Isolation of Specific Pathogenes. 8 1 



well at Neumark in 1899, and Fischer and Flatau 

 (Fischer and Flatau, 1901), who discovered an organ- 

 ism responding to g. most exhaustive series of tests for 

 the typhoid bacillus in a well at Rellingen in 1901. In 

 these cases the water was directly plated upon Eisner's 

 medium or phenolated gelatin with no preliminary process 

 of enrichment. Willson (Willson, 1905) has summarized 

 the instances in which the typhoid bacillus has been iso- 

 lated from infected drinking water, and includes, in addi- 

 tion to the above-mentioned cases, the following: 



1. By Losener, in 1895, from the Berlin water supply. 



2. By Conradi, in 1902, from a well at Pecs in Hun- 

 gary, by use of carbol gelatin plates. 



3. By Jaksch and Rau, in 1904, from the water supply 

 of Prague, and also from the river Moldau, by caffeine- 

 nutrose crystal violet agar. ' 



4. By Stroszner, in 1904, from a well near Budapest, 

 by the same method. 



The search for the typhoid bacillus is usually suggested 

 when an outbreak of the disease has cast strong suspicion 

 upon some definite source of water-supply. By the time 

 an epidemic manifests itself, however, the period of the 

 original infection is long past, and the chances are good 

 that any of the specific bacilli once present will have dis- 

 appeared. While elaborate experiments have shown that 

 B. typhi may persist in sterilized water for upwards of 

 two months and in unsterilized water from three days 

 to several weeks, the number of the organisms present is 



