SELECTED PAPERS 



this area is indispensable to elevate microbiology from its status as a 

 largely descriptive branch of science to a higher plane, and equally 

 so to the application of microbiology to many situations. And I am 

 firmly convinced that only a close cooperation between microbiol- 

 ogists and accomplished chemists can lead to advances in this respect. 



Let me then first of all show you how the unity in the divergent 

 metabolic processes of the microbes finds expression in the fact that we 

 recognise in them the same general trends that have come to light as 

 a result of investigations of the metabolism of higher organisms. With- 

 out discussing this aspect in detail, the following remarks may serve 

 to illustrate this point. Studies of the metabolism of higher organisms 

 have unequivocally shown that one can always distinguish two types 

 of processes. Part of the foodstuffs is converted into cell materials, the 

 latter being used either for growth or for replacement of degenerated 

 cellular constituents. Another fraction of the food appears to owe its 

 significance largely to the therein accumulated chemical energy 

 which is unleashed by the living cell, thus enabling it to carry out 

 energy-requiring functions ; this part is ultimately degraded, generally 

 producing heat. These two processes are differentiated as assimilation 

 and dissimilation.* 



Doubtless the dissimilatory process is the more essential charact- 

 eristic of life. Whereas other typical vital phenomena, such as growth, 

 reproduction, internal or external motion, may frequently be lacking, 

 dissimilation is absent only in some stages of latent life, resulting, for 

 example, from desiccation. 



Consequently it had been established that in the case of higher or- 

 ganisms the perpetuation of life is tied to a continuous conversion of 

 chemical into other forms of energy, and Rubner demonstrated that 

 the first law of thermodynamics applies to the energy transformations 

 in the animal body, while Atwater showed this also for man. 



As far as the nature of the energy-providing reactions is concerned, 

 Lavoisier had already pointed to the significance of the respiratory 

 process, i.e., the slow combustion taking place in living organisms, 



* Perhaps the terms 'Bau-' and 'BetriebsstoffwechseP, customarily used in the 

 German literature, make for a clearer distinction. For a further consideration of 

 these problems see, e.g., M. Rubner, 'Kraft und Stoff im Haushalte der Natur' 

 (1909), and the chapter by C. Oppenheimer, 'Energetik der lebenden Substanz', 

 in his 'Handb. d. Biochemie d. Menschen u.d. Tiere', 2nd ed., Vol. II, p. 223, 1923. 



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