NEW WORK ON ANIMAL PSYCHOLOGY, 
The Play of Animals: 
A study of Animal Life and Instinct. 
By KARL GROOS, 
Professor of Philosophy in the University of Basel. 
TRANSLATED WITH THE AUTHOR’S CO-OPERATION BY 
ELIZABETH L. BALDWIN. 
WITH A PREFACE AND AN APPENDIX ON ORGANIC SELECTION 
By J, mark BALDWIN, Professor in Princeton Academy. 
Crown IO5. 6 d 
CONTENTS. 
The Surplus Theory of 
Play. 
Play and Instinct. 
The Play of Animals. 
Experimentation. 
Movement Plays. 
Hunting Plays : With Real 
Living Prey, Living Mock 
Prey, and Lifeless Mock 
Prey. 
Fighting Plays : Teasing, 
Tussling among Young 
Animals, Playful Fight- 
ing between Adult Ani- 
mals. 
Constructive Arts. 
Nursing Plays. 
Imitative Play. 
Curiosity. 
Love Plays among Young 
Animals. 
Courtship by the Means of 
the Arts of Movement 
AND OF THE DISPLAY OF 
Unusual or Beautiful 
Forms or Colours ; and 
OF Noises and Tones. 
Coquetry in the Female. 
The Psychology of Animal 
Play. 
