A naval officer, 22, transferred from sea service, went into Belgium, November, 1914, in a Fusilleur brigade of marines and there greatly distinguished himself, growing very weary and enervated, however, about the middle of April, 1915. His attitude to the men altered: he sometimes struck them; gently, though, according to his account. They must do in ten seconds what they really could not do under ten minutes. The officer, in fact, had lost all notion of time. He went about agitatedly, contradicted his superior officers and was troubled because, as he said, they often were men of inexperience as compared to himself. He grew irritated, too, because there were Free Masons in the army and when he was sent to the asylum in July, 1915, said it was the doing of the Free Masons. He did not seem to have any hallucinations. His ideas and sentiments were very labile, and a bit confused, and not all his interpretations dealt with Free Masons and occultism. August 5, however, the phase of calmness was again followed by agitation; he broke things and laughed explosively. August 10, another attack occurred, with destructiveness. During the next few days there were alternate phases of depression and excitation. He was negativistic, resistive and struck attendants. _Re_ war stress and psychoses, Morselli finds the acute cases on psychopathic soil. First in the list, he places the neurasthenias and psychasthenias, and second, the hysterias, two groups which, more than the remainder, may be said to constitute the so-called Shell-shock group. Third, he found depressions ranging over into a delusional state with suicidal ideas; fourth, a species of stupor, occasionally catatonic, recalling dementia praecox; fifth, transient hallucinatory states; sixth, confusions (Meynert’s amentia?); last, manias. The above case of Dumesnil appears to be a pure case of manic-depressive psychosis developing on the war basis, but perhaps merely comes from a latent cyclothymia. Predisposition; war stress: Melancholia. =Case 168.= (DUMESNIL, 1915-6.)