detaching the cord-terminals at the binding
posts, and attach the terminals to the binding posts of the battery to
be tested.

_Efficient use of forceps_ requires previous practice in handling of
the forceps until it has become as natural and free from thought as
the use of knife and fork. Indeed the coordinate use of the
bronchoscopic tube-mouth and the forceps very much resembles the use
of knife and fork. Yet only too often a practitioner will telegraph
for a bronchoscope and forceps, and without any practice start in to
remove an entangled or impacted foreign body from the tiny bronchi of
a child. Failure and mortality are almost inevitable. A few hundred
hours spent in working out, on a bit of rubber tubing, the various
mechanical problems given in the section on that subject will save
lives and render easily successful many removals that would otherwise
be impossible.

It is often difficult for the beginner to judge the distance the
forceps have been inserted into the tube. This difficulty is readily
solved if upon inserting the forceps slowly into the tube, he observes
that as the blades pass the light they become brightly illuminated. By
this _light reflex_ it is known, therefore, that the forceps blades
are at the tube-mouth, and distance from this point can be readily
gauged. Excellent practice may be had by picking up through the
bronchoscope or esophagoscope black threads from a white background,
then white threads from a black background, and finally white threads
on a white background and black threads on a black background. This
should be done first with the 9 mm. bronchoscope. It is to be
remembered that the majority of foreign body accidents occur in
children, with whom small tubes must be used; therefore, practice
work, after say the first 100 hours, should be done with the 5 mm.
bronchoscope and corresponding forceps rather than adult size tubes,
so that the operator will be accustomed to work through a small
calibre tube when the actual case presents itself.

[120] _Cadaver Practice_.--The fundamental principles of peroral
endoscopy are best taught on the cadaver. It is necessary that a
specially prepared subject be had, in order to obtain the required
degree of flexibility. Injecting fluid of the following formula worked
out by Prof. J. Parsons Schaeffer for the Bronchoscopic Clinic
courses, has proved very satisfactory:
Sodium carbonate--1 1/2 lbs.
White arsenic--2 1/2 lbs.
Potassium n