ENERGY METABOLISM 433 



been found in Euglena graciUs}^^ S. C. Harvey"" found a 

 series of glycolytic enzymes in cell-free extracts of Trypano- 

 soma equiperdum. The work of R. W. McKee"^ established 

 that Plasmodiii772 gallinaceum contains enzymic systems which 

 catalyse the phosphorylation of glucose by means of ATP, 

 the splitting of fructose diphosphate into triose phosphates 

 and the oxidation of glyceraldehyde-3-phosphate to pyruvic 

 acid. In these organisms, too, the oxidative degradation of 

 pyruvic acid was superimposed on the fundamental glycolytic 

 mechanism in the course of their evolution. Their metabol- 

 ism seems to be of an aerobic nature at present but, as we 

 have seen, it is based on glycolytic mechanisms. 



Glycolytic mechanisms also form the basis of the metabol- 

 ism of another large group of heterotrophic organisms, the 

 fungi. It was, in fact, a representative of the lower unicellular 

 fungi (yeast) which served as the classical object for the study 

 of the chemical mechanism of alcoholic fermentation. In 

 other groups of fungi the energy metabolism is based on 

 glycolytic mechanisms, although many of these organisms 

 seem, at present, to be typical aerobes. The moulds, in par- 

 ticular, are of the greatest interest in this connection. They 

 are characterised by synthetic abilities peculiar among hetero- 

 trophs but they derive the energy needed for the synthesis 

 of various specific organic substances by heterotrophic means. 

 In them, as in bacteria and yeasts, the first stage in the 

 breakdown of organic substances is, as J. W. Foster rightly 

 remarked, a system of reactions similar to alcoholic fermenta- 

 tion, leading to the formation of pyruvic acid which later 

 undergoes oxidative transformation. 



The researches of S. Kostychev and others and also the 

 more recent work of H. Tamiya and Y. Miwa"' have demon- 

 strated the occurrence of alcoholic fermentation in various 

 species of Aspergillus under aerobic conditions. Other Japan- 

 ese workers (T. Takahashi, T. Asai and K. Sakaguchi,"^' "*) 

 obtained active preparations of the zymase complex from 

 Rhizopiis and isolated carboxylase from them. J. C. Wirth 

 and F. F. Nord"^ sho\ved that a cell-free juice obtained from 

 the mycelium of a Fusarium contained active zymase. 



According to the results of S. Kostychev and F. Black- 

 man,"® the systems whereby carbohydrates are broken down 



28 



