the ashes of animals into a new life. A strange partnership between Bacteria on the one hand and leguminous and cereal plants on the other has recently been discovered. There seems much likelihood that with some plants of the orders just named Bacteria live in normal partnership. The legumes and cereals in question do not thrive well without their guests, nay more, it seems as if the Bacteria are able to make the free nitrogen of the air available for their hosts.

3. Relation of Animals to the Earth.-Bacteria are extremely minute organisms, however, and stories of their industry are apt to sound unreal. But this cannot be said of earthworms. For these can be readily seen and watched, and their trails across the damp footpath, or their castings on the grass of lawn and meadow, are familiar to us all. They are distributed, in some form or other, over most regions of the globe; and an idea of their abundance may be gained by making a nocturnal expedition with a lantern to any convenient green plot, where they may be seen in great numbers, some crawling about, others, with their tails in their holes, making slow circuits in search of leaves and vegetable débris. Darwin estimated that there are on an average 53,000 earthworms in an acre of garden ground, that 10 tons of soil per acre pass annually through their bodies, and that they bring up mould to the surface at the rate of 3 inches thickness in fifteen years. Hensen found in his garden 64 large worm-holes in 14 square feet, and estimated the weight of the daily castings at about 2 cwts. in two and a half acres. In the open fields, however, it seems to be only about half as much. But whether we take Darwin's estimate that the earthworms of England pass annually through their bodies about 320,000,000 tons of earth, or the more moderate calculations of Hensen, or our own observations in the garden, we must allow that the soil-making and soil-improving work of these animals is

momentous.

In Yorubaland, on the West African coast, earthworms (Siphonogaster) somewhat different from the common Lumbricus are exceedingly numerous. From two separate square

feet of land chosen at random, Mr. Alvan Millson collected the worm-casts of a season and found that they weighed when dry 10 lbs. At this rate about 62,233 tons of subsoil would be brought in a year to the surface of each square mile, and it is also calculated that every particle of earth to the depth of two feet is brought to the surface once We do not wonder that the district is fertile

in 27 years.

and healthy.

Devouring the earth as they make their holes, which are often 4 or even 6 feet deep; bruising the particles in their gizzards, and thus liberating the minute elements of the soil; burying leaves and devouring them at leisure; preparing the way by their burrowing for plant roots and rain-drops, and gradually covering the surface with their castings, worms have, in the history of the habitable earth, been most important factors in progress. Ploughers before the plough, they have made the earth fruitful. It is fair, however, to acknowledge that vegetable mould sometimes forms independently of earthworms, that some other animals which burrow or which devour dead plants must also help in the process, and that the constant rain of atmospheric dust, as Richthofen has especially noted, must not be overlooked.

In 1777, Gilbert White wrote thus of the earthworms—

"The most insignificant insects and reptiles are of much more consequence and have much more influence in the economy of nature than the incurious are aware of. . . . Earthworms, though in appearance a small and despicable link in the chain of Nature, yet, if lost, would make a lamentable chasm. Worms seem to be

the great promoters of vegetation, which would proceed but lamely without them, by boring, perforating, and loosening the soil, and rendering it pervious to rains and the fibres of plants; by drawing straws and stalks of leaves and twigs into it; and, most of all, by throwing up such infinite numbers of lumps of earth called wormcasts, which, being their excrement, is a fine manure for grain and grass. Worms probably provide new soil for hills and slopes where the rain washes the earth away; and they affect slopes probably to avoid being flooded. The earth without worms would soon become cold, hard-bound, and void of fermentation, and consequently sterile. These hints we think proper to throw out, in order to set the inquisitive and discerning to work. A good mono

graph of worms would afford much entertainment and information at the same time, and would open a large and new field in natural history."

After a while the discerning did go to work, and Hensen published an important memoir in 1877, while Darwin's "good monograph" on the formation of vegetable mould appeared after about thirty years' observation in 1881; and now we all say with him, "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."

Prof. Drummond, while admitting the supreme importance of the work of earthworms, eloquently pleads the claims of the Termite or White Ant as an agricultural agent. This insect, which dwelt upon the earth long before the true ants, is abundant in many countries, and notably in Tropical Africa. It ravages dead wood with great rapidity. "If a man lay down to sleep with a wooden leg, it would be a heap of sawdust in the morning," while houses and decaying forest trees, furniture and fences, fall under the jaws of the hungry Termites. These fell workers are blind and live underground; for fear of their enemies they dare not show face, and yet without coming out of their ground they cannot live.

