HOW INSECTS BREATHE. 153 



them and the back will be at once filled with air, a supply of 

 which it is thus enabled to carry about with it. If this ani- 

 mal had breathed through the mouth, it could only by violent 

 exertion have brought the heaviest part of its body to the 

 surface, and, if alarmed, would have had to turn over before 

 the action of the legs could come into play, whereas by re- 

 ceiving the air at the tail, these difficulties are removed and 

 the powerful oars are ready at the least sign of danger to 

 carry their owner, by a few rapid strokes, down to the bottom 

 into the w r eeds or mud. 



Thus I have attempted to give a slight account of the 

 principal modifications of the organs of respiration in insects; 

 but I am well aware that I have only been able to mention 

 a small part of what has been already described, which is 

 itself but a fraction of that which still remains unknown. 



Still, though we must confess that God alone can see 

 all that He has made, man also, we may hope, can perceive 

 that it is "very good." Yet are we far from knowing, 

 and perhaps never shall know, how good. Every day we 

 discover fresh w r onders, every day new fields of science are 

 opened to us, and the naturalist can with truth adopt the 

 words of the illustrious Newton, " I seem to have been only 

 like a boy playing on the seashore, and diverting myself in 

 now and then finding a smoother pebble or a prettier shell 

 than ordinary, whilst the great ocean of truth lay all un- 

 discovered before me." 



