22 BACTERIA 
in line, and a regiment of 160,000 of these germs 
could be pushed through one of the squares abreast. 
This shows clearly how the finest cheese cloth 
cannot possibly filter bacteria out of milk. 
Dirty milk may look clean because it has been 
strained, but the large numbers of bacteria which 
pass through the filter will show by their pres- 
,ence that the milk was unclean. 
The cleanliness of milk cannot be measured 
by the so-called ‘‘dirt test,’’ which uses a strainer 
because milk may have been previously strained. 
The test for bacteria is therefore the best pos- 
sible way to measure the cleanliness of milk. 
