THE ANIMAL KINGDOM. 121 



animal can see at the same time the fish which menaces it 

 from the depths, and the bird which is about to swoop 

 down upon it. From the former it escapes by flight, and 

 from the latter by diving.^ 



The insect is endowed with an exquisite fineness of 

 smell. The slightest odour is perceived by it at very great 

 distances. In the perfumed air exhaling from the thou- 



G7. Little "Whirlwig — Gyrinus natator. 



sand plants of a meadow or garden, it distinguishes the one 

 it loves and settles upon jt, to dismember it or deposit its 

 offspring upon it. 



The flesh-eating insect discerns at the greatest distance 

 the smell of an animal on which it feeds. If a morsel of 

 meat be totally covered with a black bell-glass, its exhala- 

 tions quickly attract the flies to a spot where i^reviously 

 there was not one to l^e seen. 



The winged animal never makes a mistake; or if, under 

 very unusual circumstances, it should happen to do so, it 

 would be because there was a perfect identity between the 

 odorous emanations. For instance, the putrid exhalations 

 from the flowers of the Stapelia and Arum attract some 

 insects just as putrid meat would; and these, deceived b}' 



1 We speak here of the little whirlwigs, elegant aquatic C'oleoptera, extremely 

 brilliant, which sparkle like diamonds when the sun lights upon them on the sur- 

 face of the water, where they pirouette constantly with surprising velocity: hence 

 the name whirlwigs. These insects have four groups of eyes in their Iieads. Of 

 these two are placed below, and give them notice of what is going on in the depths 



of the water; the two others are turned towards the sk}'. 



16 



