conftuens and the Morphology of the Ascocarp. 341 
to. The point is not a vital one in settling the question of 
the existence of sexuality in the form, since differentiation 
of sex has been shown everywhere in plants and animals 
to occur at earlier or later stages in the life history of the 
individual as a result of the influence of factors which are as 
yet little understood. 
A section through these knots of hyphae shows that they 
are composed of multinucleated cells, with denser contents, 
but not otherwise different from ordinary vegetative mycelial 
cells. There is no one-nucleated stage in any of these cells. 
They are formed by growth and division of multinucleated 
hyphal cells in general as the cells of Cladophora are. The 
apical cells of these short branches soon show more rapid 
growth than those immediately below them, and become 
swollen. They are filled with spherical or oval vacuoles at 
this stage so that their contents have a foamy appearance as 
if growth had gone on so rapidly that sufficient protoplasm 
to fill the swelling cell could not be provided at once. At 
a very early stage it is possible to differentiate two types of 
these apical cells, one more spherical-—the young macrocyst 
of Tulasne, which is the oogonium—the other more oblong or 
club-shaped—Tulasne’s paracyst, which is the antheridium. 
Very soon a slight elevation or papilla appears on the apex 
of the oogonium, and this is the beginning of the young con¬ 
jugating tube or trichogyne (Fig. 3). Both antheridium and 
oogonium are multinucleated from the start, and the number 
of nuclei increases by division as the cells grow in size. The 
nuclear multiplication, however, is out of proportion to the 
vegetative growth, so that when the sexual cells are mature 
they contain relatively to their size many more nuclei than 
do the ordinary vegetative mycelial cells. A broad stalk-cell 
is usually cut off from the base of the oogonium relatively 
late in its development, after it has attained its full size or 
nearly that (Fig. 5). A number of stalk-cells can also as 
a rule be distinguished at the base of the antheridium (Figs. 
6 and 19). The papilla-like beginning of the conjugating 
tube on the oogonium rapidly elongates with the growth of 
