Trauma to the nervous system is one of the major types of pathology met with in clinical practice, and is therefore a subject of perennial interest. Of its various effects the most transitory, concussion, has been debated more often than any other, for its events are reversible and difficult to verify. Lacking any sharp end-point, they are not easy to measure in degree or duration. The more severe degrees of concussion, which might be expected to provide more obvious structural and functional change, are usually complicated by other types of pathology that confuse the question. We have printed two papers, one in the April issue of the Archives1 and one in this issue,11 that present some fresh points of view. Dr. Friede1 brings forward evidence that injury to the ventral aspects of highest segments of the spinal cord is a frequent concomitant of experimental concussion in animals.