Vol. XX, No. 5 December 31, 1921 
THE 
NEW PHYTOLOGIST 
A BRITISH BOTANICAL JOURNAL 
EDITED BY 
IN CONSULTATION WITH THE 
THE CAMBRIDGE BOTANY 
CONTENTS 
PAGE 
Permeability continued . By Walter Stiles . . . ■ . . .185 
A Study of some of the Factors Controlling the Periodicity of Freshwater 
Algae in Nature. By William J. Hodgetts, M.Sc. (With 6 figures 
in the text) Continued . . ..195 
A New Method of Vegetative Multiplication in Crotalaria Burhia. , Ham. 
By R. H. Dastur, M.Sc. and W. T. Saxton, M.A. (With Plate II and 
1 figure in the text).228 
A New Species of Ccelastrum. By Florence Rich, M.A. (With 15 figures 
in the text).. 234 
Notes on an Easy Method of Camera Lucida Drawing. By James Small. 
(With 2 figures in the text) . . ..238 
An Unusual Plant of Cheiranthus cheiri L. By Ethel M. Poulton, M.Sc. 
(With 16 figures in the text) ... 242 
The Theory of Geotropic Response. By V. H. Blackman . . . 246 
The Hydrion Theory of Geotropism. By R. Snow, B.A.247 
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