Origin of Species Variorum

→ species. 1859 1860 1861 1866

species when crossed. 1869 1872

→ varieties does not seem to me sufficient to overthrow the view which I have taken with respect to the very general, but not invariable, sterility of first crosses and of hybrids, namely, that it is not 1859 1860

varieties, considering how entirely ignorant we are on the causes of both fertility and sterility, does not seem to me sufficient to overthrow the view taken with respect to the very general, but not invariable, sterility of first crosses between species and of their hybrids, namely, that it is not 1861 1866

crossed species may safely be looked at not as 1869

crossed species may safely be looked at, not as 1872

→ endowment, but is 1859 1860 1861 1866

acquirement or endowment, but as 1869 1872

→ slowly acquired modifications, more especially in the reproductive systems of the forms which are crossed. 1859 1860 1861

modifications, slowly impressed, by unknown means, on the reproductive systems of the parent-forms. 1866

changes of an unknown nature in their sexual elements. 1869 1872

→ compared, 1859 1860

compared , 1861

compared, 1866 1869

compared , 1872

→ is 1859 1860 1861 1866

in both cases is 1869 1872

a fundamental distinction between

them

varieties

and →species. The general

sterility

fertility

of →varieties does not seem to me sufficient to overthrow the view which I have taken with respect to the very general, but not invariable, sterility of first crosses and of hybrids, namely, that it is not a special →endowment, but is incidental on →slowly acquired modifications, more especially in the reproductive systems of the forms which are crossed.

Hybrids

and

Mongrels

→ compared,

independently

their

fertility .

fertility .—

Independently of the question of fertility, the offspring of species

~~when crossed~~

when crossed

and of varieties when crossed may be compared in several other respects. Gärtner, whose strong wish

it was

was

to draw a

distinct

marked

line

~~of distinction~~

of distinction

between species and varieties, could find very

few,

few

and, as it seems to me, quite unimportant differences between the so-called hybrid offspring of species, and the so-called mongrel offspring of varieties. And, on the other hand, they agree most closely in

~~very~~

very

many important respects.

I shall here discuss this subject with extreme brevity. The most important distinction is, that in the first generation mongrels are more variable than hybrids; but Gärtner admits that hybrids from species which have long been cultivated are often variable in the first generation; and I have myself seen striking instances of this fact. Gärtner further admits that hybrids between very closely allied species are more variable than those from very distinct species; and this shows that the difference in the degree of variability graduates away. When mongrels and the more fertile hybrids are propagated for several

generations,

generations

an extreme amount of variability in

the

their

offspring →is

notorious;

notori- ous;