RECENT ADVANCES IN SCIENCE 



193 



degradation, since it may be precipitated from the solution 

 unchanged by the addition of alcohol or electrolytes. 



In a paper entitled " New Theory of Carbon Dioxide 

 Assimilation," Kogel {Zeitschr. wiss. Photochem., 1920, 19, 215) 

 suggests that the action of light is to cause the carbon dioxide 

 to combine with the hydrogen of water to form tetrahydroxy- 

 ethylene (I) as under : 



o = c = o 



+ 



H20 



O = C = O H,0 



HO— C— OH 



II 

 HO— ^C— OH 



(I) 



4-O2 



the tetrahydroxyethylene undergoes tautomeric change into the 

 ketonic modification (II), 



H 

 HO-C— O 



I ( 

 HO-C— O 



H 



(11) 



from which the common plant acids formic and oxalic could 

 be easily produced by simple fission, or the removal of two 

 atoms of hydrogen respectively. On the other hand, three 

 molecules of carbon dioxide would by this method produce 

 the compound (III), which by losing three oxygen atoms would, 

 after rearrangement, yield a molecule of glyceric aldehyde 

 (IV): 



H C = 



I 

 H C OH 



I 

 CHaOH 



(IV) 



(III) 



The obvious criticism of this theory is the readiness with which 

 oxygen or hydrogen atoms are dispensed with at will in order 

 to produce any compound desired by the propounder of the 

 theory. 



Langdon and Gailey (/. Amer. Chem. Soc, 1920, 42, 641) 

 reaffirm the observation previously made (loc. cit., 191 7, 39, 

 149) to the effect that the gas contained in the floaters of the 

 giant Pacific coast kelp Nereocystis leutkeana contains carbon 



