| ←Subtitle not present 1859 1860 1861 1866 1869 1872
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| ↑ 9 blocks not present in 1869 1872; present in 1859 1860 1861 1866 |
| Sterility has been said to be the bane of horticulture; but on this view we owe variability to the same cause which produces sterility; and variability is the source of all the choicest productions of the garden.
I may add, that as some organisms will breed most
freely under the most unnatural conditions (for instance, the rabbit and ferret kept in hutches), showing that their reproductive system has not been thus affected; so will some animals and plants withstand domestication or cultivation, and vary very slightly — perhaps hardly more than in a state of nature.
A long list could easily be given of "sporting plants;" by this term gardeners mean a single bud or offset, which suddenly assumes a new and sometimes very different character from that of the rest of the plant.
Such buds can be propagated by grafting, &c., and sometimes by seed.
These "sports" are extremely rare under nature, but far from rare under cultivation; and in this case we see that the treatment of the parent has affected a bud or offset, and not the ovules or pollen.
But it is the opinion of most physiologists that there is no essential difference between a bud and an ovule in their earliest stages of formation; so that, in fact, "sports" support my
view, that variability may be largely attributed to the ovules or pollen, or to both, having been affected by the treatment of the parent prior to the act of conception.
These cases anyhow show that variation is not necessarily connected, as some authors have supposed, with the act of generation.
Seedlings from the same fruit, and the young of the same litter, sometimes differ considerably from each other, though both the young and the parents, as Müller has remarked, have apparently been exposed to exactly the same conditions of life; and this shows how unimportant the direct effects of the conditions of life are in comparison with the laws of reproduction, and
of growth, and of inheritance; for had the action of the conditions been direct, if any of the young had varied, all would probably have varied in the same manner.
To judge how much, in the case of any variation, we should attribute to the direct action of heat, moisture, light, food, &c., is most difficult: my impression is, that with animals such agencies have produced very little direct effect, though apparently more in the case of plants.
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| ↑ 1 blocks not present in 1866 1869 1872; present in 1859 1860 1861 |
| Under this point of view, Mr. Buckman's recent experiments on plants seem
extremely valuable.
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| →
Effects of Habit; Correlated Variation; Inheritance.
1869 |
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Effects of Habit; Correlation of Growth; Inheritance.
1866 |
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Effects of Habit and of the Use or Disuse of Parts; Correlated Variation; Inheritance.
1872 |
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| → Habits are inherited and have a decided influence; 1869 |
| Habit also has a decided influence, 1859 1860 1861 1866 |
| Changed habits produce an inherited effect, 1872 |
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| → the flowering of 1869 1872 |
| flowering with 1859 1860 1861 1866 |
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| → they have 1869 |
| it has 1859 1860 1861 1866 |
| the increased use or disuse of parts has had 1872 |
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| → effect; for instance, 1859 1860 1861 1866 1869 |
| influence; thus 1872 |
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| → OMIT 1869 1872 |
| I presume that 1859 1860 1861 1866 |
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| → the state of 1859 1860 1861 1866 1869 |
| OMIT 1872 |
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| → one of our 1869 1872 |
| a single 1859 1860 1861 1866 |
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| → which has been suggested 1866 1869 1872 |
| suggested by some authors, 1859 1860 1861 |
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| → seldom alarmed by danger, 1866 1869 |
| much alarmed by danger, 1859 1860 1861 |
| seldom much alarmed, 1872 |
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| → which are entirely white and have 1866 1869 1872 |
| with 1859 1860 1861 |
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