ier and whole villages were wiped out; where the insignificant
measles, so innocuous in civilized communities, became a plague similar
to a scourge of the Middle Ages. It apparently has been modified by its
passage through generations of individuals, just as any bacterial
disease germ is modified by successive transmission through the bodies
of different animals. When, however, the disease breaks out in a
community which has not suffered from the disease for many years, it is,
on that account, likely to appear in a far more virulent form.

_Characteristic eruptions of measles._

Measles, like scarlet fever and chicken pox, is an eruptive disease;
that is, is accompanied with a rash, differing slightly in the three
diseases of which the presence of the rash and its progress over the
body is one of the distinguishing features. In scarlet fever, for
instance, the rash appears first on the neck and chest or back and
spreads outward to the extremities. In measles, the rash appears on the
extremities, beginning on the face usually, and spreads to the chest and
trunk. In scarlet fever, this rash appears as fine scarlet pin points
scattered around on the reddened skin, and on the second or third day
the entire body may look like a boiled lobster. In measles, the rash
appears as blotches, while the skin is not flushed but retains its
natural color. In chicken pox, the rash appears generally on the body
first and consists of small red pimples which develop into whitish
blisters about as large as a pea and well separated. They are much more
distinct and separated than the rash of scarlet fever and measles, and
are much more likely to be mistaken for smallpox pustules than for an
ordinary eruptive rash.

One of the old-time fancies connected with these eruptive diseases is
the belief that an abundant eruption is a sort of guarantee against the
severity of the disease. The old nurse was careful to keep the child in
bed, well covered, steamed in fact, until the eruption appeared, and it
was commonly thought that nothing should be done to check the rash or
to prevent its coming out. This is not sustained by later science, and
the appearance of the rash, whether it strikes in or strikes out, has
nothing to do with either the disease or with its severity. No possible
connection can be traced between the dissemination of the poison through
the system by the action of the bacteria and the appearance of the skin,
which is a minor factor