vi Transactions of the South Africa7i Philosophical Society. 



the anthers and the stigma of the flower, thus effecting cross-fertihs- 

 ation when visiting the next flower. 



A paper on the " Examination of the Validity of an Approximate 

 Solution of a Certain Velocity Equation," by Professor A. Brown, 

 was read. The question here considered is the part played by the 

 initial value of y (X) in the solution of the equation 



dy 

 It 



=- a, y -{- a^ y^ -\- a^ y -\- 



It is commonly assumed that for a small initial value of y the 

 method of successive approximation is applicable, the proviso being 

 sometimes made that the value of y, so obtained, be also small. 



This assumption is shown, in the paper, to be not necessarily 

 correct, nor in certain cases to lead to a rapid approximation when 

 correct. Sufficient conditions for the applicability of the method are 

 found in the form 



«-! negative, 



and jX! < J {1 + ^A /3)^ + 1 - (1 + 2 /3) 

 where /3 is the greatest of the set 



2a, 



3^1 



Mr. J. Medley Wood's " List of Natal Plants," was taken as read. 



Ordinary Monthly Meeting. 



Wednesday, March 27, 1907. 

 Mr. S. S. Hough, F.E.S., in the Chair. 



Mr. E. M. LiGHTFOOT, F.E.S., was elected Ordinary Member. 



Nominations. — Dr. Lewis Gough, Pretoria, by Dr. L. Peringuey 

 and Dr. J. D. F. Gilchrist; Mr. A. J. Louw, Graaff-Eeinet, by 

 Dr. L. Peringuey and Dr. J. C. Beattie ; Miss Kensit, Kenil- 

 worth, by Dr. H. Bolus and Dr. L. Peringuey ; Mr. M. Neethling, 

 Bloemfontein, by M. Wilman and Dr. L. Peringuey. 



A paper on a property of symmetric determinants connected with 

 the simultaneous vanishing of the surface and volume of a tetra- 

 hedron, by T. MuiR, was taken as read. 



Mr. Barry MacMillan exhibited some pebbles, agates, &c., 

 collected by him on Plum-pudding Island, Cape Colony. 



Professor Young said that while the pebbles exhibited were 



