62 LECTURE V. 



jecting eyes, both of which are furnished with 

 4000 lenses, appearing, through a microscope, 

 like a piece of honeycomb. These give them 

 that rapidity of motion which you must often 

 have observed in escaping capture. Their flight, 

 also, is so swift that it has been supposed they 

 can fly at the rate of nearly a mile in a minute. 

 Their interior structure is equally curious, 

 having blood-vessels and other functions which 

 are to be found in larger animals. But I must 

 draw your attention to their feet, which are 

 furnished with a sort of wet sponge, that en- 

 ables them to run up and down smooth sur- 

 faces, such as glass, with the greatest facility. 

 Some flies lay their eggs in dung-pits; others 

 in the bark of trees, which causes them to throw 

 out those gnarled and wooden projections which 

 you may sometimes see in old oak and elm- 

 trees. 



Wasps are another species of insects whose 

 proceedings are very curious and interesting. 

 Early in the spring, and on a sunny day, you 

 may see a large wasp settling on some decayed 

 wood and appearing to feed on it. This is a 

 female wasp, the parent of a large colony. The 

 wood she seems to eat is formed into a few cells, 



