THE 



SOUTH AFRICAN JOURNAL 



COMPRISING THE REPORT OF THE 



SOUTH AFRICAN ASSOCIATION 



FOR THE 



ADVANCEMENT OF SCIENCE, 



19 20, f^^^Z^^.,. 



OFFICERS: 1920-1921. 



PRESIDENT. 

 Prof. J. E. DuERDKN, M.Sc., Ph.D., A.R.C.S. 



VICE-PRESIDENTS. 



F'rof. G. E. Cory, M.A. 



Prof. R. Lksmk, M.A., F.S.S. T. R. Sim, D.Sc. 



Prof. J. A. Wilkinson, M.A., F.C.S. 



HON. GENERAL SECRETARIES. 



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



C. F. JuRlTZ, M.A., D.Sc, F.I.C., Agricultural Chemical Research Laboratory, Capetown. 



HON. GENERAL TREASURES. 



J, A. FOOTE, F.G.S., F.S.T.S., Commercial High School, 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. Telegraphic Address: "Science." 



HON. EDITOR OF JOURNAL. 

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



VOL XVII. NOVEMBER, 1920. No. 1 



JOHANNESBURG. 

 PUBLISHED BY THE ASSOCIATION. 



19 20. [Price 12«. 



