n to similar sufferers in
civil life from other causes such as railway collisions, still remains
for future determination. An ample field for such observations has at
any rate been created by the present war.

In _severe concussion_ a far more highly destructive action is exerted.
This condition may be followed by complete disorganisation of the cord,
accompanied or not by multiple parenchymatous haemorrhages into its
substance. Either or both of these pathological conditions are produced
by the impact of the bullet with the spine, given a sufficiently high
degree of velocity, and it is difficult to separate clinically the
resulting symptoms. This is a matter perhaps of less importance, since
it stands to reason that a vibratory force, capable of rupturing the
spinal capillaries, would at the same time damage the nervous tissue.

In speaking of concussion of this degree, it should be clearly
recognised that a general condition, such as is indicated by the use of
the term 'concussion of the brain,' is in no wise implied. The condition
is really far more nearly allied to one of contusion, a strictly
localised portion of the spinal cord undergoing the destructive process
which affects the segments below only in so far as it interrupts the
normal channels of communication with the higher centres.

Case 102 is an instance of such a lesion, the post-mortem examination
showing clearly that the spinal canal was not encroached upon by the
bullet. The cord in this instance appeared little changed
macroscopically, and this fact was observed in other instances, both
during operations and post mortem.

_Contusion._--This condition is very closely allied to the last. In
cases 101 and 103 the spinal canal was as little encroached upon as in
102, but the bullet struck the somewhat elastic neural arch in each
case, and post mortem an adhesion between the cord and the enveloping
dura opposite the point at which impact of the bullet was closest
suggests that, in spite of the escape of the bone from fracture, it may
have been momentarily depressed to a sufficient degree to contuse the
cord, or the latter may have suffered a _contre-coup_ injury. For these
reasons the inclusion of the cases as instances of pure concussion is
not warranted. In both Nos. 99 and 100 the neural arch had actually
suffered fracture, and although the bone was not depressed or exercising
pressure at the time of the autopsies, it was no doubt driven in
temporari