30 FOOT-NOTES TO EVOLUTION. 
itself would be without meaning or explanation. The 
essential argument in favour of “ Darwinism ” is that it 
brings all biological facts into unison from whatever 
field of investigation these facts may be derived. How- 
ever much evolutionists have at times 
seemed to drift away from Darwin’s con- 
clusions, it is always the most accurate 
research and the sanest thought which come nearest the 
opinions set forth in the Origin of Species. The body 
of facts has grown enormously year by year, but the 
conclusions we must accept are substantially those laid 
down by Darwin himself. 
The facts of “ geographical distribution,” for exam- 
ple, have a meaning to us when we view them as the 
results of centuries of the restlessness 
of individuals. Each species of animal 
or plant has been subjected to the vari- 
ous influences implied in the term “natural selection,” 
and under varying conditions its representatives have 
undergone many different modifications. Each species 
may be conceived as making each year inroads on terri- 
tory occupied by other species. If these colonies are 
able to hold their own in the struggle for possession 
they will multiply in the new conditions and the range 
of the species becomes widened. If the surroundings 
are different, new species or varieties may be formed 
with time, and these new forms may again invade the 
territory of the parent species. Again, colony after 
colony of species after species may be destroyed by 
other species or by uncongenial surroundings. 
Only in the most general way can the history of any 
species be traced; but, could we know it all, it would 
be as long and eventful a story as the history of the 
colonization and settlement of North America by immi- 
grants from Europe. Each region where animals or 
Every fact has 
a meaning. 
Geographical 
distribution. 
