shown that in some mysterious way these organisms are the cause of these
diseases, for on inoculating animals with them the peculiar disease of
which each was the accompaniment, and no other, was reproduced in the
inoculated animal.

As far as our knowledge goes at present then, we are forced to regard
each of these as a separate disease, measles never passing into
scarlatina, nor that into smallpox, but each, whether slight or severe,
retaining throughout its distinct character.

We have already seen how, in the course of various diseases, the pulse
is quickened, and the temperature raised, constituting that state which
we commonly call fever, but as the local ailment subsides the fever
disappears. There is, apart from smallpox, measles, and the other
so-called eruptive fevers, only one real essential fever commonly met
with in childhood, and that is what the doctors call _typhoid fever_.
The name, from the similarity of sound to _typhus_, from which, however,
it is essentially different, has long been a name of terror in the
nursery, and all sorts of epithets have been substituted for it, as
gastric fever, and infantile remittent fever, and so on. Name it as you
may, the fever is one and the same with the typhoid fever, which one
hears of as prevailing constantly in many continental cities, and
proving dangerous and fatal in any district almost in direct relation to
the neglect of drainage and of proper sanitary precautions.

It is extremely rare in infancy, though I saw it once in a babe eight
months old, and is comparatively seldom met with before the age of five
years. From five to ten years old it is more frequent than from ten to
fifteen, but it is consolatory to know that it is less fatal in early
childhood than at any subsequent time of life, and that cases of such
exceedingly mild character that the child's condition can be more
properly described as ailing rather than ill, are then far from
uncommon. The symptoms, however, are in all instances similar in kind,
though widely varying in degree, and the duration of the fever is, as
nearly as may be, three weeks. By this it is not meant that at three
weeks' end the child who has had typhoid fever is well again, but only
that the temperature, which had hitherto been high, and always higher at
night than in the morning, has subsided, that the skin has become less
dry, the tongue slightly moist, the intelligence more clear, that the
fever has run its course. For