26 ELEMENTS OF WATER BACTERIOLOGY 



surface contamination, their water often being fairly 

 rich in bacterial life. Egger (Wolff hugel, 1886) examined 

 60 wells in Mainz and found that 17 of them contained 

 over 200 bacteria to the cubic centimeter. Maschek 

 (Maschek, 1887) found 36 wells out of 48 examined in 

 Leitmeritz which had a bacterial content of over 500 

 per c,c. Fischer (Horrocks, 1901) reported 120 wells 

 in Kiel which gave over 500 bacteria per c.c. and only 

 51 with less than that number. 



In the examination of 147 shallow farmyard wells 

 by one of us (S. C. P.) it was found that 124 of the 

 wells which contained no B. coli, and were therefore 

 probably free from fecal pollution, averaged 190 bacilli 

 per c.c. while 23 which gave positive tests for B. coli 

 averaged 570 per c.c. The distribution of the two series 

 of samples according to the number of bacteria present 

 is indicated in the table below. 



BACTERIA IN SHALLOW FARMYARD WELLS 

 PERCENTAGE OF SAMPLES IN EACH GROUP 



Very similar results are reported for shallow wells 

 used as farm water-supplies in Minnesota by Kellerman 

 and Whittaker (1909), although the general quality 

 of the wells examined was considerably below that 

 of the series tabulated above. 



