742 BACTERIAL FLORA OF THE SYDNEY WATER SUPPLY, 



is inoculated into peptone-free bouillon without phenol, and after 

 growing at 45° is used to inoculate ordinary gelatine in which 

 the typhi colonies grow slowly. A method very similar, but at a 

 lower temperature, is employed by Jordan* for the separation of 

 Bact. cod and the elimination of other glucose fermenting bacteria, 

 e.g., Bact. cloaca?. 



Jordan's method. — A quantity of the suspected water is incu- 

 bated with acid meat extract and with phenol in the proportion 

 of 1 to 1000 of fluid. The incubation is continued for 12 to 18 

 hours at 38° to 40° C, when the culture is used to infect plates of 

 litmus-lactose-agar. The colonies that redden the medium are 

 picked out and the bacteria proved by their faculty for coagu- 

 lating milk, producing indol in bouillon, fermenting glucose and 

 not peptonising gelatine. The employment of litmus-lactose- 

 agar considerably lightens the w T ork of separation. The use of 

 phenol by itself has not found so much favour among bacteriolo- 

 gists as a mixture of phenol and hydrochloric acid which was in- 

 troduced by Parietti. 



Pariettis method. — A solution is prepared containing 5 grm. 

 phenol, 4 grin, hydrochloric acid, and 100 grm. distilled water. 

 Tubes containing 10 c.c. nutrient bouillon are treated with 3, 6, 

 and 9 drops of the prepared solution and are then incubated for 

 24 hours at 37° C. to make sure that no organisms have gained 

 access during the addition. Into the sterile tubes which are 

 placed in sets of three, a varying number of drops of the water 

 are added, and after shaking, they are placed in the incubator at 

 37° C. for 24 hours. Some of the tubes become turbid, and those 

 that contain the greatest number of drops of solution and gener- 

 ally the smallest quantity of water are taken and subcultures 

 made in order to diagnose the vegetating microbes. Franklandf 

 has pointed ont that the incubation period should be prolonged 

 for from 48 to 72 hours. HankinJ uses Parietti's solution, but 



* Jordan, Centralblatt fur Bakt. 1 Abt. xxvii. , 679, Ref. 



t Frankland, Micro-organisms in Water. 



+ Hankin, Centralblatt fur Bakt. 1 Abt. xvii. , 544. 



