COMPLEX KESPONSES 173 



mined by their immediate environment. They are ex- 

 panded or retracted, feeding or quiescent, creeping or 

 still in consequence of immediate stimulation rather than 

 as a result of internal states due to past activities. They 

 exhibit rhythmic responses only to immediate rhythmic 

 stimuli, not to the effects of past rhythmic stimulation. 

 As a result of their various activities their physiological 

 states are changed and these changes unquestionably 

 modify their capacity for renewed response, but such 

 changes have not been found to be very lasting. From 

 the evidence thus far accumulated, it appears that these 

 states persist for only a brief period, often only a few 

 minutes or at most some hours. It also appears that an 

 actinian is much more nearly an organism whose internal 

 state is one of general uniformity than one of great flux. 

 On this uniformity as a background the changing environ- 

 ment calls forth now this, now that set of responses with- 

 out, however, seriously disturbing the internal equilibrium. 

 This condition of affairs is in strong contrast with what 

 is found in the higher animals, where the responses to the 

 environmental influences are extremely diverse and vari- 

 able in consequence of the delicacy of internal equilib- 

 rium, and as a result these animals when subjected to 

 experimental study often exhibit such novel and appar- 

 ently unrelated responses that we are prone to speak of 

 many of them as accidental or spontaneous. Spontaneity 

 in this sense is not a characteristic of actinian behavior, 

 which recalls very much more the relatively simple direct 

 type of reaction as seen in such organs as the vertebrate 

 intestine. It is with this type of reactive mechanism 

 rather than with the cerebral cortex that the actinian 

 shows affinity. 



If such a view of the behavior of sea-anemones is cor- 



