It is highly probable that for long ages the waters covered the earth,
and that all the primeval vegetation consisted of simple Flagellates in
the universal Open Sea. But contraction of the earth's crust brought
about elevations and depressions of the sea-floor, and in places the
solid substratum was brought near enough the surface to allow the
floating plants to begin to settle down without getting out of the
light. This is how Professor Church pictures the beginning of a fixed
vegetation--a very momentous step in evolution. It was perhaps among
this early vegetation that animals had their first successes. As the
floor of the sea in these shallow areas was raised higher and higher
there was a beginning of dry land. The sedentary plants already spoken
of were the ancestors of the shore seaweeds, and there is no doubt that
when we go down at the lowest tide and wade cautiously out among the
jungle of vegetation only exposed on such occasions we are getting a
glimpse of very ancient days. _This_ is the forest primeval.