Progress and continuance - Hallucinations are irregular, remittent, sometimes constant - Causes which influence them in their progess. The peculiar form which the madness assumes exercises an action on hallucinations - Intermit-tences - Periodical attacks.

Duration - Exhibits great differences - Varies according to the character of the hallucination.

Diagnosis - Hallucinations easily discovered when the patient speaks of them, sometimes impossible when he maintains silence Signs by which they may be recognised - Different characteristics of nocturnal hallucinations, somnambulism and ecstasy - Difference between hallucinations and illusions - The forms of insanity may make the diagnosis uncertain.

Profnoiu - Varies according to the kind - The prognosis modified by the period - Different forms of alienation have a marked influence - Nerrous diseases aggravated by hallucinations - Hallucinations of long endurance change their nature - Prognosis of simple and general hallucinations - Hallucinations acknowledged by the patients seldom serious - The prognosis more important in hypochondria, hysteria, epilepsy, and certain varieties of illusions. - Recapitulation.

Hallucinations do not, in general, progress steadily; they return at irregular intervals, as well in the day as at night, and present very marked remissions. These remissions happen particularly in the day, and their variable return appears to us a powerful argument against the existence of a durable lesion in the organ attached to the phenomenon. This rule is not, however, without exception; in melancholy alienation, when the patient thinks he has been arrested, menaced, or is alarmed by some frightful vision, and pursued by enemies, the remission is not always appreciable. The hallucinations lasts for an indefinite period.

Hours of repose, distractions, and intellectual or manual occupations are sufficient to make hallucinations less sensible, and even sometimes to put an entire stop to them.

In a certain number of cases, the transition from waking to sleep, and vice versa, has an influence on the production of hallucinations.

Evening, darkness, and night favor the return of hallucinations, or augment their intensity. It is, in general, at night that the hallucinated are agitated, speak, sing, dispute, and shriek.

The form of insanity exercises an influence on the progress of hallucinations. Their type presents differences, according to which they exist with certain varieties of monomania, with mania and dementia. Sometimes even the type may disappear, masked by the alienation.

Intermittence has often been observed in hallucinations, and their suspension characterized by considerable lucid intervals.

The seasons have not offered any effect worthy of note.

Hallucinations having been constant, may become remittent or intermittent. Thus, it happens that an insane person is tormented night and day by a vision or a voice. After awhile these phenomena cease by day, and only occur at night. With many, the exacerbation is more powerful night and morning. At other times, hallucinations, having been intermittent and remittent, become constant.

Periodical returns have been proved in some cases, without more explanation being possible than is given to fevers.

The duration of hallucinations presents great variety; we have seen some disappear in a few hours, and others last for years. Their duration is often long when attached to chronic insanity.

When hallucination is manifested suddenly with insanity, it may quickly cease. A young lady became suddenly deranged in consequence of a disappointment in love; she thought her lover was near to her, and spoke to him constantly. In three days she became aware of her mistake. A man habituated to drinking was seized with furious delirium, and endeavored to kill two men who were on the top of the wall menacing him. Ten days afterwards he acknowledged that he had been crazy, but coolly affirmed his conviction that the two men had been in his room. In a month afterwards, he allowed that he had been strangely deceived. Hallucination may last but a few hours. A young man, seized with one of those sudden frenzies which a shock or change of place suffices to cure, said, on entering my establishment: "Who is that woman dressed in white, that walks before me?" He asked the same question several times, but in two hours spoke no more of it.

In mania and acute delirium, hallucinations may be very fugitive.

In gloomy monomania, on the contrary, and in demonomania, their persistency is great. In general, their existence is but fleeting in advanced and senile dementia, and, in general paralysis with dementia.

When hallucinations have existed for several months, and still more, for several years, in monomania, mania, and dementia in its first stage, they may be prolonged for a length of time. I have seen deranged persons who have had hallucinations for ten, fifteen, and twenty years. Examples have occurred, where they have existed almost a lifetime.

