468 THE AMERICAN NATURALIST [Vol. LII 



as an entity or agent whose system of activity or re- 

 sponses to internal and external influences are its most 

 fundamental characteristic. The activity of the animal, 

 as an agent, is its process of change or its process of 

 activity. Broadly speaking, this is a study of influences, 

 of response or behavior, a study of what animals do and 

 how they do it. Throughout it is the dynamic aspect of 

 the animal ; the pressure it exerts upon the environment ; 

 and the pressure exerted by the environment on it, that 

 is of greatest importance. I see no reason why these 

 assumptions can not be of universal application, and why 

 they can not be accepted in all investigation. This view 

 appears to be so well established that no detailed evi- 

 dence and discussion of it seems necessary at this time. 

 The animal agent itself is not a fixed thing, but one which 

 runs through a cycle; it originates, develops and disinte- 

 grates and is thus in its maintenance subject to all the ebb 

 and flow of other processes, and has similar dynamic rela- 

 tions. There is thus valid reason for assuming a 

 thoroughgoing process or dynamic program for dealing 

 with all animal problems. The same is equally true of 

 all plants which form a part of the animal environment, 

 and the physical environment lends itself, in fact, easily 

 leads, in such a treatment, and fits into this scheme har- 

 moniously, and makes it possible to give not only a uni- 

 form treatment to all phases of animal relations, but en- 

 ables the student of animals to make a perfect contact 

 with all the allied sciences, and to draw from each one 

 all possible support, with the least possible friction and 

 interference. 



2. Dynamic Principles 

 (a) Activity of Agent.— In discussing animal problems 

 from the process standpoint there are several concep- 

 tions which are fundamental. These ideas can be illus- 

 trated in simple form by an example from physical sci- 

 ence. Running water is a substance combined with 

 energy (gravitation) which exerts stress or pressure, 

 which it expends upon other substances, and it is there- 

 fore an agent. An agent thus exerting stress and expend- 



