On the nervous system of the Sphinx Ligustri (Linn.), and on the changes which it undergoes during a part of the metamorphoses of the insect

Abstract

The author gives a minute anatomical description, accompanied by drawings, of the development and arrangement of the nerves of the Sphinx Ligustri , and the successive changes they undergo during the last stage of the larva, and the earlier stages of the pupa state. As this insect, in passing from its larva to its perfect state, remains for several months in a torpid condition, it affords a better opportunity of minutely following these changes, and of ascertaining in what man­ner they are effected, than most other insects; and the great compa­rative size of this species renders the investigation still more easy. While in its larva state, this insect frequently changes its skin: it enlarges rapidly in size after each operation, and the nervous sy­stem undergoes a corresponding development. The author minutely describes the longitudinal series of ganglia, which extend the whole length of the animal. He remarks that the eleventh or terminal gan­glion is distinctly bilobate, a form which, as suggested to him by Dr. Grant, is probably acquired by the consolidation of two ganglia which had been separate at an earlier period of development. A detailed ac­count is then given of the nerves proceeding from these several ganglia.