LEPIDOP FERGUS INSECTS. 79 



species. Now, these butterflies were alive to its 

 odour at upwards of twenty feet. This fact is the 

 more striking, as the odours of flowers are said by 

 M. Le Chat to be much heavier than atmospheric air, 

 and therefore but seldom rise in it. We have ascer- 

 tained this to be true, from the circumstance, that 

 mignionette, although possessing a powerful odour, 

 and planted close to a building, can be but faintly, if 

 at all, perceived from a window one story high ; 

 although on going to the surface of the earth, we 

 find the atmosphere surcharged with its fragrance 

 at the distance even of from fifty to an hundred yards. 

 Mr Rennie remarked that even the Painted Lady 

 Butterfly, (Cynthia cardui^) which always flies at a 

 considerable height, alighted on the plants above 

 mentioned, thus proving that their perception of 

 odours is very acute. 



It is a practice with collectors to entrap the large 

 Tortoise-shell Butterfly, (Vanessa polychlorus,} by 

 spreading honey on the leaves of a tree which they 

 are in the habit of frequenting. 



There is great difficulty in determining by what 

 means the organ of smell in insects manifests itself ; 

 for, as they do not breathe like quadrupeds, or other 

 warm-blooded animals by the mouth, but by an innu- 

 merable number of spiracles along each side of their 

 bodies, where then can this organ be situated ? The 

 theory of smell in the higher animals, is, that it is 

 felt by a current of air which is impregnated with 

 odoriferous particles passing through a moistened 

 channel. This was first most ably described by 



