nerally required for blankets, but if badly soiled they should be
sterilized by steam or burned. The room should then be thoroughly
sunned and aired for a day or two, with the windows wide open both day
and night. Sunning and airing are among the most important measures in
disinfecting a room, and should not be slighted. If there has been gross
pollution, as when a careless consumptive persists in spitting on the
floor and walls, it may be necessary to remove the old paint and paper
and have the room done over. The room may safely be occupied after all
these measures have been taken.

FUMIGATION.--Many Boards of Health have abandoned fumigation after
communicable diseases, except after those which like typhus and yellow
fever, are carried by vermin or insects. Dry formaldehyde gas, which was
formerly used for fumigation, has a violent effect on mucous membranes,
but its power to kill bacteria, even on surfaces, appears to be weak,
while its penetrating power is not sufficient to disinfect bedding,
carpets, upholstered furniture, and other fabrics. Since fumigation is
costly, troublesome, and ineffectual there seems to be no good reason
for using it. Moreover, its use gives a false sense of security, so that
really effective measures like sunning, airing, and scrubbing are likely
to be neglected.

Theory and practice of disinfection, it is clear, have radically
changed in recent years. Modern knowledge requires concurrent
disinfection, or the destruction of germs from the moment when symptoms
are first noticed; all the time, day and night, this disinfection must
go on with unremitting care. Today wet sheets are not hung in doorways
nor are chemicals left about in open dishes to disinfect quite harmless
air, but scrupulous cleanliness at all stages of disease is recognized
as one of the most important measures, if not the most important
measure, in disinfection.

EXERCISES

1. Summarize the ways in which infectious diseases are spread.

2. What is meant by the incubation period? State the length of the
incubation period in measles; Liberty measles; whooping-cough; scarlet
fever; chicken-pox; diphtheria; mumps; typhoid fever.

3. Name some of the early symptoms common to most infectious diseases.
If such symptoms appear, what should be done while waiting for the
doctor to come?

4. Discuss the importance, prevention, and treatment of common colds.

5. What measures should be taken to isolate a patient who is suf