CHAPTER IV 



SENSATION AND REACTION 



The various movements of insects, some of which have been 

 considered in the previous chapter, are often observed to 

 be expressions of the creatures' responses to various kinds 

 of stimulation due to the condition of their surroundings. 

 A moth flies in through an open window on a summer night, 

 steering a straight course for the lamp, so that the observer 

 exclaims that the insect is " attracted by the light," and 

 concludes that it possesses a faculty resembling at least to 

 some degree his own power of vision. He may go several 

 steps farther in equating the insect's behaviour and sensa- 

 tions with his own by saying that " it prefers light to dark- 

 ness," or that "it is dazzled by the glare of the lamp." 

 Collectors of insects desirous of obtaining male specimens 

 of certain rare moths often take into the open country or 

 woodlands a hve female of the kind desired shut up in a 

 box, and find that this miniature prison may be surrounded 

 by large numbers of males which have directed their flight 

 towards it. The captive female, though invisible, has 

 allured them, and the observer may reasonably infer that 

 these males have been thus " assembled " because they have 

 received impressions accompanied by some recognised 

 sensation analogous to our sense of smell. Reactions of 

 insects to their surroundings, such as the two just men- 

 tioned, can be readily observed, and by study of the nervous 

 system and its connection with the various parts of the 

 body it is possible to understand, at least in part, the 

 mechanism by which the various reactions are brought 

 about. But when we ascribe to an insect sensations, or, 



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