UNDER THE APPLE-TREES 
less will be checked. The fuel in the earth will be 
exhausted in a thousand or more years, and its min- 
eral wealth, but man will find substitutes for these 
in the winds, the waves, the sun’s heat, and so forth. 
xX. AN UNKNOWN FACTOR 
How this unknown factor in life, or the vague 
consciousness of it, hovers in the background of 
the minds of even the most rigid scientists! It hov- 
ered in Darwin’s mind when he said he could not 
look upon man, with all his wonderful powers, as the 
result of mere chance, though his theories of the 
origin of species made man the result of fortuitous 
variations conserved and improved upon by natural 
selection. It hovered in Tyndall’s mind when his 
physicochemical theory of the origin of life left him 
on the brink of an abyss, and he contemplated 
“the mystery and miracle of vitality.” It hovered 
in Huxley’s mind when he resented the charge of 
materialism and gave consciousness a place with 
matter and energy as one of the three realities in 
the universe. It hovered in Haeckel’s mind when he 
admitted a psychic principle in the atom. Professor 
Osborn finds some unknown and unknowable factor 
in evolution from the fact that some parts or organs 
are adaptive, or purposeful, from the first, and were 
fitted to survive when they first appeared. 
THE END 
