Theories of Willstdtter. i6i 



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 fai' 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 

 (tJbertrager), 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. 



