o help
the tissues by removing a foreign body or a piece of dead bone, there
are employed--empirically--a number of procedures such as the induction
of hyperaemia, exposure to the X-rays, and the employment of blisters,
cauteries, and setons. Vaccines may be had recourse to in those of
bacterial origin.

CHAPTER IV

SUPPURATION

Definition--Pus--_Varieties_--Acute circumscribed abscess--_Acute
suppuration in a wound_--_Acute Suppuration in a mucous
membrane_--Diffuse cellulitis and diffuse suppuration--
_Whitlow_--_Suppurative cellulitis in different situations_--Chronic
suppuration--Sinus, Fistula--Constitutional manifestations of
pyogenic infection--_Sapraemia_--_Septicaemia_--_Pyaemia_.

Suppuration, or the formation of pus, is one of the results of the
action of bacteria on the tissues. The invading organism is usually one
of the staphylococci, less frequently a streptococcus, and still less
frequently one of the other bacteria capable of producing pus, such as
the bacillus coli communis, the gonococcus, the pneumococcus, or the
typhoid bacillus.

So long as the tissues are in a healthy condition they are able to
withstand the attacks of moderate numbers of pyogenic bacteria of
ordinary virulence, but when devitalised by disease, by injury, or by
inflammation due to the action of other pathogenic organisms,
suppuration ensues.

It would appear, for example, that pyogenic organisms can pass through
the healthy urinary tract without doing any damage, but if the pelvis of
the kidney, the ureter, or the bladder is the seat of stone, they give
rise to suppuration. Similarly, a calculus in one of the salivary ducts
frequently results in an abscess forming in the floor of the mouth. When
the lumen of a tubular organ, such as the appendix or the Fallopian tube
is blocked also, the action of pyogenic organisms is favoured and
suppuration ensues.

#Pus.#--The fluid resulting from the process of suppuration is known
as _pus_. In its typical form it is a yellowish creamy substance, of
alkaline reaction, with a specific gravity of about 1030, and it has a
peculiar mawkish odour. If allowed to stand in a test-tube it does not
coagulate, but separates into two layers: the upper, transparent,
straw-coloured fluid, the _liquor puris_ or pus serum, closely
resembling blood serum in its composition, but containing less protein
and more cholestrol; it also contains leucin, tyrosin, and certain
alb