Chap. III. BEOUGHT UP BY WOKMS. 167 



mould together with the turf was only four 

 inches in thickness, beneath which lay the 

 level surface of light-coloured sandy soil, with 

 many fragments of sandstone. Before any 

 castings were collected all the previously 

 existing ones were carefully removed. The 

 last day's collection was on October 14th, 

 1871. The castings were then well dried 

 before a fire ; and they weighed exactly 3^ lbs. 

 This would give for an acre of similar land 

 7*56 tons of dry earth annually ejected by 

 worms. 



The second square was marked on un- 

 enclosed common land, at a height of about 

 700 ft. above the sea, at some little distance 

 from Leith Hill Tower. The surface was 

 clothed with short, fine turf, and had never 

 been disturbed by the hand of man. The 

 spot selected appeared neither particularly 

 favourable nor the reverse for worms ; but I 

 have often noticed that castings are especially 

 abundant on common land, and this may, 

 perhaps, be attributed to the poorness of 

 the soil. The vegetable mould was here 

 between three and four inches in thickness. 

 As this spot was at some distance from the 



