PREFACE Vil 
him combine, with all the varied ideas and experiences 
of a man who has traversed the round globe, the 
special knowledge of the director of a zoological 
garden, and also that of him who has penetrated the 
life-secrets of the forest, and who can, moreover, take 
the point of view of the student of esthetics. If these 
are the qualifications for the special investigation of 
animal play, they are not less called for in the other 
realms of Comparative Psychology. 
While the present writer can lay claim to no such 
roundness of culture, he thinks he can confidently 
assert that nothing will be found in the following pages 
that has not some basis in his own observations or 
experience. 
The Author has on more than one occasion expressed 
his belief that mere closet psychology is of little 
value in advancing the subject as applied to animals. 
Accordingly, it will be found that by far the greater 
part of this book is made up of the facts of observation. 
In determining the form the work should take, I 
had to consider whether to re-cast all the material I 
had been accumulating for the last fifteen years, or 
republish what had already appeared in an almost 
unaltered form. It seemed to me that in the end the 
advancement of the subject would be best served by 
the latter course. While there may be some repetition 
in the papers that constitute the first part of the work, 
this will serve to emphasise the views that have been 
impressed more and more on one who has for ten years 
been in daily intimate association with animals, and a 
