PAGE 
H. H. W. Pearson, F.R.S., Sc.D. (Cambridge) ..... .... 5 
Pickering, Spencer.— T he Effect of one Plant on Another. With three Figures in the 
Text * . ' . . . . . . 181 
WILLIS, J. C. — The Relative Age of Endemic Species and other Controversial Points . 189 
Sinnott, Edmund W.— The ‘Age and Area* Hypothesis and the Problem of Endemism 209 
Blackman, V. H., and Knight, R. C.— A Method of Controlling the Rate of Air Move- 
ment in Transpiration Experiments. With one Figure in the Text . . . .217 
KNIGHT, R. C. — The Interrelations of Stomatal Aperture, Leaf Water-content, and 
Transpiration Rate. With four Figures in the Text . . . . . . 221 
Thomas, Nesta, and Ferguson, Allan.— O n the Reduction of Transpiration Observa- 
tions. With one Figure in the Text . . . . . . . . . .241 
Stopes, Marie C. — Roots in Bennettites. With Plate XIV 257 
Small, James. — Irritability of the Pollen-presentation Mechanism in the Compositae . 261 
Allen, Charles E. — The Spermatogenesis of Polytrichum juniperinum. With Plates XV 
and XVI 269 
Mangham, Sydney.— O n the Mechanism of Translocation in Plant Tissues. An Hypo- 
thesis, with special reference to Sugar Conduction in Sieve-tubes. With two Figures 
in the Text 293 
NOTE. 
Small, James.— G eotropism and the Weber-Fechner Law . ... . . ..313 
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