In 1917 Mott[97] reported the examination of the brains from two cases of pure shell shock. They showed a congestion of the meninges, scattered subpial hemorrhages, and congested vessels in the internal capsule, pons and medulla. In one case there was an extravasation of blood into the substance of the lower surface of the orbital lobe. He spoke also of a general chromatolysis in the ganglion cells. Eder[98] in 1917 advanced the theory that the symptoms of neuroses are the result of mental conflicts and that the mechanisms involved are those attributed by Freud to hysteria. As a result of an analysis of one hundred cases he reached the conclusion that mechanical shock, gas poisoning and other physical traumas were not factors in the production of these conditions. His cases occurred in persons free from hereditary or personal psychoneurotic predisposition. Chavigny in a discussion of the mental diseases in the French army asserted that psychoses and neuroses were practically unknown until trench warfare began and the use of heavy artillery became common. From this moment psychiatric units became necessities. Ballet and de Fursac[99] were very firmly of the opinion that shell shock was due to purely emotional reactions in predisposed individuals. "If disturbances from explosion and from emotional shock, existing with or without traumatism, produce identical results, it is evident that they have a common factor and this common factor can be only the emotion itself. Disturbance from explosion without external injury presupposes an emotional state, and it is from this state that it derives its causal efficacy; whatever the etiological complex found as the cause of a condition of shock, whether the explosion of a shell, bomb or mine, the sight of the dead, burial in a trench, wound from an explosion or a missile, there is only one factor of importance, the emotional factor, which is essentially responsible for all the neuropsychic disorders that together make up the shock syndrome."