and the judgment, delusions, illusions, and hallucin

ations.

Delusions.-A delusion is simply a belief in the truth of that which is not true; it is a false belief. Delusions have been and are still considered as the essential characteristic of insanity, but this can hardly be said to be true in the sense that they are at all peculiar to insanity. In fact, it is one of the most difficult of all possible definitions to define just what an insane delusion is. Beliefs of all kinds depend so much upon training or education and environment that it is almost impossible to say what may not be an individual or general faith at any one time. There are a few delusions that seem intrinsically insane, such as a man's believing himself the Deity, or thinking that he is pregnant and about to give birth to a child; but even these by themselves alone, under certain conditions, would hardly be evidence of mental disease. It is less important to the physician than the jurist to have an exact definition. We recognize insanity by the consensus of symptoms, but in courts and for legal purposes it is often necessary to be able to say in at least a general way which is an insane delusion. The following will perhaps serve as well as any other, though its defects are obvious: An insane delusion is a false belief that is incompatible with the training, education, and general environment of the individual; and moreover should be as to a matter of fact or should be contrary to the usual habit of thought of the individual.

Each case must be judged by itself, and what would be evidence of insanity in one would be of no value in another.

There are certain characteristic types of delusions in insanity, however, and these when recognized have, in connection with other signs, an almost pathognomonic value. Such are the persecutory delusions of the paranoiac, the self-accusatory ones of the melancholiac,

and the exalted and optimistic notions of paresis and some other forms of insanity. The fixed and permanent nature of some and the changeable and unsystematized character of others are also characteristic. The whole subject of delusions is one that can be best treated in connection with the separate forms in which they appear in the special pathology of insanity.

The origin of insane delusions may be in many ways, according as the original impression is made upon the disordered and defective judgment. Some delusions are simply the result of simple suggestion acting on exalted emotional conditions when judgment is in abeyance. Such, for example, are the flighty delusions of the acute maniac and the exalted paretic. Illusions are responsible for some, hallucinations for others, and in many cases, no doubt, they have their origin in dreams or the dreamy states of consciousness of many forms of insanity. In other cases they arise from excessive dwelling of the mind on single ideas and suspicions; they take their start from an egotistic misinterpretation of facts, a sort of mental illusion; such, for example, are often the persecutory delusions of systematized paranoia. In still other cases they are simply the result of day-dreams of an ill-organized intellect, as in the partial delusions of original paranoia. Whatever their origin, they are symptoms of defect of intellectual discrimination or judgment; they are the symptoms of disordered intellect par excellence.

Illusions. An illusion is a false perception of a real impression. The object sensed is not recognized in its real character, but is perceived as something else. A familiar example would be the mistake of taking a crooked stick or a piece of rope on the ground for a snake, and in this case the natural dread of the reptile aids in producing the deception. An illusion is not always or even commonly an indication of insanity;

we are all of us liable to be deceived with these common everyday impressions, but these false perceptions of real sensorial impressions are vastly more common in the insane than in the sane; they are in all cases errors of judgment of true sensorial impressions, and, as has been said, they are delusional phenomena, false beliefs based upon correct premises. The disordered condition of the brain does not permit its intellectual center to exercise correct judgment on what the senses normally bring to it.

Illusions of sight are the most common in the insane, and one of the most striking examples of this is the very frequent illusion of identity. The insane person sees an acquaintance and mistakes him for an entirely different individual, or vice versa. In conditions of great excitement almost everything that happens about the maniac and of which he is rendered cognizant by his senses is thus misinterpreted, and this is, if we consider it, readily seen to be only an exaggeration of what occurs with those who are not insane. Beard has pointed out very strikingly how no one in sudden panic or in other conditions of intense excitement is a competent witness as to what he sees, and the active maniac is in a constant state of mental excitation that vitiates his perception as well as his judgment.

Next to illusions of sight come probably those of hearing, and all the senses may be thus subject to misinterpretations in states of mental disease. A very striking class of illusions is that of the internal or visceral sensations; a vague bodily sensation is attributed to some special cause altogether different from the reality. These are sometimes indicative of local visceral disease; a patient may complain of having a snake or some other living thing in his abdomen from the sensation aroused, let us say by a colonic stricture, or some other diseased condition.

It is often extremely difficult to separate illusions

from delusions, on the one hand, and from the conditions next to be described-namely, hallucinations. An insane illusion is in fact associated so universally with a delusion that they can hardly be considered separately; and, on the other hand, it is often impossible to say where illusion ends and hallucination begins.

Hallucinations.-A hallucination is a false perception. without a material basis, not, like an illusion, merely a misinterpretation of a message conveyed to the perceptive centers by the sense organs. The whole message is, we may say, a forgery; the consciousness is deceived into accepting as true what does not exist. The pathology of hallucinations is a difficult subject in some respects; the problems it involves are complex ones, but the best explanation of them is probably that they are symptoms of excitability of cortical perceptive centers, that reveals itself by the external projection of combinations of the images that have been stored up from former impressions. A very apt illustration of a hallucination and its explanation as given here is the well-known fact that persons who have had limbs amputated still have at times sensations which they refer to the absent member. The limb is gone, and therefore they cannot really feel it, but its cortical sensory center remains, and cannot be altogether put out of action; hence the sensation of the lost member. The illustration also shows that hallucinations are not necessarily a symptom of insanity; in fact, hallucinations are not infrequently met with in the sane, and can be readily produced under certain circumstances. They are, however, always a sign of central disturbance, of disorder in the cerebral cortex, and have therefore a special pathologic importance; and while they may, and often do, occur with perfect intellectual integrity, their existence in those who in other ways also exhibit evidence of mental derangement is always a matter

for attention. Probably the most generally involved of the special senses, taking all forms of hallucination, sane and insane together, is that of sight; but any of the senses can be thus involved, and in the insane every possible form of hallucination is occasionally met with. As might be understood from their assumed pathology, hallucinations are commonly a reflex result of some peripheral irritation, sometimes a disease of the peripheral organ of the sense involved, or its central conductors; but in other cases it may be from an entirely different source-some other special sense, for example. Hallucinations may also be unilateral, and connected with disease of the corresponding sense organ of that side; and if bilateral, they may be different on the two sides. Whether there are hallucinations of purely central origin is a question that has been disputed. There is no good reason, however, to assume it impossible for excitations to arise in the cortical centers themselves, especially when one takes into consideration the usual effects of long-continued use. Habit alone will be sufficient to account for such, and there are cases enough where no exciting impressions can be detected. Local cortical disease of irritative nature may also be invoked as producing central hallucinations in some cases, the center itself being naturally involved in the irritation.

Auditory Hallucinations.-The most important class of hallucinations in the insane are those of hearing. They are important not only on account of their frequency, but also because of their association with especially dangerous types of mental disease and their relation to the prognosis. They are not very often met with in the sane, and when they do occur, are generally of rather evil significance. A patient may for a time realize their unreality, but their persistence tends somewhat more than is the case with those of sight to finally impress themselves upon his conscious