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REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 19
female by the brighter color of the tips which bear the conceptacles. A section
through the conceptacles of the male plant, as in Pl. IX, Fig. 2, shows a number of
branching filaments which line the interior of the conceptacle. Attached to the
filaments are oval bodies, the antheridia. The antheridia contain the antherozoids,
which are ovate and provided with two cilia attached at the side. Usually about daybreak
the antheridia discharge their antherozoids, which then swim about in the
water until they reach the female plant. A section through the tip of a female plant
shows a number of conceptacles similar in shape to those of the male plant. On the
walls of the conceptacle there are paraphyses, and scattered among them are the
oogonia, as shown in Pl. IX, Fig. 1. The oogonia are oval and seated on broad short
pedicels. In Fucus vesiculosus the contents of the oogonia divide into eight
oospheres, which are at first angular, but afterwards become spherical. The oogonia
become free from their attachments, and the wall, which is really double, ruptures,
and the oospheres escape into the water. In this condition they are merely spheres of
protoplasm. The antheridia then collect around the oospheres in large numbers, and
the mass begins to rotate. The rotation continues for a short time, and when it
ceases the antherozoids withdraw and soon perish. It is not yet certain whether one
or more of the antherozoids really penetrates into the substance of the oosphere
during the revolutions. As soon as it comes to rest the oosphere takes on a cell-wall
of cellulose and becomes an oospore, which after an interval of rest begins to divide
so as to form eventually a new frond.
DICTYOTEÆ.—Although no members of this order are known on our coast north of
North Carolina, the order cannot pass unnoticed in the present article, because it
forms a connecting link between the Fucaceæ and Phæosporeæ on one hand and the
Florideæ on the other. The species are olive-brown and form expanded membranous
fronds. Three kinds of reproductive organs are known, antheridia, spores, and
tetraspores. All are formed by outgrowths from the superficial cells. The tetraspores
are formed, as the name implies, in fours in a mother cell, from which they escape
and then readily germinate. The spores are borne singly in a mother cell. The
antheridia are composed of a number of oblong cells, which become divided by
numerous longitudinal and transverse divisions into small cells, each of which
contains an antherozoid. The Dictyotaceæ resemble the Florideæ in having
tetraspores and spores which germinate without first passing through a zoosporic
condition. The action of the antherozoids is at present unknown, and the spores of
this order cannot be the product of a fertilization such as we find in the Florideæ.
FLORIDEÆ.—This order is the same as the Rhodospermeæ of Harvey’s Nereis. The
species composing it form a very natural group, and are, with the exception of a few
genera, entirely marine. Their color is always some shade of red or purple when they
are growing in their