ORIGIN OF THE FIRST ORGANISMS 387 



oxidation or degradation of sugar, this substance is not con- 

 verted into its end products all at once, but by gradual stages. 

 This sort of organisation not only gives rise to the possi- 

 bility of overcoming the high barrier of the energy of activa- 

 tion of the reaction of the oxidation of sugar by atmospheric 

 oxygen at ordinary temperatures ; it also allows the living 

 cell to make rational use of the energy, which is not liberated 

 all at once but gradually in separate small portions. We have 

 already seen from the example of the Krebs cycle that this is 

 ^vhat actually takes place. At definite points on this cycle 

 energy is liberated, whereupon it is immediately taken up 

 to form ATP, or some other compound with high-energy 

 bonds, which may be used for carrying out syntheses or for 

 performing work necessary for life." 



The more highly organised the metabolism and the better 

 the co-ordination between the separate reactions of which it 

 is made up, the higher will be the coefficient of useful work. 

 Direct observations on various representatives of the living 

 world show that in poorly organised living things, standing 

 at the bottom of the evolutionary scale, the reactions of the 

 energetic network are not always strictly co-ordinated. A 

 considerable amount of the energy liberated in them is there- 

 fore dispersed aimlessly and cannot be used for vital processes, 

 in particular for the formation of new living material and 

 the growth of cells. *^ When, on the contrary, the rates of 

 the reactions are strictly co-ordinated, when they are, so to 

 speak, accurately adjusted to one another, this w^aste of energy 

 is cut down substantially. In such a case a relatively small 

 access of the organic materials serving as the source of 

 nourishment leads to considerable growth of the living thing. 



This may be seen in moulds, for example, where the 

 metabolism is very highly organised. H. Tamiya" in par- 

 ticular obtained the following data for Aspergillus oryzae : 

 for the formation of i g. of mycelium the mould assimilated 

 1 467 g. of glucose. The efficiency of the utilisation of energy 



was thus ^ :^, — z- x 100= 87 per cent. This effici- 



1-467 X 3-76 kcal ' ^ 



ency is exceptionally high and other authors®* assign a loAver 



percentage value to it, but even they obtain very high values 



