CHAP. II EAETH SWALLOWED AS FOOD. 107 



seen ; but not a single leaf was drawn into these 

 burrows. These castings from their blackness 

 and from the nature of the subsoil could not 

 have been brought up from a greater depth 

 than 6 or 8 inches. On what could these 

 worms have subsisted during this whole time, 

 if not on matter contained in the black earth ? 

 On the other hand, whenever a large number 

 of leaves are drawn into the burrows, the 

 worms seem to subsist chiefly on them, for 

 few earth-castings are then ejected on the 

 surface. This difference in the behaviour of 

 worms at different times, perhaps explains a 

 statement by Claparede, namely, that triturated 

 leaves and earth are always found in distinct 

 parts of their intestines. 



Worms sometimes abound in places where 

 they can rarely or never obtain dead or 

 living leaves ; for instance, beneath the pave- 

 ment in well-swept courtyards, into which 

 leaves are only occasionally blown. My son 

 Horace examined a house, one corner of 

 which had subsided; and he found here in 

 the cellar, which was extremely damp, many 

 small worm-castings thrown up between the 

 stones with which the cellar was paved ; and 



