ainst the same insurmountable
difficulty, we have in no wise the intention of rejecting them
altogether. On the contrary, each of them, being supported by a
considerable number of facts, must be true in its way. Each of them must
correspond to a certain aspect of the process of evolution. Perhaps even
it is necessary that a theory should restrict itself exclusively to a
particular point of view, in order to remain scientific, _i.e._ to give
a precise direction to researches into detail. But the reality of which
each of these theories takes a partial view must transcend them all. And
this reality is the special object of philosophy, which is not
constrained to scientific precision because it contemplates no
practical application. Let us therefore indicate in a word or two the
positive contribution that each of the three present forms of
evolutionism seems to us to make toward the solution of the problem,
what each of them leaves out, and on what point this threefold effort
should, in our opinion, converge in order to obtain a more
comprehensive, although thereby of necessity a less definite, idea of
the evolutionary process.

The neo-Darwinians are probably right, we believe, when they teach that
the essential causes of variation are the differences inherent in the
germ borne by the individual, and not the experiences or behavior of the
individual in the course of his career. Where we fail to follow these
biologists, is in regarding the differences inherent in the germ as
purely accidental and individual. We cannot help believing that these
differences are the development of an impulsion which passes from germ
to germ across the individuals, that they are therefore not pure
accidents, and that they might well appear at the same time, in the same
form, in all the representatives of the same species, or at least in a
certain number of them. Already, in fact, the theory of _mutations_ is
modifying Darwinism profoundly on this point. It asserts that at a given
moment, after a long period, the entire species is beset with a tendency
to change. The _tendency to change_, therefore, is not accidental. True,
the change itself would be accidental, since the mutation works,
according to De Vries, in different directions in the different
representatives of the species. But, first we must see if the theory is
confirmed by many other vegetable species (De Vries has verified it only
by the _OEnothera Lamarckiana_),[49] and then there i