2. A Selection of Physiological and Ecological Papers 100 3. Animal Behavior as a Process 102 4. A List of Selected Reviews and Bibliographies 107 5. A Selection of References on Life Histories and Behavior 108 IX. THE CONTINUOUS PROCESS OF ADJUSTMENT BETWEEN THE ENVIRONMENT AND THE ANIMAL, WITH SPECIAL REFERENCE TO OTHER ORGANISMS. (THE DYNAMIC OR PROCESS RELATIONS OF ANIMAL ASSOCIATIONS AND AGGREGATIONS) 122 1. The Struggle for Existence 123 2. The Dynamic Relations of Associations and Aggregations, with Special Reference to Animal Associations 130 _a._ The Relation of Animals to Pollination and to Plant Galls 141 _b._ Subterranean and Cave Associations 143 _c._ Selected References on Aggregations and Associations 145 INDEX 151 INDEX TO NAMES 179 LIST OF FIGURES FIG. 1. An Oyster Habitat on the South Carolina Coast _Frontispiece_ 2. Struggle for Existence on a Clam Flat. Overcrowded Condition _facing page_ 7 3. Struggle for Existence on a Clam Flat. Destruction of Clams by Predaceous Animals ” ” 8 4. A Small Mountain Stream as an Animal Environment ” ” 86 5. A Small River as an Animal Environment ” ” 87 6. An Illinois Prairie Remnant as an Animal Environment ” ” 139 7. An Illinois Deciduous Forest as an Animal Environment ” ” 146 RELATION OF ECOLOGY TO BIOLOGY “I shall try to show that life is response to the order of nature.... But if it be admitted, it follows that biology is the study of response, and that the study of that order of nature to which response is made is as well within its province as the study of the living organism which responds, for all the knowledge we can get of both these aspects of nature is needed as a preparation for the study of that relation between them which constitutes life.” “To study life we must consider three things: _first_, the orderly sequence of external nature; _second_, the living organism and the changes which take place in it; and, _third_, that continuous adjustment between the two sets of phenomena which constitutes life.” “The physical sciences deal with the external world, and in the laboratory we study the structure and activities of organisms by very similar methods; but if we stop there, neglecting the relation of the living being to its environment, our study is not biology or the science of life.”