QUANTITATIVE BACTERIOLOGICAL EXAMINATION. 27 



was much greater when the bottles were only half full 

 than when they were filled completely; and also, as shown 

 in the following very striking table, that the size of the 

 bottle markedly influenced the growth. 



EFFECT OF SIZE OP VESSEL UPON THE MULTIPLICATION OP WATER 



BACTERIA DURING STORAGE. 



(Whipple, 1901.) 



* Average of five plates. 



These results and those of other observers make it 

 obvious that samples must be examined shortly after 

 collection and that they must be kept cool during their 

 storage. If fairly pure waters are placed upon ice and kept 

 between o° and io°, they will show no material increase 

 in twelve 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 



