CHAPTER III. 



RESPIRATION OF THE IMAGO. 



PERFECT insects breathe. That this is so, the 

 following experiments'* will satisfactorily prove. 

 A spider and a fly were put into a glass jar, 

 the mouth of which was closed all but a hole by 

 which a tube was admitted. The tube was then con- 

 nected with a pipe by which a supply of common 

 coal-gas was poured into the jar, and when it was 

 considered to be full of gas, and that all the air 

 had been displaced, the tube was closed, and the 

 insects were left shut up in an atmosphere of gas. 

 In a few seconds both became very uneasy, the fly 

 more particularly so; and in a few seconds more the 

 fly began to agitate itself, to buz against the sides of 

 the glass, and to tumble over in the most extraor- 

 dinary manner ; the spider ran hurriedly about, as 

 if astonished, and not knowing what to make of his 

 new position ; but presently he became very quiet, 

 and, turning on his back, looked as if dead. For a 



* The writer is responsible for these experiments. 



