CHAPTER IY. 



THE BUTTEKFLY. 



MORE than fifty years ago, that prince of 

 dreamers, Oken, wrote as follows :* " The insect 

 passes through three stages prior to its attaining 

 the adult or perfect condition. It is at first 

 Worm, next Crab, then a perfect volant animal 

 with limbs, a Fly." 



How sagacious this observation was appears 

 from what we have already seen. In external 

 form the caterpillar so closely resembles a worm 

 that in common language it is often so called ; it 

 drags its whole length upon the ground ; its body 

 consists of a series of rings placed end to end ; its 

 head, it is true, is more or less separated from the 

 rest of the body, but yet agrees so well in general 

 size and form with the segments behind that the 

 distinction only appears upon examination ; while 

 the difference between the joints forming the 

 future thorax and those of the abdomen can only 

 be traced by careful study. In the pupal stage, 

 although the line of separation between thorax 

 and abdomen is well marked, and the latter is 



* Elements of Physiophilosophy, Engl. ed., p. 542. 



