424 Profs. Percy Frankland and Marshall Ward. 



and thus perish by the long residence in the water, whilst at the 

 higher temperature (19 C.), although the fully developed bacteria 

 are more rapidly destroyed, a larger proportion of them give rise to 

 spores and thus lead to a larger permanent bacterial population in 

 the water. 



Examination of the Unsterilised TJiam.es Waters, Infected and Unin- 

 fected by Phenol Broth-culture. 



I must now call attention to the results of the phenol broth- 

 cultivations made both with the unsterilised Thames water, as well 

 as with that infected with the typhoid bacillus and the B. coli 

 communis respectively. 



The following experiment will show how under favourable condi- 

 tions, the phenol broth test serves to distinguish a water containing 

 typhoid bacilli from another in which they are absent ; thus 



Phenol Broth Experiments (12.5.1893). 



(1) 1 c.c. uninfected unsterilised Thames water added to 10 c.c. 



broth + 5 drops phenol solution. 



(2) 1 c.c. uninfected unsterilised Thames water added to 10 c.c. 



broth + 3 drops phenol solution. 



(3) 0'5 c.c. uninfected unsterilised Thames water added to 10 c.c. 



broth + 5 drops phenol solution. 



(4) 0'5 c.c. uninfected unsterilised Thames water added to 10 c.c. 



broth + 3 drops phenol solution. 



(5) 1 c.c. unsterilised Thames water infected with typhoid added 



to 10 c.c. broth + 5 drops phenol solution. 



(6) 1 c.c. unsterilised Thames water infected with typhoid added 



to 10 c.c. broth + 3 drops phenol solution. 



(7) 0'5 c.c. unsterilised Thames water infected with typhoid added 



to 10 c.c. broth + 5 drops phenol solution. 



(8) 0'5 c.c. unsterilised Thames water infected with typhoid added 



to 10 c.c. broth + 3 drops phenol solution. 



These eight tubes, all in duplicate, were placed in an incubator at 

 38 C., and on the following day, whilst all the uninfected tubes, 1, 2, 

 3, and 4, were clear, all the infected tubes, 5, 6, 7, and 8, were turbid, 

 thus showing that whilst the addition of the phenol solution had 

 prevented the proliferation of the ordinary water-bacteria in the 

 uninfected Thames water, the extensive multiplication of the typhoid 

 bacilli in the infected Thames water had taken place in spite of the 

 presence of the same proportions of phenol. In the same way, on 

 the following day, similar quantities of the unsterilised Thames 

 water infected with the B. coli communis were introduced into broth- 



