VM. VIII • JANUARY, 1921 No. I 
AMERICAN 
JOURNAL OF BOTANY 
OFFICIAL PUBLICATION OF THE 
BOTANICAL SOCIETY OF AMERICA 
MAR 15 1921 
CONTENTS 
The fixation of free nitrogen by green plants Frank B. Wann i 
Variations in the osmotic concentrations of the guard cells during the opening 
and closing of stomata R. G. Wiggins 30 
The Linnean concept of pearl millet . Agnes Chase 41 
The effect of cloudiness on the oxygen content of water and its significance in 
cranberry culture . H. F. Bergman 50 
PUBLISHED 
IN COOPERATION WITH THE BOTANICAL SOCIETY OF AMERICA 
At 41 North Queen Street, Lancaster, Pa. 
BY THE 
BROOKLYN BOTANIC GARDEN 
Brooklyn, N. Y. 
Entered as «ecDnd-cIa»« matter February 21, 1914, at the post office at Lancaster, Pennsylvania, 
under the act of March 3, 1879 
