death from blood-poisoning frequently followed even the most trivial
operations. An operation was looked upon as a last resource, and the
inherent risk from blood-poisoning seemed to have set an impassable
barrier to the further progress of surgery. To the genius of Lister we
owe it that this barrier was removed. Having satisfied himself that the
septic process was due to bacterial infection, he devised a means of
preventing the access of organisms to wounds or of counteracting their
effects. Carbolic acid was the first antiseptic agent he employed, and
by its use in compound fractures he soon obtained results such as had
never before been attained. The principle was applied to other
conditions with like success, and so profoundly has it affected the
whole aspect of surgical pathology, that many of the infective diseases
with which surgeons formerly had to deal are now all but unknown. The
broad principles upon which Lister founded his system remain unchanged,
although the methods employed to put them into practice have been
modified.

#Means taken to Prevent Infection of Wounds.#--The avenues by which
infective agents may gain access to surgical wounds are so numerous and
so wide, that it requires the greatest care and the most watchful
attention on the part of the surgeon to guard them all. It is only by
constant practice and patient attention to technical details in the
operating room and at the bedside, that the carrying out of surgical
manipulations in such a way as to avoid bacterial infection will become
an instinctive act and a second nature. It is only possible here to
indicate the chief directions in which danger lies, and to describe the
means most generally adopted to avoid it.

To prevent infection, it is essential that everything which comes into
contact with a wound should be sterilised or disinfected, and to ensure
the best results it is necessary that the efficiency of our methods of
sterilisation should be periodically tested. The two chief agencies at
our disposal are heat and chemical antiseptics.

#Sterilisation by Heat.#--The most reliable, and at the same time the
most convenient and generally applicable, means of sterilisation is by
heat. All bacteria and spores are completely destroyed by being
subjected for fifteen minutes to _saturated circulating steam_ at a
temperature of 130 to 145 C. (= 266 to 293 F.). The articles to be
sterilised are enclosed in a perforated tin casket, which is place