IV 
Index of Subjects 
PAGE 
Heterothallism and Similar Phenomena—E. M. Cutting . io 
Higher Plants, see Thalassiophyta 
Human Implements as an Aid to the Appreciation of Principles 
of Evolution and Classification, The Study of—E. J. Salisbury 179 
Hydathodes, see Stomata 
Hydrion Differentiation Theory of Geotropism, The—A reply 
to some criticisms—James Small . . . .73 
Hydrion Theory of Geotropism, The—R. Snow . . . 247 
Introduction to the Structure and Reproduction of Plants, An— 
by F. E. Fritsch and E. J. Salisbury [Review]—A. G. T(ansley) 132 
Membranes, see Permeability 
New Species of Coelastrum , A (15 Text-figs.)—Florence Rich . 234 
Numerical Sequence of Plant Families, Note on a—Margaret 
Benson . . . . . . .90 
Osmotic Pressure, Root Pressure and Exudation (3 Text-figs.) 
—V. H. Blackman ...... 106 
Periodicity of Fresh Water Algae in Nature, A Study of Some 
of the Factors controlling the—William J. Hodgetts 
I-VI (3 Text-figs.) . . . . *150 
VII-XVI (6 Text-figs.).195 
Permeability—Walter Stiles 
I. Introduction . . . . -45 
II. The System Involved . . . .48 
III. Surface Phenomena (2 Text-figs.) . . *93 
IV. Diffusion ...... 137 
V. The Permeability of Membranes (1 Text-fig.) . 185 
Phaenology, see Studies 
Plant Biology, Text-book of, by W. Neilson Jones and M. C. 
Rayner [Review]—A. G. T(ansley) . . . .132 
Plant Families, see Numerical Sequence 
Practical Plant Biochemistry, by Muriel Wheldale Onslow 
[Review]—V. H. B(lackman) . . . . -43 
Reversal of Geotropic Response in the Stem, The (1 Plate)— 
M. J. Lynn . . . . . . .116 
Reviews: 
Practical Plant Biochemistry, by Muriel Wheldale Onslow— 
V. H. B(lackman) . . . . -43 
Genetics and Evolution, by A. L. and A. C. Hagedoorn— 
A. G. T(ansley) . . . . . .124 
