its ganglia are q
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
