PREFACE Vv 
Valuable suggestions from many teachers and students of 
botany have been gladly received, and these will doubtless serve 
to render the book more helpful and usable than it otherwise 
would have been. Especial thanks are due to Dr. Norman 
MacLeod Harris of the Department of Bacteriology of The 
University of Chicago, who has read the chapter on bacteria; 
and to Mr. William L. Eikenberry of the University High 
School, Chicago, who by his frequent suggestions, based 
on extensive experience, has been constantly helpful in the 
preparation of this book. 
JOSEPH Y. BERGEN 
OTIS W. CALDWELL 
