ges of the earth, under exceptional conditions which we do not at
present know, or can only dimly conjecture; and some think that life
is being evolved from non-life in nature to-day, and always has been so
evolving. The majority of scientific men merely assume that the earliest
living things were no exception to the general process of evolution, but
think that we have too little positive knowledge to speculate profitably
on the manner of their origin.

The first view, that the germs of life may have come to this planet on a
meteoric visitor from some other world, as a storm-driven bird may take
its parasites to some distant island, is not without adherents to-day.
It was put forward long ago by Lord Kelvin and others; it has been
revived by the distinguished Swede, Professor Svante Arrhenius. The
scientific objection to it is that the more intense (ultra-violet) rays
of the sun would frill such germs as they pass through space. But a
broader objection, and one that may dispense us from dwelling on it, is
that we gain nothing by throwing our problems upon another planet. We
have no ground for supposing that the earth is less capable of evolving
life than other planets.

The second view is that, when the earth had passed through its white-hot
stage, great masses of very complex chemicals, produced by the great
heat, were found on its surface. There is one complex chemical substance
in particular, called cyanogen, which is either an important constituent
of living matter, or closely akin to it. Now we need intense heat to
produce this substance in the laboratory. May we not suppose that masses
of it were produced during the incandescence of the earth, and that,
when the waters descended, they passed through a series of changes which
culminated in living plasm? Such is the "cyanogen hypothesis" of
the origin of life, advocated by able physiologists such as Pfluger,
Verworn, and others. It has the merit of suggesting a reason why life
may not be evolving from non-life in nature to-day, although it may have
so evolved in the Archaean period.

Other students suggest other combinations of carbon-compounds and water
in the early days. Some suggest that electric action was probably far
more intense in those ages; others think that quantities of radium
may have been left at the surface. But the most important of these
speculations on the origin of life in early times, and one that has the
merit of not assuming any essentially d