--are Americans.





VII

LIFE IN THE UNIVERSE


So far as we can judge from what we see on our globe, the
production of life is one of the greatest and most incessant
purposes of nature. Life is absent only in regions of perpetual
frost, where it never has an opportunity to begin; in places where
the temperature is near the boiling-point, which is found to be
destructive to it; and beneath the earth's surface, where none of
the changes essential to it can come about. Within the limits
imposed by these prohibitory conditions--that is to say, within
the range of temperature at which water retains its liquid state,
and in regions where the sun's rays can penetrate and where wind
can blow and water exist in a liquid form--life is the universal
rule. How prodigal nature seems to be in its production is too
trite a fact to be dwelt upon. We have all read of the millions of
germs which are destroyed for every one that comes to maturity.
Even the higher forms of life are found almost everywhere. Only
small islands have ever been discovered which were uninhabited,
and animals of a higher grade are as widely diffused as man.

If it would be going too far to claim that all conditions may have