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give rise to varieties sufficiently well-marked to have been recorded in botanical works. Hence it is the most flourishing, or, as they may be called, the dominant
which range
the
→OMIT
most diffused in their own country, and are the most numerous in
oftenest produce well-marked varieties, or, as I consider them, incipient species. And this, perhaps, might have been anticipated; for, as varieties, in order to become in any degree permanent, necessarily have to struggle with the other inhabitants of the country, the species which are already dominant will be the most likely to yield
which, though in some slight degree modified,
still inherit those advantages that enabled their parents to become dominant over their compatriots. In these remarks on predominance, it should be understood that reference is made only to
forms which come into competition with each other, and more especially to the members of the same genus or class having nearly similar habits of life. With respect to
the number of individuals
→of any
species, the comparison of course relates only to the members of the same group.
→A
may be said to be dominant if it be more numerous in individuals and more widely diffused than the other plants of the same country,
→not living under widely different conditions of life.
→Such a plant
is not the less dominant
→in the sense here used,
because some conferva inhabiting the water or some parasitic fungus is infinitely more numerous in
and more widely
→if one kind of
or parasitic fungus
its allies in the above respects, it
→would be a dominant form
within its own class. →
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| If the plants inhabiting a
described in any
be divided into two equal masses, all those in the larger genera
→being
placed on one side, and all those in the smaller genera on the other side,
→a
somewhat larger number of the very common and much diffused or dominant
might have been anticipated; for the mere fact of many species of the same genus inhabiting any country, shows that there is something in the organic or inorganic conditions of that country favourable to the genus; and, consequently, we might have expected to have found in the larger genera, or those including many species, a
proportional number of dominant species. But so many causes tend to obscure this result, that I am surprised that my tables show even a small majority on the side of the larger genera. I will here allude to only two causes of obscurity.
and salt-loving plants
very wide ranges and are much diffused, but this seems to be connected with the nature of the stations inhabited by them, and has little or no relation to the size of the genera to which the species belong. Again, plants low in the scale of organisation are generally much more widely diffused than plants higher in the scale; and here again there is no close relation to the size of the genera. The cause of lowly-organised plants ranging widely will be discussed in our chapter on
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| From looking at species as only strongly-marked and well-defined varieties, I was led to anticipate that the species of the larger genera in each country would oftener present varieties, than the species of the smaller genera; for wherever many closely related species
→
(
I. e.
of the same genus) have been formed, many varieties or incipient species ought, as a general rule, to be now forming. Where many large trees grow, we expect to find saplings. Where many species of a genus have been formed through variation, circumstances have been
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