THE PLAY OF ANIMALS 



BY 

 f 



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 BY 



J. MARK BALDWIN 



PROFESSOR IN PRINCETON UNIVERSITY 





NEW YORK 

 D. APPLETON AND COMPANY 



