384 Mr. C. H. Warner. Formaldehyde as an 



process hydrogen peroxide oxidises chlorophyll with the formation of 

 formaldehyde among other colourless products, and in support of this view it 

 may be mentioned that the aldehyde is formed in the dark when films of 

 chlorophyll extract are immersed in hydrogen peroxide solution. 



Whether these transformations play any important part in the metabolism 

 of the plant remains to be seen. Possibly some group in the chlorophyll 

 molecule suffers decomposition, thereby liberating formaldehyde, and is then 

 regenerated under the action of carbon dioxide, but the occurrence in the 

 tissues of catalases, which may partially or wholly prevent any such oxidation 

 in the living leaf, must be borne in mind. 



The observations of Bach and Chodat,* which appear to have escaped 

 attention in this relation, to the effect that plants (in their experiments, 

 fungi) are able to live in a medium containing 0"68 per cent, of hydrogen 

 peroxide, may be found to have an important bearing upon the subject under 

 discussion. 



Experiments testing the possibility of the photo-synthesis of formaldehyde 

 by colloidal chlorophyll in the presence of plant catalases and other enzymes, 

 i.e. under conditions more nearly approaching those of assimilating tissues, 

 might yield interesting results. 



Films of Carotin Extract. 



A few preliminary experiments have been carried out with films of 

 carotin extract. Carrots were extracted with hot alcohol and the liquid was 

 shaken with light petroleum, the petroleum solution being then allowed to 

 evaporate on glass plates. AVhen such films are exposed to air they become 

 bleached both in the light and in the dark,f and formaldehyde is produced in 

 both cases. A carotin film exposed to light in a sealed tube containing moist 

 carbon dioxide free from oxygen was not bleached and showed no evidence 

 of formaldehyde development, while a similar film exposed over potash solution 

 beside the first for the same time became completely bleached and gave a 

 decided reaction for the aldehyde. 



Experiments are now being arranged by means of which it is hoped that 

 the formation of hydrogen peroxide by chlorophyll and possibly by carotin 

 and other similar substances, and their derivatives, may be more or less 

 quantitatively investigated. 



Thus far the experiments have been confined to crude chlorophyll- and 



* ' Biochem. Centralblat.,' vol. 1, p. 417 (1903). 



t Compare Willstatter and Escher, ' Zeit. Phys. Chem.,' vol. 64, p. 47 (1910). 



