I04 Elements of Water Bacteriology. 



Standardization of Methods for the Bacterioscopic Exam- 

 ination of Water, 1904), although it differs from the 

 American method in certain respects. 



The American Public Health Association standard 

 procedure, as defined above, has, in the main, proved 

 satisfactory. In two respects, however, it needs modi- 

 fication. 



In the first place, the requirement that motility should be 

 demonstrated is a burdensome and needless one. Motility 

 is a fluctuating and uncertain property and one which 

 frequently requires repeated preliminary cultivations to 

 make it manifest. Furthermore, non-motile colon bacilli 

 are common in the intestine and are probably as char- 

 acteristic of intestinal pollution as the motile forms. 

 McWeeney (1904) found non-motile B. coli abundant 

 in feces and observed cases where the organisms were 

 motile at 20 degrees and not at 37 degrees. He quotes 

 Stocklin as having found 116 non-motile strains among 

 300 otherwise normal B. coli from feces. Evidence that 

 non-motile bacteria, otherwise resembling B. coli, occur 

 in unpoHuted water would furnish the only basis for 

 requiring this test as a routine procedure. No such 

 evidence exists. The great body of data which connects 

 the presence of B. coH with pollution includes aU B. coli 

 whether motile or not, since scarcely any bacteriologists 

 observe this property in actual practice. 



Another point in the Diagnostic Tests of the Committee 

 on Standard Methods which requires modification in the 