They took up some of They construct tunnels

"How do they solve the difficulty? They take the ground out along with them. I have seen white ants working on the top of a high tree, and yet they were underground. the ground with them to the tree-top. which run from beneath the soil up the sides of trees and posts; grain after grain is carried from beneath and mortared with a sticky secretion into a reddish sandpaper-like tube; this is rapidly extended to a great height-even of 30 feet from the ground-till some dead branch is reached. Now as many trees in a forest are thus plastered with tunnels, and as there are besides elaborate subterranean galleries and huge obelisk-like ant-hills, sometimes 10-15 feet high, it must be granted that the Termites, like the earthworms, keep the soil circulating. The earth-tubes crumble to dust, which is scattered by the wind; the rains lash the forests and soils with fury and wash off the loosened grains to swell the alluvium of a distant valley."

The influences of plants and animals on the earth are manifold. The sea-weeds cling around the shores and lessen the shock of the breakers. The lichens eat slowly into the stones, sending their fine threads beneath the surface as thickly sometimes "as grass-roots in a meadow-land," so that the skin of the rock is gradually weathered away. On the moor the mosses form huge sponges, which mitigate floods and keep the streams flowing in days of drought. Many little plants smooth away the wrinkles on the earth's face, and adorn her with jewels; others have caught and stored the sunshine, hidden its power in strange guise in the earth, and our hearths with their smouldering peat or glowing coal are warmed by the sunlight of ancient summers. The grass which began to grow in comparatively modern (i.e. Tertiary) times has made the earth a fit home for flocks and herds, and protects it like a garment; the forests affect the rainfall and temper the climate, besides sheltering multitudes of living things, to some of whom every blow of the axe is a death-knell. Indeed, no plant from Bacterium to oak tree either lives or dies to itself, or is without its influence on earth and beast and man.

There are many animals besides worms which influence the earth by no means slightly. Thus, to take the minus side of the account first, we see the crayfish and their enemies the water-voles burrowing by the river banks and doing no little damage to the land, assisting in that process by which the surface of continents tends gradually to diminish. So along the shores in the harder substance of the rocks there are numerous borers, like the Pholad bivalves, whose work of disintegration is individually slight, but in sum-total great. More conspicuous, however, is the work of the beavers, who, by cutting down trees, building dams, digging canals, have cleared away forests, flooded low grounds, and changed the aspect of even large tracts of country. Then, as every one knows, there are injurious insects innumerable, whose influence on vegetation, on other animals, and on the prosperity of nations, is often disastrously great.

But, on the other hand, animals cease not to pay their

filial debts to mother earth. We see life rising like a mist in the sea, lowly creatures living in shells that are like mosques of lime and flint, dying in due season, and sinking gently to find a grave in the ooze. We see the submarine volcano top, which did not reach the surface of the ocean, slowly raised by the rainfall of countless small shells. Inch by inch for myriads of years, the snow-drift of dead shells forms a patient preparation for the coral island. The tiniest, hardly bigger than the wind-blown dust, form when added together the strongest foundation in the world. The vast whale skeleton falls, but melts away till only the earbones are left. Of the ruthless gristly shark nothing stays but teeth. The sea-butterflies (Pteropods), with their frail shells, are mightier than these, and perhaps the microscopic atomies are strongest of all. The pile slowly rises, and the exquisite fragments are cemented into a stable foundation for the future city of corals.

At length, when the height at which they can live is reached, coral germs moor themselves to the sides of the raised mound, and begin a new life on the shoulders of death. They spread in brightly coloured festoons, and have often been likened to flowers. The waste salts of their living perhaps unite with the gypsum of the sea-water, at any rate in some way the originally soft young corals acquire strong shells of carbonate of lime. Sluggish creatures they, living in calcareous castles of indolence! In silence they spread, and crowd and smother one another in a struggle for standing-room. The dead forms, partly dissolved and cemented, become a broad and solid base for higher and higher growth. At a certain height the action of the breakers begins, great severed masses are piled up or roll down the sloping sides. Clear daylight at last is reached, the mound rises above the water. The foundations are ever broadened, as vigorously out-growing masses succumb to the brunt of the waves and tumble downwards. Within the surface-circle weathering makes a soil, and birds resting there with weary wings, or perhaps dying, leave many seeds of plants—the beginnings of another life. The waves cast up forms of dormant life which have floated from afar, and a ter