208 Alfred J. Ewart: 



phyll. and the carbohydrates are probably as much a product of 

 phuto-aiialysis as of photo-synthesis. So long as the supplies of car- 

 bon dioxide and light energy are in a certain ratio of equivalency, 

 and the products are continually removed, the chlorophyll is exter- 

 nally stable, though internally labile. In other words, it behaves 

 as an enzyme, and, according to whether we emphasize the source of 

 energy or of material, it might either, to coin a term, be regarded 

 as a lytase enzyme or a carboxidase enzyme. 



The following equations are put forward not as representing 

 established facts, but as indicating how chlorophyll could act as a 

 photic or lytase enzyme for the conversion of carbon dioxide and 

 water into carbohydrates. The chief difficulty in regard to them 

 is the very large mass reactions which they represent. 



(i.) 2C3,H„N,M<^ 



COOH 



COOOH,+ 36CO,+ 16H.p=.2C,oH,A + 440, 



+ 2C,iH,oN,Mg(COOH,) 



cooa„H,„ 



Amorphous chlorophyll 4- carbon dioxide and water would form xantho- 

 phyll (or carotin) oxygen and glaucophyllin. 

 (ii.) 2C4oH,„+24H.,0 + 8.0., 



= 2C,oH,,OH + 3CeHi,0s + 3aH,.A + 4CH.,0 

 Carotin (or xanthophyll) + water + oxygen 



=: Phytol + levulose + glucose + formaldehyde. 

 This reaction would take place in light with the aid of an oxidase 

 enzyme and the excess oxygen from (i.) escapes, 

 (iii.) 2C,„H,,0H + 2C,iH3oN,Mg(COOH,)-|-4C0.3 



j COOH 

 = 2C«in29N,Mg COOC H3 + 3.0,, 

 I COOC.,oH,, 



Phytol, glaucophyllin, and carbon dioxide form amorphous 

 chlorophyll and oxygen. 



This change would take place in the living plant with the aid of 

 light energy. It makes the total volume of oxygen exhaled equal 

 to the volume of carbon dioxide absorbed. 



This suggested cycle would indicate the enzymatic action of 

 chlorophyll in the presence of water, carbon dioxide and light, and 

 might serve as a basis for further investigation. Written in one- 

 line the equations would read : — 



40CO.,-f-40H,O + chloiophyll + light energy 



=3C6HiA + SCfiHiA + 4CH.,0 + 40. 0, + chlorophyll. 



