xiv SENSES 375 



itself. It is probably in order to avoid this unpleasant contingency 

 that the spider has evinced towards the Ichneumon the sincerest 

 form of flattery. 



The Senses of Spiders. 



SIGHT. Though, as has been shown, spiders are well provided 

 with eyes, their power of vision, in most cases, is by no means 

 remarkable. As might be expected, it is less developed in those 

 of sedentary than in those of nomadic habit. 



It is noticeable that, in most spiders, some of the eyes are of 

 a pearly grey colour, and others of a much darker hue. Simon 

 designates the former nocturnal and the latter diurnal eyes, 

 according to the special use which he believes them to subserve. 



This view of the matter cannot be regarded as at all established, 

 and has not found general acceptation. Moreover, Pillai * has 

 shown that certain Attid spiders can change the colour of their 

 eyes by a movement of the internal mechanism. The Epeiridae, 

 spinners of the round web, are certainly, as a rule, very dim- 

 sighted creatures. A fly may be held within an inch of them, but, 

 unless it buzz, it will excite no notice whatever. A careful observa- 

 tion of the performances of the large Garden -spider in securing 

 her prey will soon convince the onlooker that she is guided almost 

 entirely by appeals to her sense of touch communicated along the 

 tremulous lines of her snare. Interpreting these too hastily, she 

 will sometimes rush straight past the entangled fly, and wait for 

 it to renew its struggles before making sure of its whereabouts. 

 Keen sight would be of little utility to such spiders, as they 

 are concerned with nothing beyond the limits of their snare, and 

 within its range they are furnished with the equivalent of com- 

 plete telegraphic communication. 



That most of the vagabond spiders can see well within the 

 range of several inches there is no doubt, though some observers 

 have been, misled by the result of certain experiments on the 

 Lycosidae, or " Wolf-spiders." It will be remembered that the 

 female Lycosid carries her egg-bag about with her, attached 

 usually to her spinnerets. If it be removed and placed close at 

 hand, the spider experiences the greatest difficulty in finding it 

 again. Lubbock attributed this to defective sight, whereas it 

 merely arises from unfamiliarity with the appearance of the 



1 Nature, Ixviii., 1908, p. 631. 



