k. The
bacteriological examination also gives an indication as to whether
the large number of bacteria is due to gross contamination of the
milk with mud and manure, or actual growth of bacteria as in old
milk. In the latter case the ordinary acid-forming bacteria will
usually predominate in the milk, while in the former, the number of
kinds of bacteria and the proportion between the kinds will be
changed. It is of course evident that the quantitative standards
should be applied with judgment.

It is also claimed that the delay in securing the results in the
quantitative examination of milk is an objection to the bacterial
standard, since the milk is consumed before the laboratory findings
can be obtained. It is true that it does not protect the community
as far as the particular sample is concerned, but it is also true
that the examination is not made for the purpose of determining the
condition of the particular sample, so much as it is to determine
the methods that are employed on any particular farm, and these do
not vary widely from day to day. Thus, if a number of samples give
high results, it is evident that conditions surrounding production
need investigation.

If the milk is well cooled on the farm, and kept cold while being
shipped, the growth of bacteria will be slow, and the condition of
the milk as far as keeping quality is concerned, much better than if
less care is used. Some cities have temperature standards; New York
requires that the milk shall be cooled to 50 deg. F. on the farm, and
shall not be above 50 deg. F. on arrival in the city. Others require
that it shall not be above 50 deg. F. on delivery to the consumer.

=Certified milk.= In many cities the Medical Societies have appointed
Milk Commissions, that adopt rules and regulations, concerning the
production of milk that shall receive the certificate of the
commission. Producers, who desire to have their milk thus certified,
must satisfy the commission that they are able to conform to the
rules. The commission appoints a physician to examine the personnel
of the farm, a veterinarian to make frequent examinations of the
herd, a chemist to examine the milk as to its contents in fat and
other solids, and a bacteriologist to determine the bacterial
content of the milk. The rules are very stringent and cover every
point that may influence, in any way, the value of the milk as human
food. In order to conform to these requirements, a heavy
expendit