206 BACTERIA IN AIR, SOIL, WATER, AND MILK 



organic matter, for many weeks. The question is 

 often asked as to how a few germs in a glass or two 

 of water can cause typhoid fever. As a matter of 

 fact, when an epidemic of typhoid is starting there are 

 usually supposed to be many germs and not a few 

 in the water. What probably happens is that a small 

 particle of organic matter, possibly feces, is swallowed. 

 This may contain many thousand organisms. 



Although cholera organisms live in water a shorter 

 time than typhoid bacilli, they are said to be viable 

 for several weeks. Relatively more cholera organisms 

 are discharged with a cholera stool than is the ca^e of 

 typhoid bacilli in enteric fever. Dysentery bacilli live 

 only a short time in water probably, and the impor- 

 tance of water in the dissemination of dysentery is 

 questioned by some observers. Certain it is that some 

 epidemics appear to be water-borne. 



Typhoid and colon bacilli are always present in 

 typhoid stools. It is hardly probable that the former 

 could get into water without the latter. Moreover, 

 the colon bacillus is present in all alimentary tracts. 

 It is more easily detected in any mixture or solution 

 than any other of the intestinal bacteria. Therefore it 

 is taken as an indication of sew r age pollution in water. 

 This may not mean that typhoid bacilli are present, but 

 merely that contamination of water by sewage from 

 animal sources has occurred. Whether from man or 

 animals, it is obvious that dejecta should not come into 

 water intended for human consumption. The methods 

 of water examination now in use all aim at the detec- 

 tion of Bacillus coli. Because of its peculiarities in the 

 fermentation of sugars, certain media are adopted as 



