and that no unnecessary objects should
be mouthed. All food and drink should be clean or
thoroughly cooked. These simple precautions alone would
prevent many a case of infection."--(Rosenau: Preventive
Medicine and Hygiene, p. 366.)

As Dr. Chapin says:

"Probably the chief vehicle for the conveyance of nasal and
oral secretion from one to another is the fingers. If one
takes the trouble to watch for a short time his neighbors,
or even himself, unless he has been particularly trained in
such matters, he will be surprised to note the number of
times that the fingers go to the mouth and the nose. Not
only is the saliva made use of for a great variety of
purposes, and numberless articles are for one reason or
another placed in the mouth, but for no reason whatever,
and all unconsciously, the fingers are with great frequency
raised to the lips or the nose. Who can doubt that if the
salivary glands secreted indigo the fingers would
continually be stained a deep blue, and who can doubt that
if the nasal and oral secretions contain the germs of
disease these germs will be almost as constantly found upon
the fingers? All successful commerce is reciprocal, and in
this universal trade in human saliva the fingers not only
bring foreign secretions to the mouth of their owner, but
there exchanging them for his own, distribute the latter to
everything that the hand touches. This happens not once,
but scores and hundreds of times during the day's round of
the individual. The cook spreads his saliva on the muffins
and rolls, the waitress infects the glasses and spoons, the
moistened fingers of the peddler arrange his fruit, the
thumb of the milkman is in his measure, the reader moistens
the pages of his book, the conductor his transfer tickets,
the "lady" the fingers of her glove. Every one is busily
engaged in this distribution of saliva, so that the end of
each day finds this secretion freely distributed on the
doors, window sills, furniture and playthings in the home,
the straps of trolley cars, the rails and counter and desks
of shops and public buildings, and indeed upon everything
that the hands of man touch. What avails it if the
pathogens do die quickly? A fresh supply is furnished each
day."-