Century Dictionary and Cyclopedia - A division of thallogenous
chlorophyllous cryptogams found for the most part in the sea
(seaweeds) or in fresh water. They are wholly cellular, though
varying exceedingly in form and size, from a single microscopic
or sometimes large and branching cell, a shapeless, jelly-like
mass, or mere string of articulations, to forms with trunk-like
stems and membranous laminæ many feet in length. Nourishment is
absorbed by the surface of the plant, never through roots. The
mode of propagation varies greatly in the different orders. In
many no well-defined sexual differences have been discovered,
and reproduction is carried on by means of cell-division or by
non-sexual spores (tetraspores, zoöspores). In the highest order
there are distinct male and female organs (antheridia and
oögonia). The term Algæ as used by Linnæus and early botanists
included not only seaweeds, but also the Hepaticæ, Lichenes, and
Characeæ. By Harvey the Algæ were divided into three groups,
distinguished chief