henomena that are _repeated_ continually in the living
being, as in a chemical retort. This explains, in some measure, the
mechanistic tendencies of physiology. On the contrary, those whose
attention is concentrated on the minute structure of living tissues, on
their genesis and evolution, histologists and embryogenists on the one
hand, naturalists on the other, are interested in the retort itself, not
merely in its contents. They find that this retort creates its own form
through a _unique_ series of acts that really constitute a _history_.
Thus, histologists, embryogenists, and naturalists believe far less
readily than physiologists in the physico-chemical character of vital
actions.

The fact is, neither one nor the other of these two theories, neither
that which affirms nor that which denies the possibility of chemically
producing an elementary organism, can claim the authority of experiment.
They are both unverifiable, the former because science has not yet
advanced a step toward the chemical synthesis of a living substance, the
second because there is no conceivable way of proving experimentally the
impossibility of a fact. But we have set forth the theoretical reasons
which prevent us from likening the living being, a system closed off by
nature, to the systems which our science isolates. These reasons have
less force, we acknowledge, in the case of a rudimentary organism like
the amoeba, which hardly evolves at all. But they acquire more when we
consider a complex organism which goes through a regular cycle of
transformations. The more duration marks the living being with its
imprint, the more obviously the organism differs from a mere mechanism,
over which duration glides without penetrating. And the demonstration
has most force when it applies to the evolution of life as a whole, from
its humblest origins to its highest forms, inasmuch as this evolution
constitutes, through the unity and continuity of the animated matter
which supports it, a single indivisible history. Thus viewed, the
evolutionist hypothesis does not seem so closely akin to the mechanistic
conception of life as it is generally supposed to be. Of this
mechanistic conception we do not claim, of course, to furnish a
mathematical and final refutation. But the refutation which we draw from
the consideration of real time, and which is, in our opinion, the only
refutation possible, becomes the more rigorous and cogent the more
frankly the evolutioni