breeders in the production of new varieties, as a basis on which to
build an explanation of the processes of nature. In my opinion Darwin
was quite right, and he has succeeded in giving the desired proof. But
the basis was a frail one, and would not stand too close an examination.
Of this Darwin was always well aware. He has been prudent to the utmost,
leaving many points undecided, and among them especially the range of
validity of his several arguments. Unfortunately this prudence has not
been adopted by his followers. Without sufficient warrant they have laid
stress on one phase of the problem, quite overlooking the others.
Wallace has even gone so far in his zeal and ardent veneration for
Darwin, as to describe as Darwinism some things, which in my opinion,
had never been a part of Darwin's conceptions.

The experience of the breeders was quite inadequate to the use which
Darwin made of it. It was neither scientific, nor critically accurate.
Laws of variation were barely conjectured; the different types of
variability were only imperfectly distinguished. The breeders'
conception was fairly sufficient for practical purposes, but science
needed a clear understanding of the [6] factors in the general process
of variation. Repeatedly Darwin tried to formulate these causes, but the
evidence available did not meet his requirements.

Quetelet's law of variation had not yet been published. Mendel's claim
of hereditary units for the explanation of certain laws of hybrids
discovered by him, was not yet made. The clear distinction between
spontaneous and sudden changes, as compared with the ever-present
fluctuating variations, is only of late coming into recognition by
agriculturists. Innumerable minor points which go to elucidate the
breeders' experience, and with which we are now quite familiar, were
unknown in Darwin's time. No wonder that he made mistakes, and laid