OF THE PUPA STATE. 67 



After remaining for some months in the pupa con- 

 dition, the skin, or casement bursts, and the creature 

 then emerges in its perfect or imago state. This 

 term was employed by Linnaeus, from its having laid 

 aside its mask, or swaddling clothes, and become a 

 true image of its species. 



Butterflies, in their perfect form, have only six feet, 

 ten of those with which it was furnished in its cater- 

 pillar state having disappeared. The jaws, also, are 

 lost, and replaced by a curled up proboscis, incapable 

 of mastication, and only suited for extracting the 

 liquid sweets from flowers. The head is totally 

 changed in form ; and it has acquired four wings, to 

 enable it to make rapid and extensive aerial flights. 

 Two long horns project from the upper part of its 

 head, and its twelve eyes are replaced by two, which 

 are composed of at least twenty thousand convex 

 lenses, each supposed to possess distinct and effective 

 vision. 



The internal change of structure is no less asto- 

 nishing than that which is presented externally. In 

 the caterpillar, there are some thousands of muscles, 

 which are replaced in the imago by others of a form 

 and structure entirely different. Almost the whole 

 body of the caterpillar is occupied by a capacious 

 stomach. In the butterfly, this changes into an 

 almost imperceptible thread-like process ; and the 

 abdomen is inflated by two large packets of eggs, or 

 other organs, which are not visible in its former 

 condition. The caterpillar has two spirally convoluted 

 tubes filled with a silky gum, but in the butterfly 



