To my Friends and Teachers

JAMES R. ANGELL AND HENRY H. DONALDSON

this Book is Gratefully

Dedicated.

PREFACE

This volume on behavior is an elaboration of the eight lectures given at Columbia University during the winter of 1913. It has been written with the hope that it may be found serviceable in classroom work in psychology and biology. Needless technicalities and detailed references have been omitted. For this reason the general reader may find something of interest in its pages. The book must not be looked upon as a reference book or treatise. The treatment of the research material has not been exhaustive. For the most part no attempt has been made to give investigators detailed credit for their work. I have not, however, been able to carry out consistently the plan of omitting references. In most sciences which have existed for any length of time a general body of data becomes common property, and it is unnecessary to mention the original discoverers of the universally accepted facts. Some parts of the study of behavior are so involved in controversy that no results can be said as yet to be universally accepted by specialists in the subject. In dealing with these facts, especially in the chapters on the sense organs, it has been necessary to enter with some detail into the discussion of the investigations and theories of individual writers. It is hoped that the volume will contribute something towards the introduction of more careful methods in the study of behavior, and serve to mark off the study from the other sciences.

An endeavor has been made to adapt the book to the needs of various classes of readers. Where only a short time can be devoted to a classroom course in behavior, I suggest that chapters I, II, III, V, VII, and IX be omitted.

In the preparation of the manuscript my heaviest obligation is to Dr. K. S. Lashley, Bruce Fellow in Biology, the Johns Hopkins University. He has given unsparingly of