物种起源（英文全本）约15.1万字精彩阅读-全集TXT下载-(英)达尔文

of the

hybrids

produced

from them.

Pure

species

have of

course

their

organs of

reproduction

in a

perfect

condi-

tion, yet

when

intercrossed

they

produce

either few

or no

offspring.

Hybrids,

on the

other

hand, have

their

reproductive

organs

functionally

impotent,

as may be

clearly

seen in

the state

of the

male

element in

both

plants and

animals;

though the

organs

themselves

are

perfect in

structure,

as far as

the

microscope