CHANCE 



with instances of lost opportunities — clues noticed but their 

 significance not appreciated. Before Rontgen discovered X-rays, 

 at least one other physicist had noticed evidence of the rays 

 but was merely annoyed. Several people now recall having 

 noticed the inhibition of staphylococcal colonies by moulds 

 before Fleming followed it up to discover penicillin. Scott, for 

 instance, reports that he saw it and considered it only a nuisance 

 and he protests against the view that Fleming's discovery was 

 due to chance, for, he says, it was due mainly to his perspicacity 

 in seizing on the opportunity others had let pass.*^ Another 

 interesting case is related by J. T. Edwards. ^^ In 19 19 he noticed 

 that one of a group of cultures of Brucella abortus grew much 

 more luxuriantly than the others and that it was contaminated 

 with a mould. He called the attention of Sir John M'Fadyean 

 to this, suggesting it might be of significance, but was greeted 

 with scorn. It was not till later that it was discovered that 

 Br. abortus grew much better in the presence of CO2, which 

 explains why Edwards' culture had grown much better in the 

 presence of the mould. Bordet and others had casually noticed 

 agglutination of bacteria by antisera, but none had seen the 

 possibilities in it until Gruber and Durham did. Similarly, 

 others had seen the phenomenon of bacteriophage lysis before 

 Twort and D'Herelle. F. M. Burnet for one now admits having 

 seen agglutination of chick embryos' red blood cells in the 

 presence of influenza virus and probably others had too but 

 none followed it up till G. K. Hirst, and McClelland and Hare. 

 Many bacteriologists had seen rough to smooth colony variation 

 in bacteria before Arkwright investigated it and found it to be 

 associated with change in virulence and antigenicity. It is now, 

 of course, one of the fundamental facts in immunology and 

 serology. 



Sometimes the significance of the clue which chance brings 

 our way is quite obvious, but at others it is just a trivial incident 

 of significance only for the well prepared mind, the mind loaded 

 with relevant data and ripe for discovery. When the mind has 

 a lot of relevant but loosely connected data and vague ideas, a 

 clarifying idea connecting them up may be helped to crystallise 

 by some small incident. Just as a substance may crystallise out 

 of solution in the presence of a nucleus consisting of a minute 



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