vi CONTENTS VOLUME lxviii 



PAGE 



Repeated zoospore emergence in Didyuchus (with 



plate XXIII and one figure) - - - - William H. Weston 287 



Relation of nutrient solution to composition and 



reaction of cell sap of barley - - - - D. R. Hoagland 297 



Chemical constituents of Amaranthus retroflexus. 

 Contributions from the HuU Botanical Labora- 

 tory 254 (with eleven figures) - - - - M. L. Woo 313 



Staminate strobilus of Taxus canadensis. Contribu- 

 tions from the HuU Botanical Laboratory 255 

 (with plates XXIV-XXVI and twenty-two fig- 

 ures) - - - - - - - - A. W. Dupler 345 



Colloidal properties of bog water - George B. Rigg and T. G. Thompson 367 



Vegetation of undrained depressions on the Sacra- 

 mento plains (with one figure) - - - - Francis Ramaley 380 



Relative transpiration of coniferous and broad-leaved 

 trees in autumn and winter (with eighteen fig- 

 ures) - - - - - I.E. Weaver and A . Mogensen 393 



Torsion studies in twining plants (with six figures) - H. V. Hendricks 425 



Early development of floral organs and embryonic 

 structures of Scrophularia marylandica (with 

 plates XXVII-XXIX) ----- F. M. Schertz 441 



Companion cells in bast of Gnetum and angiosperms 



(with seven figures) - - - - - - W. P. Thompson 451 



Secretion of amylase by plant roots (with two fig- 

 ures) L. Kmidson and R. S. Smith 460 



Ray tracheid structure in second growth Sequoia 



washingtoniana (with five figures) _ - - E.G. Belyea 467 



Perithecia with an interascicular pseudoparenchyma 



(with plate XXX) F. L. Stevens 474 



Briefer Articles — 



A corn-poUinator (with one figure) - - - - Merle C. Coulter 63 

 Errors in double nomenclature - - - - - J. C. Arthur 147 



Parrafin solvents in histological work _ _ - Paul Weatherwax 305 



Aaron Aaronsohn (with portrait) - - - - /. if. C. 388 



Current Literature ----- 65,149,232,307,390,477 



For titles of book reviews see index under author's 

 name and reviews 



Papers noticed in "Notes for Students" are 

 indexed under author's name and subjects 



