The attack almost always comes on after midnight, and, as a rule, between the hours of two and six o'clock in the morning. Salter states that nineteen out of twenty cases occur between two and four A.M. There are, however, occasional exceptions to this rule; sometimes the patient is attacked soon after retiring, and Trousseau cites the case of his mother, who always had her attacks between eight and ten in the forenoon, and also that of a tailor, whose paroxysms invariably came on at three o'clock in the afternoon. Indeed, there is no hour of the twenty-four during which the seizure may not take place. Various attempts have been made to explain why it is that the paroxysms of asthma almost invariably occur during the latter half of the night. Many attribute it to a stasis of blood in the lungs caused by the recumbent posture of the patient, while others claim that it is due to a dulling of reflex impression, the patient during sleep failing to perceive the necessity of breathing. Germain Sée, who discredits both theories, inquires why, if the above explanations are correct, does the attack not come on soon after retiring, as is the case with the dyspnoea of cardiac diseases. The paroxysm of asthma develops very rapidly, but not so suddenly as is claimed by many authors, several minutes to half an hour or more elapsing before it attains its full height.[2] [Footnote 2: Germain Sée in _Nouveau Dictionnaire de Médecine et de Chirurgie_, tome iii. p. 617, Paris, 1865.] The patient, experiencing an urgent desire for breath, instinctively places himself in the position most favorable for the ready admission of air into the lungs. If in bed he sits up, and, resting on his hands or grasping his knees with them, he so fixes the body that the muscles of respiration may work to the greatest advantage. The shoulders are drawn up and the head thrown back. The expression of the face is one of great anxiety--pale at first, then red, and as the attack increases in severity assumes a dusky, bluish tint; the mouth is partially opened, the nostrils are dilated; the eyes, the conjunctivæ of which are much injected, are prominent, with a wild, staring look; and the forehead is moist with perspiration. Others in their desperate struggle for breath spring from the bed, throw open the window, and, regardless of everything save what they believe to be impending suffocation, recklessly gasp in the cold night air. Sometimes the sufferer prefers to kneel before a table or some other article of furniture, supporting his head with his hands. Whatever posture he assumes, he is actuated by the one impulse of placing himself in the position that will enable him to use to the greatest advantage the muscles of respiration and their auxiliaries. The sterno-cleido-mastoid muscles are contracted to the utmost, and, projecting like hard cords, with the aid of other muscles draw the chest upward. The patient instinctively avoids every