m. VIII. 
NOVEMBER, 192 1 
No. 9 
AMERICAN 
JOURNAL OF BOTANY 
OFFICIAL PUBLICATION OF THE 
BOTANICAL SOCIETY OF AMERICA 
CONTENTS 
The interrelationship of the number of the two types of vascular bundles in 
the transition zone of the axis of Phaseolus vulgaris. 
J. Arthur Harris, Edmund W. Sinnott, John Y» Pennypacker and 
|G. B. Durham 425 
Area of vein-islets in leaves of certain plants as an age determinant 
M. R. Ensign 433 
Unusual rusts on Nyssa and Urticastrum .......... E, B. Mains 44a 
Miscellaneous studies on the crown rust of oats G, R. Hoerner 452 
Comparative studies on respiration XVIII. Respiration and antagonism 
in Elodea. C. J. Lyon 458 
The effect upon permeability of (I) the same substance as cation and anion, 
and (II) changing the valency of the same ion . . . . Gran L. Raber 464 
PUBLISHED 
IN COOPERATION WITH THE BOTANICAL SOCIETY OF AMERICA 
BY THE 
BROOKLYN BOTANIC GARDEN 
At 41 North Qu' t N Street, Lancaster, Pa. 
Entered as secood-claM malt«r February 21, 1914, at the post offictsat Laacaster, Penntylvania, 
under tht^ act of March 3, 1879 
