| → he likewise does 1866 |
| he likewise includes 1859 1860 1861 |
| well as 1869 1872 |
|
| → because they may closely resemble 1866 |
| solely because they closely resemble 1859 1860 1861 |
| from their partial resemblance to 1869 1872 |
|
| ↑ 2 blocks not present in 1866 1869 1872; present in 1859 1860 1861 |
| He who believes that the cowslip is descended from the primrose, or conversely, ranks them together as a single species, and gives a single definition.
As soon as three Orchidean forms (Monochanthus, Myanthus, and Catasetum), which had previously
been ranked as three distinct genera, were known to be sometimes produced on the same spike, they were immediately included as a single species.
|
|
| ↑ 5 blocks not present in 1860 1861 1866 1869 1872; present in 1859 |
| But it may be asked, what ought we to do, if it could be proved that one species of kangaroo had been produced, by a long course of modification, from a bear?
Ought we to rank this one species with bears, and what should we do with the other species?
The supposition is of course preposterous; and I might answer by the
argumentum
ad
hominem
,
and ask what should be done if a perfect kangaroo were seen to come out of the womb of a bear?
According to all analogy, it would be ranked with bears; but then assuredly all the other species of the kangaroo family would have to be classed under the bear genus.
The whole case is preposterous; for where there has been close descent in common, there will certainly be close resemblance or affinity.
|
|
| → though in these cases the modification has been much greater in degree, and has taken a longer time to complete? 1866 |
| though in these cases the modification has been greater in degree, and has taken a longer time to complete? 1859 1860 1861 |
| all under the so-called natural system? 1869 1872 |
|
|
With species in a state of nature, every naturalist has in fact brought descent into his classification; for he includes in his lowest grade,
that of
species, the two sexes; and how enormously these sometimes differ in the most important characters, is known to every naturalist: scarcely a single fact can be predicated in common of the
and hermaphrodites of certain cirripedes,
and yet no one dreams of separating them. As soon as the three Orchidean forms,
Myanthus, and Catasetum, which had previously been ranked as three distinct genera, were known to be sometimes produced on the same plant, they were immediately considered as varieties;
now I have been able to show that they
the male, female, and hermaphrodite forms of the same species. The naturalist includes as one species the
larval stages of the same individual, however much they may differ from each other and from the
as
→he likewise does
the so-called alternate generations of Steenstrup, which can only in a technical sense be considered as the same individual. He includes
varieties, not
→because they may closely resemble
the parent-form, but because they are descended from it. ↑
↑ |
|
| As descent has universally been used in classing together the individuals of the same species, though the males and females and larvæ are sometimes extremely different; and as it has been used in classing varieties which have undergone a certain, and sometimes a considerable amount of modification, may not this same element of descent have been unconsciously used in grouping species under genera, and genera under higher groups,
→though in these cases the modification has been much greater in degree, and has taken a longer time to complete? I believe it has
been unconsciously
|
