406 



Mr. H. Wager. 



are probably therefore proportional to the photo-synthetic activity of the 

 chlorophyll in the different parts of the spectrum. 



4. The presence of formaldehyde is not very clearly indicated in my 

 experiments. Bimini's test, as modified by Schryver, gives indications of a 

 trace of formaldehyde when chlorophyll is exposed to light both in the presence 

 and in the absence of carbon dioxide, but I do not consider the results reliable, 

 and in any case the reaction given is nothing like so strong as is indicated by 

 Schiff's solution. The test used by Harvey Gibson is also very sensitive to 

 formaldehyde, but is unreliable as it gives a pronounced reaction with 

 solutions of sugar and starch and other substances. All that can be said at 

 present is that in the photo-decomposition of chlorophyll a considerable 

 quantity of aldehyde is formed, with possibly a small amount of formaldehyde. 



5. The oxidising substance appears not to be hydrogen peroxide, but it 

 may be an organic peroxide derivative of the chlorophyll. 



6. The bleaching of chlorophyll in situ in dead green leaves, algae, and 

 other chlorophyll-containing organisms, gives the same products as the 

 chlorophyll extracts outside the plant. 



7. If a fresh green leaf of Oxalis acetosella is exposed to an intense light 

 concentrated upon it by a lens, as in Pringsheim's experiments, the bleached 

 chlorophyll gives an aldehyde reaction when placed in Schiff's solution. If 

 the leaf contains abundance of starch, it may, after the action of the 

 intense sunlight, be placed in a solution of potassium iodide, when the 

 oxidising agent set free from the chlorophyll will liberate the iodine, and 

 the starch grains will be coloured blue. The experiment is not an easy one 

 to perform, as it is so very difficult to hit just the right moment to stop the 

 bleaching, in order to get the potassium iodide reaction. See also the 

 experiments on Laminaria. 



8. The decomposition of chlorophyll with the production of aldehyde and 

 peroxide takes place just as readily in the absence of carbon dioxide as when 

 carbon dioxide is present. My experiments show that carbon dioxide is not 

 used up in the process even when present in considerable quantities. Carbon 

 dioxide is not necessary therefore to the production of the aldehyde. 



9. The photo-decomposition of chlorophyll takes place only in the presence 

 of oxygen. Oxygen is used up in the process. If sufficient chlorophyll is 

 present, all the oxygen in the air in contact with the chlorophyll is absorbed. 

 Chlorophyll may be used instead of caustic potash and pyrogallol in the 

 analysis of air. 



10. Chlorophyll is slowly oxidised in the dark by a solution of hydrogen 

 peroxide. In the light the action is more rapid, but not more so than when 

 light acts on chlorophyll in the presence of oxygen. A rapid oxidation of 



