Ordinarily, however, the sufferer groans, and tosses about the bed; he appears to be endeavoring to speak, and to escape from his imaginary danger; his face, neck, and chest are flushed; a cold perspiration appears, especially on his forehead, and he is sometimes seized with a general trembling of the whole body. The respiration appears to be particularly disturbed; he gasps for air, and occasionally the breathing is stertorous. As to the pulse, strange as it may appear, there is rarely any marked change from the healthy standard, beyond the slight irregularity induced by the disorder of the respiration. Among the mental symptoms, in addition to the fear with which he is filled, the sufferer is most sensibly impressed with a sense of his utter helplessness. His will is actively engaged in endeavoring to bring his muscles into action, but they cannot be made to obey its behests, and he consequently feels himself powerless to escape from the enemies which attack him. In regard to the kind of images which make their appearance, there is more or less uniformity. Generally they consist of animals, such as hogs, dogs, monkeys, or nondescripts created by the imagination of the dreamer. At other times they are demons of various forms. A gentleman, whose case came under my notice, was visited almost nightly by a huge black walrus, which appeared to roll off of a large cake of ice, and, crawling up the bed, to throw itself on his chest. Another was tormented by an animal, half lion and half monkey, which seemed to fasten its claws in his throat while seated on his breast. At other times there are no images, but only painful delusions, in which the dreamer is placed in dangerous positions, or suffers some kind of torturing operation. Thus a lady informs me that she is subject to frequent attacks of nightmare, during which she imagines she is standing on the top of a high mast, and in extreme fear of falling off. Again she is dragged through a key-hole by some invisible power; and again has her nose and mouth so tightly closed that she can get no breath of air. The _causes_ of nightmare may be divided into the _exciting_ and the _immediate_. The _exciting causes_ are very numerous. Unusual fatigue, either of mind or of body, recent emotional disturbance, such as that produced by fright, anxiety, or anger, and intense mental excitement of any kind may produce it. I have known a young lady to have a severe attack the night after a school examination, in which she had been unduly tasked. Another young lady is sure to be attacked after witnessing a tragedy performed. A young man, who was under my care for a painful nervous affection, always had a paroxysm of nightmare during the first sleep after delivering an address, which he was obliged to do every month for a year or more.