How to Solve One of the Problems of Science [pp. 787-793]

THE HIGHEST PROBLEMS OF SCIENCE.
more ancient periods to those of recent times and of our own
day."* Evolution gives the only plausible solution of these
facts of embryology, and when confronted with them the believers in special creations have nothing to say. Nevertheless,
despite their silence, they may rightly challenge us to give an
unmistakable proof of our theory, although they cannot give us
a proof of theirs. Now, in order to convince them that evolution is true, we must begin by experiments, and we must not
stop short of transforming one animal or plant into an entirely
new plant or animal hitherto unknown.
To do this we must establish among us a school of original
research, and let it-work on the lines laid down by Professor
Henry de Varigny in his lectures delivered before the summerschool of art and science in Edinburgh, two years ago.t In
these lectures he earnestly encourages believers in evolution to
put it to the test of experiment: and why should we not begin
to make experiments here in America? The field to be investigated is a wide one. What is the cause of variability? What
is the modifying influence of environment? Here we quote
from Darwin's Origin of Species, p. IO7: "When a variation is
of the slightest use to any being, we cannot tell how much to
attribute to the accumulative action of natural selection, and
how much to the definite action of the conditions of life. Thus,
it is well known to furriers that animals of the same species
have thicker and better fur the further north they live; but
who can tell how much of this difference may be due to the
warmest-clad individuals having been favored and preserved
during many generations, and how much to the action of the
severe climate? For it would appear that climate has some
direct action on the hair of our domestic quadrupeds." Heredity, hybridism, and sexuality also demand a thorough study, and
many things in nature which are now mysterious will be made
clear when more light is thrown on these subjects. Changes
which merely strike the eye may be more significant than we
imagine. We know, for instance, that change of environment
and change of food may change the color of an animal; but
variation of color is something more than a mere outward
change: there are underlying it modifications of a chemical
order, and these accompanying, underlying changes offer a most
tempting field for investigation. We do not know why food
and environment should influence animal coloration (Wal * Evolution and Christianity, Cosmopolitan magazine, June, x892.
t Since published in Nature Series under the title Experimental Evolution.
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