Origin of Species Variorum

→ less than a 1872

a few 1859 1860 1861 1866 1869

→ safest 1869 1872

under the mark 1859 1860 1861 1866

→ six 1872

three pair of 1859 1860 1861 1866 1869

→ and surviving till one hundred years old; if 1872

if 1859 1860 1861 1866 1869

→ after a period of from 740 to 750 years 1872

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

→ such as the cardoon and a tall thistle, which are now the commonest 1872

now most numerous 1859

such as the cardoon and a tall thistle, now most numerous 1860 1861

such as the cardoon, and a tall thistle, now most numerous 1866 1869

→ Their 1872

In such cases the 1859 1860 1861 1866 1869

→ OMIT 1872

of naturalised productions 1859 1860 1861 1866 1869

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 →less than a 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

....

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 →six young in

this

the

interval;

interval,

→and surviving till one hundred years old; if this be so, →after a period of from 740 to 750 years there would be

alive fifteen

nearly nineteen

million

elephants,

elephants

descended

alive, 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

....

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 of the

plants

plants,

→such as the cardoon and a tall thistle, which are now the commonest over the wide plains of La Plata, clothing square leagues of surface almost to the exclusion of

all

every

other

plants,

plant,

have been introduced from Europe; and there are plants which now range in India, as I hear from Dr. Falconer, from Cape Comorin to the Himalaya, which have been imported from America since its discovery. In such cases, and endless

instances

others

could be given, no one

supposes

supposes,

that the fertility of

these

the

animals or plants has been suddenly and temporarily increased in any sensible degree. The obvious explanation is that the conditions of life have been

very

highly

favourable, and that there has consequently been less destruction of the old and young, and that nearly all the young have been enabled to breed. →Their geometrical ratio of increase, the result of which never fails to be surprising, simply explains

the

their

extraordinarily rapid increase and wide diffusion →OMIT