ASSIMILATION OF FORMALDEHYDE 59 



FORMATION OF FORMALDEHYDE. 



Formaldehyde, as is well known, is poisonous, so that, if 

 formed, it must be polymerized before it has time to injure 

 the protoplasm, and experiments have shown that, in certain 

 conditions, formaldehyde may be made use of by the plant. 

 Thus Bokorny * showed that Spirogyra in the absence of 

 carbon dioxide can make starch when supplied with a compound 

 of formaldehyde and sodium hydrogen sulphite ; also Tre- 

 boux f and Bouilhac have stated that Elodea, Sinapis, and 

 certain Algae can form starch in the dark when supplied with 

 dilute (-0005 per cent.) solutions of formaldehyde. 



Grafe X found that green seedlings grown in the light, in an 

 atmosphere free from carbon dioxide and containing not more 

 than I *3 per cent, of formaldehyde vapour showed a greater 

 increase in growth and in dry weight as compared with the 

 controls. These results were corroborated by Baker,§ who 

 concluded from most carefully controlled experiments that 

 formaldehyde could be assimilated to a certain extent in the 

 light, but not in the dark, in an atmosphere void of carbon 

 dioxide. 



Jacoby || compared the dry weights of starch-free leaves 

 of Tropceolum, grown in an atmosphere lacking carbon di- 

 oxide, with and without the addition of gaseous formaldehyde. 

 Those treated with formaldehyde were more green and showed 

 an increase in dry weight varying from 17 to 5-4 per cent, 

 over the controls. He concluded that in all probability not 

 only was the formaldehyde fixed, but underwent a conden- 

 sation similar to that formulated by Willstatter and Stoll ; 

 in other words, formaldehyde is an intermediate product in 

 carbon assimilation. 



Bodnar, Roth and Bernauer ^ similarly found an increase 

 in the dry weight and carbohydrate content of leaves exposed 



* Bokorny : " Biol. Zentrbl.," 1897, 17, 1 ; 1916. 3 6 > 3 8 5 ; " Ber - deut - 

 chem. Gesells.," 1891, 24, 103. 



t Treboux : " Flora," 1903, 9 2 > 49- 



% Grafe : " Ber. deut. bot. Gesells.," 191 1. 29* 19- 



§ Baker : " Ann. Bot.," 1913, 27, 411. 



|| Jacoby : " Biochem. Zeit.," 1919. « OI » *• 



TI Bodnar, Roth and Bernauer : " Biochem. Zeit.," 1927, 190, 304. 



