110 STUDIES OE PHOTO-SYNTHESIS 



to be possible by supplying formaldehyde when carbon dioxide is 

 shut off to make green cells grow and flourish. 



Many attempts have been made in this direction, but have all 

 failed, or given very dubious results, because of the highly poisonous 

 action of formaldehyde. Formaldehyde, if and when formed in a 

 green cell, must immediately be condensed into a sugar or some 

 other non-poisonous organic compound or the cell will perish ; there 

 is, accordingly, no demonstrable amount of formaldehyde in the 

 cell. If now it be supposed that the cell in sunlight is always pro- 

 ducing formaldehyde which at once is changed into something else, 

 then in order to mimic this process experimentally a system must be 

 invented in which formaldehyde at minute concentrations is fed in 

 slowly, at a rate not greater than the cells of the system can assimilate 

 it. The formaldehyde must not be added to the solution in which 

 the cells are growing at the outset, for any quantity detectable 

 afterwards by increase in the cells would kill them. It must be 

 continuously and very slowly administered as a dilute vapour. 



Two glass tubes of about 0-5 cm. in diameter, each about 18 cm. 

 long, were sealed at the one end so as to make narrow test-tubes. 

 One of these was about half filled with formol (40 per cent, form- 

 aldehyde), the other with methylic alcohol. The tube containing 

 formol was placed slanting in bottle No. 9, the closed end resting 

 on the bottom of the bottle, and the upper end on the inside of the 

 neck close beneath the glass lid. The tube containing methylic 

 alcohol was similarly placed in No. 11. Both glass lids were tightly 

 screwed down to exclude atmospheric carbon dioxide. The nutrient 

 solutions contained nitrite as well as phosphate. The two flasks 

 were kept exposed to light, and after some weeks there were good 

 growths obtained in both. 



Judged from the amounts of nitrogen, there was a fixation of 

 3-5 mgrms. in the formaldehyde nutrition, and a fixation of 

 7-1 mgrms. in the methylic alcohol nutrition. To get from the 

 nitrogen fixation to the carbon fixation these figures must be 

 multiplied by a factor of at least 8, for the weight of carbon even in 

 protein is treble that of the nitrogen, and there is carbon but no 

 nitrogen in carbohydrates and fats. If this factor be applied there 

 is a fixation of 28 mgrms. of carbon from formaldehyde (=70 mgrms. 

 of formaldehyde) and of 56-8 mgrms. of carbon from methylic alcohol 

 (=151 mgrms. of methylic alcohol). The bottles Nos. 10 and 12 

 were a similarly conducted experiment, but without available 



