RESISTANCE OF BACTERIA 



221 



transformation which a colon bacillus subjected to the action of a bac- 

 teriophage sometimes undergoes. It was noted first by Bordet and 

 Ciuca.^^ The growth is dense, shining, and even fluent. I have shown 

 that this is a true mutation of B. coli into B. aerogenes and it is impossible 

 to distinguish such cultures from those of typical bacilh of this species. 

 They have the same morphology, the same growth characteristics, 

 and give characteristic fermentative reactions. Moreover, Gratia^^^ 

 has shown that cultures of this type are ultrapure. Here is, 

 then a mutation, effected through the action of the bacteriophage, 

 which persists after the elimination of the latter. It seems to be 

 permanent. 



TABLE 19 



O = Original undifferentiated culture. 



In the fifth column is expressed the tendency to assume the mucoid form when 

 exposed to a Coli-bacteriophage. 



With regard to mutations of B. coli occurring under the action of the 

 bacteriophage, Gratia^^^ has succeeded in isolating 10 different strains 

 derived from a single culture of B. coli* Table 19, taken from the paper 

 of Gratia, gives the characteristics of these mutations. 



Table 20 summarizes the experiments of Gratia"^ on the crossed 

 agglutination of these different mutations when subjected to the action 

 of three antisera prepared by the injection of rabbits with strains 

 "Original," "S" and "R." 



* This history of this strain is interesting. It came from my collection and was 

 given to Ciuca during my absence in Indo-China. It was a mixed culture (a 

 transplant on agar of a secondary culture). The strain was originally derived 

 from a B. coli maintained among the stock cultures of the Pasteur Institute. 



