Vol. XLII Se 
THE 
BOTANICAL GAZETTE 
June 1907 
Editors: JOHN M. COULTER and CHARLES R. BARNES 
CONTENTS 
The Influence of Tension on the Formation of Mechanical 
Tissue in Plants Rufus Percival Hibbard 
Periodicity in the Production of the Sexual Cells of 
Dictyota dichotoma W. D. Hoyt 
The Function of Invertase in the Formation of Cane and 
' Invert Sugar Dates A. E. Vinson 
New or Noteworthy North American Convulvulaceae 
omer D. House 
Briefer Articles 
Heterothallism in Bread Mold, Rhizopus nigricans A. F. Blakeslee 
Two Embryo-Sac Mother Cells in Lilium longifiorum 
Margaret C. Ferguson 
Current Literature 
News 
Sh University of Chicago Press 
CHICAGO and NEW YORE 
William ‘Wesley and Son, London 
