May 1911.] BOTANICAL SOCIETY OF EDINBURGH 179 
I first observed this Alga in its younger stages growing 
on the rootlets of Lemna minor and the leaves of some 
aquatic phanerogams, but it grew later on in great profusion 
together with Coleocheete scutata, Bréb., on the sides of the 
glass vessel in which I preserved various species of Algze 
collected from the Elf Loch. Although kept in cultivation 
for over two months during August and September 1910, 
I could only observe the vegetative stage of this plant. 
After an absence of several weeks I found Phzeothamnion 
had entirely disappeared from the culture, and to my 
great regret I was unable to contribute anything to our 
knowledge of the life-history of this alge. 
A Palmella-stage such as is reported both by Lagerheim 
and Borzi I was unable to obtain even by varying the 
conditions under which the plant grew in “ hanging-drop ” 
cultures. Empty cells showing the characteristic circular 
opening by which the zoospores had escaped I found several 
times, and also in one instance a few zoospores, but owing 
to lack of time I was unable to fix and stain these in order 
to investigate the number and position of the cilia. 
tegarding the remarkable colour of the chromatophore, I 
can confirm Lagerheim’s and other investigators’ statements 
as to the action of a weak alcoholic solution, which dissolves 
the brown colouring matter and leaves the green chloro- 
phyll, and exactly the same effect can be obtained with 
the brown chromatophores of the Diatomacee. 
The systematic position of Phzeothaimnion and the other 
lower Phzeophyceze was thoroughly investigated by A. 
Scherffel in 1900 (8) and 1901 (9), and also by Oltmanns 
in 1904 (10). De Toni in his “Sylloge Algarum,” vol. ii1., 
published in 1895 (11), places Pheeothamnion, following 
Hansgirg, under the Phzeophycee or Fucoidexw. N. Wille, 
in Engler and Pranti’s “ Natiirliche Pflanzenfamilien ” (12), 
however, regards this Alga, as was suggested by its dis- 
coverer Lagerheim, as a genus of the family Chzetophoracee, 
and therefore one of the Chlorophycez or Green Alge. 
In Oltmann’s great work on the Algz (10), Pheeothamnion 
and all the Unicellular Brown Algz are considered apart 
from the class Phaophycez, and as being nearer related 
to the Flagellate than to the true Algz. Pheothamnion 
is regarded by him as one of the Chrysomonadineex, and 
