The Dynamic or Process Relations of the Animal
1. General Physiology and Development.
2. A Selection of Physiological and Ecological Papers.
3. Animal Behavior as a Process.
4. A List of Selected Reviews and Bibliographies.
5. A Selection of References on Life Histories and Behavior.
“Seeing, then, that in all cases we may consider the external phenomena as simply in relation, and the internal phenomena also as simply in relation; the broadest and most complete definition of Life will be—The continuous adjustment of internal relations to external relations.”—Herbert Spencer.
“It is of the utmost importance, if we are to understand the behavior of organisms, that we think of them as dynamic—as processes, rather than as structures. The animal is something happening.”—H. S. Jennings (1907).
Not only is the environment subject to an orderly sequence of changes, but this same law applies with equal thoroughness to the living animal itself. The animal is an agent which transforms, in “an orderly sequence,” by its processes of metabolism, both energy and substance, resulting in growth, differentiation, multiplication, and behavior. These activities take place in an orderly manner and are dependent upon both energy and substance derived from the environment. For these reasons the processes or changes in metabolism, growth, development, and behavior, in so far as they are responses to the orderly sequence of environmental changes, are ecological problems. The changes in behavior during the life of the animal or the development of its behavior give one of the main clues to the physiological conditions which determine some of the most characteristic forms of responses, and finally as a result of all these activities and processes of adjustment to the conditions of life, a relatively mature and adjusted condition of the struggle for existence in animals and associations may be reached, the culmination of animal harmonies. For this reason studies in modifications of behavior are of fundamental ecological importance, because they consider behavior not only as ready-made, but also in the process of making. Such considerations as these make it desirable to include some of the most valuable and suggestive books and papers which deal with those general physiological processes influencing growth, development, multiplication, and behavior, and particularly those which aid one in realizing their order or successive changes, or “orderly sequence.”
In studying the activities of the individual animal, the normal environment to which it is attuned forms the natural unit or basis for study. All processes which modify or change such an optimum will stimulate the animal, cause responses and adjustments. There are many degrees or stages in the development of these optima which change with the functional rhythms and with the development of the animal. There are those conditions which influence the activity of certain functions or organs; those which influence the general vital processes in general, the vital optimum; those which appear to condition the best development of certain families, genera, etc.; and finally those of animal associations. Of course these grade imperceptibly into one another, and a single animal may in its development, traverse all of these stages in the development of its associational optimum. Optima thus have histories, and their development and laws of transformation are of the most fundamental ecological importance (Adams, 1904, 1909; Blackman, 1905, 1906; Shelford, 1911, 1912).
In the selection of these papers I have been guided by several considerations. Studies of common animals are given preference, also those papers which by their method of treatment and point of view are especially suggestive and may act as models for further study, and particularly those papers which treat of the activities from the standpoint of their changes, cycles, modifiability, and development. It is to such papers that we must look for suggestions regarding the methods or processes of adjustment between the animal and the environment. All of these papers are not equally ecological, but all will be of much utility in ecological work.
(General works are listed first, followed by special papers arranged alphabetically.)
1. General Physiology and Development
Verworn, M.