NT
IN THE HISTORY OF THE EARTH to which their adaptations were appropriate,
and precisely at the proper place in which all the conditions of life to
which they were adapted occurred: the humming-birds at the same time as
the flowers; the trichina at the same time as the pig; the bark-coloured
moth at the same time as the oak, and the wasp-like moth at the same
time as the wasp which protects it. Without processes of selection we
should be obliged to assume a "pre-established harmony" after the famous
Leibnitzian model, by means of which the clock of the evolution of
organisms is so regulated as to strike in exact synchronism with that of
the history of the earth! All forms of life are strictly adapted to the
conditions of their life, and can persist under these conditions alone.

There must therefore be an intrinsic connection between the conditions
and the structural adaptations of the organism, and, SINCE THE
CONDITIONS OF LIFE CANNOT BE DETERMINED BY THE ANIMAL ITSELF, THE
ADAPTATIONS MUST BE CALLED FORTH BY THE CONDITIONS.

The selection theory teaches us how this is conceivable, since it
enables us to understand that there is a continual production of what is
non-purposive as well as of what is purposive, but the purposive alone
survives, while the non-purposive perishes in the very act of arising.
This is the old wisdom taught long ago by Empedocles.

II. THE LAMARCKIAN PRINCIPLE.

Lamarck, as is well known, formulated a definite theory of evolution at
the beginning of the nineteenth century, exactly fifty years before
the Darwin-Wallace principle of selection was given to the world.
This brilliant investigator also endeavoured to support his theory by
demonstrating forces which might have brought about the transformations
of the organic world in the course of the ages. In addition to other
factors, he laid special emphasis on the increased or diminished use
of the parts of the body, assuming that the strengthening or weakening
which takes place from this cause during the individual life, could be
handed on to the offspring, and thus intensified and raised to the rank
of a specific character. Darwin also regarded this LAMARCKIAN PRINCIPLE,
as it is now generally called, as a factor in evolution, but he was not
fully convinced of the transmissibility of acquired characters.

As I have here to deal only with the theory of selection, I need not
discuss the Lamarckian hypothesis, but I must express my opinion that