A priori, the production of hallucination not easily explained by an anatomical lesion - How account, by pathological anatomy, for the hallucinations of the child, the thinker, and the poet? - Interimittence another objection - Autopsy without characteristic anatomical disorders - The greater number of physicians do not believe, in the present state of science, in any special known alteration - The relation of lesions to hallucinations offers nothing positive - The brain is doubtless modified; but its mode of change is entirely unknown - Recapitulation.

A priori, it seems difficult to connect hallucinations with anatomical lesion. The transformation of an idea into an image, or rather its division (dedoublement), doubtless presents different appearances in the child, the rational man, the deranged person, the hysteric, and he who is a prey to fever, but it is no less the fundamental fact of hallucination. By what lesions can the false sensations of the child be explained, whose fear makes him see demons, assassins, and robbers - or those of the rational man, who sees before him villages, cities, and groups of men, without, however, being duped by these fantastic forms? Must this psychological phenomenon be attributed to a few drops more or less of blood, to a nervous erethismus? The same explanation is always given to a multitude of different diseases: "Doubtless it is a cerebral modification;" but it is contrary to the simplest good sense to give a uniform explanation to symptoms so varied and so numerous.

Are solitary hallucinations identical in the alienated, the epileptic, the hypochondriac, and the furious madman? And how can we suppose them connected with an anatomical derangement, when we see them disappear suddenly, return at indefinite periods, in the morning, the day, the evening, or the night? The cerebral fibre is evidently affected to a certain degree in the formation of the idea; but who has ever comprehended the 29 modification? It may be anything excepting what it appears to the senses.

When a man of genius has so concentrated all his faculties on one favorite thought that it takes a bodily form, do we know how this marvel is effected? No more than we can understand the mechanism of thought. Thus, by reasoning, we arrive at the conclusion that there cannot be appreciable anatomical derangement in the case of hallucinations.

Let us now see if cases of anatomical pathology resolve the question differently.

Case CXLIX

On the first of August, 1839, a man was received in the hospital of the Hotel-Dieu, aged thirty-nine, a printer by trade, of ordinary height, a good and strong constitution, beard and hair black. He related that, seventeen days previously, he had been attacked in the street, about two in the morning, by several men, and thrown down; and that, in falling, he got a wound on the upper part of the occipital region. This accident alarmed him greatly, and on the following night he opened his door under the impression that some one knocked. Soon afterwards, some armed men entered the room, who seized and ill-treated him. During the day he was tranquil, but this hallucination was reacted every night. This vision, however, was not the first that he had experienced; for seven years he had been visited at times by similar ones, all occurring at night.

On the day after his arrival, his countenance expressed nothing remarkable; his mind was perfectly clear; no heat in the skin, no fever; all the functions acted well. On the posterior and superior portion of the head was a wound, which had injured the scalp, 15 lines long by 13 broad.

Sweetened barley-water, castor-oil, 30 grammes. Diet.

About eight at night the delirium returned, the patient arose, and we were obliged to put on him the strait waistcoat. He manifested much fear, spoke of the men who had come to seize him, and endeavored to take refuge behind the beds of the other patients, uttering cries of terror. At three in the morning, he had recovered his mind, replied to the questions addressed to him, and was aware that he was the sport of an illusion. (Bleeding in the foot, soluble tartar, 15 grammes, lemonade, diet.)

All the symptoms of hallucination were reproduced in the night; in the morning, he was more calm, and replied sensibly to the questions asked; but there was a wildness in his look, and he soon endeavored to get free. (Sulphate of quinia.) No febrile symptoms.

On the 5th, the violent delirium ceased; but he still saw visions; from this time he sank, his features fell, he became pale and thin, and refused to eat. On the 11th he had vomitings, which nothing could check; neither draughts, nor a blister on the epigastrium. On the 16th, the patient expired, at four in the morning.

