420 BOTANICAL GAZETTE [NOVEMBER 
in true solution in ether or alcohol, and in colloidal solution, as watery acetone. 
The former is exceedingly stable toward alkali and acids, while the latter is 
stable toward alkali, but so sensitive to acids that CO, splits it readily into 
Mg(H CO,).and phaeophytin (C,;H;,0,;N,Mg+ 2CO.+ 2H.0—> Mg (H CO;)2+ 
C;;H,,O;N,). Such a solution loses half of its metal in 4 days when treated 
with 5 per cent CO.. Before the Mg is displaced, however, an intermediary 
dissociable compound is formed, maximum in quantity at low temperatures. 
The time factor is much more active in the chlorophyll @ than in the other | 
compound. Leaves are thus endowed with a mechanism for storing CO, 
much as the blood is. Instead of the albumin of the serum holding the CO,, 
however, it is possible that carbamino compounds of amino acids or proteins 
are involved here. This dissociable CO, chlorophyll compound may take up 
the light energy and give an isomer of greater energy content which is suitable 
for spontaneous decomposition. This may be the substance that is split 
enzymatically, 
Interesting i in this connection is a paper by SporHR.? In an excellent 
critical review of the literature he points out certain facts that seem to weigh 
heavily against the theory of formaldehyde as an intermediate product in 
photosynthesis and in favor of formic acid as such. Discussing the work of 
Logs with CO, and silent discharge, USHER and PRIESTLY, BERTHELOT and 
GuaDEcHow, and Srockiasa with CO, and ultraviolet light, he concludes 
that we have no clear record of a reduction of carbonic acid on its salts to 
formaldehyde which is applicable to the process going on in the plant leaf 
or is compatible with conditions met in the leaf. Nrr’s success in condensing 
formaldehyde to sugar might be of significance, he believes, if an enzyme 
could be substituted for the strong alkali and high temperature used. WILL- 
STATTER’s work shows clearly that enzymes and the colloidal state of chloro- 
phyll and the plasma are important factors in this process. It also shows 
that the greatest progress in physiology is to be made by work that combines 
chemical and physiological technique judiciously. SporHR finds that while 
formaldehyde yields sugars in light or dark only in the presence of relatively 
strong bases, such as do not exist in the plant, CO, in aqueous solution in ultra- 
violet light produces formic acid as the only product, and exposure of this to 
ight or ultraviolet light gives a substance having several properties and the 
nutritive value of sugars. He believes formic acid may well be the intermediary 
product of photosynthesis, as suggested by ENGELMANN, especially since organic 
acids in sunlight give rise to formaldehyde and vice versa. The formaldehyde 
reported in green leaves, as shown by WaGER and WARNER, may be due to 
the activity of light on chlorophyll and other plant substances. SPOEHR feels 
that the findings of Grare, BoKorny, and Baker, that formaldehyde is assimi- 
lated by the green leaf only in presence of sunlight, introduces an entirely new 
2Spormr, H. A., The ngs of photosynthesis in the light of some new facts. 
Plant World 19: ote 1916, 
