Origin of Species Variorum

→ variation 1859 1860 1861 1869 1872

because new varieties are very slowly formed, for variation 1866

→ individual differences or variations 1869 1872

variations chance to 1859 1861 1866

varia- tions chance to 1860

→ to see only 1872

only to see 1859 1860 1861 1866 1869

→ within each isolated 1866 1872

in each broken 1859 1860 1861

formerly within each isolated 1869

→ 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

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

the wide

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,

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.

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,

first,

because new varieties are very slowly formed, for →variation is a

very

....

slow process, and natural selection can do nothing until favourable →individual differences or variations 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 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

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

have existed →within each isolated portion of the land, but these links →during the process of natural selection will have been supplanted and exterminated, so that they will no longer

exist

be found

in a living state.

Thirdly, when two or more varieties have been formed in different