VITALITY OF ACTINIA BERMUDENSIS 357 



Experiment 3 — CO 2. Accordingly specimens were put in 100 

 cc. of carbon dioxide contained in an inverted large-mouth bottle, 

 which was placed in a small finger-bowl with sufficient sea-water 

 to seal the edges. An atmosphere of carbon dioxide not only 

 deprives the animal of oxygen, but is at the same time toxic to 

 the organism. Moreover, if the anemone should prove better 

 able to live in such an atmosphere when exposed to sunlight than 

 when put in the dark room it would establish definitely the sym- 

 biotic* nature of the Zooxanthellae which it contains. Conse- 

 quently, the experiment was repeated several times with fresh 

 animals to insure accuracy. 



When A. bermudensis is placed in carbon dioxide the animal 

 at once becomes limp, and fails even to contract its tentacles, 

 thus giving the appearance of being completely overcome. Grad- 

 ually, however, after several hours, it commences to recover. 

 The body slowly regains its tone and (at the end of six hours) the 

 tentacles are slowly contracted. Twenty-four hours after being 

 placed in CO 2, all of the animals appeared quite normal. At the 

 end of forty hours one specimen had commenced to slough off a 

 reddish mucus, which is always indicative of approaching death. 

 After a lapse of forty-eight hours all of the specimens were dead. 

 In a repetition of this experiment one actinian lived in carbon 

 dioxide until the third day. 



The control specimens, which were placed in the dark room, 

 showed practically the same degree of vitality as those which had 

 remained in the sunlight. After one day in the CO 2 they were 

 still alive, and did not die until after from forty to forty-five 

 hours' confinement. As with the two preceding experiments, 

 this one also gives a very real indication that the Zooxanthellae 

 are not symbiotic in A. bermudensis. 



Experiment 4 — Oxygen. Three specimens of A. bermudensis 

 were put into an atmosphere of pure oxygen, the container being 

 arranged as in the preceding experiment. Under these circum- 

 stances, two individuals died on the seventh day and one 

 revived when put into sea-water on the eighth day. The 



^ When 'symbiotic' is used with reference to the Zooxanthellae, it refers only 

 to a state of photosynthetic symbiosis. 



