Origin of Species Variorum

→ a few 1859 1860 1861 1866 1869

less than a 1872

→ safest 1869 1872

under the mark 1859 1860 1861 1866

→ three pair of 1859 1860 1861 1866 1869

six 1872

→ if 1859 1860 1861 1866 1869

and surviving till one hundred years old; if 1872

→ at the end of the fifth century 1859 1860 1861 1866 1869

after a period of from 740 to 750 years 1872

there must in every case be a struggle for existence, either one individual with another of the same species, or with the individuals of distinct species, or with the physical conditions of life. It is the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms; for in this case there can be no artificial increase of food, and no prudential restraint from marriage. Although some species may be now increasing, more or less rapidly, in numbers, all cannot do so, for the world would not hold them.

There is no exception to the rule that every organic being naturally increases at so high a rate,

that

that,

if not destroyed, the earth would soon be covered by the progeny of a single pair. Even slow-breeding man has doubled in twenty-five years, and at this rate, in →a few thousand years, there would literally not be

standing room

standing-room

for his progeny. Linnæus has calculated that if an annual plant produced only two

seeds—

seeds—and

and

....

there is no plant

nearly so

unproductive as

this—

this—and

and

....

their seedlings next year produced two, and so on, then in twenty years there would be a million plants. The elephant is reckoned

to be

....

the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural

increase;

increase:

it will be →safest to assume that it

breeds

begins breeding

when thirty years old, and goes on breeding till ninety years old, bringing forth →three pair of young in

the

this

interval,

interval;

→if this be so, →at the end of the fifth century there would be

nearly nineteen

alive fifteen

million

elephants

elephants,

alive, descended

descended

from the first pair.

But we have better evidence on this subject than mere theoretical calculations, namely, the numerous recorded cases of the astonishingly rapid increase of various animals in a state of nature, when circumstances have been favourable to them during two or three following seasons. Still more striking is the evidence from