INSECTS : THEIR BREATHING ORGANS. 95 



This, I say, is the breathing system, or a large portion 

 of it. These pipes receive the air from without through 

 trap- doors which we will examine presently, and convey it 

 to the most distant parts of the body. In ourselves the 

 air is inhaled into a great central reservoir the lungs 

 and the blood dispersed through every part is brought to 

 this reservoir to be oxygenated. In insects it is the blood 

 that is collected into a great central reservoir, and the air 

 is distributed by a minutely divided system of vessels over 

 the blood-reservoir. 



The trachea or air-pipes have a silvery white appear- 



AIE-PIPE OF FLY. 



ance by reflected light; but if we use transmitted light 

 and put on a high power, we discern a wonderful struc- 

 ture, which I will describe in the eloquent language of 

 Professor Bymer Jones, and you shall estimate its truth as 

 you examine the object : 



* ' There is one elegant arrangement connected with the 

 breathing-tubes of an insect specially worthy of admira- 

 tion ; and perhaps in the whole range of animal mechanics 

 it would be difficult to point out an example of more 

 exquisite mechanism, whether we consider the object of 



