64 HABITS OF WOKMS. Chap. II. 



the worms pertinaciously opened their bur- 

 rows almost every nighty when these had 

 been closed by being trampled on, although 

 they were rarely able to find a few minute 

 stones wherewith to protect them. 



Intelligence shown hy worms in their manner 

 of plugging up their burrows, — If a man had to 

 plug up a small cylindrical hole, with such 

 objects as leaves, petioles or twigs, he would 

 drag or push them in by their pointed ends ; 

 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- 



