2 PHYSIOLOGY OF BACTERIA 



isms is more fit for this purpose than the lowest fungi 

 which Hve on dissolved food. That some of the human 

 physiologists do not agree entirely with this viewpoint, 

 may be seen from the following statement in Bayliss' 

 ^'Principles of General Physiology" (1924): 



''Without denying the great value of the comparative method in 

 ehminating merely incidental phenomena, it must be pointed out 

 that this very simplicity is, in the majority of cases, a disadvantage. 

 The same organ, or even cell, fulfils a variety of purposes which, 

 in the higher organisms, are relegated to distinct groups of cells. 

 Moreover, the size of the organism is of much importance. The 

 science of nutrition would be almost impossible without the larger, 

 warm-blooded animals. The advantage of the increased rate of 

 reactions, owing to the higher temperature, is not to be undervalued. 



The physiology of unicellular organisms, although of considerable 

 importance in special aspects, is not to be regarded as a ''general 

 physiology." Indeed, if the choice had to be made between the 

 investigation of simple or complex organisms alone, there is no doubt 

 that a much more general and fundamental body of doctrine would 

 be obtained from the latter." 



Of course, it would be ridiculous to try to belittle 

 the value of the physiology of man and of mammals 

 as a guide to the understanding of the functions of the 

 body of all kinds and types of animals and bacteria, for it is 

 quite evident that the original conception of the nutrition 

 of bacteria was based exclusively upon its analogy with 

 animal nutrition. There are, however, certain facts 

 which could not be observed in the highly specialized 

 physiology of animal tissues, consequently, new concep- 

 tions have been brought into general physiology through 

 the study of bacteria; e.g., the conceptions of anaerobio- 

 sis; of thermophilic organisms; of nitrogen fixation; of 

 fermenting endo-enzymes; the understanding of the 

 organic chemistry of alcoholic fermentation with its 

 intermediate stages; and a new understanding of the 

 laws of death. In fact, the conception of higher plants 



