Prof. Marshall Ward, On a Problem, etc. 



On a Problem concerning Wood and Lignified cell-ivalls. By 

 H. Marshall Ward, D.Sc, F.R.S., Professor of Botany. 



[Read 31 October 1904.] 



During past years Dr W. J. Russell has published several 

 papers bringing forward the results of a remarkable discovery. 

 He finds that if bodies such as leather, cork, wood and numerous 

 others, are allowed to lie on a sensitive dry photographic plate in 

 the dark, for periods varying from a few hours to some weeks, the 

 plate on undergoing development in the ordinary way may have 

 an image on it, in many cases of extraordinary sharpness and 

 beauty. 



I am not here concerned with any of his many interesting and 

 important experiments, excepting those in which wood was em- 

 ployed ; and he has just summarised the results of his latest 

 work in a paper in the Philosophical Transactions of the Royal 

 Society, Vol. cxcvil, Ser. B, pp. 281 — 289, entitled "On the 

 Action of Wood on a Photographic plate in the Dark"*. This 

 memoir, illustrated with a series of excellent plates, shows clearly 

 the progress that the author has made towards the solution of the 

 various questions he has raised. Dr Russell finds that almost all 

 the woods he has tried act on the plate in the dark ; though they 

 vary as regards intensity of action, and as regards the length of 

 time and the temperature needed for tangible results. 



His method is to obtain a smooth face on a block of wood, dry, 

 and place this face in contact with the plate, the whole being left 

 in the dark until development of the plate. 



Dr Russell had previously shown the probability that hydrogen 

 peroxide is the active agent, and thinks that resin in the wood is 

 probably the indirect causal agent : he gives proofs that it is not 

 a case of radio-activity. 



He gives a fairly long list of British and Foreign woods used, 

 and summarises the results ; and he also tests the question of the 

 action of ordinary resin (colophony), various other resins, turpen- 

 tine and a number of gums, with the result that while the bodies 

 of more gum-like nature are inactive, those of more resinous nature 

 are active. 



' Sue also Nature, Sept. 22, 1904, p. 521. 



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