iv PREFACE 



review all the literature on behavior. Only such works 

 are here referred to as appear to have a theoretical bear- 

 ing, but many others are considered elsewhere. 



Part II is devoted largely to the description and dis- 

 cussion of experimental observations on orientation made 

 by the author during the past five years. Only a few of 

 these have been previously published. The remaining 

 parts of the book are more general and contain relatively 

 much less original matter. 



A large part of the experimental work connected with 

 this volume was done at Johns Hopkins University dur- 

 ing my residence as Johnston Research Scholar. To this 

 institution I am greatly indebted, not only for the scholar- 

 ship, but also for exceptional facilities placed at my com- 

 mand by the late Professor W. K. Brooks, Director of the 

 Zoological Laboratory during my residence, and for friendly 

 courtesies extended on every hand by other members of 

 the University. I am also under obligation to the Marine 

 Biological Laboratory of Woods Hole, Massachusetts, for 

 research facilities during the summer of 1907, and to the 

 United States Bureau of Fisheries for similar privileges 

 during the following two summers, and especially to the 

 Director of the Laboratory of the Bureau of Fisheries at 

 Woods Hole, Massachusetts, Doctor F. B. Sumner, for 

 generously supplying my needs. It is a pleasure to ac- 

 knowledge my further indebtedness to Professor H. S. 

 Jennings for his enthusiastic interest and support in the 

 work at all times and for critically reading the manuscript; 

 to Professors G. H. Parker and J. B. Watson for valuable 

 suggestions after reading much of the work in manuscript; 

 to Professor R. M. Yerkes for his thorough criticism re- 

 garding both composition and contents; and to my wife, 

 Grace Tennent Mast, for invaluable literary aid and criti- 

 cism. The author however must be held responsible for 



all of the subject-matter. ^ ^ ,^ 



Samuel Ottmar Mast. 



Baltimore, Maryland, 

 February 4, 1910. 



