QUANTITATIYE EXAMINATION OF WATER 39 



EFFECT OF SIZE OF VESSEL UPON THE MULTIPLICATION 

 OF WATER BACTERIA DURING STORAGE 



(Whipple, 1901) 



I Average of five plates. 



Whipple's table, quoted above, shows that the multi- 

 plication during storage was greater at a higher tem- 

 perature; and this is a well-recognized general rule. 

 In order to obviate the abnormal results of storage 

 increase it is therefore obvious that samples must be 

 examined shortly after collection and that they must 

 be kept cool during their necessary storage. If fairly 

 pure waters are placed upon ice and kept between o 

 degrees and 10 degrees, they will show no material 

 increase in 12 hours. With polluted water, however, 

 another danger is here introduced. Samples of such 

 water when packed in ice show a marked decrease 

 due to the large number of sensitive intestinal bacteria 

 present. Jordan (Jordan, 1900) found that three 

 samples of river-water packed in ice for 48 hours fell 



