↑ 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.
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→ of Verbascum present no other difference besides the mere 1859 1860 1861 1866 |
differ in no respect except in the 1869 1872 |
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→ when 1859 1860 1861 1866 |
than the other varieties, when 1869 1872 |
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→ 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 |
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→ 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 |
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→ proved to be infertile 1866 1869 1872 |
infertile 1859 1860 1861 |
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→ 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 |
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→ his 1866 1869 1872 |
the production of the most distinct 1859 1860 1861 |
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→ 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 |
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→ 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 |
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→ species. 1859 1860 1861 1866 |
species when crossed. 1869 1872 |
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→ 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 |
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