Comparison with 1860 |
|
yellow and white varieties of one species are crossed with yellow and white varieties of a
distinct
species, more seed is produced by the crosses between the
similarly similarly 1860 1861 1866 1869 1872 | same 1859 |
coloured flowers, than between those which are differently coloured. ↑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.
|
Yet these varieties of Verbascum present no other difference besides the mere
colour of the
flower;
and one variety can sometimes be raised from the seed of the
other.
|
|
From observations
which I have made on certain varieties of hollyhock, I am inclined to suspect that they present analogous facts. |
|
Kölreuter, whose accuracy has been confirmed by every subsequent observer, has proved the remarkable fact, that one variety
of the common tobacco is
more fertile,
when
crossed with a widely distinct species,
than are the other varieties.
He experimentised
on five 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 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;
from
the great difficulty of ascertaining the infertility of varieties in a state of nature, for a supposed variety
if infertile
in any degree
would generally
be ranked as species; from man selecting only
external
characters in the production of the most distinct
domestic varieties, and from not wishing or being able to produce recondite and functional differences in the reproductive system; from
these several considerations and facts, I do not think that the very general fertility of varieties can be proved to be of universal occurrence, or to form |
yellow and white varieties of one species are crossed with yellow and white varieties of a
distinct
species, more seed is produced by the crosses between the
same same 1859 | similarly 1860 1861 1866 1869 1872 |
coloured flowers, than between those which are differently coloured. ↑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.
|
Yet these varieties
of Verbascum present no other difference besides the mere of Verbascum present no other difference besides the mere 1859 1860 1861 1866 |
differ in no respect except in the 1869 1872 |
colour of
the the 1859 1860 1861 1866 | their 1869 1872 |
flower; flower; 1859 1860 1861 1866 | flowers; 1869 1872 |
and one variety can sometimes be raised from the seed of
the the 1859 1860 1861 1866 | the 1869 1872 |
other. other. 1859 1860 1861 1866 | another. 1869 1872 |
|
|
From
observations observations 1859 1860 | experiments 1861 |
which I have made on certain varieties of hollyhock, I am inclined to suspect that they present analogous facts. |
|
Kölreuter, whose accuracy has been confirmed by every subsequent observer, has proved the remarkable fact, that one
variety variety 1859 1860 1861 1866 | particular variety 1869 1872 |
of the common tobacco
is is 1859 1860 1861 1866 | was 1869 1872 |
more
fertile, fertile, 1859 1860 1861 1866 | fertile 1869 1872 |
when when 1859 1860 1861 1866 |
than the other varieties, when 1869 1872 |
crossed with a widely distinct
species, species, 1859 1860 1861 1866 | species. 1869 1872 |
than than 1859 1860 1861 1866 | than 1869 1872 |
are are 1859 1860 1861 1866 | are 1869 1872 |
the the 1859 1860 1861 1866 | the 1869 1872 |
other other 1859 1860 1861 1866 | other 1869 1872 |
varieties. varieties. 1859 1860 1861 1866 | varieties. 1869 1872 |
He
experimentised experimentised 1859 1860 | experimented 1861 1866 1869 1872 |
on five
forms, forms, 1859 1860 1861 1866 1869 | forms 1872 |
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
father father 1859 1860 1861 1866 | the father 1869 1872 |
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. 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 |
Hence the reproductive system of this one variety must have been in some manner and in some degree modified. |
|
From these
facts; facts; 1859 1860 1861 1866 | facts 1869 1872 |
from 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 |
the great difficulty of ascertaining the infertility of varieties in a state of nature, for a supposed
variety variety 1859 1860 1861 | variety, 1866 1869 1872 |
if
infertile infertile 1859 1860 1861 |
proved to be infertile 1866 1869 1872 |
in any
degree degree 1859 1860 1861 | degree, 1866 1869 1872 |
would
generally generally 1859 1860 1861 | almost universally 1866 1869 1872 |
be ranked as
species; from man selecting only species; from man selecting only 1859 1860 1861 |
a species; from man selecting only 1866 |
a species;—from man attending only to 1869 |
a species;— from man attending only 1872 |
external external 1859 1860 1861 1866 1869 | to external 1872 |
characters in
the production of the most distinct the production of the most distinct 1859 1860 1861 |
his 1866 1869 1872 |
domestic varieties, and from
not wishing or being able to produce recondite and functional differences in the reproductive system; from not wishing or being able to produce recondite and functional differences in the reproductive system; from 1859 1860 1861 |
not wishing or being able to produce recondite and functional differences in their reproductive systems; from 1866 |
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 |
these several considerations
and facts, I do not think that the very general fertility of varieties can be proved to be of universal occurrence, or to form 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 |
and facts, I do not think that the fertility of varieties can be proved either to be of universal occurrence, or to form 1866 |
we may conclude that fertility does not constitute 1869 1872 |
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