SMELL IN INSECTS. 



45 



PainU'd lady butterfly (Cynthia Cardui) ; and Alpine bluebottle (Centau- 

 rca montana). 



being much heavier than air, seldom rise in it, and 

 when they do, it is only in consequence of the velo- 

 city with which they are ejected from bodies, — in the 

 same manner that a horse at full speed, and the wind 

 together, will raise a cloud of heavy dust on a high- 

 way.* 



The ingenious experiments of Redi also show the 

 acuteness of smell in blow-flies, which actually laid 

 their eggs on the silk covering of the meat he em- 



* Trait'^ des Sensations, Paris, 1767. 



