Photosynthesis 395 



is obtained in the gas phase. Vessels so prepared were illuminated * 2, 1, or 5 

 minutes and then, along with dark control vessels, immersed in hot water in order 

 to stop all enzymatic reactions and at the same time extract the soluble materials 

 from the cells. After centrifugation, the heated extracts were chromatographed in 

 two dimensions, and measurements were made with a Geiger counter. 



It can be seen from Table 3, first, that the amino acids, alanine and aspartic 

 acid, rapidly became radioactive— indeed, more rapidly than the phosphorylated 

 glyceric acid, contrary to previous reports in the literature for experiments of this 

 general type. Second, the table shows that aspartic acid and alanine become ra- 

 dioactive more quickly than glutamic acid, so that one can think that an alanine- 

 aspartic acid system enters before the glutamic acid System. Manometric experi- 

 ments alone have not as yet given any such indication, and one must wait until 

 combined radiometry, manometry, and bolometry have become so far developed 

 quantitatively that one can draw more certain conclusions. Radiometry alone has 

 already led to a multiplicity of errors. 



Summary 



With the establishment of conditions for optimum cukuring and measurement, 

 there is now final proof that in photosynthesis at high as well as low light intensities 



Table 2. Comparative action of fluoride on decomposition 

 of glutamic acid and on inhibition of photosynthesis. 



the light energy can be almost completely converted into chemical energy. There 

 is thus drawn to a close an investigation that was initiated many years ago in Berlin 

 in the Imperial Institute of Physics 9 . 



The second result is the establishment of a general physical mechanism of photo- 

 synthesis, involving an interplay between light energy and respiratory energy, and 

 therewith the Solution of the quantum problem in photosynthesis. 



The third result is the establishment of the function of Chlorophyll as a stoichio- 

 metric, chemically reacting component in photosynthesis. 



There remains the special chemistry of photosynthesis. In this still-unfinished 

 field of investigation, the latest discovery is the labile carbon dioxide of Chlorella, 

 connected with the decomposition and resynthesis of glutamic acid in living Chlo- 

 rella, and connected with the possible function of the amino acids, aspartic and 

 glutamic, in the binding and reduction of carbonic acid. The dissociating CO? is 

 bound by Chlorella only in the presence of O2 and of cellular glutamic acid. This 

 CO '2 is released if the oxygen pressure is lowered below 2 mm of water or if — in the 

 presence of oxygen — the glutamic acid is split in the living Chlorella, for example, 



