to supposed traces of tin, zinc, or solder, which have
become dissolved in the fluids of the meat, but in the vast majority
of cases such poisoning is due to toxins accompanying the germs of
putrefaction, the meats having been unfit for canning at the outset.
In such cases the symptoms are the same as in other food poisoning,
and the treatment must be such as is elsewhere directed (see pp. 147
and 149).

While human breast milk is germ free, the cows' milk sold in cities is
a very common source of disease. Scrupulous care of the cows, of the
clothing and hands of the milkers, of the stables at which the herds
are quartered, and of the cans, pails, and pans used, reduces to a
minimum the amount of filth and impurity otherwise mixed with milk. In
the household, as well as during transportation, milk should be kept
cool, with ice if necessary. It should also never be left uncovered,
for it readily absorbs gases, effluvia, and contaminating substances
in the air, and affords an excellent medium for the growth and
propagation of germs. When partially or entirely soured, it should not
be used, except in the preparation of articles of food by cooking, as
directed in cook books. It should never be used if there is any doubt
about its purity. Unless all doubt has been removed, it is best to
subject milk intended for children's consumption to a temperature of
160 deg. F. for ten minutes, and then put it on the ice, especially during
hot weather. Germs are thus rendered harmless, and the nourishing
qualities of the milk remain unimpaired.

Summer diarrhea of children, also called cholera infantum, occurs as
an epidemic in almost all large cities during the hottest days of
summer. The disease is largely fatal, especially during the first hot
month, because the most susceptible and tender children are the first
affected. It is due to the absorption into the systems of these
children of the toxins formed during the putrefying of milk in the
stomachs and bowels of the little sufferers. Clean, pure sweet milk,
free from bacteria should be used to prevent the occurrence of this
disease. Its treatment is outlined in Vol. III. Exactly what bacteria
cause the disease is not decided. Possibly the milk is infected, but
probably the poisonous results come from toxins.

=FOOD CONTAINING PARASITES.=--The parasites found in food in this
country are echinococcus, guineaworm, hookworm, trichina, and
tapeworm. Echinococcus cannot be understood