The nature and cause of shell shock has been the subject of much controversy. In 1875 Ericksen called attention to the effect of intense emotional shock on the nervous system. This he explained as "dependent on molecular changes in the cord itself." Oppenheim's monograph in 1899 was responsible for the general use of the term "traumatic neurosis." His conception of these conditions was not accepted by Charcot, who at the time insisted that they belonged to the domain of hysteria, and were due solely to psychic traumas. Oppenheim's[91] observation of cases during the first year of the war confirmed his previous views. He expressed the opinion in 1915 that "in absolutely healthy and mentally normal individuals, without any trace of hereditary taint, war trauma may cause psychoses or neuroses. The causal injury may be of an objective, psychic or mixed nature. Violent detonations illustrate the mixed type. Their effect upon the nerve of hearing is certainly physical, but the psychic effect—terror—is also an important element in the resulting condition. The enormous air pressure exerted by the close passage of these missiles is another influential factor. An element that tends to complicate etiology is the frequent long duration of the exciting causes (prolonged and continuous artillery fire, a series of injuries received at brief intervals, exhaustion from various causes, lack of sleep, insufficient nourishment, extreme heat or cold, etc.)." He admits that the symptoms indicate a combination of neurasthenic and hysterical complexes which may be explained on a psychogenic basis, but maintains that the war has demonstrated them to be of a different nature. An external shock causes "a functional disturbance of the delicate mechanism of the psychic centers shown in 1, faulty distribution of motor impulses, 2, hypo-innervation, 3, hyper-innervation, causing tremors, tonic and clonic spasms, etc., instead of single muscle actions." He admits that a hysterical temperament may be an important factor. Max Nonne[92] in 1915 called attention to the fact that conditions combining symptoms of hysteria, neurasthenia and hypochondriasis plus vasomotor changes may occur without any history of injury and should not be called traumatic neuroses for that reason. He felt that the sudden recoveries occurring so frequently strongly discredited any theories suggesting an anatomical basis. He expressed the opinion that the most common cause was the explosion of hand grenades and that the main factor involved was an emotional disturbance. Binswanger[93] was of the opinion that mechanical injuries to the nervous system were responsible for the clinical pictures in war hysterias. He found that in a few cases only was there a history of predisposition, and maintained that in pre-war conditions hysteria was the result of a combination of psychic traumas with physical disturbances. Exciting causes were "over-exertion, irregular and insufficient nutrition, loss of sleep