Chap. I. MENTAL QUALITIES. 35 



They perform a few actions instinctively, that 

 is, all the individuals, including the young, 

 perform such actions in nearly the same 

 fashion. This is shown by the manner in 

 which the species of Perichseta eject their 

 castings, so as to construct towers; also by 

 the manner in which the burrows of the 

 common earth-worm are smoothly lined with 

 fine earth and often with little stones, and 

 the mouths of their burrows with leaves. 

 One of their strongest instincts is the plug- 

 ging up the mouths of their burrows with 

 various objects ; and very young worms act 

 in this manner. But some degree of in- 

 telligence appears, as we shall see in the next 

 chapter, to be exhibited in this work, a 

 result which has surprised me more than 

 anything else in regard to worms. 



Food and Digestion. Worms are omnivo- 

 rous. They swallow an enormous quantity of 

 earth, out of which they extract any diges- 

 tible matter which it may contain ; but to 

 this subject I must recur. They also con- 

 sume a large number of half-decayed leaves 

 of all kinds, excepting a few which have an 

 unpleasant taste or are too tough for them ; 



