PREFACE 



present volume is largely devoted to sub- 

 jects with which the writer's own investigations 

 in animal behavior have been more or less closely 

 concerned. For the interest of the general reader 

 the special contributions of the writer have been 

 made subordinate to the broader aspects of these 

 subjects. Although there is little relationship be- 

 tween the various topics dealt with, the different 

 chapters are not devoid of a certain unity of aim. 

 The several types of behavior here described were 

 studied in the endeavor to get a fuller insight into 

 their mechanism, or to interpret them from the ge- 

 netic point of view. These two methods of attack 

 are not opposed or mutually exclusive, as is some- 

 times implied, but complementary. We cannot ob- 

 tain a complete explanation of behavior by an analy- 

 sis of the activities of the individual alone ; it is nec- 

 essary to know also the evolutionary history of the 

 species, and the various steps by which its present 

 behavior has been acquired. 



The first chapter is historical and will, it is hoped, 

 prepare the reader for a better appreciation of the 

 general aim and import of what follows. Some of 

 the chapters in this volume have appeared elsewhere 

 as special articles. I wish to thank Dr. J. McKeen 



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