I 20 
Notes . 
Again, if a leaf be illuminated by light which has passed through another leaf, the 
current at once ceases, reappears if illuminated by blue-violet light, and becomes 
nearly as great when illuminated by red light as it is when illuminated by white light. 
Meldola in his Presidential Address to the Chemical Society (1906) says: — 
‘From formaldehyde to fructose the laboratory evidence is fairly complete. It 
remains only to connect formaldehyde with carbonic acid by some photolytic method 
which may be regarded as above suspicion — and the discovery of such a method may 
be looked for sooner or later — In order to say that the chain of chemical evidence is 
quite complete.’ 
In our forthcoming paper the detailed evidence will be given on which we 
believe that we are justified in claiming that our work fills the gap indicated by 
Prof. Meldola in the sentences quoted ; the present note is merely an outline of the 
chain of evidence and does not touch on various collateral problems which have 
arisen in the course of the investigation. 
R. J. HARVEY GIBSON. 
University of Liverpool. 
