548 Williams — - The A ntherozoids of 
arisen, as to the swarming organisms being the antherozoids 
of Dictyota , were set at rest by the direct observation of the 
contents of the antheridia starting into activity and swimming 
away. This could easily be seen by focussing the microscope 
on the surface of a sorus. 
The following is a summary of the principal points observed 
in connexion with the antherozoids. 
If mature antheridial sori are examined, the surface is seen 
to be white and glistening. Each antheridium is divided 
into a large number of small cells, the contents of each cell 
forming a single antherozoid. These at first seem to present 
no differentiation of structure, but a closer examination 
shows the presence of a small round globule in each of the 
cells, situate either at the centre or near the periphery. 
After fixing and staining the antheridia, this spherical body 
is not always evident. The greater part of the circumference 
of the antherozoid stains deeply, showing the presence of 
denser protoplasm irregularly disposed in roundish or elon- 
gated masses which occasionally cross the surface of the cell. 
The cause of this appearance will be discussed later on.. 
With regard to the spherical bodies above mentioned, it may 
be further added that in some cases a very faint tinge of 
yellow is observable in them. This suggests the possibility 
of their representing the ‘chromatic spot’ characteristic of 
the antherozoids of the Fucaceae. Though smaller and very 
much less obvious than the latter, they are quite easily 
recognizable in the antheridia of Dictyota , Taonia , and 
Halyseris. In motile antherozoids they very often seem 
to project beyond the periphery of the head, as also do the 
eye-spots in the antherozoids of Fucus . The study of fixed 
material, however, makes it rather doubtful that these granules 
represent ‘ eye-spots. 3 In the first place they are not invariably 
present, and even where they occur, their position has no 
definite relation to the points of insertion of the cilia. My 
opportunities for collecting during the past summer have not 
been many. It has also been difficult to secure all the con- 
ditions necessary for the exhibition of motility in the anthero- 
