ually compatible with Lamarck's theory of use
and development. The wings of birds of great power of flight, the
relations of insects to flowers, the claws of beasts of prey, are
all cases in point."

Professor J. A. Thomson's useful _Synthetic Summary of the Influence of
the Environment upon the Organism_ (1887) takes for its text Spencer's
aphorism, that the direct action of the medium was the primordial factor
of organic evolution. Professor Geddes relies on the changes in the soil
and climate to account for the origin of spines in plants.

The botanist Sachs, in his _Physiology of Plants_ (1887), remarks: "A
far greater portion of the phenomena of life are [is] called forth by
external influences than one formerly ventured to assume."

Certain botanists are now strong in the belief that the species of
plants have originated through the direct influence of the environment.
Of these the most outspoken is the Rev. Professor G. Henslow. His view
is that self-adaptation, by response to the definite action of changed
conditions of life, is the true origin of species. In 1894[253] he
insisted, "_in the strictest sense of the term_, that natural selection
is not wanted as an 'aid' or a 'means' in originating species." In a
later paper[254] he reasserts that all variations are definite, that
there are no indefinite variations, and that natural selection "can take
no part in the origination of varieties." He quotes with approval the
conclusion of Mr. Herbert Spencer in 1852, published

"seven years before Darwin and Dr. Wallace superadded natural
selection as an aid in the origin of species. He saw no necessity
for anything beyond the natural power of change with adaptation; and
I venture now to add my own testimony, based upon upwards of a
quarter of a century's observations and experiments, which have
convinced me that Mr. Spencer was right and Darwin was wrong. His
words are as follows: 'The supporters of the development hypothesis
can show ... that any existing species, animal or vegetable, when
placed under conditions different from its previous ones,
immediately begins to undergo certain changes of structure fitting
it for the new conditions; ... that in the successive generations
these changes continue until ultimately the new conditions become
the natural ones.... They can show that throughout all organic
nature there is at work a modifying influence of the kind they
assign as th