DIGESTIVE ORGANS OP INSECTS. 



157 



to accommodate it to this altered condition of its function, 

 considerable changes must t>e made in its structure. Hence, 

 it will be interesting to trace the gradual transitions in the 

 conformation of the alimentary canal, during the progressive 

 development of the insect, and more especially while it is 

 undergoing its different metamorphoses. 



These changes are most conspicuous in the. Lepidoptera, 

 where we may observe the successive contractions which 

 take place in the immensely voluminous stomach of the ca- 

 terpillar, while passing into the state of chrysalis, and thence 

 into that of the perfect insect, in which its form is so changed 

 that it can hardly be recognised as the same organ. I have 



given representations of these three different states of the en- 

 tire alimentary canal of the Sphinx ligustri, or Privet Hawk- 

 moth, in Figures 326, 327, and 32S;* the first of which 



* These figures also have been engraved from the drawing's of Mr. New- 

 port, which he was so obliging as to make for me, from preparations of his 

 own, the result of very careful dissections. 



