lly
low--3000 or 4000--and this condition is known as _leucopenia_. It
occurs in typhoid fever, especially in the later stages of the disease,
in tuberculous lesions unaccompanied by suppuration, in malaria, and in
most cases of uncomplicated influenza. The occurrence of leucocytosis in
any of these conditions is to be looked upon as an indication that a
mixed infection has taken place, and that some suppurative process is
present.

The absence of leucocytosis in some cases of virulent septic poisoning
has already been referred to.

It will be evident that too much reliance must not be placed upon a
single observation, particularly in emergency cases. Whenever possible,
a series of observations should be made, the blood being examined about
four hours after meals, and about the same hour each day.

The clinical significance of the blood count in individual diseases will
be further referred to.

_The Iodine or Glycogen Reaction._--The leucocyte count may be
supplemented by staining films of the blood with a watery solution of
iodine and potassium iodide. In all advancing purulent conditions, in
septic poisonings, in pneumonia, and in cancerous growths associated
with ulceration, a certain number of the polynuclear leucocytes are
stained a brown or reddish-brown colour, due to the action of the iodine
on some substance in the cells of the nature of glycogen. This reaction
is absent in serous effusions, in unmixed tuberculous infections, in
uncomplicated typhoid fever, and in the early stages of cancerous
growths.

CHAPTER III

INFLAMMATION

Definition--Nature of inflammation from surgical point of
view--Sequence of changes in bacterial inflammation--Clinical
aspects of inflammation--General principles of treatment--Chronic
inflammation.

Inflammation may be defined as the series of vital changes that occurs
in the tissues in response to irritation. These changes represent the
reaction of the tissue elements to the irritant, and constitute the
attempt made by nature to arrest or to limit its injurious effects, and
to repair the damage done by it.

The phenomena which characterise the inflammatory reaction can be
induced by any form of irritation--such, for example, as mechanical
injury, the application of heat or of chemical substances, or the action
of pathogenic bacteria and their toxins--and they are essentially
similar in kind whatever the irritant may be. The extent to which the
proce