Origin of Species Variorum

↑ 1 blocks not present in 1859 1860 1861 1866; present in 1869 1872

Mr. Scott, also, has experimented on the species and varieties of Verbascum; and although unable to confirm Gärtners results on the crossing of the distinct species, he finds that the dissimilarly coloured varieties of the same species yield fewer seeds, in the proportion of 86 to 100, than the similarly coloured varieties.

→ of Verbascum present no other difference besides the mere 1859 1860 1861 1866

differ in no respect except in the 1869 1872

→ when 1859 1860 1861 1866

than the other varieties, when 1869 1872

→ glutinosa. 1859 1860 1866 1869 1872

glutinosa. Hence the reproductive system of this one variety must have been in some manner and in some degree modified. 1861

→ from 1859 1860 1861 1866

it cannot be maintained that varieties when crossed are invariably quite fertile;—from 1869

it can no longer be maintained that varieties when crossed are invariably quite fertile. From 1872

→ proved to be infertile 1866 1869 1872

infertile 1859 1860 1861

→ a species; from man selecting only 1866

species; from man selecting only 1859 1860 1861

a species;—from man attending only to 1869

a species;— from man attending only 1872

→ his 1866 1869 1872

the production of the most distinct 1859 1860 1861

→ not wishing or being able to produce recondite and functional differences in their reproductive systems; from 1866

not wishing or being able to produce recondite and functional differences in the reproductive system; from 1859 1860 1861

such varieties not having been exposed for a very long period to uniform conditions of life;—from 1869

such varieties not having been exposed for very long periods to uniform conditions of life;— from 1872

→ and facts, I do not think that the fertility of varieties can be proved either to be of universal occurrence, or to form 1866

and facts, I do not think that the very general fertility of varieties can be proved to be of universal occurrence, or to form 1859 1860

and facts, I do not think that the very general fertility of varieties can be proved either to be of universal occurrence, or to form 1861

we may conclude that fertility does not constitute 1869 1872

→ species. 1859 1860 1861 1866

species when crossed. 1869 1872

→ 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

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

crossed species may safely be looked at not as 1869

crossed species may safely be looked at, not as 1872

more seed is produced by the crosses between the

same

similarly

coloured flowers, than between those which are differently coloured. ↑ Yet these varieties →of Verbascum present no other difference besides the mere colour of

their

the

flowers;

flower;

and one variety can sometimes be raised from the seed of

~~the~~

the

another.

other.

Kölreuter, whose accuracy has been confirmed by every subsequent observer, has proved the remarkable fact, that one

particular variety

variety

of the common tobacco

was

fertile

fertile,

→when crossed with a widely distinct

species.

~~than~~

~~are~~

~~the~~

~~other~~

~~varieties.~~

experimentised

on five

forms

forms,

which are commonly reputed to be varieties, and which he tested by the severest trial, namely, by reciprocal crosses, and he found their mongrel offspring perfectly fertile. But one of these five varieties, when used either as

the father

father

or mother, and crossed with the Nicotiana glutinosa, always yielded hybrids not so sterile as those which were produced from the four other varieties when crossed with N. →glutinosa. Hence the reproductive system of this one variety must have been in some manner and in some degree modified.

From these

facts

facts;

→from the great difficulty of ascertaining the infertility of varieties in a state of nature, for a supposed

variety

variety,

if →proved to be infertile in any

degree

degree,

would

generally

almost universally

be ranked as →a species; from man selecting only

to external

external

characters in →his domestic varieties, and from →not wishing or being able to produce recondite and functional differences in their reproductive systems; from these several considerations →and facts, I do not think that the fertility of varieties can be proved either to be of universal occurrence, or to form a fundamental distinction between

varieties

them

and →species. The general

sterility

fertility

of →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