THE PART PLATED BY WORMS. 45 



INTELLIGEITCE OF WOEMS. 



p J "We can hardly escape from the conclusion 



that worms show some degree of intelligence 

 in their manner of plugging up their burrows. Each 

 particular object is seized in too uniform a manner, and 

 from causes which we can generally understand, for the 

 result to be attributed to mere chance. That every ob-~ 

 ject has not been drawn in by its pointed end, may be 

 accounted for by labor haying been saved through some 

 being inserted by their broader or thicke:|: ends. No 

 doubt worms are led by instinct to plug up their burrows ; 

 and it might have been expected that they would have 

 been led by instinct how best to act in each particular 

 case, independently of intelligence. We see how diflScult 

 it is to judge whether intelligence comes into play, for 

 even plants might sometimes be thought to be thus di- 

 rected ; for instance, wh^n displaced leaves redirect their 

 upper surfaces toward t^e light by extremely complicated 

 movements and by the shortest course. With animals, 

 actions appearing due to intelligence may be performed 

 through inherited habit without any intelligence, although 

 aboriginally thus acquired. Or the habit may have been 

 acquired through the' preservation and inheritance of 

 beneficial variations of some other habit ; and in this 

 case the new habit will have been acquired independently 

 of intelligence throughout the whole course of its devel- 

 opment. There is no a priori improbability in worms 

 having acquired special instincts through either of these 

 two latter means. Nevertheless, it is incredible that in- 

 stincts should have been developed in reference to objects, 

 such as the leaves or petioles of foreign plants, wholly un- 

 known to the progenitors of the worms which act in the 

 described manner. Nor are their actions so unvarying 

 or inevitable as are most true instincts. 



