60 METAMORPHOSES OF MAN 



dibles. The jaws have been immensely elongated; 

 their horny tissue has disappeared, and flexor and 

 extensor muscles have been developed in its place. 

 Each jaw is penetrated by nerves and tracheae, and is 

 grooved deeply on its inner surface. These organs, 

 when placed side by side and soldered to each other, 

 constitute a sort of tube twice as long as the whole body, 

 and continuous with the mouth. From having been 

 organs of mastication, they are now converted by this 

 process of fusion into a proboscis, which the insect 

 rolls or unrolls at will, and which can penetrate the 

 deepest calyx and allow it to suck up the juices of the 

 flower as perfectly as if a siphon had been employed. 



The chest or thorax bears the legs and wings. The 

 first correspond to the horny feet of the caterpillar, 

 but are very unlike them in appearance. The limbs 

 of the caterpillar were short and massive, those of the 

 butterfly are long and slender. Besides, their struc- 

 ture is entirely different. In the butterfly' s limb there 

 are five distinct parts, and the last or tarsus is itself 

 composed of five joints and a pair of hooklets. The four 

 wings are attached in pairs to each side of the back. 

 Each one is united to the solid structures through the 

 intervention of a chain of horny pieces, connected 

 together by strong ligaments and supplied with power- 

 ful muscles, and to these are due the suppleness 

 and force which are exhibited in the movements of 

 flight. From this basal portion spring four main 

 nervures, which diverge from each other, and by 

 their ramifications support the wing-membranes, which 

 are thus stretched upon a horny frame. Notwith- 

 standing their solid appearance, these nervures are 

 really hollow in their interior, and are pierced by tra- 



