Modifiahility in Behavior. 463 



The facts may be summed up for the anemone as follows: 

 Performance of a certain action involves the assumption of certain 

 structural conditions. These conditions persist in a slight degree 

 even in the intervals between the actions. At a new action they 

 show their influence by causing it to take place in the same way as 

 the former one. This gives the same results as what we are accus- 

 tomed to call habit. 



.ft 



4. GENERAL AND COMPARATIVE. 



The sea anemones are among the lowest of the Metazoa, and 

 their behavior, when compared with that of most other animals, 

 is of a very simple character. Yet it is evident that even in these 

 low organisms the reaction to a given external stimulus depends 

 upon many things beside the nature of the stimulus itself. Vary- 

 ing states of metabolism induce totally different reactions to the 

 same stimulus, one state producing the long train of actions look- 

 ing toward the ingestion of food, another inducing the equally long 

 and variable chain of activities resulting in rejection. The same 

 factors cause marked changes in reaction to other stimuli than 

 possible food. Past stimuli received and past reactions per- 

 formed likewise determine the reaction to a given external con- 

 dition, resulting sometimes in a cessation of reaction, in other 

 cases in a complete change in its character. Certain simple con- 

 ditions produce a tendency in the organism to perform more 

 readily an act previously performed (bending, on extension, in a 

 certain direction). 



Examination of the conditions under which the animals live 

 shows clearly that all the usual reactions and modifications of the 

 reactions are such as to assist in adapting the organism to its 

 environment. In other words, they aid the physiological processes 

 of which the organism is the seat. Aiptasia annulata, for example, 

 lives in crevices beneath and among stones or coral rocks. It is, 

 of course, evident that its food reactions maintain its metabolic 

 processes, which would necessarily cease in their absence, that the 

 rejecting reaction keeps the surface clean, so that respiration may 

 take place uninterruptedly, and obstacles or injurious substances 

 be avoided. The transformation of the food reaction into the 

 rejecting reaction after the animal is satiated with food is of course 

 as much to the interest of the sea anemone as it is to that of higher 



