

W 



o 



By J. Burtt-Davy, F.L.S. - - 



Fruits of species of Conopharyngia have been received 

 from Mr. R. Noble Fletcher, from "Success Camp, on the Lim- 

 popo River, N.E. Zoutpansberg, three days from Shewas P.O. 

 Mr. Fletcher suggests that this bush yields a kind of rubber, 

 but does not furnish sufficient material to determine this point. 

 Similar fruits v^^ere received some time ago from Delagoa Bay, 

 but this is the first record we have of the occurrence of this 

 genus in the Transvaal. Further material has been asked for. 



THEORIES AND HYPOTHESES.— Prof. H. B. Dixon, 

 M.A., Ph.D., F.R.S., expressed himself as follows in the in- 

 troductory paragraph of his recent Presidential Address 

 to the Chemical Society: — "In his presidential address last 

 year my distinguished predecessor in this Chair quoted w^ith 

 approval that clever definition which distinguishes a theory 

 from a hypothesis — ' a theory is a supposition we hope to be 

 true; a hypothesis is a supposition we expect to be useful." 



" I do not know whether the majority of scientific people hope 

 that the theories they employ are true; I feel very sure they 

 become convinced of their truth by a long habit of using them. 

 Suppositions that have stood the criticism of Time, and have 

 been taught to us as accepted theories, take possession of our 

 minds, whether we will or no. I have heard St. Claire Deville, 

 who professed his disbelief in (/// theories, lapse unconsciously 

 into the atomic theory in moments of controversy. Such 

 theories become almost an essential part of our mental ap- 

 paratus, and perhaps no great harm results if the majority of 

 us believe in them as an article of scientific faith. The danger 

 lies in the hypothesis ' we expect to be useful.' In its incep- 

 tion it is a more or less plausible guess — often arrived at by 

 analogy. We try it (with proper scepticism) to see if it will 

 ' work.' If it serves we try it again with less mental reserve. 

 The hypothesis suggests certain consequences under certain 

 conditions; if we find these consequences follow in a few trials 

 we are apt to regard our hypothesis as ' verified,' and we begin 

 to think in terms of it — especially if we have published it. By 

 and bv our hypothesis becomes crystallised in our system, and 

 if further consequences are not in accord with it, we disregard 

 the consequences. But the hypothesis, however useful it mav 

 be as a means of winning new facts, or new views of facts, is 

 by no means proved to be true by successful prediction. We 

 must be continually on our guard lest we become the bondmen 

 of our own hypotheses, although I do not think that we 

 Britons, as a race, are the worst offenders. ' Chemists,' wrote 

 Stas, ' the instant they see certain facts are reproduced with 

 an appearance of regularity, believe this is a simple natural 

 law; moreover, they have contracted the habit of considering 

 that the law has been demonstrated the moment they have 

 made any measurements not greatly differing from it.' " 



