Davis . — The Fertilization of Batrachospermum. 57 
times near the base. It seems to the writer that the trichogyne 
must be considered as a true cell. There is a nucleus and 
a body certainly derived from a chromatophore, and which 
is probably functional, at least in the young trichogyne. 
These are the two most important structures in the vegetative 
cells of Batrachospermum , and having these, the only differences 
between the trichogynes and the former are those of shape, 
position, and mere arrangement and relative proportions of 
the cell-contents. The last-mentioned difference would seem 
to be the most important, for in the trichogyne the hyaline 
cytoplasm is proportionally very large, while the chromato- 
phore is represented in its lowest terms. The trichogyne is 
united to the carpogonium by a wide strand of protoplasm, 
but this is not a great distinction, for intercellular communi- 
cation is characteristic of all the cells of the frond. 
Bearing in mind the nuclear and cytological conditions 
of the procarps, we are now ready to consider the phenomenon 
of fertilization. The conditions are, a nucleus in the tricho- 
gyne, a nucleus in the carpogonium, and the connexion of 
the two cells by a broad strand of protoplasm. When the 
antherozoid is applied against the trichogyne, the surfaces 
of the two cell-walls flatten somewhat and finally become 
completely united. The masses of protoplasm in the two 
structures are still separated by a cell-wall of appreciable 
thickness. The antherozoid then puts forth as a rule a very 
evident, although small, papilla, that apparently absorbs the 
cell-wall as it works its way down towards the protoplasm 
of the trichogyne. Finally, cytoplasmic fusion of the two 
cells is accomplished ; but the point of union is at first very 
small, so small that it is impossible to determine exactly 
when the act takes place. The point of fusion then gradually 
broadens, until in some cases the opening becomes two-thirds 
the width of the antherozoid : the process goes on rather 
slowly, and, as will be shown later, the size of the opening 
is very variable. These points are more readily determined 
from fixed and stained specimens than from living material, 
because of the hyaline character of the protoplasm of the 
