. (165 gallons), making the total quantity of milk
produced in the twelve months by cows and heifers on the
farms, and that produced calves during the twelve months
(June, 1909-1910), 158,800,000 cwts. (1,746,800,000
gallons), or about 426 gallons per head, and about 400
gallons per head for all the cows and heifers in milk or
in calf in 1910. There remains to add the milk yielded by
the cows that were sold during the twelve months, and of
cows and heifers in feeding pastures that were milked
during the twelve months, June to June, 1909-10, and which
probably formed one tenth of the whole supply, making the
total supply for the twelve months 176,444,000 cwts., or
1,940,884,000 gallons. This equals 2 tons, or 440 gallons
per head, crediting the whole supply to the 4,400,000 cows
and heifers in milk or in calf in June, 1910. At 7-1/4d.
per gallon the value of milk produced in the United
Kingdom in the twelve months was L58,600,000. Including
the value at birth of the calves, the total value of the
produce of the milk-giving class would be about
L62,000,000. The value of the milk, butter, cheese, and
cream sold or consumed in farmhouses would be about
L48,000,000, or equal to about 24 per cent. of the gross
annual income of farmers.

The average consumption of new milk is about 15 gallons
per head of the population. During the twelve months of
1911, the quantity required for this purpose will be about
682,500,000 gallons, or about 35 per cent. of the total
supply; calves will require about 10 per cent. of the
supply; the quantity available for butter and cheese will
equal about 55 per cent. of the supply.[43]

_The Milk Industry in the United States._--In the United States of
America, where the habits of the people are somewhat analogous to those
in the United Kingdom, it is estimated that the milk from five million
cows is annually consumed, which averages twenty-five and one half
gallons per year for each person, or equal to an ordinary sized
tumblerful each day.[44]

Such a vast industry, so intimately associated with the food of the bulk
of the people, naturally invites the closest study, and, as a
consequence, the literature on the subject, which has arisen during the
last twenty years, has been of a voluminous character, not only from the
point of view of practice, but from that of bacteriology, chemistry, and
hygiene.

A pure milk supply is essential