XIII. 
CONTENTS 
INTRODUCTION . 
Rerisx Actiox 
Tue TROPISMS . 
Tue Brexavior or Protozoa 
INSTINCT . 
Tue Evo.vution or Instinct 
THe NON-INTELLIGENT MopIFICATIONS OF BEHAVIOR. . 
PLEASURE, PAIN, AND THE BEGINNINGS OF INTELLIGENCE . 
Primitive Tyres or INTELLIGENCE IN CRUSTACEANS AND 
Mo.uuuscs . 
INTELLIGENCE IN INSECTS . 
INTELLIGENCE IN THE LowER VERTEBRATES. . . 
Tur INTELLIGENCE OF MAMMALS . 
Tur Menta Lire or APES AND MonKEYs. 
UND Bee eee se tee a ap ee st 
. 115 
. 139 
164 
. 180 
. 191 
. 218 
. 232 
. 260 
. 283 
