njoy the
kindly fruits of the earth in due season. When we leave a garden to
itself for a few short years, we realize at once what effect the
competition of hardy natives has upon our carefully tended and unstable
exotics. In a very brief time the dahlias and phloxes and lilies have
all disappeared, and in their place the coarse-growing docks and
nettles and thistles have raised their heads aloft to monopolize air
and space and sunshine.

Exactly the same struggle is always taking place in the fields and
woods and moors around us, and especially in the spots made over to
pure nature. There, the greenwood tree raises its huge umbrella of
foliage to the skies, and allows hardly a ray of sunlight to struggle
through to the low woodland vegetation of orchid or wintergreen
underneath. Where the soil is not deep enough for trees to root
securely, bushes and heathers overgrow the ground, and compete with
their bell-shaped blossoms for the coveted favour of bees and
butterflies. And in open glades, where for some reason or other the
forest fails, tall grasses and other aspiring herbs run up apace
towards the free air of heaven. Elsewhere, creepers struggle up to the
sun over the stems and branches of stronger bushes or trees, which they
often choke and starve by monopolizing at last all the available carbon
and sunlight. And so throughout; the struggle for life goes on just as
ceaselessly and truly among these unconscious combatants as among the
lions and tigers of the tropical jungle, or among the human serfs of
the overstocked market.

An ounce of example, they say, is worth a pound of precept. So a single
concrete case of a fierce vegetable campaign now actually in progress
over all Northern Europe may help to make my meaning a trifle clearer.
Till very lately the forests of the north were largely composed in
places of the light and airy silver birches. But with the gradual
amelioration of the climate of our continent, which has been going on
for several centuries, the beech, a more southern type of tree, has
begun to spread slowly though surely northward. Now, beeches are greedy
trees, of very dense and compact foliage; nothing else can grow beneath
their thick shade, where once they have gained a foothold; and the
seedlings of the silver birch stand no chance at all in the struggle
for life against the serried leaves of their formidable rivals. The
beech literally eats them out of house and home; and the consequence is