THE MECHANISM OF CONTRE-COUP INJURY.

WHEN one considers the various types of intracranial lesion produced by trauma to the head-extradural haemorrhage, subdural hemorrhage, cortical laceration, haemorrhage into brain substance or ventricles-there is one type of injury which of recent years has excited much speculation as to the mechanism of its causation, namely, " contre-coup injury." It has long been observed in persons who have died as a result of trauma to the head and have come to autopsy that gross damage to brain tissue most frequently occurred, not in the situation immediately underlying the area of skull at which the traumatic force was applied, but rather at the pole of the brain diametrically opposite to the point struck. Thus, for example, a blow impinging on the skull in the region of the occiput might in some cases cause