. The transformations (or metamorphoses) of insects (Insecta, Myriapoda, Arachnida, and Crustacea) : being an adaptation, for English readers, of M. Émile Blanchard's "Metamorphoses, moeurs et instincts des insects;" and a compilation from the works of Newport, Charles Darwin, Spence Bate, Fritz Müller, Packard, Lubbock, Stainton, and others. he second and third ganglions unite and fuse toge-ther. Very frequently this takes place with regard to the firstalso, and one thoracic medullary centre is produced. By comparing the number and the position of the thoracicganglions of the silkworm when in
. The transformations (or metamorphoses) of insects (Insecta, Myriapoda, Arachnida, and Crustacea) : being an adaptation, for English readers, of M. Émile Blanchard's "Metamorphoses, moeurs et instincts des insects;" and a compilation from the works of Newport, Charles Darwin, Spence Bate, Fritz Müller, Packard, Lubbock, Stainton, and others. he second and third ganglions unite and fuse toge-ther. Very frequently this takes place with regard to the firstalso, and one thoracic medullary centre is produced. By comparing the number and the position of the thoracicganglions of the silkworm when in the caterpillar state withthose of the moth, a very good idea can be formed of theimportant modifications in the nervous system which occur inconsequence of the alterations in the general development ofthe insect. The first or prothoracic ganglion is invariably united by longeror shorter nervous links to the sub-oesophageal mass, and all themedullary centres or ganglions are united to those in front andbehind in the same manner. In the silkworm caterpillar thethree thoracic nervous centres are small and wide apart, and eachone is in a segment of the bod\; but in the moth condition 38 7RAiVSFORMATIONS OF INSECTS. these formerly separate ganglions are united, and form a bulkymass in the middle of the thorax. Nevertheless, the points of. THE NERVOUS SYSTEM OF THE SILK-WORM MOTH (Magnified). THE NERVOUS SYSTEM OF THE SILK-WORM CATERPILLAR (Magnified). union may be detected by unusual care. The connecting cordsare, however, lost. THE METAMORPHOSES OF THE NERVOUS SYSTEM. 39 The beetles {Coleoptcra), the locusts {Ortkoptera), and the bees{Hymenopterd), do not have their thoracic ganglions all fusedinto one mass when they attain adult age, and the nervouscentre, which is known as the first of the thoracic segments—the prothorax—never unites with the others. But the next twoganglions do become fused together in those species which attaingreat perfection of organisation. In the la
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Keywords: ., bookcentury1800, bookdecade1870, booksubjec, booksubjectcrustacea
