1656 



CHEMICAL PATH OF CARBON DIOXIDE REDUCTION 



CHAP. 36 



of the numerous tagged compounds obtained in their experiments with 

 C(14). The procedure consists in placing a drop of the cell extract (in 

 aqueous alcohol or acid) in one corner of a sheet of filter paper, letting it 



Fig. 36.13. Scheme of paper chromatography of photosynthetic products (after 

 Calvin 1950). The coordinates, taken from a large number of radiograms, were 

 plotted by using serine and alanine as reference points. PGA, phosphoglyceric 

 acids; HMP, hexose monophosphates; HDP, hexose diphosphates; A, B, C, 

 unidentified sugar phosphates (for subsequent identification, see section 7); 

 D, unidentified compound containing glucose and a glucose phosphate (for subse- 

 quent identification, see section 10). 



dry and then allowing a solvent to pass slowly through the paper (which, 

 for this purpose, is suspended vertically from a trough containing the 

 solvent). The solvent moves the various constituents out of the original 

 spot for different distances down the sheet. The sheet can then be dried, 



