TABLE OF CONTENTS, VOLUME VIII, 1921 
No. I, January 
Page 
The fixation of free nitrogen by green plants (with one text figure and 
Plate I) Frank B. Wann i 
Variations in the osmotic concentrations of the guard cells during the 
opening and closing of stomata (with seven text figures) 
R. G. WiGGANS 30 
The Linnaean cor cept of pearl millet Agnes Chase 41 
The effect of cL idiness on the oxygen content of water and its sig- 
nificance ir cranberry culture (with three text figures) 
H. F. Bergman 50 
No. 2, February 
Influence of temperature on the relations between nutrient salt pro- 
portions and the early growth of wheat W. F. Gericke 59 
The vascular anatomy of dirnerous and trimerous seedlings of Phaseolus 
vulgaris (with twenty-three text figures) 
J. Arthur Harris, Edmund W. Sinnott, John Y. Pennyp acker, 
and G. B. Durham 63 
Aspergillus flavus, A. oryzae, and associated species (with one text 
figure) Charles Thom and Margaret B. Church 103 
No. 3, March 
A study of Rhus diversiloba with special reference to its toxicity (with 
two text figures and Plate II) James B. McNair 127 
The effect of salt proportions and concentration on the growth of 
Aspergillus niger (with six text figures) C. M. Hafjnseler 147 
Suggestions with respect to the measurement of osmotic pressure 
(with one text figure) L. Knudson and S. Ginsburg 164 
Thick-walled root hairs of Gleditsia and related genera (with three 
text figures) W. B. McDougall 171 
A simple method for growing plants (with one text figure) 
J. M. Brannon 176 
No. 4, April 
The morphology and anatomy of Rhus diversiloba (with Plates III 
and IV) James B. McNair 179 
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