CHAPTER IX 

 METABOLISM 



1. Energy Requirement by Extremely Primitive Organism^ 



The constant renewal of substances and energy is often believed 

 to be the essential feature of life, and consequently life is sometimes 

 compared to a fountain or a flame, which has a constant shape but 

 whose component is being continuously renewed. 



Such a view, however, may be erroneous. Viruses exhibit every 

 principal character of organisms, but there is no proof of metabolism 

 involved in them ; all the attempts by a number of workers to de- 

 monstrate the metabolism in viruses have been failed. Furthermore, 

 it seems possible to present the evidence that no significant energy 

 may be required even for the multiplication of viruses. Thus, it is 

 generally recognized that viruses can multiply in dead cells. For 

 example, as already stated in Chapter VII, Part II, influenza virus 

 can proliferate in chick embryos killed by the exposure to a low tem- 

 perature, and phage multiplies in bacteria killed by various agents, 

 such as penicillin, mustard-gas, and ultraviolet ray. 



In these cases, killing means to render them non-viable. For the 

 proliferation of cells high metabolism of both substances and energy 

 should be necessary, and accordingly viability may be lost by the 

 destruction of the metabolic systems. The multiplication of viruses 

 in the cells devoid of the reproducing faculty, therefore, may indicate 

 that at least the energy so great as required for the multiplication of 

 cells is not necessary for the rearrangement of protoplasm structure 

 to answer the pattern of the virus. On the one hand, it is known 

 that neither heat is produced nor energy is consumed when a protein 

 is affected by proteolytic enzymes. On the other hand, multiplication 

 of a virus may be looked upon only as the structural change of 

 protoplasm protein by the action of a virus, which can be regarded 

 as a special type of enzymes. Even in this respect it seems also pro- 

 bable that no peculiar energy is required for the multiplication of 

 viruses. 



In this connection it should be mentioned that there are numerous 

 facts suggesting that virus multiplication is closely connected with the 



