I2O W. J. CROZIER. 



as the adults. Of course, it might be supposed that during the 

 period of low water changes in oxidation or the accumulation of 

 metabolites within the ccelenteron might rhythmically influence 

 the behavior of the embryos and juveniles. But the important 

 point is the significance of purely mechanical stimuli, derived 

 from motion of the water, for the relaxation of the column- 

 sphincter. In a contracted sea-anemone, small or adult, expan- 

 sion could always be secured by gentle movements of a glass 

 rod in the nearby water. The necessary conclusion is that in the 

 absence of such mechanical stimulation the actinian contracts; 

 the latent period for this response is rather long. There is no 

 evidence of tidal "memory." 



Summary. The behavior of Actinia bermudensis is considered 

 with reference to its intertidal habitat. It is likely that the habit 

 of contracting when uncovered by the sea is important for the 

 maintenance of the species between tidal limits, but there is no 

 evidence for persistence of the rhythm of contraction and 

 expansion in the absence of the tidal rise and fall. After a 

 period of about three hours in still water, the actinians close; 

 they can at any time be caused to expand by agitating this 

 water. Young individuals, never directly exposed to the tidal 

 cycle, behave in the same manner. 



CITATIONS. 

 Elmhirst, R., and Sharpe, J. S. 



'20 On the Colors of Two Sea Anemones, Actinia equina and Anemonia sulcata. 



Biochem. Jour., Vol. 14, pp. 48-57. 

 Parker, G. H. 



'17 Actinian Behavior. Jour. Exp. Zool., Vol. 22, pp. 193-229. 



