201 



even more excited and bold, so that it was quite evident that 

 they were unable to distinguish the hard paper from the dchcate, 

 soft wings of the real butterfly. 



These facts prove the fallacy of the often defended view 

 that insects are very short-sighted or are only able clearly to 

 see objects in motion. Every collector knows that butterflies 

 closely observe their approaching enemy, and often defeat 

 every effort of his to come near them. The representatives of 

 the Genus Apaiura, Eunica, Parthenos, and certain species of 

 Vanessa {antiopa) and Argynnis {pandora) are decidedly more 

 far-sighted and wary than others. Even when asleep (or rather 

 at rest) their sight is pretty sharp. Thus one mav without 

 great difficulty approach from the opposite side a tree on which 

 a Catocala or a Geometrid (f.i. Boarmia) has alighted, if only 

 one avoids making any noise; but immediately the net, or the 

 hand carrying the cyanide-glass, appears on the side of the tree 

 where the butterfly sits, it takes to its wings. It has been 

 supposed that it is only the act of moving which frightens the 

 insects, but that they are unable to distinguish the objects 

 themselves. While it is certain that butterflies are more 

 frightened b\- a quick and sudden motion than if we approach 

 carefully and g(Mitly. it is no less true that blades of grass, flowers, 

 or branches \iolently shaken by the wind do not disturb in the 

 least insects resting near by, whereas a hand stretched forth 

 to catch them would at once cause them to fly away. If one 

 carefully pushes a long branch, from the end of which the fresh 

 leaves have not been remo\'ed, towards some not excessively 

 shy butterfly (as f.i. Picris brassicœ) sipping the nectar from 

 a flower, one may often touch it or e\-en push it awav without 

 its becoming frightened, whereas it would ccrtainlv fly away 

 at once if we were to touch it with the lingers. This would 

 indicate in the butterfly a fair amount of ability to recognise 

 the outline of objects, an ability which may at least in principle 

 be compared with that attaching U) the eyes of vertrbratcs ; 

 and this k-ads us to ask furthiT whether also the sense of colour 

 de\eloped in the com[)ound eye may be compared with that 

 of the simple eye. In the case of the human eve ophthal- 

 mologieal exi)erinients ha\e >how ii that among all eoJDurs red 

 can be seen hiithest, blue luuch le>^ far. When once standing, 

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