contents of autheridial cells of different forms.

8 _Oscillatoriaceae_.--Plants growing either in the sea, fresh water, or
on damp ground, of a gelatinous substance and filamentous structure.
Filaments very slender, tubular, continuous, filled with colored,
granular, transversely striated substance; seldom blanched, though often
cohering together so as to appear branched; usually massed together
in broad floating or sessile strata, of a very gelatinous nature;
occasionally erect and tufted, and still more rarely collected into
radiating series bound together by firm gelatine and then forming
globose lobed or flat crustaceous fronds. Fructification: the internal
mass or contents separating into roundish or lenticular gonidia.

9. _Nostochacae_.--Gelatinous plants growing in fresh water, or in damp
situations among mosses, etc.; of soft or almost leathery substance,
consisting of variously curled or twisted necklace-shaped filaments,
colorless or green, composed of simple, or in some stages double rows
of cells, contained in a gelatinous matrix of definite form, or heaped
together without order in a gelatinous mass. Some of the cells enlarged,
and then forming either vesicular empty cells or densely filled
sporangial cells. Reproduction: by the breaking up of the filaments, and
by resting spores formed singly in the sporanges.

10. _Ulvaceae_.--Marine or aquatic algae consisting of membranous, flat,
and expanded tubular or saccate fronds composed of polygonal cells
firmly joined together by their sides.

Reproduced by zoospores formed from the cell contents and breaking
out from the surface, or by motionless spores formed from the whole
contents.