226 PRINCIPLES AND PRACTICE OF MILK HYGIENE 
after a herd sample is tested and the results compared. 
The establishment of a legal standard for the per cent. 
of fat and total solids in milk has made it unnecessary in 
many states to prove that milk has been actually diluted 
or skimmed. All that is required is to show that the 
fat and total solids are below the legal standard; con- 
sequently the question of taking a stable sample for com- 
parison does not arise. 
Individual Samples—When a sample of milk is 
taken from an individual cow for the determination of 
the specific gravity and the per cent. of fat and total 
solids, the milk should be drawn into a pail in the usual 
manner and the sample taken from the pail after the 
milk has been thoroughly mixed. [If it is desired to ascer- 
tain the average for the day, which is the usual method, 
an equal quantity of milk is taken from the morning and 
evening milking, mixed, and then tested. When the 
ferment tests are to be applied or the number of bacteria 
is to be determined, the sample must be drawn with a 
sterile pipette and placed in a sterile bottle, the contents 
of the pail being first thoroughly mixed. If the milk is 
to be examined for pathological conditions, a small quan- 
tity may be milked from each quarter into a sterile bottle; 
it is best, however, to have each quarter milked dry and 
to collect a small quantity of milk at the beginning, in 
the middle, and at the end of the milking. 
Mixing the Milk Sample.—Previous to removing 
milk from the sample bottle for a test in the laboratory, 
the milk should be thoroughly mixed. This may be 
done by inverting the bottle several times if it is tightly 
stoppered, or by pouring the milk from the bottle into a 
beaker and back again several times. No cream should 
