352 



ZOOLOGY. 



is voracious, and leads a diSereiit life from the quiescent, 

 sleeping pupa or chrysalis, Avhich takes no food ; on the 

 other hand, the imago or butterfly has mandibles, which 

 are rudimentary, and incapable of biting, while the maxilla, 

 or ''tongue," which were rudimentary in the caterpillar, 

 become now greatly developed ; and the butterfly takes 



Pig. 301. — Embryo of a 

 Water-beetle illydrophUus). E, 

 egs; ; -ST, head ; ol, njiper lip; m, 

 mouth ; an, antfrniLC ; ^j. man- 

 dibles ; ^2' ^3' maxillfe ; J5, 

 thorax ; &], h^^o-^, legs ; Ai-Ak,, 

 ten pairs of rudimentary abdo- 

 minal legs, of which all except Aj 

 disappear before the inseci 

 hatches ; a, anus, — Ai'ter Kowa- 

 levsky. 



Fig. 302.— Profile view of embryo 

 Honey-bee, lettering as in Fig. 

 301. BM^ nervous cord; oG, brain; 

 Z*, digestive canal ; sch, the oeso- 

 phagus ; 8t, stigmatal openings of 

 the tracheal system ; iJ, heart. — 

 After Bliitschli. 



liquid food and but little of it, while its surroundings and 

 mode of life are entirely changed with its acquisition of 

 wiugs. Thus the butterfly leads three different lives, differ- 

 ing greatly in structure, externally and internally, at these 

 three periods, and with different environments. 



