This may be used as a type with which to compare the ulcers seen at the
bedside, so that we may determine how far, and in what particulars,
these differ from the type; and that we may in addition recognise the
conditions that have to be counteracted before the characters of the
typical healing sore are assumed.

For purposes of contrast we may indicate the characters of an open sore
in which bacterial infection with pathogenic bacteria has taken place.
The layer of coagulated blood and lymph becomes liquefied and is thrown
off, and instead of granulations being formed, the tissues exposed on
the floor of the ulcer are destroyed by the bacterial toxins, with the
formation of minute sloughs and a quantity of pus.

The discharge is profuse, thin, acrid, and offensive, and consists of
pus, broken-down blood-clot, and sloughs. The edges are inflamed,
irregular, and ragged, showing no sign of growing epithelium--on the
contrary, the sore may be actually increasing in area by the
breaking-down of the tissues at its margins. The surrounding parts are
hot, red, swollen, and œdematous; and there is pain and tenderness both
in the sore itself and in the parts around.

#Classification of Ulcers.#--The nomenclature of ulcers is much involved
and gives rise to great confusion, chiefly for the reason that no one
basis of classification has been adopted. Thus some ulcers are named
according to the causes at work in producing or maintaining them--for
example, the traumatic, the septic, and the varicose ulcer; some from
the constitutional element present, as the gouty and the diabetic ulcer;
and others according to the condition in which they happen to be when
seen by the surgeon, such as the weak, the inflamed, and the callous
ulcer.