iv] MENTAL POWERS OF SPIDERS 29 



the lesson learnt on one day seemed to be entirely 

 forgotten the next morning, but thereafter a definite 

 change of habit seemed to result. This does not 

 appear a very great intellectual achievement, but it 

 is by no means despicable, for it must be borne in 

 mind that the habit of dropping when alarmed is 

 almost the only means of defence such a spider 

 possesses, and the instinct which prompts it must be 

 very strongly ingrained. In the words of the experi- 

 menters "Taking this into consideration, it seems 

 remarkable that one of them should so soon have 

 learned the sound of the vibrating fork, and should 

 have modified her action accordingly." 



This single experiment has been here described in 

 some detail largely for the purpose of impressing the 

 reader with the importance of reducing the problem 

 to its simplest terms before any inferences are drawn, 

 and it may well act as a model for any which he may 

 be inclined to undertake on his own account. The 

 more complicated the action, the more likely is the 

 experimenter to read into it motives and mental 

 operations which exist only in his own imagination, 

 and with this warning we must take leave of a subject 

 which might tempt us to encroach too much on an 

 allotted space. 



