58 HABITS OF WORMS. Chap. II. 



digestive fluid. They cannot attack such 

 strong leaves as those of sea-kale or large 

 and thick leaves of ivy ; though one of the 

 latter after it had become rotten was reduced 

 in parts to the state of a skeleton. 



Worms seize leaves and other objects, not 

 only to serve as food, but for plugging up 

 the mouths of their burrows ; and this is 

 one of their strongest instincts. Leaves and 

 petioles of many kinds, some flower-pedun- 

 cles, often decayed twigs of trees, bits of 

 paper, feathers, tufts of wool and horse-hairs 

 are diagged into their burrows for this pur- 

 pose. I have seen as many as seventeen 

 petioles of a Clematis projecting from the 

 mouth of one burrow, and ten from the 

 mouth of another. Some of these objects, 

 such as the petioles just named, feathers, &c., 

 are never gnawed by worms. In a gravel 

 walk in my garden I found many hundred 

 leaves of a pine-tree (P. austriaca or nigri- 

 cans) drawn by their bases into burrows. 

 The surfaces by which these leaves are articu- 

 lated to the branches are shaped in as pecu- 

 liar a manner as is the joint between the leg- 

 bones of a quadruped; and if these surfaces 



