IV 
Contents. 
On a Fungus — OvulaTioi)sis ])aim'yae,'s, sp. — which causes Powdery 
Mildew on the Leaves op the Pawpaw Plant {Carica 
])a2)aya, Linn.). By Paul A. van der Bijl. (With Plate X 
and one Text-fig.) .187 
Note on Lysurus Woodii (MacOwan), Lloyd. By Paul A. van 
der Bijl. (With Plate XI) ...... . 191 
A Prehistoric Eock-Sculpture from the North-Eastern 
Transvaal. By C. Pijper. (With Plate XII) . . .195 
The Action of TJrginea Biirl:ei (Baker). By J. W. C. G-unn. 
(With five Text-figs ) . . .197 
Colour and Chemical Constitution : Part XII. — ^The Calcula- 
tion OF Colour from the Tautomeric Theory. By James 
MoiR 205 
Medical Folk-Lore of the Abantu in the Lijdenburg District, 
Transvaal. By Cornelis Pijper ...... 217 
On a Species of Microdon Fly (Diptera) from Natal. By 
S. H. Skaife, M.A., M.Sc. (With Plate XIII) . 221 
On the Integrated Velocity Equations of Chemical Eeactions. 
By J. P. Dalton 223 
A Revision of the South African Agamas allied to Agama 
liisinda and A. atra. By G. A. Boulenger and J. H. Power. 
(With three Text-figs.) 229 
A Possible Lunar Influence upon the Velocity of the Wind 
AT KiMBERLEY. (Fourth Paper.) By J. R. Sutton. (With 
one Text-fig.) 289 
Detection of Induced Beta-Ray Emission from Substances 
Exposed to Runtgen-Rays by a Photographic Method. 
By Lewis Simons, B.Sc.Lond. (With Plate XIV) . .297 
Experimental Infestation of Fresh- Water Snails. By F. Gr. 
Cawston ........... 301 
Some Notes on Ancient Ideas concerning the Diamond. By 
J. R. Sutton 305 
A Study of the B. coli Gtroup with Special Reference to the 
Serological Characters of these Organisms. By T. J. 
Mackie 315 
A Contribution to the Study of the Rainfall Map of South 
Africa. By J. R. Sutton. (With 13 Maps) . . . .367 
