352 The Physiology of Plants book hi 



Similar conditions appear to attend the utilization of 

 compounds of ammonia. In 1895 Kinoshita showed that 

 when germinating in darkness, barley and maize can make 

 use of ammonia, and a large formation of asparagin follows. 



Godlewski's suggestion of the two stages of protein con- 

 struction has received considerable support. The idea in 

 a somewhat more primitive form was not due to him, but, 

 as we shall see later, was advanced at least twenty years 

 earlier. He, however, gave it the force of his support and 

 based it on the evidence of his experiments. It appears 

 to lead to the view of a combination of amido-compounds 

 with carbohydrate to form protein, but many observations 

 are in conflict with so simple a hypothesis. Some experi- 

 ments made by Suzuki in 1898 showed that the presence 

 of sugar is necessary for the formation even of the amido- 

 compound asparagin from nitrates by etiolated plants. He 

 found, however, that protein can be formed in darkness 

 when nitrates and sugar are present. 



An experiment of Hansteen, made in 1896, has some 

 interest as bearing on the relative advantages of ammonia 

 and nitric acid as starting-points in the synthesis. He 

 found that Lemna minor can produce protein in the dark 

 if supplied with sugar and either sulphate or chloride of 

 ammonium, but not if nitrate is substituted for the latter. 

 There is, as we have seen, a good deal of evidence pointing 

 to an action of light during protein construction. As the 

 latter is a very complicated process, and as all its stages 

 are not equally affected, it will be convenient here to con- 

 sider the progress of research into the synthetic processes 

 and to return afterwards to the influence of light upon 

 them. 



Experiment upon the processes in question dates back 

 to about 1881, when Emmerling conducted a number of 

 researches upon Vicia Faba, which led him to the view that 

 the nitrates of the root are decomposed by organic acids 



