as this, and farther no one can go. The point at
issue between him and his predecessors involves neither the main fact of
evolution, nor yet the geometrical ratio of increase, and the struggle
for existence consequent thereon. Messrs. Darwin and Wallace have each
thrown invaluable light upon these last two points, but Buffon, as early
as 1756, had made them the keystone of his system. "The movement of
nature," he then wrote, "turns on two immovable pivots: one, the
illimitable fecundity which she has given to all species: the other, the
innumerable difficulties which reduce the results of that fecundity."
Erasmus Darwin and Lamarck followed in the same sense. They thus admit
the survival of the fittest as fully as Mr. Darwin himself, though they
do not make use of this particular expression. The dispute turns not
upon natural selection, which is common to all writers on evolution, but
upon the nature and causes of the variations that are supposed to be
selected from and thus accumulated. Are these mainly attributable to the
inherited effects of use and disuse, supplemented by occasional sports
and happy accidents? Or are they mainly due to sports and happy
accidents, supplemented by occasional inherited effects of use and
disuse?

The Lamarckian system has all along been maintained by Mr. Herbert
Spencer, who, in his "Principles of Biology," published in 1865, showed
how impossible it was that accidental variations should accumulate at
all. I am not sure how far Mr. Spencer would consent to being called a
Lamarckian pure and simple, nor yet how far it is strictly accurate to
call him one; nevertheless, I can see no important difference in the main
positions taken by him and by Lamarck.

The question at issue between the Lamarckians, supported by Mr. Spencer
and a growing band of those who have risen in rebellion against the
Charles-Darwinian system on the one hand, and Messrs. Darwin and Wallace
with the greater number of our more prominent biologists on the other,
involves the very existence of evolution as a workable theory. For it is
plain that what Nature can be supposed able to do by way of choice must
depend on the supply of the variations from which she is supposed to
choose. She cannot take what is not offered to her; and so again she
cannot be supposed able to accumulate unless what is gained in one
direction in one generation, or series of generations, is little likely
to be lost in those that pres