Oxidation Product of Chlorophyll Extracts. 385 



carotin-containing extracts prepared as described ; it is intended shortly to 

 investigate similarly the behaviour in this relation of the isolated leaf pigments 

 and some of their derivatives. This is especially important in view of the very 

 recent work of Spoehr,* who has shown that various acids which occur in the 

 leaves of succulent plants may be decomposed by light, yielding formaldehyde. 

 A decomposition such as this would well account for the formaldehyde which 

 Kimpflinf found in the leaves of Agave mexicana. Again, NeubergJ has shown 

 that a number of substances, under the action of light and in the presence of 

 an optical sensitiser, form this aldehyde ; indeed it is probable that there are 

 in the plant many substances which under suitable conditions can give rise to 

 formaldehyde or to hydrogen peroxide. 



Summary. 



1. The photo-chemical development of formaldehyde, which has been 

 observed to occur in films of chlorophyll extract in contact with air containing 

 carbon dioxide and water vapour, is due solely to the decomposition of the 

 films under the action of the oxygen of the air. No formaldehyde is produced 

 when such films are illuminated in a moist atmosphere of nitrogen or of 

 carbon dioxide. There is thus at present no evidence for the photo-synthesis 

 of the aldehyde from carbon dioxide by chlorophyll outside the plant. 



2. The above oxidation is accompanied by the bleaching of the films, and 

 appears to be effected by the action of hydrogen peroxide, in the formation of 

 which carbon dioxide can have no share, since there is no decolorisation in 

 moist carbon dioxide free from oxygen. 



3. The bleaching (oxidation) of films of carotin extract is also associated 

 with the production of formaldehyde. 



Since the experiments are being continued along the lines indicated, a full 

 discussion of the results obtained is for the present deferred. In conclusion, 

 the author wishes to express his indebtedness to Prof. V. H. Blackman, 

 at whose suggestion this work was undertaken, for his very valuable help 

 throughout the course of the research. 



* ' Biochem. Zeitschr.,' vol. 57, p. 95 (1913). 

 t ' Comptes Kendus,' vol. 150, p. 529 (1910). 

 % ' Biochem. Zeitschr.,' vol. 13, p. 305 (1908). 



