Comparison with 1860 |
|
CHAPTER I. |
VARIATION UNDER DOMESTICATION. |
Causes of Variability— Effects of Habit— Correlation of Growth—
Inheritance— Character of Domestic Varieties— Difficulty of distinguishing between Varieties and Species— Origin of Domestic Varieties from one or more Species— Domestic Pigeons, their Differences and Origin— Principle
of Selection
anciently followed, its
Effects— Methodical and Unconscious Selection— Unknown Origin of our Domestic Productions— Circumstances favourable to Man's power of Selection. ↑Subtitle not present 1859 1860 1861 |
Causes
of
Variability. 1866 1869 1872 |
|
WHEN we look to
the individuals of the same variety or sub-variety of our older cultivated plants and animals, one of the first points which strikes us,
is, that they generally differ much more
from each other,
than
do the individuals of any one species or variety in a state of nature. When
we reflect on the vast diversity of the plants and animals which have been cultivated, and which have varied during all ages under the most different climates and treatment, I think
we are driven to conclude that this greater
variability is simply
due to our domestic productions having been raised under conditions of life not so uniform as, and somewhat different from, those to which the parent-species have
been exposed under nature. There is,
also, I think,
some probability in the view propounded by Andrew Knight, that this variability may be partly connected with excess of food. It seems pretty
clear that organic beings must be exposed during several generations to the
new conditions of life
to cause any appreciable
amount of variation; and that
when the organisation has once begun to vary, it generally continues
to vary
for many generations.
|
CHAPTER I. |
VARIATION UNDER DOMESTICATION. |
Causes of Variability— Effects of
Habit— Correlation of Growth— Habit— Correlation of Growth— 1859 1860 1861 1866 |
Habit— Correlated Variation— 1869 |
Habit and the use or disuse of Parts— Correlated Variation— 1872 |
Inheritance— Character of Domestic Varieties— Difficulty of distinguishing between Varieties and Species— Origin of Domestic Varieties from one or more Species— Domestic Pigeons, their Differences and Origin—
Principle Principle 1859 1860 1861 | Principles 1866 1869 1872 |
of
Selection Selection 1859 1860 1861 | Selection, 1866 1869 1872 |
anciently followed,
its its 1859 1860 1861 | their 1866 1869 1872 |
Effects— Methodical and Unconscious Selection— Unknown Origin of our Domestic Productions— Circumstances favourable to Man's power of Selection. ↑Subtitle not present 1859 1860 1861 |
Causes
of
Variability. 1866 1869 1872 |
|
WHEN we
look to look to 1859 1860 1861 1866 | compare 1869 1872 |
the individuals of the same variety or sub-variety of our older cultivated plants and animals, one of the first points which strikes
us, us, 1859 1860 1861 1866 | us 1869 1872 |
is, that they generally differ
more more 1860 1861 1866 1872 | much more 1859 | more 1869 |
from each
other other 1860 1861 1866 1869 1872 | other, 1859 |
than than 1859 1860 1861 1866 1872 | more than 1869 |
do the individuals of any one species or variety in a state of nature.
When When 1859 1860 1861 1866 | And if 1869 1872 |
we reflect on the vast diversity of the plants and animals which have been cultivated, and which have varied during all ages under the most different climates and treatment,
I think I think 1859 1860 1861 1866 | I think 1869 1872 |
we are driven to conclude that this
great great 1860 1861 1866 1869 1872 | greater 1859 |
variability is
simply simply 1859 1860 1861 1866 | simply 1869 1872 |
due to our domestic productions having been raised under conditions of life not so uniform as, and somewhat different from, those to which the parent-species
have have 1859 1860 1861 1866 | had 1869 1872 |
been exposed under nature. There
is is 1860 1861 1866 1869 | is, 1859 1872 |
also,
I think, I think, 1859 1860 1861 1866 1869 | I think, 1872 |
some probability in the view propounded by Andrew Knight, that this variability may be partly connected with excess of food. It seems
pretty pretty 1859 1860 1861 1866 | pretty 1869 1872 |
clear that organic beings must be exposed during several generations to
the the 1859 1860 1861 1866 | the 1869 1872 |
new conditions
of life of life 1859 1860 1861 1866 | of life 1869 1872 |
to cause any
appreciable appreciable 1859 1860 1861 1866 1869 | great 1872 |
amount of variation; and
that that 1859 1860 1861 | that, 1866 1869 1872 |
when the organisation has once begun to vary, it generally
continues continues 1859 1860 1861 1866 1872 | con- tinues 1869 |
to vary to vary 1859 1860 1861 1866 | varying 1869 1872 |
for many generations.
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