Chap. II. THEIR INTELLIGENCE. 67 



but if these objects were very thin relatively 

 to the size of the hole, he would probably 

 insert some by their thicker or broader ends. 

 The guide in his case would be intelligence. 

 It seemed therefore worth while to observe 

 carefully how worms dragged leaves into 

 their burrows ; whether by their tips or 

 bases or middle parts. It seemed more espe- 

 cially desirable to do this in the case of plants 

 not natives to our country ; for although the 

 habit of dragging leaves into their burrows 

 is undoubtedly instinctive with worms, yet 

 instinct could not tell them how to act in 

 the case of leaves about which their pro- 

 genitors knew nothing. If, moreover, worms 

 acted solely through instinct or an unvary- 

 ing inherited impulse, they would draw all 

 kinds of leaves into their burrows in the 

 same manner. If they have no such definite 

 instinct, we might expect that chance would 

 determine whether the tip, base or middle was 

 seized. If both these alternatives are ex- 

 cluded, intelligence alone is left ; unless the 

 worm in each case first tries many different 

 methods, and follows that alone which 

 proves possible or the most easy ; but to act 



G 



