THE FLY. 85 



do they go and hide themselves ? As far as I am aware, no better 

 answer can be given now than was given 150 years ago : — 



" From every chink 

 And secret corner, where they slept away 

 The wintry storms — or rising from their tomb 

 To higher life — by myriads forth at once 

 Swarming they pour." 



Let us now enter upon the life-history of a Fly ; and, passing 

 from the general to the particular, take the House-fly for our type, 

 combining with it for purposes of illustration the almost equally 

 common and well-known Blow-fly. There are diflerences as to 

 habit as well as to size ; but as far as I am aware there is not much 

 difference anatomically, except that of a larger development. 



Is there any analogy between this Fly and the Worm ? The 

 question seems startling at first sight. But when we are told that 

 the great French naturalist — Cuvier — was of that opinion, and 

 actually classed them together, and that the late Professor Busk 

 supported it, we must needs conclude that there are weighty 

 arguments in favour of it. It has been well observed that " The 

 lowest creatures in any particular section strongly resemble, when 

 in their perfect form, the early or embryonic stage of the higher 

 animals in the same section; the latter undergoing changes of 

 form and structure before assuming their perfect state." This 

 statement is well illustrated in the case of our Fly. 



There are four stages in its life-history : the egg, the larva, the 

 pupa, and the imago. Leaving the first stage— the egg — simply 

 remarking that it is soon hatched in warm weather, we come to 

 the second stage, the larva or maggot. Shortly described, this is 

 soft, destitute of legs, but having minute hooks for locomotion, 

 cylindrical in form, and divided into rings. In the worm, also, the 

 body is soft, destitute of legs, having hooks for locomotion, is 

 cylindrical in form, and divided by rings — -"articulated," as 

 naturalists say. It is said also that internally their physiology is 

 the same. Thus explained, the analogy would seem to be estab- 

 lished : that is to say, between the worm in its perfect state and 

 the fly in its larval or imperfect state. It does not remain long 

 in this condition, though while it does it eats voraciously as if 



