DOUBLE NUMBER. 



THE 



South African Journal 

 of science: 



COMPRISING THE REPORT OF THE 



SOUTH AFRICAN ASSOCIATION 



FOR THE 



ADVANCEMENT OF SCIENCE 



192 1. 



DURBAN. 



OFFICERS, 1921-1922: 



PRESIDENT. 



A. W. Rogers, Sc.D., F.R.S. 



VICE-PRESIDENTS. 



Prof. A. Brown, M.A., B.So. 



Prof. R. B. Denison, D.Sc, Ph.D.- E. Fabhah. 



Prof. T. M. Forsyth, M.A., D.Phil. 



HON. GENERAL SECRETARIES. 



H. E. Wood, M.Sc, F.R.A.S.,. Union Observatory, Johannesburg. 

 C. F. Juritz, M.A., D.Sc,, F.I.C., Division of Chemistry, Dept. of Agriculture, Capetown. 



HON. GENERAL TREASURER. 

 Jas. Gray, F.I.C., Johannesburg. 



HON. LIBRARIAN. 



Annie Porter, D.Sc, South African Institute for Medical Research, Johannesburg. 



ASSISTANT GENERAL SECRETARY. 



H. A. G. Jeffreys, O.B.E., Box 6894, Johannesburg. Telegraphio Address : " Science." 



HON. EDITOR OP JOURNAL. 



Prof. H. B. Fantham, M.A., D.Sc, The University, Johannesburg. 



~VOL. XVIII. JUNE, 1922. Nos. 3 and 4. 



JOHANNESBURG. 

 PUBLISHED BY THE ASSOCIATION. 



1922, 



Price 17«. 



