Movement and Problem Solving in Ophiura 219 



than many others, that behavior is structure in motion, and that 

 complexity of behavior depends on the complexity of that which 

 behaves. An act performed by one arm may also be performed 

 by any of the others. The arms may all do the same thing at the 

 same time; some may do one thing and others another; and finally 

 a single arm may execute different movements at different levels. 

 As the disc itself may also execute varied movements, the number 

 of possibilities is enormous. With this marked versatility to 

 contend v^ith, it is not surprising that resolution, demonstrated 

 according to Jennings ('04, '05, '06) for Protozoa, Coelente rates, 

 and other forms lower in the scale of complexity than echinoderms, 

 or as low, should remain undemonstrated for ophiurans. The 

 number of movements possible to an ophiuran is immense; if 

 the animal only acts, the chances that it will perform movements 

 fitted to relieve a certain physiological state are better than the 

 chances that such will be the case in most other animals. If one 

 of the many movements that will serve is not performed, another 

 will be, and we should not expect to find resolution, unless the fit 

 things to be done are few. Any of the problems presented might 

 have been solved in a variety of ways. One or more of these 

 ways were superior to any of the others, but all served the purpose. 

 Where the variety of solutions to a problem is great, there is no 

 need of resolution, and it does not occur. 



I have profited much by the elaborate criticism which Professor 

 Jennings made of an earlier draft of this paper, and I take this 

 occasion to thank him for his kindness. 



University of Michigan 

 Ann Arbor, Mish. 

 February i, 1907 



