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XVIII. 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. 
By George Newport, Esq. Communicated by P. M. Roget, M.D. Sec. R.S. 
Read June 7, 1832. 
In this paper it is proposed to describe the development and arrangement of 
the nerves, and the changes which they undergo, in the Sphinx ligustri, Linn., 
during the last stage of the larva, and the earlier stages of the pupa state. 
The labours of that industrious naturalist Heroldt have already shown us, 
to a certain extent, in what manner similar changes occur in the Papilio bras- 
sicce, Linn. ; and therefore the author of the present essay would not have ven- 
tured to trespass upon the attention of the Royal Society, were it not that these 
changes are capable of more minute explanation than those which take place 
with such rapidity in the P. brassicce. But the Sphinx ligustri, Linn., re- 
maining as it does for several months in an apparently torpid condition, be- 
tween its larva and perfect state, allows us an opportunity of more deliberately 
observing in what manner the changes are effected ; while the superior bulk of 
the insect enables us to trace them with greater precision. 
The Sphinx ligustri, like other Lepidopterous insects, after coming from the 
egg, has three very distinct periods of existence, recognised as the larva, the 
pupa, and the perfect state. In the larva state there are also distinct periods, 
terminated by the change of skin which takes place at the expiration of each. 
This change of skin occurs six times before the insect passes into the pupa state. 
After each change the larva becomes much enlarged, feeds more voraciously 
than at any preceding period, and when arrived at the sixth and last, which 
is always of longer duration than the earlier ones, increases so rapidly in bulk 
as to become at least a third larger than at any earlier period. Its nervous 
system undergoes a corresponding development. In every stage it is composed 
of two longitudinal cords, united at certain distances by ganglia. Of these 
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