ult to be certain that we have
discovered the whole extent of any fistula. An equal difficulty, therefore,
exists in being certain that we have placed the caustic in the position
in which it is most wanted--namely, at the furthermost end of the fistula
where the necrotic tissue is to be found.

When a caustic is used at all, it is far better to employ it in the liquid
form, when either of the drugs we have just mentioned may again be used. In
the first place, the liquid is far more likely to be brought into contact
with the diseased structures than is the solid salt. Also, its action may
be regulated by altering the strength of the solution, and the liability to
form impermeable albuminates thus diminished.

Probably the best solution for use in this way is the old-fashioned
Villate's solution (see p. 199).

This liquid should be injected at least every day, and, in a bad case,
even two or three times daily. Practical hints to be borne in mind when
attempting to cure quittor by means of injections are these:

If the fistulas are numerous, the fluid should be injected into their
various orifices.

In order to force the fluid to the bottom of each diseased track, it is
necessary, when injecting one opening, to firmly close all others.

Several injections should be made at each time of injection. In other
words, we must not be content with just forcing fluid in. It must be forced
in, and again forced out by a further syringeful. The fistulous tracks
must, in fact, be washed in the liquid.

The effect of the injection during the first eight or ten days is to render
suppuration more abundant and whiter. After two weeks of the treatment
sloughing of the inside of the sinuses occurs, and healing of the wound
commences. Signs that this is occurring are--slight haemorrhage at the end
of each injection, and a gradually increasing difficulty in forcing in the
fluid.

_The Making of Counter-openings to the Fistulas_.--Although Villate's
solution or any other caustic used in the manner we have described
often effects a cure, many practitioners insist on the fact that a
counter-opening to the fistula must also be made.

The probe is used and the direction and depth of the fistula ascertained.
Through the wall is then made an opening at exactly opposite the lowest
point found by the probe, or through the sole if the probe should there
lead us. This opening is best made with a sharp-pointed iron, and may
afterwards be kept la