nsequence of the second peculiarity, the
position and direction of secondary fissures are not so dependent on
anatomical structure as in the corresponding injuries of civil practice.
Thus, fractures of the base, for instance, were less constant in their
course and position. The cases as a whole are best divided into four
classes.

[Illustration: FIG. 60.--Mauser Bullet in Nasal Fossa. (Skiagram by H.
Catling.) Case No. 47]

1. Extensive sagittal tracks passing _deeply_ through the brain, and
vertical wounds passing from base to vertex or _vice versa_, in the
posterior two thirds of the skull. These will be referred to as general
injuries.

2. Vertical or coronal wounds in the frontal region.

3. Glancing or obliquely perforating wounds of varying depth in any part
of the head.

4. Fractures of the base.

Of these classes the first was nearly uniformly fatal; the second
relatively favourable, and with low degrees of velocity often
accompanied by surprisingly slight immediate effects; while the third
had perhaps the best prognosis of all, but this varied as to the defects
that might be left, and with the region of the head affected.

1. _General injuries._--Fractures of this class may be treated of almost
apart. For their production the retention of a considerable degree of
velocity on the part of the bullet was always necessary, and the results
were consequently both extensive and severe.

The aperture of entry was comparatively small, since to take so direct
and lengthy a course through the skull the impact of the bullet needed
to be at nearly an exact right angle to the surface of the bone. Any
disposition to assume the oval form, therefore, depended mainly upon the
degree of slope of the actual area of the skull implicated. In size the
aperture of entry did not greatly exceed the calibre of the bullet; in
outline it was seldom exactly circular, but rather roughly four-sided,
with rounded angles, slightly oval, or pear-shaped. The margin of the
opening consisted of outer table alone, the inner being always
considerably comminuted. Fragments of the latter, together with the
majority of those corresponding to the loss of substance of the outer
table, were driven through the dura mater and embedded in the brain.
These bony fragments were more or less widely distributed over an area
of a square inch or more, and not confined to a narrow track.

[Illustration: FIG. 61.--Diagram of Aperture of Entry in Occipital B