16 
DARWINISM 
CHAP. 
wild in New Zealand. But Sir Joseph Hooker informs us 
that the late Mr. Bidwell habitually scattered Australian seeds 
during his extensive travels in New Zealand, yet only two or 
three Australian plants appear to have established themselves 
in that country, and these only in cultivated or newly moved 
soil. 
These few illustrations sufficiently show that all the plants 
of a country are, as De Candolle says, at war with each other, 
each one struggling to occupy ground at the expense of its 
neighbour. But, besides this direct competition, there is one 
not less powerful arising from the exposure of almost all plants 
to destruction by animals. The buds are destroyed by birds, 
the leaves by caterpillars, the seeds by weevils; some insects 
bore into the trunk, others burrow in the twigs and leaves; 
slugs devour the young seedlings and the tender shoots, wire- 
worms gnaw the roots. Herbivorous mammals devour many 
species bodily, while some uproot and devour the buried 
tubers. 
In animals, it is the eggs or the very young that suffer most 
from their various enemies; in plants, the tender seedlings 
when they first appear above the ground. To illustrate this 
latter point Mr. Darwin cleared and dug a piece of ground 
three feet long and two feet wide, and then marked all the 
seedlings of weeds and other plants which came up, noting 
what became of them. The total number was 357, and out 
of these no less than 295 were destroyed by slugs and insects. 
The direct strife of plant with plant is almost equally fatal 
when the stronger are allowed to smother the weaker. When 
turf is mown or closely browsed by animals, a number of 
strong and weak plants live together, because none are allowed 
to grow much beyond the rest; but Mr. Darwin found that 
when the plants which compose such turf are allowed to 
grow up freely, the stronger kill the weaker. In a plot of 
turf three feet by four, twenty distinct species of plants were 
found to be growing, and no less than nine of these perished 
altogether when the other species were allowed to grow up 
to their full size. 1 
But besides having to protect themselves against competing 
plants and against destructive animals, there is a yet deadlier 
1 The Origin of Species, p. 53. 
