CHAPTER THREE 



CHANCE 



" Chance favours only those who know 

 how to court her." — Charles Nicolle 



Illustrations 



IT WILL be simpler to discuss the role of chance in research if 

 we first consider some illustrative examples of discoveries in 

 which it played a part. These anecdotes have been taken from 

 sources believed to be authentic, and one reference is quoted 

 for each although in many instances several sources have been 

 consulted. Only ten are included in this section but seventeen 

 others illustrating the role of chance are to be found in the 

 Appendix. 



Pasteur's researches on fowl cholera were interrupted by the 

 vacation, and when he resumed he encountered an unexpected 

 obstacle. Nearly all the cultures had become sterile. He attempted 

 to revive them by sub-inoculation into broth and injection into 

 fowls. Most of the sub-cultures failed to grow and the birds 

 were not affected, so he was about to discard everything and 

 start afresh when he had the inspiration of re-inoculating the 

 same fowls with a fresh culture. His colleague Duclaux relates : 



" To the surprise of all, and perhaps even of Pasteur, who was 

 not expecting such success, nearly all these fowls withstood the 

 inoculadon, although fresh fowls succumbed after the usual 

 incubation period." 



This resulted in the recognition of the principle of immunisation 

 with attenuated pathogens.^ ^ 



The most important method used in staining bacteria is that 

 discovered by the Danish physician G. Gram. He described how 

 he discovered the method fortuitously when trying to develop a 

 double stain for kidney sections. Hoping to stain the nuclei violet 

 and the tubules brown, he used gentian violet followed by iodine 



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