teral body plane, it will be found to be in the esophagus,
for it assumed that position by passing down flatwise behind the
larynx. If, however, the object is seen to be in the sagittal plane it
must lie in the trachea. This position was necessary for it to pass
through the glottic chink, and can be maintained because of the
yielding of the posterior membranous wall of the trachea.

THE ROENTGENOGRAPHIC SIGNS OF EXPIRATORY-VALVE-LIKE BRONCHIAL
OBSTRUCTION

The roentgenray signs in expiratory valve-like obstruction of a
bronchus are those of _an acute obstructive emphysema_ (Fig. 74),
namely,
1. Greater transparency on the obstructed side (Iglauer).
2. Displacement of the heart to the free side (Iglauer).
3. Depression and flattening of the dome of the diaphragm on the
invaded side (Iglauer).
4. Limitation of the diaphragmatic excursion on the obstructed side
(Manges).

It is very important to note that, as discovered by Manges, the
differential emphysema occurs at the end of expiration and the plate
must be exposed at that time, before inspiration starts. He also noted
that at fluoroscopy the heart moved laterally toward the uninvaded
side during expiration.*

* Dr. Manges has developed such a high degree of skill in the
fluoroscopic diagnosis of non-opaque foreign bodies by the obstructive
emphysema they produce that he has located peanut kernels and other
vegetable substances with absolute accuracy and unfailing certainty in
dozens of cases at the Bronchoscopic Clinic.

[FIG. 74--Expiratory valve-like bronchial obstruction by
non-radiopaque foreign body, producing an acute obstructive emphysema.
Peanut kernel in right main bronchus. Note (a) depression of right
diaphragm; (b) displacement of heart and mediastinum to left; (c)
greater transparency of the invaded side. Ray-plate made by Willis F.
Manges.]

_Complete bronchial obstruction_ shows a density over the whole area
the aeration and drainage of which has been cut off (Fig. 75).
Pulmonary abscess formation and "drowned lung" (accumulated secretion
in the bronchi and bronchioli) are shown by the definite shadows
produced (Fig. 76).

[140] Dense and metallic objects will usually be readily seen in the
roentgenograms and fluoroscope, but many foreign bodies are of a
nature which will produce no shadow; the roentgenologist should,
therefore, be prepared to interpret the pulmonary pathology, and
should not dismiss the case as negative for foreign b