1909.] Formatio7i of Formaldehyde in Green Plants. 229 



described below, yielded by chlorophyll, can only be due, therefore, to 

 formaldehyde. 



Presence of Formaldehyde in Chlorophyll. 



Grass was always employed as a source of chlorophyll in the following 

 tests. It was first washed with warm water, and no formaldehyde was ever 

 detected in the aqueous washings. It was then pressed by hand, to free it, 

 as completely as possible, from the wash water, and extracted with methylated 

 spirit. After standing for some time (generally over-night) the alcohol was 

 filtered off on a Buchner funnel. Several times the alcoholic extract was 

 tested directly for formaldehyde. It was evaporated to dryness, and the 

 residue warmed with 10 c.c. of water and 2 c.c. of the phenylhydrazine 

 reagent. The ferricyanide reagent and hydrochloric acid were then added. 

 In no case did a colour develop. If, however, the alcohol were evaporated off 

 in vacuo, and the residue taken up by ether, and the ether were then 

 distilled off, a residue was obtained, which in certain cases gave a positive 

 result when examined for formaldehyde. The reason for this behaviour was 

 found to be due to the fact that the alcoholic extract contained substances, 

 probably sugars, which interfered with the formaldehyde reaction, for after 

 evaporating off the alcohol in vacuo at about 40° and extracting with 

 ether, a residue insoluble in the latter solvent was obtained, which readily 

 reduced Fehling's solution. For this reason, the chlorophyll must always be 

 purified by solution in ether before carrying out the test. 



In most of the samples of chlorophyll examined, formaldehyde was found. 

 These were collected, however, during the summer season, after a long spell 

 of daylight. A sample collected early on a foggy morning, after little sun- 

 shine, contained only a trace of formaldehyde. 



In carrying out the test for formaldehyde with chlorophyll, the latter 

 had been extracted with alcohol ; this extract had been evaporated to 

 dryness, and the residue thus obtained extracted with ether. The ethereal 

 solution was itself evaporated to dryness. The formaldehyde reaction was 

 then only obtained after allowing a film of the chlorophyll* obtained by 

 evaporating the ethereal solution on a glass plate, either to stand for some 

 time with a cold mixture of 10 c.c. water and 2 c.c. of a 1-per-cent. phenyl- 

 hydrazine hydrochloride solution, or by warming the same mixture for a few 

 minutes to 100° C. On addition of the ferricyanide solution and acid, the 

 characteristic colour then developed. 



The fact that formaldehyde coidd be detected in chlorophyll after repeated 

 evaporation of the solutions, and that warming or standing with the phenyl- 



* The crude product thus obtained is hereafter called chlorophyll, and is probably a 

 mixture of several substances. 



