Comparison with 1861 |
|
slowly modified and improved. It is the same principle which, as I believe, accounts for the common species in each country, as shown in the second chapter, presenting on an average a greater number of well-marked varieties than do the rarer species. I may illustrate what I mean by supposing three varieties of sheep to be kept, one adapted to an extensive mountainous region; a second to a comparatively narrow, hilly tract; and a third to
wide wide 1859 1860 1861 1866 1869 | the wide 1872 |
plains at the base; and that the inhabitants are all trying with equal steadiness and skill to improve their stocks by selection; the chances in this case will be strongly in favour of the great holders on the mountains or on the
plains plains 1859 1860 1861 1866 1869 | plains, 1872 |
improving their breeds more quickly than the small holders on the intermediate narrow, hilly tract; and consequently the improved mountain or plain breed will soon take the place of the less improved hill breed; and thus the two breeds, which originally existed in greater numbers, will come into close contact with each other, without the interposition of the supplanted, intermediate
hill-variety. hill-variety. 1859 1860 1861 1866 1869 | hill variety. 1872 |
|
|
To sum up, I believe that species come to be tolerably well-defined objects, and do not at any one period present an inextricable chaos of varying and intermediate links:
firstly, firstly, 1859 1860 1861 1866 | first, 1869 1872 |
because new varieties are very slowly formed, for variation
is a
very very 1859 1860 1861 1866 | very 1869 1872 |
slow process, and natural selection can do nothing until favourable
variations chance to variations chance to 1859 1861 1866 |
varia- tions chance to 1860 |
individual differences or variations 1869 1872 |
occur, and until a place in the natural polity of the country can be better filled by some modification of some one or more of its inhabitants. And such new places will depend on slow changes of climate, or on the occasional immigration of new inhabitants, and, probably, in a still more important degree, on some of the old inhabitants becoming slowly modified, with the new forms thus produced and the old ones acting and reacting on each other. So that, in any one region and at any one time, we ought
only to see only to see 1859 1860 1861 1866 1869 |
to see only 1872 |
a few species presenting slight modifications of structure in some degree permanent; and this assuredly we do see. |
|
Secondly, areas now continuous must often have existed within the recent period
in in 1859 1860 1861 1866 | as 1869 1872 |
isolated portions, in which many forms, more especially amongst the classes which unite for each birth and wander much, may have separately been rendered sufficiently distinct to rank as representative species. In this case, intermediate varieties between the several representative species and their common parent, must formerly
have existed
in each broken in each broken 1859 1860 1861 |
within each isolated 1866 1872 |
formerly within each isolated 1869 |
portion of the land, but these links
will have been supplanted and exterminated during the process of natural selection, will have been supplanted and exterminated during the process of natural selection, 1859 1860 1861 |
during the process of natural selection will have been supplanted and exterminated, 1866 1869 1872 |
so that they will no longer
exist exist 1859 1860 1861 1866 | be found 1869 1872 |
in a living state. |
|
Thirdly, when two or more varieties have been formed in different
|
slowly modified and improved. It is the same principle which, as I believe, accounts for the common species in each country, as shown in the second chapter, presenting on an average a greater number of well-marked varieties than do the rarer species. I may illustrate what I mean by supposing three varieties of sheep to be kept, one adapted to an extensive mountainous region; a second to a comparatively narrow, hilly tract; and a third to
the wide the wide 1872 | wide 1859 1860 1861 1866 1869 |
plains at the base; and that the inhabitants are all trying with equal steadiness and skill to improve their stocks by selection; the chances in this case will be strongly in favour of the great holders on the mountains or on the
plains, plains, 1872 | plains 1859 1860 1861 1866 1869 |
improving their breeds more quickly than the small holders on the intermediate narrow, hilly tract; and consequently the improved mountain or plain breed will soon take the place of the less improved hill breed; and thus the two breeds, which originally existed in greater numbers, will come into close contact with each other, without the interposition of the supplanted, intermediate
hill variety. hill variety. 1872 | hill-variety. 1859 1860 1861 1866 1869 |
|
|
To sum up, I believe that species come to be tolerably well-defined objects, and do not at any one period present an inextricable chaos of varying and intermediate links:
first, first, 1869 1872 | firstly, 1859 1860 1861 1866 |
because new varieties are very slowly formed, for
variation variation 1859 1860 1861 1869 1872 |
because new varieties are very slowly formed, for variation 1866 |
is a
....... 1869 1872 | very 1859 1860 1861 1866 |
slow process, and natural selection can do nothing until favourable
individual differences or variations individual differences or variations 1869 1872 |
variations chance to 1859 1861 1866 |
varia- tions chance to 1860 |
occur, and until a place in the natural polity of the country can be better filled by some modification of some one or more of its inhabitants. And such new places will depend on slow changes of climate, or on the occasional immigration of new inhabitants, and, probably, in a still more important degree, on some of the old inhabitants becoming slowly modified, with the new forms thus produced and the old ones acting and reacting on each other. So that, in any one region and at any one time, we ought
to see only to see only 1872 |
only to see 1859 1860 1861 1866 1869 |
a few species presenting slight modifications of structure in some degree permanent; and this assuredly we do see. |
|
Secondly, areas now continuous must often have existed within the recent period
as as 1869 1872 | in 1859 1860 1861 1866 |
isolated portions, in which many forms, more especially amongst the classes which unite for each birth and wander much, may have separately been rendered sufficiently distinct to rank as representative species. In this case, intermediate varieties between the several representative species and their common parent, must
formerly formerly 1859 1860 1861 1866 1872 | formerly 1869 |
have existed
within each isolated within each isolated 1866 1872 |
in each broken 1859 1860 1861 |
formerly within each isolated 1869 |
portion of the land, but these links
during the process of natural selection will have been supplanted and exterminated, during the process of natural selection will have been supplanted and exterminated, 1866 1869 1872 |
will have been supplanted and exterminated during the process of natural selection, 1859 1860 1861 |
so that they will no longer
be found be found 1869 1872 | exist 1859 1860 1861 1866 |
in a living state. |
|
Thirdly, when two or more varieties have been formed in different
|