It is remarkable, I think, that Professor Osborn, in his "Origin and
Evolution of Life," makes no account of the micro-organisms or
unicellular lives that are older than the continents, older than the
Cambrian rocks, and that have survived unchanged even to our times. I
saw in the Grand Cañon of the Colorado where they were laid down
horizontally on the old Azoic or original rocks, as if by the hand of a
mason building the foundation of a superstructure. All the vast series
of limestone rocks are made up from the skeletons of minute living
bodies. Other strata of rocks are made up of the skeletons of diatoms.
Some of our polishing powders are made from these rocks. Formed of pure
silex, these rocks are made up of the skeletons of organisms of many
exquisite forms, _Foraminiferæ_. The Pyramids are said to be built of
rocks formed by these organisms. "No single group of the animal
kingdom," says Mr. W. B. Carpenter, "has contributed, or is at present
contributing, so largely as has the _Foraminiferæ_ to the formation of
the earth's crust." In the face of these facts, how unsatisfactory seem
Professor Osborn's statements that life probably originated on the
continents, either in the moist crevices of rocks or soils, in the fresh
waters of continental pools, or in the slightly saline waters of the
"bordering primordial seas." This last suggestion comes nearer the mark.
There is no variation during geologic time of these primordial living
organisms. All conceivable changes of environment have passed over them,
but they change not. Bacteria struggle together, one form devouring
another form. Unicellular life long precedes multicellular. Biologists
usually begin with the latter; the former are fixed; with the latter
begins development or evolution, and the peopling of the world with
myriads of animal forms.