provisional species, that is, are not known strictly to fulfil the definition above given of a true species.
It
should be added that De Candolle no longer believes that species are immutable creations, but concludes that the derivative theory
is
the
...OMIT 1872 |
succession of forms is the 1866 1869 |
most natural one, "and the most accordant with the known facts in palæontology, geographical botany and zoology, of anatomical structure and
classification." classification." 1872 | classification;" 1866 1869 |
..
..
....... 1872 | adds, 1866 1869 |
....... 1872 | direct 1866 1869 |
....... 1872 | proof 1866 1869 |
..
....... 1872 | still 1866 1869 |
....... 1872 | wanting. 1866 1869 |
↑5 blocks not present in 1866 1869 1872; present in 1859 1860 1861 | Close investigation, in most cases, will bring naturalists to an agreement how to rank doubtful forms.
Yet it must be confessed,
that it is in the best-known countries that we find the greatest number of forms of doubtful value.
I have been struck with the fact, that if any animal or plant in a state of nature be highly useful to man, or from any cause closely attract his attention, varieties of it will almost universally be found recorded.
These varieties, moreover, will be often ranked by some authors as species.
Look at the common oak, how closely it has been studied; yet a German author makes more than a dozen species out of forms, which are very generally
considered as varieties; and in this country the highest botanical authorities and practical men can be quoted to show that the sessile and pedunculated oaks are either good and distinct species or mere varieties.
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|
|
When a young naturalist commences the study of a group of organisms quite unknown to him, he is at first much perplexed
in in 1872 | to 1859 1860 1861 1866 1869 |
determining determining 1872 | determine 1859 1860 1861 1866 1869 |
what differences to consider as specific, and what as
varietal; varietal; 1866 1869 1872 | varieties; 1859 1860 1861 |
for he knows nothing of the amount and kind of variation to which the group is subject; and this shows, at least, how very generally there is some variation. But if he confine his attention to one class within one country, he will soon make up his mind how to rank most of the doubtful forms. His general tendency will be to make many species, for he will become impressed, just like the pigeon or
poultry fancier poultry fancier 1860 1861 1866 1869 1872 | poultry-fancier 1859 |
before alluded to, with the amount of difference in the forms which he is continually studying; and he has little general knowledge of analogical variation in other groups and in other countries, by which to correct his first impressions. As he extends the range of his observations, he will meet with more cases of difficulty; for he will encounter a greater number of closely-allied forms. But if his observations be widely extended, he will in the end generally be
able able 1872 | enabled 1859 1860 1861 1866 1869 |
to make up his own
mind; mind; 1872 | mind 1859 1860 1861 1866 1869 |
...OMIT 1872 |
which to call varieties and which species; 1859 1860 1861 1866 1869 |
but he will succeed in this at the expense of admitting much variation,— and the truth of this admission will often be disputed by other naturalists.
When When 1872 | When, 1859 1860 1861 1866 1869 |
....... 1872 | moreover, 1859 1860 1861 1866 1869 |
he comes to study allied forms brought from countries not now continuous, in which case he
cannot cannot 1866 1869 1872 | can hardly 1859 1860 1861 |
hope to find
....... 1872 | the 1859 1860 1861 1866 1869 |
intermediate
links, links, 1872 | links 1859 1860 1861 1866 1869 |
...OMIT 1872 |
between his doubtful forms, 1859 1860 1861 1866 1869 |
he will
be compelled be compelled 1872 | have 1859 1860 1861 1866 1869 |
to trust almost entirely to analogy, and his difficulties
will will 1859 1872 | will 1860 1861 1866 1869 |
rise to a climax. |
|
Certainly no clear line of demarcation has as yet been drawn between species and
sub-species— sub-species— 1859 1860 1861 1872 | sub-species—that 1866 1869 |
that that 1859 1860 1861 1872 | that 1866 1869 |
is, the forms which in the opinion of some naturalists come very near to, but do not quite arrive
at, at, 1866 1869 1872 | at 1859 1860 1861 |
the rank of
species: species: 1872 | species; 1859 1860 1861 1866 1869 |
or, again, between sub-species and well-marked varieties, or between lesser varieties and individual differences. These differences blend into each other
by by 1872 | in 1859 1860 1861 1866 1869 |
an insensible series; and a series impresses the mind with the idea of an actual passage. |
|
Hence I look at individual differences, though of small interest to the systematist, as of
the highest the highest 1869 1872 | high 1859 1860 1861 1866 |
importance for us, as being the first
steps steps 1869 1872 | step 1859 1860 1861 1866 |
towards such slight varieties as are barely
thought thought 1859 1860 1861 1869 1872 | though 1866 |
worth recording in works on natural history. And I look at varieties which are in any degree more distinct and permanent, as steps
|