th cold and woad, may have known that the strange
black stone, of which he found lumps here and there in his wanderings,
would burn, and so help to warm his body and cook his food. Saxon, Dane,
and Norman swarmed into the land. The English people grew into a powerful
nation, and Nature still waited for a full return of the capital she had
invested in the ancient club-mosses. The eighteenth century arrived, and
with it James Watt. The brain of that man was the spore out of which was
developed the modern steam-engine, and all the prodigious trees and
branches of modern industry which have grown out of this. But coal is as
much an essential condition of this growth and development as carbonic
acid is for that of a club-moss. Wanting coal, we could not have smelted
the iron needed to make our engines, nor have worked our engines when we
had got them. But take away the engines, and the great towns of Yorkshire
and Lancashire vanish like a dream. Manufactures give place to
agriculture and pasture, and not ten men can live where now ten thousand
are amply supported.

Thus, all this abundant wealth of money and of vivid life is Nature's
interest upon her investment in club-mosses, and the like, so long ago.
But what becomes of the coal which is burnt in yielding this interest?
Heat comes out of it, light comes out of it; and if we could gather
together all that goes up the chimney, and all that remains in the grate
of a thoroughly-burnt coal-fire, we should find ourselves in possession
of a quantity of carbonic acid, water, ammonia, and mineral matters,
exactly equal in weight to the coal. But these are the very matters with
which Nature supplied the club-mosses which made the coal She is paid
back principal and interest at the same time; and she straightway invests
the carbonic acid, the water, and the ammonia in new forms of life,
feeding with them the plants that now live. Thrifty Nature! Surely no
prodigal, but most notable of housekeepers!

VI

ON THE BORDER TERRITORY BETWEEN THE ANIMAL AND THE VEGETABLE KINGDOMS

[1876]

In the whole history of science there is nothing more remarkable than the
rapidity of the growth of biological knowledge within the last half-
century, and the extent of the modification which has thereby been
effected in some of the fundamental conceptions of the naturalist.

In the second edition of the "Regne Animal," published in 1828, Cuvier
devotes a special section to the "Division of O