The Microbe as a Whole 7 



much more refined explanation. Even the mechanism of 

 enzyme action through electron transfer is by no means as 

 well understood as, for example, the reaction mechanisms 

 between diatomic molecules. Probably, more attention 

 gradually will be devoted to such problems, and as long as 

 microorganisms promise to be useful for the isolation of 

 hitherto unknown enzymes or for a more fundamental 

 study of the mechanism of enzyme action, it would be inde- 

 fensible to discourage the use of microorganisms in enzyme 

 studies. 



Nor am I concerned with the question of whether these 

 should properly be called biochemistry or microbiology; 

 I have little interest in definitions and delineations of fields 

 of scientific endeavor. But I should like to emphasize that 

 the microbe is potentially significant also for the study 

 of phenomena that are not directly associated with either 

 disease or enzymology, of phenomena that present prob- 

 lems far less clearly defined or definable but nonetheless 

 equally fascinating. Such problems can perhaps best be 

 indicated by referring to that realm of complexity of or- 

 ganization where a collection of chemical compounds ex- 

 hibits the properties of a living organism. Again, I shall 

 not attempt to define where the distinction between "liv- 

 ing" and "nonliving" should be drawn; in the long run 

 this may become the task for academicians desirous of 

 formulating a useful dictionary type of definition of these 

 terms. What I am concerned with is the attainment of a 

 better comprehension of manifestations of matter on a 

 level of complexity such as characterizes a microbe, imply- 

 ing organization, growth, and responses to environmental 

 factors through irritability, variability, and adaptation, 

 all of which may be combined in the term "individuality." 

 I do not mean to express a belief that such phenomena 

 cannot ultimately be explained on the basis of physico- 

 chemical events. But in view of the record of the history 

 of scientific developments, I am inclined to think that these 



