Imagini ale paginilor
PDF
ePub

Worms are poorly provided with senseorgans, for they cannot be said to see, although they can just distinguish between light and darkness; they are completely deaf, and have only a feeble power of smell; the sense of touch alone is well developed. They can therefore learn little about the outside world, and it is surprising that they should exhibit some skill in lining their burrows with their castings and with leaves, and in the case of some species in piling up their castings into tower-like constructions. But it is far more surprising that they should apparently exhibit some degree of intelligence instead of a mere blind instinctive impulse, in their manner of plugging up the mouths of their burrows. They act in nearly the same manner as would a man, who had to close a cylindrical tube with different kinds of leaves, petioles, triangles of paper, &c., for they commonly seize such objects by their pointed ends. But with thin objects a certain number are drawn in by their broader ends. They do not act in the same unvarying manner in all cases, as do most of the lower animals; for instance, they do not drag in leaves by their

foot-stalks, unless the basal part of the blade is as narrow as the apex. or narrower than it.

When we behold a wide, turf-covered expanse, we should remember that its smoothness, on which so much of its beauty depends, is mainly due to all the inequalities having been slowly levelled by worms. It is a marvellous reflection that the whole of the superficial mould over any such expanse has passed, and will again pass, every few years through the bodies of worms. The plough is one of the most ancient and most valuable of man's inventions; but long before he existed the land was in fact regularly ploughed, and still continues to be thus ploughed by earth-worms. It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures. Some other animals, however, stiil more lowly organised, namely corals, have done far more conspicuous work in having constructed innumerable reefs and islands in the great oceans; but these are almost confined to the tropical zones.

INDEX.

Abinger, Roman villa at, 178

castings from Roman villa, with rounded

particles, 253

Acids of humus, action on rocks, 240

Africa, dust from, 235

Air, currents of, worms sensitive to, 28

Amount of earth brought to the surface by worms, 129

Ants. intelligence of, 93

Archiac, D', criticisms on my views, 4

Artemisia, leaves of, not eaten by worms, 33

Ash-tree, petioles of, 79

Beaulieu Abbey, burial of the old pavement, 193
castings from, with rounded particles,

255

Beaumont, Élie de, on vegetable mould, 2

178

the rubbish underlying great cities,

the transport of dust, 237

the permanence of mould, 289

the permanence of ancient tumuli, 290

Beech-forests, stones not buried under by castings, 144
Bengal, worms of, 123

Bones, crushed, burial of, under castings, 146

Brading, Roman villa at, 199

[ocr errors][merged small]

Bridgman, Mr., on worms eating leaves of a Phlox, 33
Buckman, on grasses profiting by being rolled, 10
Burial of the remains of ancient buildings by worns,
176

Burrows, depth of, 109

direction of, on a slope, 270

excavation of, 98

lined with black earth, 111

lined with leaves, 112

mouths of, worms lie motionless near, 15

old, their collapse, 118

plugged up, 58

terminating in a small chamber, often lined with

stones or seeds, 114

Calciferous glands, 17, 43

Cannibal worms, 36

- Carnagie, Mr., depth of burrows, 114

Castings, acid, 52

from Beaulieu, 101

tower-like, near Nice, 106

ejection of, 116

tower-like, from near Calcutta, 123

of great size on the Nilgiri Mountains, 126
weight of, from a single burrow and from a given
area, 160

thickness of layer formed from, during a year, 169
ejected over ancient buildings, 253

flowing down slopes, 261

washed away, 272

dry, disintegration of, 275

blown to leeward, 283

Cells, free, with calcareous matter in the calciferous

glands, 47

Cellulose, digestion of, 37

« ÎnapoiContinuă »