rtain cases of syphilis.

Leucocytosis is met with in nearly all acute infective diseases, and in
acute pyogenic inflammatory affections, particularly in those attended
with suppuration. In exceptionally acute septic conditions the extreme
virulence of the toxins may prevent the leucocytes reacting, and
leucocytosis may be absent. The absence of leucocytosis in a disease in
which it is usually present is therefore to be looked upon as a grave
omen, particularly when the general symptoms are severe. In some cases
of malignant disease the number of leucocytes is increased to 15,000 or
20,000. A few hours after a severe haemorrhage also there is usually a
leucocytosis of from 15,000 to 30,000, which lasts for three or four
days (Lyon). In cases of haemorrhage the leucocytosis is increased by
infusion of fluids into the circulation. After all operations there is
at least a transient leucocytosis (_post-operative leucocytosis_)
(F. I. Dawson).

The leucocytosis begins soon after the infection manifests itself--for
example, by shivering, rigor, or rise of temperature. The number of
leucocytes rises somewhat rapidly, increases while the condition is
progressing, and remains high during the febrile period, but there is no
constant correspondence between the number of leucocytes and the height
of the temperature. The arrest of the inflammation and its resolution
are accompanied by a fall in the number of leucocytes, while the
occurrence of suppuration is attended with a further increase in their
number.

In interpreting the "blood count," it is to be kept in mind that a
_physiological leucocytosis_ occurs within three or four hours of taking
a meal, especially one rich in proteins, from 1500 to 2000 being added
to the normal number. In this _digestion leucocytosis_ the increase is
chiefly in the polynuclear neutrophile leucocytes. Immediately before
and after delivery, particularly in primiparae, there is usually a
moderate degree of leucocytosis. If the labour is normal and the
puerperium uncomplicated, the number of leucocytes regains the normal in
about a week. Lactation has no appreciable effect on the number of
leucocytes. In new-born infants the leucocyte count is abnormally high,
ranging from 15,000 to 20,000. In children under one year of age, the
normal average is from 10,000 to 20,000.

_Absence of Leucocytosis--Leucopenia._--In certain infective diseases
the number of leucocytes in the circulating blood is abnorma