26 THE BACTERIAL TEST 
dipper, or anything unsterilized which the milk 
touches will spoil the sample. 
(2) The sample is kept ice-cold until tested, 
otherwise the bacteria will multiply. 
DILUTING THE MILK WITH STERILE WATER 
(3) In the laboratory exactly 1 cc. of milk 
(about a thimbleful) is drawn out of the sample 
with a glass tube and discharged into a bottle 
of sterilized water so as to make a dilution of 
I per cent. If the milk is believed to contain 
large numbers of bacteria, the dilution is made 
higher. 
