CDOGONIACEA. 149 
breaking away of the wall of the mother cell. In this manner the new 
cell soon attains a length equal to the one from whence it sprung (the 
successive stages shown on Plate LVII, figs.1 to 4). When the young 
cell has matured it becomes in turna mother cell, the splitting round is 
repeated, a second streak or cap is carried upwards, and thus as many as 
four, five, or six successive cells are formed, as indicated by the four, 
five, or six strize or caps which may be counted at the apex of acell. The 
number of caps corresponding to the number of cells produced in this 
manner“consecutively immediately beneath the caps. 
Asexual reproduction takes place by the formation of a single zoospore 
in one of the cells of the filament (Plate LVI, fig. 15). It is of a globose 
or somewhat ovate form, furnished near its apex with vibratile cilia (fig. 
14). When mature it escapes by rupture or fissure of the mother cell, 
moves about for awhile, then becomes attached by the ciliated end, and 
ultimately developes into a young plant. 
Sexual reproduction is varied in three ways. In the moncecious species 
the oogonium is an inflated cell, more or less globose, enclosing a single 
oospore of similar form. The oogonium is either perforated by a pore, 
or splits round and opens with a lid or operculum. The same thread 
bears above or below the oogonium very much shortened cells, in which 
one or two active spermatozoids are produced. These escape when 
mature, and fecundate the oospore through the perforation or opening of 
the oogonium, after which they disappear, and the oospore ripens into a 
perfect, fertile, resting spore. 
In the dioecious species there are two modes of sexual reproduction. 
In one group of species the males are dwarf, almost might be called 
antheridia. The oogonia and oospores are the same as in the moneecious 
species. In like manner there are also abbreviated cells in some other 
part of the same thread, but these do not produce spermatozoids, buat 
androspores, small active ciliated bodies, which move about for a time, 
and then attach themselves either upon or near the oogonia, grow into 
the form of an inverted flask (figs. 8 to 10), being supported by a more or 
less elongated stem, and constitute the dwarf male (nannandrous) plants, 
the cells at the apex of which contain the spermatozoids, the upper cell 
opening by a lid, or cap, to permit of the escape of its contents, which 
fertilize the oospore as in the previous method. 
The second group of dicecious species have male filaments, which in 
all respects resemble the sterile females, except that they are usually a 
little thinner. The female filaments produce only the oogonia. 
The male filaments, in certain abbreviated cells, give origin 
to the spermatozoids, which in due time escape and fertilize the 
oospores of the female plants. Thus, in the first group, the dwarf males 
are generated in certain privileged cells of the female plants, whilst in 
the second group the male and female filaments are from the first dis- 
tinct. The former are called nannandrous species, the latter macran- 
drous. 
The fertilized oospore becomes a resting spore, which ultimately 
passes through the following stages :—Previous to germination the spore 
has an egg-shaped figure; the cell contents are densely crowded, and 
composed of minute brownish-green granules, closely surrounded by a 
distinct cell-membrane. Outside this membrane there is found besides 
quite a distinct cell-membrane. Upon germination there are formed in 
both membranes slit-like openings, whereupon the cell contents emerge, 
surrounded by an extremely delicate hyaline covering. The cell contents 
are composed not of one, but usually of four green masses, each sur- 
rounded by its cell-membrane. Sometimes also as it appears, abnor- 
mally, the masses are two or three innumber. The four cells which 
proceed from germination possess an oval form, and their cell-membrane 
is hyaline. After the contents of the spore have emerged there remaing 
