XIII. 
CONTENTS 
INTRODUCTION . 
REFLEX ACTION . 
THE TROPISMs . 
THE BEHAVIOR OF PROTOZOA 
INSTINCT 
THE EvouuTion or INSTINCT 
Tue NON-INTELLIGENT MODIFICATIONS OF BEHAVIOR . 
PLEASURE, PAIN, AND THE BEGINNINGS OF INTELLIGENCE . 
PRIMITIVE TYPES OF INTELLIGENCE IN CRUSTACEANS AND 
MOo.uuvscs . 
INTELLIGENCE IN INSECTS . 
INTELLIGENCE IN THE LOWER VERTEBRATES . 
THE INTELLIGENCE OF MAMMALS . 
Tue Menta Lire or ApEs AND MONKEYS. 
INDEX 
Pe 
