In sharp contrast to Lamarckianism, so called,--although it did not
originate in the mind of the noted man of science whose name it bears,--is
the doctrine of natural selection, first proposed in its full form by
Charles Darwin. This doctrine presents a wholly natural description of the
method by which organisms evolve, putting all of the emphasis upon the
congenital causes of variation, although the reality of other kinds of
change is not questioned. But the contrast between Darwinism and the other
descriptions of secondary factors can best be made after a somewhat
detailed discussion of the former, which has gained the adherence of the
majority of the naturalists of to-day. However, we must not pass on
without pointing out that however much the explanations given by various
men of science may differ, they all agree in expressly recognizing the
complete naturalness of the secondary as well as of the primary factors of
evolution.

* * * * *

The doctrine of natural selection forms the best basis for the detailed
discussion of the way evolution has come about in the past and how it is
going on to-day. This is true because it was the first description of
nature's program to carry conviction to the scientific world, and because
its major elements have stood the test of time as no other doctrine has
done. Much has been added to our knowledge of natural processes during
post-Darwinian times, and new discoveries have supplemented and
strengthened the original doctrine in numerous ways, although they have
corrected certain of the minor details on the basis of fuller
investigation.

At the outset it must be clearly understood that Darwin's doctrine is