204 Perspectives in Microbiology 



These and many other questions that pertain to the 

 world of microbes in which we live have been only partly 

 answered. Many questions still await the investigator. 

 These problems are fundamental in nature, but the an- 

 swers promise rich rewards in practical applications. Many 

 questions have remained unanswered because the proper 

 methods of investigation have not yet been discovered. We 

 are dealing with microscopic and ultramicroscopic forms 

 of life, which we often recognize not by what they look 

 like but by what they do; not by how they behave in a 

 normal environment, but by how their reactions in an 

 abnormal environment can be interpreted in terms of their 

 life processes and role in the cycle of life in nature. 



Claude Bernard emphasized the fact that reasoning is 

 correct only when applied to correct facts; when facts are 

 originally tainted with error and inaccuracy, reasoning 

 based on them can lead only to error: "The art of investi- 

 gation is the cornerstone of all the experimental sciences. 

 If the facts used as a basis for reasoning are ill-established 

 or erroneous, everything will crumble or be falsified; and 

 it is thus that errors in scientific theories must often origi- 

 nate in errors of fact." If this applies to higher forms of 

 life, it applies with even greater force to the life of the 

 microbes. Bernard stated further: "The investigator must 

 be at once a theorist and a practitioner. He must com- 

 pletely master the art of establishing experimental facts, 

 which are the materials of science, and he must also clearly 

 understand the scientific principles which guide his rea- 

 soning through the varied experimental studies of natural 

 phenomena. Head and hand must go together. An able 

 hand without a head to direct it is a worthless tool; the 

 head is powerless without its executive hand." 



We can subscribe heartily to these principles. Pasteur 

 himself said at the dedication ceremonies of his institute: 

 "My dear collaborators, keep your enthusiasm, but let its 

 inseparable companion be rigorous control. Do not ad- 



