333 



ZOOLOGY. 



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

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

 other hand, the imago or butterfly has mandibles, which 

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

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

 become now greatly developed ; and the butterfly takes 



Fig. 296. — Embryo of a 

 Water-beetle (Hydrophilus). E, 

 egg ; K, head ; ot, upper lip; m, 

 moutli ; aw, antennae ; ^]. man- 

 dibles ; k^, &g, maxillpE ; B, 

 thorax ; &], 65, Og, legs ; hi-hio, 

 ten pairs of rudimentary abdo- 

 minal legs, of which all except A, 

 disappear before the insect 

 hatches ; a, anus, — After Kowa- 

 levsky. 



Fig. 297. —Profile view of embryo 

 Honey-bee, lettering as in Fig. 

 296. BM. nervous cord; oG, brain; 

 7?, digestive canal ; sch, the (Eso- 

 phagus ; Si^ stigmatal openings of 

 the tracheal system ; A, heart. — 

 After BlUtschli. 



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

 mode of life are entirely changed with its acquisition of 

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

 ing greatly in structure, externally and internally, at these 

 three periods, and with different environments. 



