54 Davis . — The Fertilization of Batrachospermum . 
protoplasm directly around the nucleus usually stains light 
blue, and the remaining cytoplasm is coloured more or less 
deeply, depending upon certain structures which will be con- 
sidered later. The cytoplasm in the carpogonium is often 
very dense, and is apt to stain deeply, but the very darkly- 
stained nucleus is usually prominent by virtue of its central 
position. 
The very earliest beginnings of trichogynes cannot be 
readily distinguished from the tips of ordinary vegetative 
branches ; but a point is soon reached in their development 
when the form clearly designates the character of the struc- 
ture. The terminal cell of a branch begins to extend first as 
a little process, which gradually swells and finally assumes the 
size and shape of the adult trichogyne. The cell from which 
the trichogyne springs is of course the carpogonium. It 
contains a somewhat irregularly lobed chromatophore that 
lies in the layer of protoplasm next the cell-wall. The 
chromatophore fills up a large part of the cell, and is very apt 
to be massed at the end from which the trichogyne arises. 
When the young trichogyne begins to extend from the carpo- 
gonium cell, some of .the chromatophore of the latter is 
apparently drawn up into it. At all events, one finds in the 
basal portion of young trichogynes, and as a rule also of 
mature individuals, an irregularly-shaped body that is clearly 
an extension of the chromatophore of the carpogonium. 
A glance at Fig. 2, a young trichogyne drawn from living 
material, will make clearer what has just been described. 
The shaded portion of the carpogonium (lettered c ) is the 
chromatophore, coloured a light green in this species, and all 
the rest of the cell is quite hyaline but for a few granules 
scattered here and there, and perhaps one or more vacuoles. 
It will be seen that the chromatophore of the carpogonium 
runs up into the trichogyne in the form of an irregular exten- 
sion. The colour of this extension in the base of the 
trichogyne is often identical with that of the portion in the 
carpogonium, but in the upper part of the trichogyne the tint 
is usually very much lighter. The shapes assumed are very 
