scovered the most efficient and
practically sole cause of the origin of species, he carried the doctrine
to its extreme limits, and after over twenty years of observation and
experiment along this single line, pushing entirely aside the
Erasmus-Darwin and Lamarckian factors of change of environment, though
occasionally acknowledging the value of use and disuse, he triumphantly
broke over all opposition, and lived to see his doctrine generally
accepted. He had besides the support of some of the strongest men in
science: Wallace in a twin paper advocated the same views; Spencer,
Lyell, Huxley, Hooker, Haeckel, Bates, Semper, Wyman, Gray, Leidy, and
other representative men more or less endorsed Darwin's views, or at
least some form of evolution, and owing largely to their efforts in
scientific circles and in the popular press, the doctrine of descent
rapidly permeated every avenue of thought and became generally accepted.

Meanwhile, the general doctrine of evolution thus proved, and the
"survival of the fittest" an accomplished fact, the next step was to
ascertain "how," as Cope asked, "the fittest originated?" It was felt by
some that natural selection alone was not adequate to explain the first
steps in the origin of genera, families, orders, classes, and branches
or phyla. It was perceived by some that natural selection by itself was
not a _vera causa_, an efficient agent, but was passive, and rather
expressed the results of the operations of a series of factors. The
transforming should naturally precede the action of the selective
agencies.

We were, then, in our quest for the factors of organic evolution,
obliged to fall back on the action of the physico-chemical forces such
as light, or its absence, heat, cold, change of climate; and the
physiological agencies of food, or in other words on changes in the
physical environment, as well as in the biological environment. Lamarck
was the first one who, owing to his many years' training in systematic
botany and zooelogy, and his philosophic breadth, had stated more fully
and authoritatively than any one else the results of changes in the
action of the primary factors of evolution. Hence a return on the part
of many in Europe, and especially in America, to Lamarckism or its
modern form, Neolamarckism. Lamarck had already, so far as he could
without a knowledge of modern morphology, embryology, cytology, and
histology, suggested those fundamental principles of transformis