552 Lloyd Williams. — Studies in the Dictyotaceae . 
I gathered between Penlee and Rame Head a unique specimen. Though 
I have examined many thousands of plants in different parts of the coast, I 
have never come across one similar to this. It was apparently a male plant 
with the antheridia mature, but in the lower part the sori had very numerous 
oogonia as well. All the sori on the distal third of the plant were male. 
On the remainder of the plant the number of oogonia progressively 
increased towards the base, so that they were most numerous on the 
weakest part of the plant. Some of the sori had a few oogonia at one 
end or close to the periphery : in a few curious cases the borders of the 
male sori had been converted into oogonia. Some sori were wholly female 
and devoid of borders, and in cases where there were a few antheridia 
these were squeezed up in the centre between the swelling oogonia. Besides 
the general appearance of the plant, another circumstance pointed to its 
being a male which had developed female cells, and that was that in a 
great many cases the oogonia were derived from half-antheridia : that is to 
say, the antheridium rudiment divided once, or even twice, and then the 
two, three, or four resulting cells became oogonia. This, of course, resulted 
in very great inequality of size in the oospheres. While examining the 
specimen many of the eggs could be seen emerging from the oogonia. 
Three pieces of the plant were placed in as many culture-vessels, to see 
if the eggs would be fertilized ; and as a control experiment, pieces of 
ordinary male and female plants were placed in a fourth. The anthero- 
zoids were not attracted by the oospheres. Sometimes wandering sperms 
would approach an egg, stop an instant above its surface and then proceed 
on their way — a fact which is of some significance in view of recent 
attempts to prove that there is no attraction in external fertilization. 
When the cultures were examined a few days afterwards the eggs in the 
control-culture had become normal germlings in an advanced stage of 
segmentation, but in the three other cultures a few eggs had divided par- 
thenogenetically (a further proof that the bodies were eggs, and not gigantic 
sperms), while the rest remained undivided. At the time of writing the 
control-germlings are growing well, the other three sets died. An examina- 
tion of the older scars shows conclusively that the previous crops were 
similarly anomalous. 
Periodicity in Haliseris. 
During the two past summers strenuous attempts have been made to 
work out the history of sexual reproduction in the remaining British genera 
of the Dictyotaceae — as yet, however, with but indifferent success. Though 
abundance of Taonia and Padina have been obtained, not a single sexual 
plant of the former, and but very few of the latter, have been collected. Hali- 
seris is a more uncommon plant, but there is not the same disproportion 
between the numbers of the sexual and asexual individuals. At Plymouth 
