23 8 



STEPHEN DEM. GAGE 



ordinary water bacteria by coagulation and sedimentation, and by 

 nitration, is greater than is the removal of bacteria capable of devel- 

 oping at 40, as previously noted in the discussion of the 30 series. 

 The peculiar significance in the ratios between the bacteria and the 

 acid-formers at 20 appears to be in the much larger ratios obtained 

 for sewages and the effluents from sewage filters than for the other 

 waters examined. This distinction does not hold true for the 40 

 and 50 bacteria-acid-producing-organism ratios, the high and low 

 values being distributed among all classes of waters. 



TABLE 5. 

 BACTERIAL RATIOS FOR DIFFERENT CLASSES OF WATERS, 20, 40, AND 50 C. Series. 



Bacterial determinations at 20 and 40 on polluted waters. In 

 addition to the results obtained in the 30 and 50 series previously 

 discussed, we have somewhat more extended information regarding 

 the relation between the numbers of bacteria developing at 20 and 

 at 40 C. Throughout 1905 both total colonies and red colonies 

 were counted on all litmus-lactose agar plates. Comparative counts 

 are thus available on some 200 samples of sea waters, and on samples 



