BACTERIOLOGICAL EXAMINATION OF WATER. 169 



tions. Eventually it may be useful to stain the 

 flagella. The characteristics of the typhoid bacillus 

 are enumerated in detail in a later chapter. It must 

 however be mentioned that on the other hand it is 

 by no means easy to distinguish the typhoid bacillus 

 from other similar organisms : in order to do so all 

 the peculiarities must be considered together j a 

 single characteristic, such as its growth upon potatoes, 

 is quite insufficient by itself. 



In closing this chapter it may be mentioned that in 

 cold weather the cultivations in Esmarch's tubes are 

 very suitable for examining the bacteria found in 

 water. They possess this great advantage that they 

 can be prepared and rolled out on the spot, and in 

 many cases this is extremely useful. As a rule, how- 

 ever, it is more convenient to make the cultivations 

 at home, where they caa be more accurately executed. 



