In _slight concussion_ the usually transient effects of the injury, and its happy tendency not to destroy life, place us in a state of uncertainty as to the occurrence of anatomical changes, since no opportunity of post-mortem examination occurred. The clinical condition included under this term corresponds with that implied in 'spinal concussion' in civil practice. One point of extreme interest, whether the subjects of small-calibre bullet spinal concussion will in the future suffer from the remote effects common 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.