Chap. I. SITES INHABITED. 11 



but on the more level parts, where a bed of 

 fine earth had been washed down from the 

 steeper parts and had accumulated to a thick- 

 ness of a few inches, worm-castings abounded. 

 These spots seemed to be overstocked with 

 worms, so that they had been compelled to 

 spread to a distance of a few feet from the 

 grassy paths, and here their castings had been 

 thrown up among the heath ; but beyond this 

 limit, not a single casting could be found. A 

 layer, though a thin one, of fine earth, which 

 probably long retains some moisture, is in 

 all cases, as I believe, necessary for their 

 existence ; and the mere compression of the 

 soil appears to be in some degree favourable 

 to them, for they often abound in old gravel 

 walks, and in foot-paths across fields. 



Beneath large trees few castings can be 

 found during certain seasons of the year, and 

 this is apparently due to the moisture having 

 been sucked out of the ground by the innu- 

 merable roots of the trees ; for such places 

 may be seen covered with castings after the 

 heavy autumnal rains. Although most cop- 

 pices and woods support many worms, yet in a 

 forest of tall and ancient beech-trees in Knole 



