iv] MENTAL POWERS OF SPIDERS 27 



that a sense so necessary for the discrimination of 

 suitable food should be lacking in animals with so 

 respectable a sensory equipment. 



There is no doubt at all that the sense of touch 

 is extremely well developed in spiders, especially 

 perhaps, in the sedentary groups, and it is probable 

 that, under ordinary cirumstances, the garden-spider 

 works almost entirely by its guidance. Whether in 

 the centre of the web or in its retreat under a neigh- 

 bouring leaf it is in direct communication with every 

 part of its snare by silken lines, and the least 

 disturbance usually suffices to bring it to the spot ; 

 and then, as Ave have said, it will generally touch the 

 disturbing object, however unpromising in appearance, 

 before deciding on its line of action. There is little 

 doubt that many of the numerous hairs and bristles 

 with which its limbs are furnished are distinctly 

 sensory in function. 



So much, then, as to the senses of spiders; but 

 what about their " educability ' -their power of 

 learning from experience ? Here is evidently a wide 

 subject, and a difficult one full of pit-falls for the 

 unwary, but we may nevertheless draw some inferences 

 from the quite elementary experiments on the senses 

 which have been outlined above. A spider drops on 

 account of the sounding of the tuning-fork in its 

 neighbourhood; can it be educated to take no notice 

 of the sound after repeatedly finding that no evil 



