物种起源（英文全本）-全本TXT下载 isas-精彩免费下载

special

endowment,

beyond the

province

of our

reasoning

powers.

The

fertility

of

varieties,

that is of

the forms

known or

believed

to have

descended

from

common

parents,

when

intercrossed,

and

likewise

the

fertility

of their

mongrel

offspring,

is, on my

theory, of

equal

importance

with the

sterility

of

species;

for it

seems to

make a

broad and

clear

distinction

between

varieties

and

species.

First, for

the

sterility