1^0. 647] PROGRESSION OF LIFE IN THE SEA 



483 



Heilbron, and Barker," extending and correcting previous 

 work by Benjamin Moore and Webster,*' have shown that 

 light of very short wave-length {\ = 200 ^^fji) , obtained 

 from a mercury-vapor lamp, acting upon water and car- 

 bon dioxide alone, is capable of producing formaldehyde, 

 with liberation of free oxygen. Light of a somewhat 

 longer wave-length (A ==290/*/*) causes the molecules of 

 formaldehyde to unite or polymerize to form simple 

 sugars, six molecules of formaldehyde, for example, uni- 

 ting to form hexos6. The arresting fact brought out in 

 these researches is that the reactions take place, under 

 the influence of light of appropriate wave-lengths, with- 

 out the help of any catalyst, either organic or inorganic. 

 Where a source of light is used which furnishes rays of 

 many wave-lengths, the simple reaction of the formation 

 of formaldehyde is masked by the immediate condensa- 

 tion of the formaldehyde to sugar, but this formation of 

 sugar can be prevented by adding to the solution a sub- 

 stance which absorbs the longer wave-lengths, so that 

 only the short ones which produce formaldehyde are able 

 to act. 



When the formation of sugars is postulated, the intro- 

 duction of nitrogen into the organic molecule offers little 

 theoretical difficulty ; for not only has Moore ' shown that 

 nitrates are converted into the more chemically active 

 nitrites under the influence of light of short wave-length, 

 but he maintains that marine algaB, as well as other green 

 plants, can under the same influence assimilate free nitro- 

 gen from the air. Baly ^ also has succeeded in bringing 

 about the union of nitrites with active formaldehyde in 

 ordinary test-tubes by subjecting the mixture to the light 

 of a quartz-mercury lamp. 



It will be admitted that these three reactions: (1) the 



5Journ. Chem. Soc, London, Vols. 119 and 130, 1921, p. 1025. Nature, 

 Vol. 109, 1922, p. 344. 



«Proc. Roy. Soc. B., Vol. 87, p. 163 (1913), p. 556 (1914); Vol. 90, p. 

 168 (1918). 



Troc. Boy. Soc. B., Vol. 90, p. 158 (1918); Vol. 92, p. 51 (1921). 

 8 Baly, Heilbron and Hudson, Joum-. Chem. Soc, London, Vols. 121 and 

 122, 1922, p. 1078. 



