IV THE COLOURS AND PIGMENTS OF CCELENTERA 89 
the coral polypes to physiologically replace the miss¬ 
ing plants. The suggestion has the more force in 
view of the fact that many anemones have in their 
inner layer the so-called “ yellow cells,” which many 
regard as symbiotic Algae. Further, Prof. Geddes 
some years ago succeeded in showing that some 
green anemones, eg. Anthea cereus , possess in sun¬ 
light the power of evolving free oxygen. Kruken- 
berg was unable to confirm Geddes’s results as to 
the evolution of oxygen, but subjected the pigments 
of Anthea to a careful examination. He chose 
specimens of Anthea which were bright green with 
purple tips to the tentacles ; and though he found 
that an alcoholic extract contained a mixture of 
pigments, he could not succeed in persuading himself 
that it contained chlorophyll. He speaks with con¬ 
siderable reserve on the question of the affinities of 
the pigments, and carefully guards himself against 
an absolute denial of the existence of symbiotic 
Algae; his point simply being that there is consider¬ 
able evidence against the hypothesis that Anthea 
contains chlorophyll. Observations on other pig¬ 
ments which have been made since Krukenberg’s 
work, seem to justify us in speaking a little more 
decidedly on the subject of this pigment. 
Krukenberg’s observations may be summarised as 
follows : he obtained a pigment which dissolved in 
alcohol to form a solution which varied in colour 
from brown to green, showed distinct red fluorescence, 
and gave a banded spectrum ; the addition of acid 
turned the green solution blue, and added a new 
band at the junction of the yellow and the green, as 
well as altering the position of the other bands. 
