PREFACE 



THIS book is the direct result of what, at the time of its 

 occurrence, seemed to be an unimportant incident in the 

 course of my scientific work the presentation of a pair of 

 dancing mice to the Harvard Psychological Laboratory. 

 My interest in the peculiarities of behavior which the crea- 

 tures exhibited, as I watched them casually from day to day, 

 soon became experiment-impelling, and almost before I real- 

 ized it, I was in the midst of an investigation of their senses 

 and intelligence. 



The longer I observed and experimented with them, the 

 more numerous became the problems which the dancers 

 presented to me for solution. From a study of the senses 

 of hearing and sight I was led to investigate, in turn, the 

 various forms of activity of which the mice are capable ; the 

 ways in which they learn to react adaptively to new or novel 

 situations ; the facility with which they acquire habits ; the 

 duration of habits; the roles of the various senses in the 

 acquisition and performance of certain habitual acts; the 

 efficiency of different methods of training ; and the inheritance 

 of racial and individually acquired forms of behavior. 



In the course of my experimental work I discovered, much 

 to my surprise, that no accurate and detailed account of this 

 curiously interesting animal existed in the English language, 

 and that in no other language were all the facts concerning 

 it available in a single book. This fact, in connection with 

 my appreciation of the exceptional value of the dancer as a 

 pet and as material for the scientific study of animal behavior, 

 has led me to supplement the results of my own observation 



