n in Kent, the other by Alfred Wallace
in Ternate, in the Malay Archipelago. It was a splendid proof of
the magnanimity of these two investigators, that they thus, in all
friendliness and without envy, united in laying their ideas before a
scientific tribunal: their names will always shine side by side as two
of the brightest stars in the scientific sky.

But it is with Charles Darwin that I am here chiefly concerned, since
this paper is intended to aid in the commemoration of the hundredth
anniversary of his birth.

The idea of selection set forth by the two naturalists was at the time
absolutely new, but it was also so simple that Huxley could say of it
later, "How extremely stupid not to have thought of that." As Darwin was
led to the general doctrine of descent, not through the labours of
his predecessors in the early years of the century, but by his own
observations, so it was in regard to the principle of selection. He was
struck by the innumerable cases of adaptation, as, for instance, that
of the woodpeckers and tree-frogs to climbing, or the hooks and
feather-like appendages of seeds, which aid in the distribution of
plants, and he said to himself that an explanation of adaptations was
the first thing to be sought for in attempting to formulate a theory of
evolution.

But since adaptations point to CHANGES which have been undergone by the
ancestral forms of existing species, it is necessary, first of all, to
inquire how far species in general are VARIABLE. Thus Darwin's attention
was directed in the first place to the phenomenon of variability, and
the use man has made of this, from very early times, in the breeding of
his domesticated animals and cultivated plants. He inquired carefully
how breeders set to work, when they wished to modify the structure and
appearance of a species to their own ends, and it was soon clear to him
that SELECTION FOR BREEDING PURPOSES played the chief part.

But how was it possible that such processes should occur in free
nature? Who is here the breeder, making the selection, choosing out one
individual to bring forth offspring and rejecting others? That was the
problem that for a long time remained a riddle to him.

Darwin himself relates how illumination suddenly came to him. He had
been reading, for his own pleasure, Malthus' book on Population, and, as
he had long known from numerous observations, that every species gives
rise to many more descendants than ever attain to m