ead and dying on the field, that
thoracic wounds, putting aside those that directly implicated the heart,
were responsible for but a small proportion of the fatalities.

The escape of the posterior mediastinal viscera, the great vessels, and
the heart, is, I believe, to be explained by the fact that all are
supported and held in position by the loose meshed mediastinal tissue,
which allows for their displacement after the manner observed in the
case of the vessels and nerves lying in the loose tissue of the great
vascular clefts.

_Wounds of the heart._--Perforating wounds of the heart were probably
fatal in all instances, in spite of the fact that, in some patients who
survived, the position of wound apertures on the surface of the body
made it difficult to believe that the heart had not been penetrated.
(See cases below.)

In the case of this organ, we must bear in mind its constant variations
in bulk, its elastic compressibility, and its variations in position in
systole and diastole. The variations in bulk and position would be
capable of explaining the escape of the organ from injury at some
particular moment, when a second shot apparently through the same wound
track might implicate it. Beyond this, reasoning from the case of
analogous hollow viscera, as the arteries or the intestine, a bullet
might readily score the surface of the heart without perforating its
cavity.

Such accidents were observed. Thus, in a case examined by Mr. Cheatle,
the patient died of suppurative pericarditis, secondary to a wound of
which the external apertures had closed. In this patient both auricle
and ventricle were scored externally by the passage of the bullet.

I am, however, disinclined to allow that many patients survived direct
blows on the heart, since I believe that in the majority if not in all
cardiac wounds the actual cause of death was not haemorrhage, but sudden
stoppage of the heart's action. This is to be inferred from the fact
that severe external haemorrhage did not occur; in some cases the shirt
was hardly stained, and in all death occurred in the course of a very
few minutes. Again, in none of the patients whom I saw who had received
possible wounds of the heart-wall were there evident signs of
haemo-pericardium. In view of the difficulty of detecting this condition
from physical signs, this argument is naturally not of great weight, but
must be allowed.

One or two death scenes from cardiac wound were descri