330 IVAN C. HALL AND LILLIAN J. ELLEFSON 



birds or lower mammals whose intestinal diseases are not ordi- 

 narily transferable to man, or even in certain non animal sources, 

 e.g., grains. Methods have recently been described which 

 promise some degree of differentiation of certain of these forms; 

 the literature was fully reviewed by Winslow (1916) and need 

 not be repeated in detail here. While fully appreciative of the 

 refinements in interpretation which the work of Rogers, Clark 

 and Davis (1914), Rogers, Clark and Evans (1915), Clark and 

 Lubs (1915), and others makes possible, we are convinced that 

 an equally important problem concerns the use to be made of 

 the presumptive test. We are not willing to discard this test 

 aS Professor Winslow advises in case of water of fair quality; 

 indeed we feel that inasmuch as negative presumptive tests are 

 most significant it is in just this type of water, even more than 

 in badly polluted water, that the presumptive test is of most 

 value. We fully agree however as to the need of the colon con- 

 firmatory test where the presumptive test is positive. Finally, 

 and most important, the finding of B. coli in water should prop- 

 erly be interpreted only as an indication of the absolute neces- 

 sity of a sanitary survey to locate, identify, and, if possible, 

 eradicate the source of pollution. 



In a varying proportion of cases, subcultures from positive pre- 

 smnptive tests upon the litmus lactose agar plate for the purpose 

 of isolating and identifying the gas former fail to yield acid form- 

 ing colonies. In these instances it is customarj^ to interpret the 

 result as non-significant *so far as concerns pollution, since Creel 

 (1914) has pointed out the role of sporulating lactose fermenting 

 anaerobes in the presumptive test, a point which the latest 

 standard methods seem not to have emphasized sufficiently. 

 Even when Whipple (1903) used the glucose broth presumptive 

 test following its original suggestion by Theobald Smith (1893) 

 (1895) and Jackson (1906, 1907), modified this by substituting 

 lactose bile, it was known, according to Winslow (1916), that 

 certain organisms other than B. coli might be responsible for 

 positive tests, but the factor of error introduced thereby was 

 believed to be nearly negligible. Unfortunately Whipple's paper, 

 which we quote from Professor Winslow's, is not available, but 



