550 Williams \ — The Anther ozoids of 
On one occasion I was examining antheridial plants about 
3 p.m. The liberation of antherozoids was so great that the 
slide was covered with them, but there was no sign of activity 
to be seen anywhere among them. The microscope was 
taken to a window on which the sun was shining and some 
of the rays were caused to pass through the slide. In a very 
short time the antherozoids were swarming like bees on 
a hot summer’s day. On examining other parts of the slide 
it was seen that motility was strictly confined to the portion 
directly exposed to sunlight. There the swarming continued 
for a time, but stopped entirely at the end of ten minutes from 
its commencement. This observation shows that these bodies 
are highly sensitive to light and that they can only exhibit 
active movement under the influence of this stimulus. 
Want of opportunity prevented my making direct obser- 
vation on their phototactic characters, but the following may 
be of some interest in this connexion. One evening I was 
examining a half-empty sorus. The light used was that of 
a small oil-lamp. In the cavity of the sorus a few antherozoids 
were floating and showing a scarcely perceptible motion. 
I observed that all were slowly sinking in the cavity, at 
the same time changing their places relatively to each other. 
The light was turned off for a short time and then it was 
found that they had re-ascended. This experiment was several 
times repeated with the same result, showing that in this 
particular instance, where the light was not very strong 
and the antherozoids not vigorous, the phototaxis was 
positive. 
Several lots of antherozoids were fixed, the best results 
having been obtained with dilute Flemming’s solution. All 
were stained with Hoffmann’s blue, either in dilute glycerine 
or after drying on the slide according to the bacterial method. 
In the latter preparation the cilia are particularly well shown. 
Contrary to what obtains in all other Phaeophyceae hitherto 
described, instead of there being two cilia, each antherozoid 
has a single very long flagellum. When fully extended, as 
it is in the dried preparation, the flagellum often extends 
