ISOLATING THE TYPHOID BACILLUS. 449 



of 1 to 3 millimetres, rarely larger. Their color is 

 blue, with a tendency toward violet. In structure they 

 are glistening, with a single contour, somewhat of the 

 nature of a dew drop. Only in isolated instances is the 

 colony larger and more cloudy in appearance. 



METHOD OF HOFFMANN AND FICKER. Hoffrminn 

 and Picker l have published a new method for the isola- 

 tion of bacillus typhosus from infected waters, which 

 consists in the addition of increasing quantities of caf- 

 fein, crystal violet, and nutrose to large quantities of the 

 water. They add 1 per cent, of nutrose, 0.5 per cent, 

 of caffein, and 1 per cent, of a 0.1 to 100 solution of 

 crystal violet to the water, and incubate at 37 C. for 

 twelve to thirteen hours. In this manner they reduce 

 the number of water bacteria, while bacillus typhosus 

 increases in numbers. The three solutions to be added 

 to the water are prepared as follows : 



1. A solution of 10 grammes nutrose in 80 c.c. of 

 distilled water. The solution is placed in a water-bath 

 for several hours and is not filtered. 



2. A solution of 5 grammes of caffein in 20 c.c. of 

 warm (80 C.), sterile distilled water. The solution is 

 to be freshly prepared and should not be shaken. 



3. A solution of 0.1 gramme of crystal violet in 100 

 c.c. of sterile distilled water. This must be freshly 

 prepared each time. 



900 c.c. of the water to be examined are placed in a 

 flask and the three solutions are added, and the mixture 

 thoroughly shaken. After incubation, the water is exam- 

 ined according to several well-known methods. For 

 instance, some of the supernatant portion of the fluid 

 is removed and spread out in a thin layer upon plates 



1 Hoffmann and Ficker : Hygienische Kuudschau, Bd. 14, 1904, p. 1. 

 29 