Autopsy on the 17th, 30 hours after death. - Head. The meninges, and particularly the pia mater, are injected, but are easily separated; they have not contracted any adherence to the cortical substance. This, carefully examined, presents neither injection nor change of texture; the convolutions are in a normal state. There is no serosity in the ventricles. The cerebellum has its natural consistence and color. The olfactory and auditory nerves require no notice. No serosity in the base. The surface of the stomach on a grayish base presents a very slight injection; it is universally mammillated, with the exception of the great cul-de-sac.

A slight arborescent injection is observable in the duodenum. The liver very large. The wound on the head healed; the bone uninjured.

This case of hallucination, as simple as possible, does not present any anatomical lesion which can account for the disorder of the sensations, unless, indeed, we consider the injection of the meninges as a cause. It is, however, worthy of note that, for seven years, the patient had been subject to these visions, and that during this lapse of time an alteration could easily have been developed.

This is not the only autopsy of the hallucinated which we have made; in some cases we have discovered nothing; in others, we have noticed injections, several times alterations in the meninges and the cerebral substance; but, even in these cases, it has been impossible for us to discern the connection between the lesion and the disordered sensations experienced during life.

This opinion is that of the immense majority of physicians who have devoted years to the study of autopsical researches. M. Lelut does not admit of any anatomical lesion in hallucinations. M. Calmeil agrees in this view of the subject. Leuret has formally protested against those who assign an appreciable material lesion to hallucinations. It may be generally asserted that the brain of an hallucinated person does not resemble, point for point, that of one exempt from hallucinations, but we cannot indicate wherein it differs.

M. Aubanel, whose treatise proves him to have been a dose observer, says: "In three subjects of whom he made post-mortem examinations, two of whom had hallucinations of sight, the other of hearing, he could not detect the slightest change of texture or color in the optic or auditory nerves." Farther on, he states: "I have made very numerous autopsies of the alienated in Bicetre. I have encountered multiplied alterations, but I have never established their connection with the phenomena that engage our attention, whether by reason of their nature, of their inconstancy and variety, or of the different affections which have existed. These alterations, moreover, did not always exist. There was nothing to prove that they were not old lesions."

The treatise of M. Dupeyre on some points relative to delirium tremens, contains nothing peculiar to hallucinations in the autopsies which are there described; they are known lesions.

Some localizers have attributed hallucinations to the irritation of a portion of the encephalus, but up to the present time, they cannot show either the situation or character of this lesion.

A physician of note has found in hallucinations the nervous cords hard, yellowish, and withered; and, proceeding higher, has found the cerebral portion, to which the nerve is attached, to exhibit more or less serious alterations; he has especially noticed adherences of the fibres. When these facts shall have been published in all their details, they will attract the attention of men who are cultivating our science. But I fear that it is only a simple coincidence; and it would require much more decided proofs to destroy the arguments which we have employed in the opening of this chapter, or to effect any alteration in the present state of science. We have frequently found the optic and acoustic nerves wasted and altered in their texture, without the individuals having hallucinations. As to lesions of the cerebellum, mentioned by the same author, it would appear that he has himself observed them in deranged persons who were not hallucinated.

Recapitulation. - Even if a particular lesion existed in hallucination, it still remains to discover its mode of action in converting an idea into an image, or rather in rendering visible its sensible sign.

The same objection exists in describing the lesion which peoples the solitude of the child with phantoms, and that of the rational man with all kinds of images.

Hallucinations vary according to cases, and the same lesion cannot apply to all.

To explain hallucinations as caused by the presence of a little more or a little less blood, would be to remain still in the circle in which all cerebral diseases are at present clustered.

The researches of pathological anatomy have not, up to the present time, furnished any positive data on the mode of lesion peculiar to hallucinations; it is, nevertheless, that which reasoning might conjecture.

The facts collected by Mr. Foville are neither sufficiently numerous nor sufficiently well known to modify general opinion; we must, therefore, be content to wait until this gentleman has published his anatomico-pathological researches.