Comparison with 1872 |
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favourable for variation; and hence we might expect that the circumstances would generally be still favourable to variation. On the other hand, if we look at each species as a special act of creation, there is no apparent reason why more varieties should occur in a group having many species, than in one having few. |
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To test the truth of this anticipation I have arranged the plants of twelve countries, and the coleopterous insects of two districts, into two nearly equal masses, the species of the larger genera on one side, and those of the smaller genera on the other side, and it has invariably proved to be the case that a larger proportion of the species on the side of the larger genera
presented presented 1869 1872 | present 1859 1860 1861 1866 |
varieties, than on the side of the smaller genera. Moreover, the species of the large genera which present any varieties, invariably present a larger average number of varieties than do the species of the small genera. Both these results follow when another division is made, and when all the
least least 1866 1869 1872 | smallest 1859 1860 1861 |
genera, with from only one to four species, are
altogether altogether 1872 | absolutely 1859 1860 1861 1866 1869 |
excluded from the tables. These facts are of plain signification on the view that species are only
strongly-marked strongly-marked 1866 1869 1872 | strongly marked 1859 1860 1861 |
and permanent varieties; for wherever many species of the same genus have been formed, or where, if we may use the expression, the manufactory of species has been active, we ought generally to find the manufactory still in action, more especially as we have every reason to believe the process of manufacturing new species to be a slow one. And this certainly
holds true, holds true, 1872 |
is the case, 1859 1860 1861 1866 1869 |
if varieties be looked at as incipient species; for my tables clearly show as a general rule that, wherever many species of a genus have been formed, the species of that genus present a number of varieties, that is of incipient species,
beyond the average. It is not that all large genera are now varying much, and are thus increasing in the number of their species,
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favourable for variation; and hence we might expect that the circumstances would generally be still favourable to variation. On the other hand, if we look at each species as a special act of creation, there is no apparent reason why more varieties should occur in a group having many species, than in one having few. |
|
To test the truth of this anticipation I have arranged the plants of twelve countries, and the coleopterous insects of two districts, into two nearly equal masses, the species of the larger genera on one side, and those of the smaller genera on the other side, and it has invariably proved to be the case that a larger proportion of the species on the side of the larger genera
present present 1859 1860 1861 1866 | presented 1869 1872 |
varieties, than on the side of the smaller genera. Moreover, the species of the large genera which present any varieties, invariably present a larger average number of varieties than do the species of the small genera. Both these results follow when another division is made, and when all the
smallest smallest 1859 1860 1861 | least 1866 1869 1872 |
genera, with from only one to four species, are
absolutely absolutely 1859 1860 1861 1866 1869 | altogether 1872 |
excluded from the tables. These facts are of plain signification on the view that species are only
strongly marked strongly marked 1859 1860 1861 | strongly-marked 1866 1869 1872 |
and permanent varieties; for wherever many species of the same genus have been formed, or where, if we may use the expression, the manufactory of species has been active, we ought generally to find the manufactory still in action, more especially as we have every reason to believe the process of manufacturing new species to be a slow one. And this certainly
is the case, is the case, 1859 1860 1861 1866 1869 |
holds true, 1872 |
if varieties be looked at as incipient species; for my tables clearly show as a general rule that, wherever many species of a genus have been formed, the species of that genus present a number of varieties, that is of incipient
species, species, 1859 1861 1866 1869 1872 | species 1860 |
beyond the average. It is not that all large genera are now varying much, and are thus increasing in the number of their species,
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