MODIFIABILITY IN BEHAVIOR. 

 I. BEHAVIOR OF SEA ANEMONES. 



BY 



H. S. JENNINGS. 



A thorough study of the modifiabiHty of reactions to external 

 stimuH in lower organisms seems at present one of the great 

 desiderata in the study of animal behavior. Recent work has 

 been devoted largely to the study of sharply defined forms of 

 reaction and to the discovery of conditions under which these 

 forms appear in the typical way. As a result there is a wide- 

 spread impression that the behavior of lower organisms is com- 

 posed of invariable reflexes, occurring always in the same way 

 under the same external circumstances. This is far from the 

 truth and leads, as it seems to the writer, to a fundamentally 

 false conception of the nature of animal behavior. Inner states 

 and changes are fully as important in determining behavior as are 

 external stimuli, modifying fundamentally the reactions which 

 the latter produce. The present studies are devoted to an analysis 

 of some of these modifying factors; in other words to some of 

 the inner factors in behavior. 



The study of the behavior of sea anemones herewith presented 

 was made possible by a stay at the Carnegie Research Laboratory 

 at the Tortugas. I am under great obligations to the Carnegie 

 Institution and to the director of the laboratory, Dr. A. G. Mayer, 

 for opportunity to carry on the work, and for supplying every 

 facility that could assist it. The Tortugas laboratory furnishes 

 an ideal situation for carrying on such investigations. An indefi- 

 nite number of species of sea anemones and corals can be procured 

 at a few moments notice, and they live as well in the laboratory as 

 in the sea, since the water becomes cooler instead of warmer when 

 brought into the house. 



