Vol. III. 
JULY, 1916 
No. 7 
AMERICAN 
JOURNAL OF BOTANY 
OFFICIAL PUBLICATION OF THE 
BOTANICAL SOCIETY OF AMERICA 
CONTENTS 
The development of the Phylloxera vastatrix leaf gall Harry R. Rosen 337 
Correlations between morphological characters and the saccharine content 
of sugar beets • • Frederick J. Pritchard 361 
Mutation in Mattiola annua, a " Mendelizing" species. .Howard B. Frost 377 
The growth of forest tree roots . .W. B. McDougall 384 
PUBLISHED st^i^-^^ 
IN COOPERATION WITH THE BOTANICAL SOCIETY OF AMERICA^ 
BY THE 
BROOKLYN BOTANIC GARDEN 
At 41 North Queen Street, Lancaster, Pa. 
Entered as seeond-class matter February 21, 1914, at the post office at Lancaster, Pennsylvania, 
under the act of March 3, 1879. 
