Carbon Assimilation. 
95 
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 there is no phaeophytin present which 
would give absorption bands before the line E and between the 
lines E and P). 
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 Willstatter’s 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 
