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110
THE MARINE ALGÆ OF NEW ENGLAND.
Suborder PORPHYREÆ.
Fronds brownish purple, composed of cells imbedded in a gelatinous net-work,
arranged in filaments or in membranes formed of a single layer of cells; spores
formed by the division of a mother-cell into eight cells, arranged by fours in two
layers; antherozoids spherical, colorless, destitute of proper motion, formed by
division of a mother-cell into 32-64 parts.
The present suborder comprises the genera Porphyra and Bangia, and perhaps also Erythrotrichia and
Gonotrichum. In Porphyra the frond consists of a single layer of cells, of which those near the base send
down wards root-like appendages, by means of which the fronds are attached to the substratum. The
spores are formed at the marginal portion of the frond by the division of the vegetative cells, at first
into two cells by a vertical partition, and the subsequent division of the two cells into four by cruciate
partitions. Thus, when mature and seen from above, the eight spores seem to be arranged in two
superimposed series of four. The spores escape by the dissolution of the outer part of the frond, leaving
behind the empty gelatinous net-work. When free they are found to consist of protoplasm without a
cellulose wall, and they move about for a short time with an amoeboid motion. The antherozoids are
also formed by the division of the vegetative cells, but the division is carried farther than in the
production of the spores, for, in addition to the vertical and cruciate partitions described in the latter
case, a second vertical and cruciate division takes place, so that the original vegetative cell is divided
into 32-64 cells. Janczewski applies the name antheridium to the collective mass of antherozoids
formed from a single vegetative cell. As the division takes place the antherozoids lose their color. When
mature they are spherical and escape in a manner similar to that of the spores. Bornet and Janczewski
state that the antherozoids are destitute of any proper motion, and we can confirm
fronds are distorted by parasites, which produce deformities like those described by Reinsch as due to species of
Choreocolax. Such distortions are perhaps most frequently found on Cystoclonium purpurascens. In our present
ignorance of the fructification, specific identification is out of the question, and, in this connection, it is only
necessary to quote the generic descriptions of Reinsch, l. c., with an enumeration of the species attributed to our
coast:
CHOREOCOLAX. True vegetable parasites; fronds consisting of two portions, one of which extends through the
tissue of the infected plant, the other of which swells above the surface of the infected plant, forming a convex mass,
which is hemispherical or spherical, semi-ellipsoidal or irregular in outline; the cells which are contained in the
infected plant either more slender than the others or of the same shape, cells of external portion equal or unequal,
arranged without order in densely intricate subramose threads, terminal cells sometimes longer and more slender;
fructification?; polysporangia? C. RABENHORSTI. On Delesseria sinuosa, Anticosti; Gloucester, Mass.
C. POLYSIPHONIÆ. On P. fastigiata, Atlantic shore of North America.
C. MIRABILIS. On Rhodomela subfusca, Atlantic shore of North America.
C. AMERICANUS. On Lophura Royana, &c., Atlantic shore of North America.
C. TUMIDUS. On Ceramium involutum, West Gloucester, Mass.
PSEUDOBLASTE. False vegetable parasites; frond convex, more or less regular in outline, formed of similarly
shaped cells, generally arranged in longitudinal series, arising from a densely appressed base (the cells without any
organic connection with the cells of the infected, plant); propagation?
P. IRREGULARIS, On Lophura Royana, Atlantic coast of North America.