164 BOTANICAL GAZETTE [MARCH 
Sargassum the oocyst has no stalk cell. It is an embedded organ, 
being almost surrounded by wall cells of the conceptacle. As both the 
size and contents of a conceptacle are dependent upon the activity of 
wall cells (as described later), this conceptacle in Sargassum is smaller 
and has fewer sexual organs and paraphyses than the corresponding 
conceptacle in Fucus. The unisexual tendency in the conceptacle of 
Sargassum may be due in part to the unproductiveness of the many 
wall cells which abut upon the embedded oocyst. 
The anatomy of the thallus of Sargassum has been studied in four 
species. In 1876, REINKE reported its development in Sargassum 
Boryanum from a three-sided apical cell situated at the bottom of a 
pit in the apex of the stem. He stated that the holdfast is composed 
of rhizoids and that a few intercellular filaments occur in the old parts 
of the thallus. OxtManns (’89) in an anatomical investigation of 
Sargassum linifolium and S. varians, likewise described a three-sided 
apical cell, and in addition gave an account of the origin both of the 
apical cell of a leaf and of a branch. He believes that the branching 
in Sargassum holds no relation to dichotomy. He figures an enlarged 
epidermal cell near the apical cell of the stem, and states that it 
becomes a three-sided apical cell. This young cell develops an out- 
growth in which a second apical cell is soon differentiated, between 
the first and the stem. The first formed apical cell develops a leaf 
and the last a branch. OLTMANNs agrees with Kuntze (’81) that 
there are all gradations between leaves and floats, and that floats are 
modified portions of leaves. 
In 1892, HANSTEEN published the results of an anatomical and 
physiological investigation of Sargassum bacciferum. He also reported 
a three-sided apical cell, but did not trace its origin in any structure. 
He described three kinds of tissues, naming them the assimilating 
system, the storage system, and the conducting system. The assimi- 
lating system, according to HANSTEEN, includes only the outer layer 
of cells, or epidermis. Its cells are twice as long as broad, have undu- 
lating walls, like the epidermal cells in higher plants, and contain 
“‘phaeoplasts.” The cells of this system add to their own number by 
radial, and to the cells below by tangential, divisions. The storage 
system occupies a zone several cells wide between the assimilating 
system and the innermost tissue which constitutes the conducting 
