150 Mr. E. H. Acton. Jhe Assimilation of Carbon 



" The Assimilation of Carbon by Green Plants from certain 

 Organic Compounds." By E. Hamilton Acton. M.A., 

 Eellow of St. John's College, Cambridge. Communicated 

 by W. T. Thiselton Dyer, C.M.G., F.R.S. Received April 

 20 —Read May 16, 1889. 



The recent synthesis of a true glucose (" acrose ") by Fischer and 

 Tafel,* from acrolein (acrylic aldehyde) and also from glycerin,f in 

 conjunction with the additions to our knowledge of the constitution 

 of dextrose and lsevulose by Kiliani,J &c, suggests fresh attention to 

 the " aldehyde theory " regarding the synthetical formation of carbo- 

 hydrate in green plants. 



It is now widely believed by vegetable physiologists that a glucose 

 is produced in the first instance from C0 2 and H 2 0, but the nature 

 of the intermediate changes is still uncertain. The experiments 

 described in this paper were commenced to ascertain whether starch 

 can be produced in the assimilating cells of a green plant by sup- 

 plying it with acrolein or closely related bodies, and subsequently 

 extended to other organic compounds related to carbohydrates. 



The well-known theory§ that formic aldehyde (HCOH) is first 

 produced from C0 2 and H 2 0, and then becomes polymerised to 

 glucose, has not yet received any direct experimental proof, although 

 it is stated by Reinke|| that formic aldehyde has been detected in the 

 product obtained by distilling the leaves of several plants with water. 



The artificial polymerisation of formic aldehyde appears to yield a 

 complex mixture of aldehyde and ketone alcohols, w r hich has been 

 variously described as methylenitan, formose, pseudo-formose, &c. 

 Quite recently Fischer^" and Loew** have independently stated that a 

 small quantity of a true glucose can be proved to occur in " formose " 

 by the pheuylhydrazine reaction. ft According to Loew this polymeri- 

 sation only occurs with dilute solutions of the aldehyde, and better 

 with PbO or Pb(OH) 2 than Ca(OH) 2 . 



Loew supports the view that formic aldehyde is formed as an 



* ' Berichte der Deutsch. Chem. Gesell.,' 1888, pp. 1088, 2566. 

 f Ibid., p. 3384. 

 X Ibid., p. 22.1. 



§ Compare Vines, ' Physiology of Plants,' Lecture 9, Cambridge, 1886. 

 || ' Berichte der Deutsch. Chem. Gesell.,' 1881, p. 2144. 

 % Ibid., 1889, p. 359. 

 ** Ibid., 1889, p. 470, 



ft For an account of the views as to nature of formose, pseudoformose, methyl- 

 enitan, &c, generally held before the publication of Fischer and Loew's papers 

 referred to above, see Tollens, ' Handbuch der Kohlenhydrate Sec. IT, 250— 

 252, &c. Breslau, 1888. 



