author's abstract of this paper issued 

 by the bibliographic service, mat 23 



CONCERNING THE VITALITY OF ACTINIA BERMU- 

 DENSIS: A STUDY IN SYMBIOSIS^ 



JOHN F. FULTON, JR. 



Bermuda Biological Statio7i for Research 



While investigating the pigmentation of several species of 

 actinians common in the Bermuda Islands, the writer observed 

 that Actinia bermudensis Verrill possessed great resistance to 

 unfavorable environmental conditions. It had been noted previ- 

 ously that the gastrovascular fluid of this actinian teemed with 

 Zooxanthellae — holophytic flagellates of the suborder Crypto- 

 monadina — and consequently the question arose as to whether 

 or not these organisms increased in any way the vitality of the 

 anemone. The results of the investigation are recorded in the 

 present paper. 



The work was carried on during the summer of 1920 at the 

 Bermuda Biological Station for Research, and the writer wishes 

 to express his warmest thanks to Dr. E. L. Mark, to whom he 

 is indebted both for the facilities of the laboratory and for re- 

 vision of the manuscript. 



Actinia bermudensis is a deep-red anemone, 20 to 30 mm. in 

 diameter and of slightly greater length, which is found hanging 

 on shaded areas of rock between the levels of high and low tide, 

 and consequently is out of the water at least half of the time. 

 The specimens used in the present study were collected at low 

 tide, when they are found with contracted tentacles hanging limp 

 from crevices in the rock. They were usually obtained by chip- 

 ping off pieces of the sandstone to which they were attached. 



The presence of Zooxanthellae in A. bermudensis may very easily 

 be demonstrated by withdrawing a small quantity of the gas- 

 trovascular fluid with an injecting needle and examining it on 



^ Contributions from the Bermuda Biological Station for Research, no. 127. 



353 



