lackwell's Island).]

All the time, by the condensation, the diameter of the earth was being
diminished. The irregular cooling of the crust caused irregular
contractions on the surface, and as the diameter of the molten mass
within was continually diminishing, many elevations and depressions were
caused, which were the foundations of mountains and valleys.

After the temperature of the earth had been reduced by the thickening of
the crust--when it became sufficiently cool--the water which existed in
steam was condensed and precipitated, falling in torrents, washing down
the elevations, filling the depressions with the mud carried along, and
depositing it in layers. It was not until the earth became covered with
water that life was possible in any form, as both animals and plants
consist to a very great extent of water. At this stage in the history of
the earth, then, the little mass of protoplasm, which we have spoken so
much about, came into existence in all probability, as has been stated,
by spontaneous generation.

LAWS OF EVOLUTION.

Let us now examine some of the laws of evolution, as also some of the
connecting links which blend one stage of man's development with
another, which at first thought would seem unexplainable.

Haeckel[31] summarizes the inductive evidences of Darwinism as follows:
1. Paleontological series (phylogeny); 2. Embryological development of
the individual (ontogeny); 3. The correspondence in the terms of these
two series; 4. Comparative anatomy (typical forms and structures); 5.
Correspondence between comparative anatomy and ontogeny; 6. Rudimentary
organs (dipeliology); 7. The natural system of organisms (classification);
8. Geographical distribution (chorology); 9. Adaptation to the environment
(oecology); 10. The unity of biological phenomena.

It will of course be impossible to consider even hastily all of the
inductive evidence belonging to the several groups mentioned above, for
the scope of this work would not permit of it. Only such facts as
present themselves most forcibly to the mind will be considered.

Darwinism, as has already been stated, is not the doctrine of evolution;
it is, however, a successful attempt to explain the law or manner of
evolution. The _law of natural selection_, pointed out by Darwin, is
called by Herbert Spencer, _The struggle for existence_. Darwin
discovered that natural selection produces fitness between organisms and
their circumstances, whic