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, e.g. 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 

 Algse ; 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. 



