152 GLIMPSES OF NATURE. 



upon a time the fly-race possessed all four wings. 

 How and why the hinder wings disappeared is more, 

 1 believe, than any one can venture to say. 



As for flight, it is tolerably clear the insect con- 

 trives its aerial movements with excellent skill. In- 

 deed, if we appeal to M. Marey, ot Paris, as an autho- 

 rity on animal locomotion, we learn that our fly, when 

 held captive, moves its wings 330 times a second. 

 Now, this is a really high rate of speed when com- 



Fig. 32. The Common House-fly (enlarged). 



pared with the rate of movement of the honey-bee at 

 190 times a second ; and it throws the butterfly (only 

 nine times a second) into the shade altogether. 



So also Landois has studied for us the music of 

 a fly's wings. Every one knows the difference be- 

 tween the droning and the sharp " buzz " of a fly. 

 Taking the correspondence of the sounds made by 

 the insect with musical notes, Landois tells us that 

 a fly which produces the note F moves its wings 

 352 times a second; a bee making the sound of A 



