Carbon Assimilation. 
85 
metals, which they contain in the form of complex organic com¬ 
pounds. They differ chemically by the nature and function of the 
metal. The life of chlorophyll-containing plants is mainly 
synthesizing. While biology so far has been incapable of giving 
an explanation, the proof of the presence of magnesium in 
chlorophyll from all classes of plants allows the conclusion to be 
drawn that the assimilation of carbon dioxide is a reaction of the 
basic metal magnesium, which as well known exhibits great power 
of combination in complex organic molecules. The intake of carbon 
dioxide is probably a process similar to the Grignard synthesis. 
The disintegrating (abbauende) life of blood-containing animals 
requires for the oxidation of organic substances a carrier 
(Ubertrager), particularly iron, which, perhaps, on account of its 
oxidisability, combines loosely with the oxygen and transports it to 
a series of comparatively unstable compounds. Besides along these 
main roads natural development along less important roads and 
blind alleys may have succeeded in the formation of organisms 
which live by the action of other metals, e.g., copper, and which 
have shown themselves less capable of evolution. 
It is thus seen that there are essentially two kinds of life, 
which develop along parallel lines of evolution: synthesizing life 
with magnesium, and disintergrating life with iron, i.e., reducing 
life and oxidising life.” 
We have given a translation of Willstatter’s views on life in 
full. Plant physiologists will probably appreciate them without any 
comment from us. But we may draw attention to the fact that 
some people regard iron as a synthesizing agent in life, for instance, 
B. Moore (1914), who has elaborated a theory of carbon assimila¬ 
tion on this view. We do not deal at length with this theory as it 
involves the formaldehyde hypothesis, and is open to all the 
criticisms that may be levelled against that hypothesis and a good 
many more. Moore, besides attempting to explain life as it is at 
present, utilises his hypothesis for speculation on the origin of life. 
It may be well to keep in mind the remarks of Darwin in a letter writ¬ 
ten in 1863, “ It is mere rubbish, thinking at present of the origin of 
life; one might as well think of the origin of matter.” (See Darwin, 
1902, p. 257.) 
Willstatter, it will be observed, attempts to utilise the work of 
Grignard in justification of the part he attributes to magnesium in 
his theory. Grignard however rightly points out how very different 
are the conditions in any Grignard synthesis from those in the plant. 
