m on
which rests the selective principle.

Had his works been more accessible, or, where available, more carefully
read, and his views more fairly represented; had he been favored in his
lifetime by a single supporter, rather than been unjustly criticised by
Cuvier, science would have made more rapid progress, for it is an
axiomatic truth that the general acceptance of a working evolutionary
theory has given a vast impetus to biology.

We will now give a brief historical summary of the history of opinion
held by Lamarckians regarding the causes of the "origin of the fittest,"
the rise of variations, and the appearance of a population of plant and
animal forms sufficiently extensive and differentiated to allow for the
play of the competitive forces, and of the more passive selective
agencies which began to operate in pre-cambrian times, or as soon as the
earth became fitted for the existence of living beings.

The first writer after Lamarck to work along the lines he laid down was
Mr. Herbert Spencer. In 1866-71, in his epochal and remarkably
suggestive _Principles of Biology_, the doctrine of use and disuse is
implicated in his statements as to the effects of motion on structure in
general;[204] and in his theory as to the origin of the notochord, and
of the segmentation of the vertebral column and the segmental
arrangement of the muscles by muscular strains,[205] he laid the
foundations for future work along this line. He also drew attention in
the same work to the complementary development of parts, and likewise
instanced the decreased size of the jaws in the civilized races of
mankind, as a change not accounted for by the natural selection of
favorable variations.[206] In fact, this work is largely based on the
Lamarckian principles, as affording the basis for the action of natural
selection, and thirty years later we find him affirming: "The direct
action of the medium was the primordial factor of organic
evolution."[207] In his well-known essay on "The Inadequacy of Natural
Selection" (1893) the great philosopher, with his accustomed vigor and
force, criticises the arguments of those who rely too exclusively on
Darwinism alone, and especially Neodarwinism, as a sufficient factor to
account for the origin of special structures as well as species.

The first German author to appreciate the value of the Lamarckian
factors was that fertile and comprehensive philosopher and investigator
Ernst Haeckel, who also harmo