48 Carbon Assimilation. 



2. The phytol content should be one-third of the molecule. 



3. The chlorophyll must contain no yellow pigments. On 

 saponification as described in experiment 6, the ether layer must 

 remain colourless. 



4. By saponification with alkali, the brown phase must appear 

 (experiment 4) showing that the chlorophyll is not allomerised. 



5. Phytochlorin e and phytorhodin g must be given as 

 dissociation products (experiment 8). 



6. In solution the chlorophyll must give the same spectrum 

 as leaf extracts (showing theie is no phseophytin present which 

 would give absorption bands before the line E and between the 

 lines E and F). 



We have earlier referred to Etard's work in which the existence 

 of a huge number of chlorophyll substances is asserted. There 

 has now recently appeared a paper by Albert and Alexandre Mary 

 (1915) in which the authors claim to have synthesised chlorophyll 

 from nitrous oxide and aniline. It is indeed surprising that these 

 workers, as the result of the synthesis of a substance with a green 

 colour and a complex absorption spectrum, should put forward 

 conclusions so completely at variance with Willstatters work. But 

 perhaps these authors have as much justification for their conclusions 

 as Ewart (1915) who from the observation of a substance with a 

 yellow colour and a simple absorption spectrum possessed by 

 hundreds of substances, deduces the presence of xanthophyll in 

 his preparations. It is perhaps significant that the " pure xantho- 

 phyll " extracted by Ewart should have properties different from 

 Willstatter's. 



The conclusions of Albert and Alexandre Mary and of Ewart have 

 perhaps as sound a basis as that of Wager (1914), who is of opinion 

 that chlorophyll is an auto-oxidisable substance which " in fact could 

 replace pyrogallol in the quantitative estimation of the oxygen in 

 the air." The simple phase test described in experiment 4 in 

 section E of this chapter would have shown in this author's 

 chlorophyll, the presence of the yellow pigments, which are of 

 course autoxidisable (cf. experiment 6). 



It may be well here to point out that Willstatter's researches 

 only confirm the observations of the English physicist G. G. Stokes, 

 whose work is mentioned by Willstatter with much respect. A few 

 quotations from Stokes' work will show how near he came to the 

 truth. In a paper published in the Proceedings of the Royal 

 Society of London for 1864 he writes, '' I find the chlorophyll of 



