8 H. A. SPOEHR 



As was found by the earlier workers, and noticed by Stoklasa 

 himself, potassium bicarbonate is reduced to formic acid by 

 nascent hydrogen in the dark. Hence there is no reason for as- 

 suming, that the formic acid in his experiments is a product of the 

 action of the ultraviolet light. Again, Stoklasa concludes from 

 the fact that formaldehyde plus oxygen in the light yields formic 

 acid, that formic acid with hydrogen must yield formaldehyde. 

 There are absolutely no experiments by Stoklasa or any one else 

 to verify this latter statement. The writer may here be per- 

 mitted to state that in connection with his experiments on the 

 photolysis of certain plant acids, he has tried for the past three 

 years to obtain formaldehyde from formic acid in the light, 

 under a great variety of conditions of concentration, intensity 

 of illumination, etc., but has never been able to accomplish this 

 directly. 



Passing on to the physiological discussion, the question im- 

 mediately arises what is the source of the nascent hydrogen neces- 

 sary for the reduction? The amount of hydrogen necessary un- 

 der the Stoklasa theory is by no means insignificant, probably 

 at least two volumes of hydrogen to one of carbon dioxide. 

 Stoklasa^^ theoretically derives this hydrogen from the breaking 

 down of sugars by glucolytic enzymes. While it is probable 

 that some hydrogen is formed in this latter process, there is no 

 evidence that hydrogen is formed in such quantities. 



It can therefore be safely said, that as yet we have no clear 

 record of a reduction of carbonic acid or its salts to formaldehyde 

 which could be applied to the process going on in the leaf, and is 

 compatible with our present conceptions of the conditions existing 

 in the chlorophyllous cell. 



Turning now to the second theme, the detection of formalde- 

 hyde in illuminated leaves: Curtius and Franzen,^* report that 

 they obtained formaldehyde from beech leaves by distillation 

 with steam. Their methods of analysis, however, have been se- 



" Stoklasa, J., und Zdobnicky, W., Ueber die Glukolytische Enzyme in den 

 Pflanzenorganismen. Zeitschr. f. physiol. Chem. 50:303-60, 1907. 



1^ Curtius, und Franzen, H., Die Chemische Bestandteile grilner Pflanzen. 

 Ann. Chem. (Liebig) 390:89-121, 1912. Ibid, 404: 93-130, 1914. 



