[Proc. Roy. Soc. Victoria, 30 (N.S.I, Ft. II.. 1918]. 



Art. XIX. — On ChloropJtyll, Carotin and Xanthopltyli, and 

 on the Production of Sugar from Fonnaldehyde. 



By ALFRED J. EWART, D.Sc, Ph.D. 



(Professor of Botany and Plant Physiology in the Melbourne 

 University and Government Botanist). 



[Read 13th December, 1917]. 



In a previous paper the theory was put forward that the produc- 

 tion of carbohydrates in plants did not take place by a direct 

 synthesis of carbon dioxide and water to form formaldehyde, and 

 then sugars by polymerization, but that the carbon dioxide and 

 water combined with the phytyl base of chlorophyll to form xantho- 

 phyll or carotin, and that this by photo-oxidation produced for- 

 maldehyde, reducing sugar and phytyl, the latter recombining with 

 the chlorophyll molecule. This would represent a change in which 

 chlorophyll played the part of an enzyme, requiring a supply of 

 energy in the form of light for its activity. This conclusion was 

 mainly based upon the facts that formaldehyde is produced by the 

 photo-oxidation of chlorophyll films in the presence or absence of 

 carbon dioxide, and that chlorophyll films in contact with water 

 saturated with carbon dioxide turn first yellow and then brownish 

 white, slowly in darkness and rapidly in light, while at the same 

 time they appeared to gain in weight and did not set free any 

 oxygen. 



In the earlier work I was able to extract small amounts of 

 xanthophyll from chlorophyll fibns decomposed by carbon dioxide 

 by treatment with potash and extraction with alcohol and separation 

 with ether. Hence the conclusion was made that an actual produc- 

 tion of xanthophyll had taken place. Jiirgensen and Kidd^i suggest, 

 however, that the chlorophyll films used might have contained 

 xanthophyll as an impurity, and they confirm Willstatter's^ state- 

 ment that the action of carbon dioxide on chlorophyll is due to its 

 removing magnesium, and converting the chlorophyll into phaeo- 

 phytin, which in the form of films is yellow in colour. 



On using chlorophyll separted from 80 per cent, acetone by 

 petrol ether, and removed from the latter, after washing, by the 



1 Proc. Roy. Soc, J.-inuary, 1917, p. 342. 



•2 Sitzungsb. d. Ksl. Press. Akad. der Wiss, 191fi, pp. 322, 544. 



