744 BACTERIAL FLORA OF THE SYDNEY WATER SUPPLY, 



culture 100,000,000 times, produced cultures of the organism in 

 tubes containing 3 drops of Parietti's solution. In the presence 

 of Bad. coli comnmne, however, Bad. typhi could not be 

 found even in suspensions diluted only 100 times. It is apparent, 

 that in diluted Parietti's fluid, coli prevents the growth of typhi. 

 Wittlin* in testing the effect of 3 to 7 drops of Parietti's solu- 

 tion in 10 c.c. of fluid found that the ordinary water bacteria, 

 whose presence in water is unimportant, either do not develop or 

 grow very feebly. The latter fact was made evident by the 

 motile bacteria becoming non-motile. On the other hand, the 

 pathogenic bacteria, as well as those which normally inhabit the 

 animal intestine, are quite unaffected by the acid phenol solution. 

 The coli group are indifferent to 7 drops of solution per 10 c.c. 

 Similarly the bacteria of the excrement, e.g., Staphylococcus 

 aureus, Streptococcus erysipelatis, Bad. pyocyaneum and Bad. 

 ochraceuta are unrestricted in their development. After standing 

 in the acid medium, motile bacteria gradually lose their motility, 

 the saprophytes becoming motionless much sooner than the 

 pathogenic organisms with the exception of Bad. pyocyaneum. 

 Wittlin grew many bacteria in pure culture in carbolised bouillon 

 and noted the growth on the first or second day. Development 

 always occurred with those bacteria which are not influenced by 

 the reagent, however small the number of cells originally taken. 

 This was especially the case with Staphylococcus albus and 

 aureus, Streptococcus, Proteus immobilis, Bad. pyocyaneum, typhi, 

 coli comm., and its varieties as well as the thrush fungus. 

 Parietti's solution, however, is useless for isolating Bad. typhi, 

 because in its presence many other bacteria grow more luxuri- 

 antly, that is to to say, typhi is more susceptible to the disinfect- 

 ing action of the solution than many other bacteria as, for 

 example, the various species of coli. Wittlin arrived at the 

 conclusion that Parietti's solution, though useless for separating 

 Bad. typhi from water, was yet of great service for separating 

 other pathogenic bacteria. 



* Wittlin, Centralblatt fur Bakt. 1. Abt. xx., 710. 



