ral selection" substitute the words "survival of the fittest,"
which we may do with Mr. Darwin's own consent abundantly given.

To the words "survival of the fittest" add what is elided, but what is,
nevertheless, unquestionably as much implied as though it were said
openly whenever these words are used, and without which "fittest" has no
force--I mean, "for the conditions of their existence."

We thus find that when Mr. Darwin says that natural selection is the
most important, but not exclusive means of modification, he means that
the survival in the struggle for existence of those creatures which are
best fitted to comply with the conditions of their existence is the most
important, but not exclusive means whereby the descendants of a
creature, we will say, A, have become modified, so as to be now
represented by a creature, we will say, B.

But the word "_circonstances_," so frequently used by Lamarck for the
conditions of an animal's existence, contains, by implication, the idea
of animals _which shall exist or not according as they fulfil those
conditions or fail to fulfil them_. Conditions of existence are
conditions which something capable of existing must fulfil if it would
exist at all, and nothing is a condition of an animal's existence which
that animal need not comply with and may yet continue to exist. Again,
the words "animals" and "plants" comprehend the ideas of "fit,"
"fitter," and "fittest," "unfit," "unfitter," and "unfittest" for
certain conditions, for we know of no animals or plants in which we do
not observe degrees of fitness or unfitness for their "_circonstances_"
or environment, or conditions of existence.

The use, therefore, of the term "conditions of existence" is sufficient
to show that the person using it intends to imply that those animals and
plants will live longest (or survive) and thrive best which are best
able to fulfil those conditions. Hence it implies neither more nor less
than what is implied by the words "struggle for existence, with
consequent survival of the fittest"--that is to say, if we hold the
complying with any condition of life to which difficulty is attached to
be part of "the struggle" for life, and this we should certainly do.

The words "conditions of existence" may, then, be used instead of the
"struggle for existence with consequent survival of the fittest," for as
they cannot imply any less than the "struggle, &c.," when they are set
out in full, and without