On the Origin of Species By Means of Natural Selection: Or, the Preservation of Favoured Races in the Struggle for LifeDarwin, Charles
Science
On the Origin of Species By Means of Natural Selection: Or, the Preservation of Favoured Races in the Struggle for Life
Darwin, Charles
Evolution (Biology); Natural selection
But seeds may be occasionally transported in another manner. Drift
timber is thrown up on most islands, even on those in the midst of the
widest oceans; and the natives of the coral-islands in the Pacific,
procure
stones for their tools, solely from the roots of drifted trees, these
stones being a valuable royal tax. I find on examination, that when
irregularly shaped stones are embedded in the roots of trees, small
parcels of earth are very frequently enclosed in their interstices and
behind them,—so perfectly that not a particle could be washed away in
the longest transport: out of one small portion of earth thus
_completely_ enclosed by wood in an oak about 50 years old, three
dicotyledonous plants germinated: I am certain of the accuracy of this
observation. Again, I can show that the carcasses of birds, when
floating on the sea, sometimes escape being immediately devoured; and
seeds of many kinds in the crops of floating birds long retain their
vitality: peas and vetches, for instance, are killed by even a few
days’ immersion in sea-water; but some taken out of the crop of a
pigeon, which had floated on artificial salt-water for 30 days, to my
surprise nearly all germinated.
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 I think safely assume that under such circumstances their
rate of flight would often be 35 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 will pass uninjured through even the digestive organs of
a turkey. In the course of two months, I picked up in my garden 12
kinds of seeds, out of the excrement of small birds, and these seemed
perfect, and some of them, which I tried, germinated. But the following
fact is more important: the crops of birds do not secrete gastric
juice, and do not in the
least injure, as I know by trial, 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 12 or
even 18 hours. A bird in this interval might easily be blown to the
distance of 500 miles, and hawks are known to look out for tired birds,
and the contents of their torn crops might thus readily get scattered.
Mr. Brent informs me that a friend of his had to give up flying
carrier-pigeons from France to England, as the hawks on the English
coast destroyed so many on their arrival. 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
Zoological Gardens, include seeds capable of germination. Some seeds of
the oat, wheat, millet, canary, hemp, clover, and beet germinated after
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