Origin of Species Variorum

→ a few 1859 1860 1861 1866 1869

less than a 1872

→ under the mark 1859 1860 1861 1866

safest 1869 1872

→ 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

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—and

seeds—

~~and~~

and

there is no plant

nearly so

unproductive as

this—and

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~~

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 →under the mark to assume that it

begins breeding

breeds

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 our domestic animals of many kinds which have run wild in several parts of the

world;

world:

if the statements of the rate of increase of slow-breeding cattle and horses in

South America,

South-America,

and latterly in Australia, had not been well authenticated, they would have been

~~quite~~

quite

incredible. So it is with

plants;

plants:

cases could be given of introduced plants which have become common throughout whole islands in a period of less than ten years. Several