388 THE FIRST ORGANISMS 



in moulds. In some bacteria, on the other hand, this efficiency 

 is incomparably less and this is associated with incomplete 

 co-ordination of the various links of their chains of energy 

 metabolism. 



The energy metabolism of the primaeval organisms must 

 certainly have been at a still lower level of development. The 

 commencement of this metabolism must, however, have 

 taken place in the very early stages of the evolution of our 

 original systems as the only easily mobilised sources of energy 

 available to them were organic compounds which entered 

 the system from outside. However, if the energy contained 

 in these substances was to be released, they had to be broken 

 down in some way. At first this breaking down took many 

 forms and followed various paths and its efficiency must 

 therefore have been very low. 



Later, however, selection led to the formation of several 

 standard paths which formed the basis of the energy exchange 

 of all living things without exception. The earliest reactions 

 in the process of glycolysis, in particular, seem to constitute 

 such paths. They have been found in all organisms where 

 they have been looked for. 



As we saw above, the definite organisation of the network 

 of metabolic reactions also forms the basis for the synthesis 

 of all the substances formed in living matter. This may be 

 demonstrated above all by the origin of the property which 

 first Pasteur^^ and then Vernadskii®® considered to be one 

 of the most characteristic features of life, namely, the asym- 

 metry of protoplasm. 



What is the cause of this asymmetry? Why is there only 

 formed in living protoplasm one particular optical configura- 

 tion of amino acids and other similar compounds? 



In Chapter V we indicated that in the original solution of 

 organic substances the action of circularly polarised light or 

 selective synthesis on the surfaces of quartz crystals could 

 have led to the appearance of a certain dissymmetry, some 

 predominance of the dextro or laevo antipodes of particular 

 compounds. This original asymmetry may have formed the 

 basis for the asymmetry of all later organic formations. 



It is generally supposed that one molecule with a particular 

 optical configuration gave rise to another exactly similar 



