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THE MARINE ALGÆ OF NEW ENGLAND.
organ, the antherozoid, borne in an antheridium, and a female, called in this order
the oogonuim. [sic] The order is divided into two suborders, in which, although the
general plan of reproduction is the same, the details vary.
VAUCHERIEÆ.—This suborder includes a number of species of green algæ which form
dense turfs upon the mud in brackish ditches and rivers‚ or else loosely floating
masses of green filaments. They may generally be recognized at sight by their deepgreen
shining color and velvety appearance. They consist entirely of long green
threads, which occasionally branch, but which are destitute of any cross-partitions
except at the time of reproduction. The non-sexual reproduction is by means of
zoospores. A cross-partition is formed near the end of a filament, and in the cell thus
cut off from the rest of the plant a single very large zoospore is formed. In some
species the zoospore escapes through an opening in the apex of the cell, and when
free its whole surface is seen to be covered by a large number of vibratile cilia. In
other species the cell containing the zoospore breaks off from the rest of the plant
and the zoospore remains in a more or less passive condition. The antheridia grow
from the sides of the filaments, and are either in the form of oblong, at times nearly
sessile, cells, or else a lateral shoot is formed which ends in one or more convolute
processes, at the tips of which a cell is cut off from the rest. The antherozoids are
very small bodies with two cilia. The oogonia, or female organs, are generally
situated near the antheridia, and are irregularly ovoid, with a blunt tip. The cell
contents collect in a roundish mass at the center, called the oosphere, while at the tip
of the oogonium is a mass of slimy substance. At the time of fertilization the
antheridium opens and discharges the antherozoids and the tip of the oogonium
opens to admit the antherozoids, which remain for a short time in the interior of the
oogonium and then withdraw. The oogonium is then closed and, the oosphere, which
before fertilization was merely a mass of protoplasm, has now formed around it a
wall of cellulose, and ripens, forming an oospore. The oospore finally escapes from
the oogonium and germinates.
FUCACEÆ.—This suborder includes the rock-weeds, Fuci and Sargassum, of our
coast, which constitute the bulk of the olive-brown sea-weeds found between tidemarks.
The admirable paper of Thuret on the fertilization of Fucus leaves nothing to
be desired on that subject, and his observations are now so widely known in this
country that little need be said in this connection. In the two common rock-weeds of
our coast, Fucus vesiculosus and F. nodosus, the two sexes are on distinct
individuals. In F. evanescens and F. furcatus they are on the same individual. The
Fuci fruit principally in winter and spring, but F. vesiculosus may be found in fruit
throughout the year. In the last-named species, if we examine the swollen tips of the
frond, we find certain granular bodies, which on section are seen to be sacks opening
outwards. The sacks are called conceptacles. The male plant can generally be
distinguished from the