ange the vegetable products into bone and muscle and nerve and brain,
and finally into thought and consciousness; run by the solar energy and
dependent upon it, yet involving something which the sunlight cannot
give us; in short, an activity in matter, or in a limited part of
matter, as real as the physico-chemical activity, but, unlike it,
defying all analysis and explanation and all our attempts at synthesis.
It is this character of life, I say, that so easily leads us to look
upon it as something _ab extra_, or super-added to matter, and not an
evolution from it. It has led Sir Oliver Lodge to conceive of life as a
distinct entity, existing independent of matter, and it is this
conception that gives the key to Henri Bergson's wonderful book,
"Creative Evolution."

There is possibly or probably a fourth change in matter, physical in its
nature, but much more subtle and mysterious than any of the physical
changes which our senses reveal to us. I refer to radioactive change, or
to the atomic transformation of one element into another, such as the
change of radium into helium, and the change of helium into lead--a
subject that takes us to the borderland between physics and chemistry
where is still debatable ground.

I began by saying that there were three kinds of changes in matter--the
physical, the chemical, and the vital. But if we follow up this idea and
declare that there are three kinds of force also, claiming this
distinction for the third term of our proposition, we shall be running
counter to the main current of recent biological science. "The idea that
a peculiar 'vital force' acts in the chemistry of life," says Professor
Soddy, "is extinct."

"Only chemical and physical agents influence the vital processes," says
Professor Czapek, of the University of Prague, "and we need no longer
take refuge in mysterious 'vital forces' when we want to explain these."

Tyndall was obliged to think of a force that guided the molecules of
matter into the special forms of a tree. This force was in the ultimate
particles of matter. But when he came to the brain and to consciousness,
he said a new product appeared that defies mechanical treatment.

The attempt of the biological science of our time to wipe out all
distinctions between the living and the non-living, solely because
scientific analysis reveals no difference, is a curious and interesting
phenomenon.

Professor Schaefer, in his presidential address before the Br