Darwinism stated by Darwin himself: Characteristic passages from the writings of Charles DarwinDarwin, Charles
Science
Darwinism stated by Darwin himself: Characteristic passages from the writings of Charles Darwin
Darwin, Charles
Evolution (Biology)
Living birds can hardly fail to be highly effective agents in the
transportation of seeds. I could give many facts showing how frequently
birds of many kinds are blown by gales to vast distances across the
ocean. We may safely assume that under such circumstances their rate
of flight would often be thirty-five miles an hour; and some authors
have given a far higher estimate. I have never seen an instance of
nutritious seeds passing through the intestines of a bird; but hard
seeds of fruit pass uninjured through even the digestive organs of a
turkey. In the course of two months I picked up in my garden twelve
kinds of seeds out of the excrement of small birds, and these seemed
perfect, and some of them, which were tried, germinated. But the
following fact is more important: the crops of birds do not secrete
gastric juice, and do not, as I know by trial, injure in the least the
germination of seeds; now, after a bird has found and devoured a large
supply of food, it is positively asserted that all the grains do not
pass into the gizzard for twelve or even eighteen hours. A bird in this
interval might easily be blown to the distance of five hundred miles,
and hawks are known to look out for tired birds, and the contents of
their torn crops might thus readily get scattered. Some hawks and owls
bolt their prey whole, and, after an interval of from twelve to twenty
hours, disgorge pellets, which, as I know from experiments made in the
Zoölogical Gardens, include seeds capable of germination. Some seeds
of the oat, wheat, millet, canary, hemp, clover, and beet germinated
after having been from twelve to twenty-one hours in the stomachs of
different birds of prey; and two seeds of beet grew after having been
thus retained for two days and fourteen hours. Fresh-water fish, I
find, eat seeds of many land and water plants: fish are frequently
devoured by birds, and thus the seeds might be transported from place
to place. I forced many kinds of seeds into the stomachs of dead fish,
and then gave their bodies to fishing-eagles, storks, and pelicans;
these birds, after an interval of many hours, either rejected the seeds
in pellets or passed them in their excrement; and several of these
seeds retained the power of germination. Certain seeds, however, were
always killed by this process.
Locusts are sometimes blown to great distances from the land; I myself
caught one three hundred and seventy miles from the coast of Africa,
and have heard of others caught at greater distances.
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[Page 328.]
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