PAGE 
CONTENTS. 
Vines, S. H. — The Proteases of Plants. Ill .... 171 
Allen, C. E. — Nuclear Division in the Pollen Mother-cells of Lilium 
canadense. With Plates VI-IX 189 
Gwynne-Vaughan, D. T.— On the Anatomy of Archangiopteris 
Henryi and other Marattiaceae. With Plate X . . . 259 
Berridge, Miss E. M. — On two New Specimens of Spencerites 
insignis. With Plates XI and XII and three Figures in the 
Text . . . . . . . . . . * . 273 
Blackman, F. F.— Optima and Limiting Factors. With two 
Diagrams in the Text . . . . . . . .281 
Leake, H. M,— The Localization of the Indigo-producing Substance 
in Indigo-yielding Plants. With Plate XIII . . . 297 
Newcombe,F. C. — Geotropic Response at Various Angles of Inclination 3,1 1 
NOTES. 
Massee.— On the Presence of Binucleate Cells in the Ascomycetes. 
With a Figure in the Text 325 
Arber. — On some Species of Lagenostoma : a Type of Pterido- 
spermous Seed from the Coal-measures 326 
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