PREFACE 
The papers contained in this volume were presented on April 20-— 
21, 1917, either in person or by title, at the Scientific Program, which 
formed part of the Dedication Exercises on the occasion of the com- 
pletion of the Laboratory Building and Plant Houses of the Brook- 
lyn Botanic Garden. 
ORLAND E. WHITE, 
EpGAR W. OLIVE, 
ALFRED GUNDERSEN, 
Publication Committee 
iti 
