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A lake water should be condemned if it contains organisms 
of ‘class: in’ rere: or tess: 
If fecal organisms are present in the characteristic 
arrangement of fresh faces. 
If lactis zrogenes is scarce. 
If the acid and gas line in glucose and lactose broth is 
the same, or close together. 
If faecal streptococci are found present. 
In condemning a lake water, however, it should be remem- 
bered that even 48 hours will make an enormous difference 
to the purity of such a water, and the entire aspect of affairs 
may be changed within: as short a period as one week, 
RIVER WATERS. 
A good river water may contain up to from 100 to 1,000 
colonies: (on agar at 37°C.). 
Lactose fermenters may be present in 5 C.c. 
Organisms of class 1 should not be present in 20 c.c. 
Glucose fermenting organisms may be present in ‘I C.c. 
Fecal organisms present should not contain a large number 
ot different varieties in 10 colonies, and the prevalence of 
lactis ezrogenes is a favourable sign. 
River water should be condemned if it contains countless’ 
colonies (on agar at 37°C.). 
If lactose fermenting fecal organisms are present I0 
to 100 per C.C. 
If glucose fermenting organisms are present in same 
quantity. 
If streptococci are present. 
If the lactose fermenting organism shows class I in I to 5 c.c. 
If the number of varieties is considerable in 10 colonies. 
WELL AND SPRING WATER. 
Good water should contain no lactose fermenting fecal 
organism in 50 C.Cc. 
No class I in I00C.c, 
Total colonies should be under 50 per c.c. 
At present we are unable to give further standards than this. 
