CONTENTS 
No. CXXXVII, January, 1921. page 
Bews, J. W. — Some General Principles of Plant Distribution as illustrated by the South African 
Flora • 1 
Thoday, M. G. — Anatomy of the Ovule and Seed in Gnetum Gnemon, with Notes on 
Gnetum funiculare. With Plate I and five Figures in the Text . . *37 
Stopes, Marie Carmichael. — T he Missing Link in Osmundites. With Plate II and one 
Figure in the Text 55 
Cutting, E. M. — On the Pollination Mechanism of Incarvillea Delavayi, Franch. With three 
Figures in the Text ............. 63 
Torrey, R. E. — Telephragmoxylon and the Origin of Wood Parenchyma. With Plate III 
and three Figures in the Text . . • • 73 
Cayley, Dorothy M. — Some Observations on the Life-history of Nectria galligena, Bres. 
With Plates IV and V 79 
Gregory, F. G. — Studies in the Energy Relations of Plants. I. The Increase in Area of 
Leaves and Leaf Surface of Cucumis sativus. With fifteen Figures in the Text . 93 
Wormald, H. — On the Occurrence in Britain of the Ascigerous Stage of a ‘ Brown Rot ’ 
Fungus. With Plates VI and VII 125 
NOTES. 
Walkden, H. — The Isolation of the Organism causing Crown Gall on Chrysanthemum 
frutescens in Britain . . . . . . . . . . . . 137 
Williamson, H. S. — A New Method of preparing Sections of Hard Vegetable Structures . 139 
No. CXXXVIII, April, 1921. 
Campbell, Douglas Houghton. — T he Gametophyte and Embryo of Botrychium obliquum, 
Miihl. With Plate VIII and eleven Figures in the Text 141 
Blackburn, Kathleen B., and Harrison, J. W. ILeslop. — T he Status of the British Rose 
Forms as determined by their Cytological Behaviour. With Plates IX and X and 
five Figures in the Text . . . . . . . . . . . • I 59 
Smith, T. O., and Butler, O. — Relation of Potassium to Growth in Plants . . . .189 
Jeffrey, Edward Charles, and Torrey, Ray Ethan.— T ransitional Herbaceous 
Dicotyledons. With Plates XI-XIII and five Figures in the Text . . . .227 
Holmes, M. G. — A Contribution to the Study of Water-conductivity in Sycamore Wood. 
With thirteen Figures in the Text . . . . . . . . . . 251 
Seifriz, William. — O bservations on some Physical Properties of Protoplasm by Aid of 
Microdissection. With one Figure in the Text 269 
NOTES* 
Sahni, B. — Note on the Presence of a ‘Tent-pole’ in the Seed of Cephalotaxus pedunculata. 
With two Figures in the Text 297 
Welsford, E. J. — Division of the Nuclei in Sync.hytrium endobioticum, Perc. With one 
Figure in the Text ............. 298 
No. CXXXIX, July, 1921. 
Arber, Agnes. — The Leaf Structure of the Iridaceae, considered in Relation to the Phyllode 
Theory. With sixty-six Figures in the Text 301 
Boyle, C. — Studies in the Physiology of Parasitism. VI. Infection by Sclerotinia Libertiana. 
With Plate XIV 337 
