We thus have not only a deficiency of _proper_ stimulus, but a _deleterious_ condition of the blood, which acts as a poison to the brain. In fatal cases of coma and delirium, we observe deep red points, chiefly in the _cineritious_ part of the brain, from this congestion of its vessels. Sound sleep is thus prevented, but the congestion of carbonized blood acting as a sort of narcotic, depresses the energy of the brain so far as to prevent waking, inducing that middle state, drowsiness or slumber; so that sleep may thus depend on congestion _from exhaustion_; and “spectral illusion” from congestion in that state _short of slumber_; and insanity itself from congestion _still more copious and permanent_. From this results a disturbed condition of the brain; it is _irritated_, not excited, by its healthy or proper stimulus; and it follows that such derangement of the manifestations of mind ensues as we term a dream. Waking, however, soon takes place, and the blood is more scarlet, and the faculties themselves gradually awake. As this is more perfect, we remember the dream, and are enabled to explain it, and know _that it was a dream_. The mind is now _restored_, so that scarlet blood indicates _healthy thought_, and black blood its _reverse_. Your pardon for this prolixity and dulness. The healthy or unhealthy crisis of the blood is a most important subject in our argument, and too constantly slighted in the question of illusion. Monsieur Denis records the story of a young man of Paris, in the 17th century, who was cured of a stubborn and protracted lethargy, by the transfusion of the _arterial blood of a lamb_; and another of a recovery from madness, by that of the arterial blood of a calf, and these in presence of men both of _science_ and _high quality_. I do not affirm my implicit faith in this statement, of the effect of _gentle_ blood, but I am certain of the poisonous influence of that of _another quality_; and I will cite a passage from Hoffman, the German poet, whom Monsieur Poupon, in his “Illustrations of Phrenology,” adduces as a specimen of marvellousness, ere I offer my cases. “Why do my thoughts, whether I am awake or asleep, always tend, in spite of all my efforts, to the gloomy subject of insanity? It seems to me as if I felt my disordered ideas escaping from my mind, like _hot blood from a wounded vein_.” This was figurative, but it was true; for of itself this black blood may be suddenly the cause of furious and fatal mania. When Dionis, in his “Cours d’Opérations de Chirurgie,” is referring to that operation that has lately, by its revival, occupied so much of the attention of the medical world (the process of _transfusion_) he says: “La fin funeste de ces malheureuses victimes de la nouveauté, detruisit, en un jour, les hautes idées qu’ils avoient conçues; ils devinrent foux, _furieux, et moururent ensuite_.”