vi PREFACE. 
for several generations be subjected to divergent forms of selection ; 
and in all the forms of animal life that are capable of learning by 
experience, accommodation, controlled by the principles producing 
habitudinal segregation, is constantly guiding and shaping racial 
segregation. 
Though more familiar words have been chosen for the title of this 
volume, the subject here treated would have been clearly expressed 
if the title had read: ‘‘Habitudinal and Racial Segregation; or, the 
origin and intensification of organic types, guided by innovation and 
tradition acting under segregate association, and established by 
variation and heredity acting under segregate intergeneration.” 
Joun T. GULICK. 
OBERLIN, OHIO. 
