CHAPTEE XIII. 



BACTERIOLOGICAL EXAMINATION OF WATER, 

 FILTERS, MILK, AIR, SOIL, ETC. 



The bacteriological examination of water — The nature and niunber of 

 the organisms found in water — Determination of the number of 

 micro-organisms in water — Exanaination for sewage bacteria — Isola- 

 tion of the typhoid bacillus from water — Inhibition by phenol — 

 Eesistance of the typhoid and colon bacillus to phenol — Eisner's 

 method — Other methods — Isolation of the cholera bacillus from 

 water — Examination of filters — Examination of milk— Number of 

 bacteria found in milk — Tuberculous mili — MUk diseases— Blue, red, 

 yellow, bitter, stringy, soapy mUk, etc. — The organisms producing 

 these diseased conditions — Necessity for improved sanitary control 

 of dairies — Examination of air — Number of bacteria in the air — 

 Sewer air — Filtration of air — Examination of air by Hesse's and 

 other raethods — Examination of soU — Number of micro-organisms 

 foimd in the soil — Methods of bacteriological examination of soil. 



THE BACTERIOLOGICAL EXAMINATION OF WATER. 



All natural waters necessarily contain micro-organisms, as 

 they are constantly being carried into it by air-currents, 

 and by the drainage from land- surfaces. It is only in water 

 from deep artesian wells and deep-seated springs that 

 organisms are very few in number, and it is very rare even 

 in these to find them entirely absent. The number and 

 variety of the bacteria in water depends upon several 

 conditions, such as the amount of organic matter in the 

 water, the temperature, depth, whether running or stagnant, 

 pollution, source, etc. 



Water forms the most natural vehicle for the distribution 



