220 BACTERIOLOGICAL EXAMINATION OF WATER. 



conditions of life of the B. typhosus are different. Robertson's 

 experiments appeared to show that typhoid bacilli may exist in 

 earth under natural conditions for several months. Martin's 

 latest studies on the behaviour of B. typhosus in soil, however, 

 throw some doubt on these results ; everything seems to depend 

 on the nature of the soil and the other organisms present in it. 

 Still, the endemic prevalence of enteric fever year after year in 

 certain localities, characterised by polluted soils, renders it 

 extremely probable that the life of the B. typhosus in soil is 

 longer than in water-supplies. If this be so the bacilli may be 

 carried from the soil into drinking water by rising ground water 

 or rain, and in this way outbreaks of enteric fever may occur 

 long after the initial infection. 



CASKS IN WHICH THE B. TYPHOSUS HAS BEEN ISOLATED FROM 

 WATER-SUPPLIES. 



The discovery of the B. typhosus in water-supplies has often 

 been announced. Moers, in 1886, was the first to isolate the 

 bacillus from a contaminated well supplying water to a number 

 of people amongst whom cases of enteric fever had occurred. 

 Michael, in the same year, claimed to have found the bacillus 

 in a well-water suspected to have caused enteric fever in 

 Dresden. Chantemesse and Widal, Thoinot, Loir, and Vincent 

 have all found the typhoid bacillus in the water of the river 

 Seine. Fodor stated that he found the bacillus five times in the 

 water-supply of Budapest. Most of the early announcements 

 of the discovery of the B. typhosus must be accepted with great 

 reserve, as at that time the appearance of the colonies on gela- 

 tine plates was considered sufficient to prove the presence of the 

 bacillus, and most of the tests now required were not applied. 

 Cassedebat studied with great care the water-supply of Mar- 

 seilles in 1890, employing special methods, but he failed to 

 discover the typical B. typhosus of Eberth and Gaffky. He, 

 however, isolated three other bacilli which he called pseudo- 

 typhoid ; these organisms bore a close resemblance to the true 

 typhoid, and could only be distinguished from it with great 

 difficulty. Cassedebat made about two hundred and fifty cul- 

 tures, employing ten drops of water for each culture, and was 

 careful to state that his failure to discover the typhoid bacillus 



