OF THE SPHINX LIGUSTRI. 
391 
able from the lobes themselves, upon the upper part of which they are situated, 
while an ovate patch of a purplish substance is observed upon their surface. 
This has existed in every specimen I have dissected, and seems to form part 
of what is to become the dark pigment for the eye of the future moth. The 
ganglion that produces the nerve to the oesophagus and stomach has undergone 
no alteration, nor have the anterior lateral ganglia, [Plate XII. fig. 3. ( a , a),] 
and there is still a loop or nervous ring around the anterior part of the oeso- 
phagus, as in the perfect larva. There are still eleven ganglia [fig. 3. (1 to 11)] 
upon the longitudinal cords ; but none of these are yet increased in size, nor 
is there any particular alteration in the distribution of the nerves from the six 
abdominal ones, while the cords are still disposed in an irregular manner, and 
have not increased in diameter. But in the thorax the nerves are much en- 
larged, particularly those sent to the wings, while in some instances the nerves 
belonging to the posterior pair of legs are curiously convoluted within the 
thorax, preparatory to their being unrolled at the instant of the change to the 
pupa, [fig. 3. (4, &).] The superadded or transverse plexus of nerves are also 
enlarged, particularly at the points of union with the filaments which connect 
the plexus with the ganglia. They are occasionally so much increased at those 
points as to form distinct but irregularly shaped ganglia, nearly one third the 
size of the longitudinal ones of the cord, [Plate XII. fig. 4. (e, The lateral 
branches of the plexus have sometimes minute ganglia, [fig. 4. (e),] from which 
the nerves are produced ; but this is not often the case. 
Four days after the insect has become a pupa, the nervous system is much 
in the same state as at the moment of transformation, the chief difference being 
in the fifth ganglion having advanced nearer to the fourth, and become more 
indistinct, while the diameter of the cords has increased, so as to equal the 
whole diameter of the ganglion. The cerebral lobes, optic nerves, and ante- 
rior lateral ganglia, as well as the ganglia of the trunk and abdomen, continue 
nearly in the same state as before, and the cords, although a little shortened, 
are still irregularly disposed in the abdomen. 
Thirty days after the change there is a considerable alteration in the ner- 
vous system, [PI. XII. fig. 5.] The cerebral lobes are more increased, the optic 
nerves a little extended, and the first ganglion has been brought so very close 
to the lobes as to appear to constitute with them a single mass, through which 
3 e 2 
