Le INTERNAL ANATOMY OF INSECTS. 
tions, the first being the longest’. There are three free 
bile-vessels on each side, proceeding from a single 
branch’. It will not be uninteresting here to abstract 
from Herold the progressive changes which take place 
in the intestinal canal in this Order, during the transition 
of the animal from the larva to the imago state. In the 
larva, the gullet, the small intestine, and the rectum, are 
short and thick‘, there are a pair of silk reservoirs (se- 
ricteria), as well as vessels for the secretion of saliva 
(sialisteria): if you examine it two days after its first 
change, you will find the gullet and the small intestine 
much lengthened and become very slender; the stomach 
contracted both in length and size; the rectum also 
changed, and the silk vessels contracted‘. ‘These in a 
pupa eight days old have wholly disappeared; the gullet 
is become still longer, its base is dilated into a crop or 
food-reservoir; the stomach is still more contracted, and 
instead of a cylinder represents a spindle; the small in- 
testine also is lengthened*: at a still more advanced pe- 
riod, when it is near appearing under its last form, the 
gullet and small intestine are still more drawn out; and 
the honey-bag, though very minute, has become a lateral 
appendage of the gullet‘; and lastly, in the butterfly it 
appears as a large vesicle’; the small intestine is grown 
very long"; and the rectum has changed its form and ac- 
quired a coecum', When we consider the adaptation of 
all these changes of form, the loss of old organs and the 
acquisition of new ones, to the new functions and mode 
* Ramdohr ¢. xviii. f. 1. F, G. Or Lbid. Ls, Ke 
© PratEe XXX. Fic. 7. 4 Tbid. Fie. 8. ® Jbid. Fie. 9. 
f Ibid. Fic. 10. © ‘Thid.-Eie,-}1,.a. » Tbid. e, 
tetbided: 
