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Show 10 HABI'l'S OF WORMS. CHAP. I. burrowed through the floor of a very damp cellar. I have seen worms in black peat in a boggy field; but they are extrmneJy rare, or quite absent in the drier, brown, fibrous peat, which is so 1nuch valued by gardeners. On dry, sandy or gravelly tracks, where heath with some gorse, ferns, coarse grass, moss and lichens alone grow, hardly any worms can be found. But in many parts of England, wherever a path crosses a heath, its surface becomes covered with a fine short sward. Whether this change of vegetation is due to the taller plants being killed by the occasional trampling of man and animals, or to the soil being occasionally manured by the droppings from animals, I do not know.* On such grassy pat~s worm-castings may often be seen. On a heath in Surrey, which was carefully examined, there were only a few castings on these paths, where they were much inclined ; • There is eveu some reason to believe that pressure is actually favourable to the growth of grasses, for Professor Buckman, who macle many observations on their growth in the experimental gardens of the Royal Agricultural College, remarks (' Ganleners' Chronicle,' 1854, p. 619): "Another circumstance in the cultivation of grasses in tho separate form or small patches, is the impossibility of rolling or treading them firmly, without which no pasture can continue good." OIIAP. I. SITES INIIABI'l'ED. lJ 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 thickness 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 innumerable roots of the trees ; for such places ntay be seen covered with castings after the heavy autumnal rains. Although most coppices and woods support many worms, yet in a forest of tall and ancient beech-trees in Knole |