It is only however in the advanced stage of the disease, that this severe struggle takes place. In the general way the patient is instantly liberated from the paroxysm, as soon as he can succeed in moving any of his limbs. I have seldom met with any one who was able to articulate during the paroxysm, though I have generally been able myself to call any person by name, who might be near me, and to beg of them to wake me, but this is always effected with difficulty, and only after the paroxysm has already continued some time. 4th. It frequently happens, especially when a person is anxious about rising at a particular hour, and afraid of over-sleeping it, that he becomes conscious of that circumstance in his sleep, and feels an ardent desire to wake himself; to many persons this is by no means a difficult task, and is soon accomplished; but to those who are subject to Night-Mare, the reverse of this takes place. They strive with all their might to awake, and soon become conscious of their precise circumstances, but cannot recover the power of volition; after contending for this a short time, the breathing at length becomes laborious, and a complete paroxysm of Night-Mare succeeds, which always is severe in proportion as the patient happens to be more perfectly awake. From these observations it results, that the nature of Incubus is essentially different to that of either sleeping or waking, and is an absolute state of disease which may occur during sleep in a slight degree, without breaking that sleep; that it consists in a suspension of the power of volition very different to what takes place in natural sleep, because it is accompanied with a consciousness of that suspension, and a strong desire of recovering this power. But neither is this sufficient to constitute Night-Mare, although this disease will, I believe always, result from such a state of things, yet the paroxysm is by no means complete, until, in addition to the general paralysis of all the muscles of voluntary motion, there shall occur likewise a partial paralysis of some of those concerned in the functions, which are performed independently of the will, especially of respiration and the circulation of the blood, the consequence of which will be a difficulty of breathing, with a sense of oppression about the præcordia, and fluttering of the heart. I conceive these symptoms to arise principally from a temporary paralysis of the nerves of the diaphragm; or rather an inaptitude in those nerves, together with some others of the principal branches of the intercostals, to perform their functions. Thus then, from this partial paralysis of the diaphragm and thoracic muscles, the patient is rendered incapable of dilating the chest so as to allow of the expansion and consequent inflation of the lungs; the blood consequently meets with some interruption in its passage through that organ, and this interruption is speedily communicated to the heart; the re-action which takes place here