THE FLY. 29 



resembles a worm, not only in its external shape^ but 

 also in its internal physiology ; it possesses loco- 

 motive hooks similar to those of the Worm, but not 

 so numerous, and more perfectly developed, and its 

 elongated cylindrical body is divided into rings only. 

 (The points of difference between the two creatures 

 will be noticed hereafter.) When it has passed a 

 certain length of time in this stage, it assumes the 

 pupa form, being enclosed in a hard fusiform case, 

 perfectly motionless, and to all appearance inanimate. 

 Whilst in this state, the remarkable change from one 

 of the lowest to one of the highest examples of the 

 Articulate type is going on ; first the legs and then 

 the wings becoming developed ; and when the meta- 

 morphosis is complete, the insect bursts its prison- 

 house and issues forth in its perfect or ' imago ' form, 

 furnished with legs and wings, and all those wonder- 

 ful appliances, which we shall presently describe in 

 detail. 



The foregoing comparison will show you, that not 

 oidy the outward forms of animals, but also their life- 

 history, and the metamorphoses to which they are 

 subject, are all duly considered by scientific zoo- 

 logists, in their systematic classification. But the 

 knowledge of this fact is all that need be deemed 

 essential for our purpose ; for we are not dealing with 

 groups, nor even genera, but only Avith species ; and it 

 matters very little to us whether zoologists have 

 placed the Earthworm at the head of one group, of 

 which it is a perfect representative, or at the base of 



