The disorders of perception comprise : (1) illusion, or the false interpreta tion of things actually seen ; a condition not at all uncommon in normal life. (2) Hallucination, or a perception \ vhich has no real foundation. Many hallucinations are due to defects in the eye, ear, nose, or other organ of sense ; and in some insane people it may be possible to discover the defect by careful examination, and to remove it by intelligent treatment, thus effecting a cure. (3) Clouding of consciousness, a defect of perception, whereby outside impressions are received with difficulty or not at all.
The disorders of thinking are more complex. Some of the most important symptoms are : (r) Delusions, or false beliefs. These are not in themselves sufficient evidence of any one type of the insanities. (2) Obsessions, or impulsive ideas, or fixed ideas. These are very common ; and, if uncontrolled, or not educated out of the patient, they often result in mental breakdown.
(3) Dream stales, a condition in which the ideas are dreamy and ill-defined.
(4) Flight o/ ideas, a symptom characterised by the phenomenon that the train of thoughts, instead of leading to a definite end, is diverted and jinni); from one subject to another. (5) Retardation, extreme slowness of thinking, which may go on to paralysis of thought.
The disorders of action may be characterised by : (t) In-tense psycho motor activity, seen in violent patients ; or there may be (2) psychomotor depression, the reverse condition. A third symptom is (3) stereotypy, or the repetition of motions. In addition to these common symptoms, the emotional tone may be exalted, or deprei3sed, or degraded ; the memory may be defective or exaggerated. Among the many different forms of insanity the following chief types may be mentioned here : 1. Infection Psychoses.—These are such as follow or occur during typhoid fever, pneumonia, or other acute infectious diseases. Confusional mental states, NVIth delirium, hallucinations, etc., are very common in the infection psychoses. Many patients recovering from a severe illness refuse to take their medicines. They are suspicious, and fear they are being poisoned. The appearance of such a symptom should be regarded as a sign that the effects of the original disease have been very marked on the mental organs, and should call for a greater care during the convalescence of these patients, or else a mental defect may persist, perhaps permanently. These patients are not well even when they seem to be well ; and they should be kept as con valescents longer than the attending physician himself may think necessary, unless he is a specialist in nervous and mental disorders.
2. Toxic Psychoses.—These may follow alcoholic intoxication, diabetes, Bright's disease, the habitual taking of opium or cocaine, and various other forms of poisoning. The alcoholic insanities are extremely numerous and very complicated.
3. Paranoia.—This is the type of insanity which the lay mind often associates with craziness or madness. Usually, this disease runs insidiously,
and is incurable. The delusions may or may not spring from sensory illusions. When they exist without sensory illusions, they are generally found in persons who from their earliest childhood have been abnormal, eccentric, and peculiar. Their peculiarities become more and more pro nounced. To this class belong inventors who claim to have solved the problem of squaring the circle or the problem of perpetual motion ; also the " Saviours " and " Messiahs," the " Adventists " and " Health Apostles," the persons who are jealous without cause, the individuals of " noble descent " who lay claim to this or that throne, and the erotomaniacs who believe them selves beloved by persons of high position and overwhelm them with effusive letters. Such persons frequently possess a fine rhetorical gift, as a consequence of which they always find some stupid followers who swear by them ; and during times of political or religious excitement such persons may therefore bring some influence to bear upon the excited masses. The border-line between normal and abnormal persons is very hard to determine in such cases. Some founders of religions have been paranoiacs.
Delusions in consequence of sensory illusions are readily recognised as abnormal even by the layman. There are two main groups in these para noias—the delusions of persecution and those of egotism. Both conditions may be found in the same patient. The disease develops very slowly. The patient begins to be suspicious and distrustful ; he believes every remark to have a personal allusion, feels himself " observed," and everything seems to him to have a double meaning. Sensory illusions follow these first symptoms. The patient hears threatening words, secret whisperings, and sees people talking about him ; and through the incessant repetition of these wrong impressions lie becomes fully convinced that there is a " grudge " against him. The patient believes he is being followed, and he muses and worries about the cause of this persecution and about his enemies. At one time he may imagine them to be Jesuits, then the police. or the Social Democrats. After a time he will imagine certain individuals to be inimical to him, and will make efforts to guard himself against them, either by announcement to the Public Prosecutor or by personal force, even with the aid of weapons. This frame of mind transforms the patient himself into a persecutor, and a very dangerous one at that. At this stage of the condition the patient is generally placed in an asylum, where, after months or years, his ideas of persecution develop into a regular system. When this stage has been reached the condition is beyond help. At last, sometimes after decades, the patient becomes quiet and indifferent ; he has resigned himself to his fate ; his delusions become more and more disjointed and confused, until finally his sad plight ends in a state of dementia.