INTERNAL ANATOMY OF INSECTS. 25 
ably more than a third of its length a . On the fourteenth 
day, the internodes, except the double ones, have be- 
come nearly straight again ; the fourth and fifth gan- 
glions have coalesced so as to form one, and the sixth 
and seventh have each lost their pairs of nerves b . Shortly 
after this, these last ganglions have nearly disappeared, 
and the chords of the three first internodes have again 
approached each other c . The next change exhibited 
is the absorption of the first ganglion by the brain, the 
union of the chords of the first internode, which is now 
straight, the approximation of the second and third gan- 
glions, and the enlargement of the one formed by the 
union of the fourth and fifth, at the expense perhaps of 
the sixth and seventh, which have now intirely disap- 
peared, and in their place is a very long internode. 
These united ganglions retain the pairs of nerves they 
had when separate d . Just before the assumption of the 
imago, the direction of the lobes of the brain becomes 
horizontal, the second and third ganglions unite, and the 
internode between the third and fourth is shortened e . 
Lastly, when the animal is become a butterfly, the se- 
cond and third ganglions have coalesced, and are joined 
to that formed by the union of the fourth and fifth ; a 
short isthmus or rather constriction, with an orifice, 
being their only separation : each of these united gan- 
glions send forth laterally four pairs of nerves'. In his 
figure, Dr. Herold has not represented the orifice for 
the passage of the gullet, but doubtless one exists, which 
for an animal that imbibes only fluid food is probably 
■ Plate XXX. Fig. 3. b Herold Schmeit. U ii./. 6. 
c Ibid. t. ii./. 7. d Plate XXX. Fig. 4. 
c Ibid. Fig. 5. c Ibid. Fig. 6. 
