530 ANNUAL REPOET SMITHSONIAN INSTITUTION, 1917. 



corresponding series of cliaiiges which take phice within the animal, 

 and also be the basis for a study of the reciprocal responses taking 

 place between the animal and the environment. 



In this section an outline will be given of some of the most impor- 

 tant phases of environmental changes in inland areas viewed as law- 

 ful and ordeidy, particularly those changes which influence animal 

 habitats. 



2. THE DTNA3IIG AND GENETIC STANDPOINT. 



Since Lj/ell taught the scientific world that a study of processes 

 now in operation is the key to an understanding of the present as well 

 as of the past, the process method has been slowly but inevitably pene- 

 trating to the utmost subdivisions of inquiry. With the progressive 

 appreciation and use of this method its efhciency has been increased. 

 Its progress has been the most rapid where the principles of its appli- 

 cation have been most clearly understood. As models become known 

 in each field of work others w ill find the method nmch easier to apply, 

 and for this reason it is desirable that such examples become fairly 

 numerous and widespread. 



In the application of the process method to an imperfectly under- 

 stood subject, and particularly to a complex one, it is desirable to con- 

 sider the subject as a unit or entity. This unit may then be regarded 

 as an agent whose process of activity is to be studied, for the activity 

 of an agent gives us a process. Thus an organism, a plant society, or 

 an animal community is a ver}' complex unit or agent, which largely 

 through chemical energ}^, under conditions of a normal environment, 

 responds in an orderly sequence of changes. The environment changes, 

 the internal conditions of the animal change, and so do the correspond- 

 ing responses on the part of the animal. When all of these changes 

 are studied as orderly processes^ we are able to see the advantage of 

 this method of study. It is desirable to investigate all phases of ani- 

 mal responses in this manner, such as growth, development, heredity, 

 etc., in order to determine the causes and conditions of this orderly 

 sequence. As a rule our recogTiition of the orderli/ seqiience orloyfs of 

 action or succession precedes our knowledge of the causes and condi- 

 tions of the sequence. This order of sequence is thus of fundamental 

 importance and must be recognized before it can be investigated or 

 explained. This method of studying the activity of agents, the char- 

 acter of their processes, constitutes the dynamic standpoint. 



When the dynamic relations of an agent have been investigated, the 

 orderly sequence of its responses established, and the causes and con- 

 ditions of its activity determined, it is then possible to explain fully 

 the origin of genesis of its activities. The genetic method is the 

 study of origins in tei'mis of the processes involved^ and therefore the 

 classification of facts genetically implies a knowledge of the j)roc- 



