216 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
rocks, the mosses form huge sponges on the moors which keep the 
streams flowing in days of drought. Many little plants are forever 
smoothing away the wrinkleson the earth’s—their mother’s—face, and 
they adorn herwithjewels. Others that have formed coal have enriched 
her with ages of entrapped sunlight. The grass—which began to 
appear in Tertiary ages—protects the earth like a garment; the 
forests affect rainfall and temper climate, besides sheltering multitudes 
of living things, to many of whom every blow of the axe is a death- 
knell. No plant, from bacterium to oak-tree, lives or dies to itself, 
or is without its influence upon the earth. So among animals there 
are destructive borers and burrowers and conservative agents, such 
as the coral-polyps and the chalk-forming Foraminifera. 
Practical importance of a realisation of the web of life——What 
has Darwinism to do with human life? The answer at this stage in 
our inquiry is clear: we must respect the web of life if we wish to 
master Nature. She must be humoured, not bullied. Emerson 
included in his vision of a perfected earth the absence of spiders, but 
the absence of spiders—which snare so many injurious insects—would 
mean the absence of much else, man probably included. Ina northern 
county in Scotland the proprietors were justly annoyed at the injuries 
inflicted on young trees by squirrels, and they formed a squirrel club, 
setting a price on the beautiful rodent’s head. Perhaps a wiser course 
would have been to begin by inquiring what disturbance of the balance 
of nature had allowed the squirrels to multiply so disastrously. But, 
after a period of squirrel-slaughter and some jubilation thereat, a 
cloud began to rise in the sky. The wood-pigeons were multiplying 
worse than ever, and the farmers, at least, said with no uncertain voice 
that they preferred the squirrels. An imperfect recognition of the 
web of life had left out of account the notable fact that squirrels’ 
destroy large numbers of young wood-pigeons. 
One of the hopeful symptoms of the last few years is the reawaken- 
ing of an interest in woods and forests. Everyone knows how terribly 
these have been wasted, and how the disastrous results have affected 
rainfall and irrigation, climate and crops, and even the character of the 
people. Here what was once a pleasant stream is now like a gravelly 
road, and there the fertile plains are flooded; here the wind is sweeping 
away the soil, and there both beauty and health have departed. The 
birds which the woods once sheltered are driven elsewhere, and the 
insect-pests are rife among the crops. For “the cheapest and most 
effective insecticides are birds.”’ 