The diagnosis of hallucinations appears, at the first glance, to present no difficulty. It seems, in fact, impossible to misapprehend the acts of a man who sees figures invisible to all others, and hears voices no one else can hear. But such is not always the case; sometimes the hallucinated is conscious that his sensations are false; he therefore carefully conceals them. This state may last for a long time, without any indication of its existence. At other times, a man acts irrationally; but he says nothing of it; the greatest mystery seems to pervade his conduct; and years may pass without the enigma being solved. Dr. Marc has related a curious case, and he judiciously observes, that in this instance the more unique and eccentric the actions appear, the more they may be presumed to be caused by hallucinations.

It is necessary, on being consulted in a case of medical jurisprudence, for the purpose of ascertaining if hallucination exists, to take account of antecedents, to examine actual symptoms, and, above all, to take into consideration the physiognomy of the person under examination. The observations required are of three orders: discourse, actions, and writings. If the person speaks of angels, devils, and animals which he has seen, and these visions are connected with his habitual ideas; if they occur at irregular hours of the day and night, suddenly; if the voices have uttered nonsense, abuse, or menace, and these relations are made incoherently, it is almost certain that the individual has hallucinations of sight and hearing. This opinion presents greater force when the person stops, is angry and furious because the voices insult him, or is constantly moving about to avoid their menaces. The refusal of food under pretext that it is poisoned, the fear of entering a room because men are concealed there, the action of looking under beds, up the chimney, and disarranging all the bedclothes to seek for them, are so many proofs of disease. Finally, letters, memoranda, and notes dispel all doubts; for, howsoever plausible the reasons alleged may be in his favor, insanity will soon betray itself in these. This examination is no less useful in medico-legal estimates, when the individual is suspected of simulating madness.

We have endeavored, in the course of this work, to prove that dreams, somnambulism, and ecstasy had numerous points of resemblance with hallucinations, but we have never professed that they were identical; this distinction is important, and we invite attention to it. Their different characteristics have been described. Thus, nocturnal hallucinations could not be confounded with dreams, inasmuch as they make a deep impression on the mind, and remain clearly engraven on the memory. "With the dreamer," says Esquirol, "waking ideas are continued during sleep, whilst the hallucinist completes (I should prefer to say continues) his dream when almost entirely awake. Hallucinists differ from somnambulists in this respect, that in the greater number of cases they retain a faithful remembrance of their sensations, whilst somnambulists recollect nothing. This is, however, not so constant a fact as has been stated; we have mentioned proofs to the contrary.

The nature of ecstasy is not that of hallucination, but they follow each other as the shadow follows the substance. In ecstasy, the nervous influence is concentrated on a single point; and all the functions, excepting imagination, are suspended. In the hallucinated, on the contrary, all the functions are accomplished; the augmented action of the centre of sensibility is sufficient.* These differences do not strike us to be so decided as some pretend; for it appears to us that the hallucinated person is under the influence of strong preoccupation, and that his imagination is also in action.

* Monneret and Fleury, Compendium de Medecine Pratique, art Folic.

Illusion, separated by some, writers from hallucination, and united to it by others, although having a common centre and numerous points of contact, should not, it appears to us, be confounded. Friedreich, M. Aubanel, and others, who would reduce them to one class, say, in support of this opinion, that hallucinations and illusions originate in the same spot, the brain; that they are constantly changing from the one to the other; and that hallucinations of touch, taste, and smell could not, in most cases, be distinguished from illusions of the same senses. These statements are much more specious than real; because hypochondria and hysteria have each their origin in the brain, does it follow that they are alike, as even esteemed authors have maintained? M. Dubois, of Amiens, in his excellent work, has clearly resolved the question. Their transformation into each other is no more a reason for confounding them, than the passage from monomania to mania, and sometimes from dementia (although much more rarely), into these two forms, is sufficient to cause these three kinds to be described under the generic name of insanity. The difficulty of distinguishing them in the three senses designated is real, but not insurmountable; for in this case even, the difference may be established. Thus, in the case we are about to relate, the characters of hallucination are distinct, and it would be difficult to confound it with illusion.