trate their nature, just as, in the matter of languages, German is
not the parent, but the cousin of Anglo-Saxon, or Greek of Latin. The
original parental languages are lost. But a language like Sanscrit
survives to give us a good idea of the type.

The law of evolution is based on such a mass of evidence that we may
justly draw deductions from it, where the direct evidence is incomplete.
This is especially necessary in the early part of our ancestral tree,
because the fossil record quite fails us. For millions of years the
early soft-bodied animals left no trace in the primitive mud, which time
has hardened into rocks, and we are restricted to the evidence of
embryology and of comparative zoology. This suffices to give us a
general idea of the line of development.

In nature to-day, one of the lowest animal forms is a tiny speck of
living plasm called the _amoeba_. We have still more elementary forms,
such as the minute particles which make up the bluish film on damp
rocks, but they are of a vegetal character, or below it. They give us
some idea of the very earliest forms of life; minute living particles,
with no organs, down to the ten-thousandth part of an inch in diameter.
The amoeba represents the lowest animal, and, as we saw, the ovum in
many cases resembles an amoeba. We therefore take some such one-celled
creature as our first animal ancestor. Taking food in at all parts of
its surface, having no permanent organs of locomotion, and reproducing
by merely splitting into two, it exhibits the lowest level of animal
life.

The next step in development would be the clustering together of these
primitive microbes as they divided. This is actually the stage that
comes next in the development of the germ, and it is the next stage
upward in the existing animal world. We assume that these clusters of
microbes--or cells, as we will now call them--bent inward, as we saw the
embryo do, and became two-layered, cup-shaped organisms, with a hollow
interior (primitive stomach) and an aperture (primitive mouth). The
inner cells now do the work of digestion alone; the outer cells effect
locomotion, by means of lashes like oars, and are sensitive. This is, in
the main, the structure of the next great group of animals, the hydra,
coral, meduca, and anemone. They have remained at this level, though
they have developed, special organs for stinging their prey and bringing
the food into their mouths.

Both zoology and the appearance