DEVELOPMENT OF INSECTS. 219 



Steps in preparation for a more important change. A time 

 comes when the whole of the coverings of the hody are at 

 once cast off, and the insect assumes the form of :i pupa or 

 chrysalis; being wrapt as in a sliroiul, presenting no appear- 

 ance of external members, and retaining but feeble indica- 

 tions of life. In this condition it remains for a certain pe- 

 riod: its internal system continuing in secret the farther 

 consolidation of the organs; until the period arrives when 

 it is qualified to emerge into the world, by bursting asun- 

 der the fetters which had confined it, and to commence a 

 new career of existence. The worm, which so lately crawled 

 with a slow and tedious pace along the surface of the ground, 

 now ranks among the sportive inhabitants of air; and ex- 

 panding its newly acquired wings, launches forward into 

 the element on which its powers can be freely exerted, and 

 which is to waft it to the objects of its gratification, and to 

 new scenes of pleasure and delight. 



Thus do the earlier stages of the development of insects 

 exhibit a recurrence of those structures which are found in 

 the lowest department of this series of animals. The larva, 

 or infantile stage of the life of an insect, is, in all its me- 

 chanical relations, a mere worm. The imago, or perfect 

 state, on the other hand, exhibits strong analogies with the 

 crustaceous tribes, not only in the general form of the body, 

 but also in the consolidated texture of its organs, (especially 

 of those which compose its skeleton) and in the possession 

 of rigid levers, shaped into articulated limbs, and furnished 

 with large and powerful muscles, from all which circum- 

 stances great freedom and extent of motion are derived. To 

 this elaborate frame, nature has added wings, those refined 

 instruments of a higher order of movements, subservient 

 to a more expanded range of existence, and entitling the be- 

 ings on which they have been conferred to the most elevated 

 rank among the lesser inhabitants of the dobe. 



The mechanical functions of insects scarcely admit of be- 

 ing reduced to general principles, in consequence of the 

 great diversity of forms, of habits, and of actions, that is met 



