I shall
reserve for my future work the discussion of these difficulties, and
the tables themselves of the proportional numbers of the varying
species. Dr. Hooker permits me to add, that after having carefully
read my manuscript, and examined the tables, he thinks that the
following statements are fairly well established. The whole subject,
however, treated as it necessarily here is with much brevity, is
rather perplexing, and allusions cannot be avoided to the "struggle
for existence," "divergence of character," and other questions,
hereafter to be discussed.
Alph. De Candolle and others have shown that plants which have very
wide ranges generally present varieties; and this might have been
expected, as they become exposed to diverse physical conditions, and
as they come into competition (which, as we shall hereafter see, is a
far more important circumstance) with different sets of organic
beings. But my tables further show that, in any limited country, the
species which are most common, that is abound most in individuals, and
the species which are most widely diffused within their own country
(and this is a different consideration from wide range, and to a
certain extent from commonness), often 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 species,--those which range widely over the world, are the
most diffused in their own country, and are the most numerous in
individuals,--which oftenest produce well-marked varieties, or, as I
consider them, incipient species.
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