This clinical group has become well established, not only in its recognition from the dominant symptoms as indicated above, but also from rather definite causes. The immediate cause seems to be an abnormal blood state, or so-called toxemia, which may result from infectious diseases, or states of exhaustion, or autointoxications, or foreign poisons; the poison acts as an irritant to the brain. In states of exhaustion so-called “fatigue bodies” are formed and are apparently toxic in character. The autointoxicants may have various sources, such as chronic kidney disease, or diabetes, and the like. The most important of the foreign poisons are alcohol and morphine. This morbid group is further characterized not only by a toxic cause and dominant symptom complex of delirium, or confusion, or stupor, but by a similar onset and course. The onset is usually acute and the course somewhat wave like, gradually reaching a climax and subsiding, or resulting in death or becoming chronic. To emphasize the clinical symptoms of confusion which is so important the term “acute confusional insanity” has often been used, or “amentia,” according to the common German terminology. Hallucinations also play a prominent part, particularly those of vision; hence, another common appellation, “acute hallucinatory confusion.” Heredity is mentioned at most as creating a predisposition, though often the personal and family histories show no such evidence whatsoever. Intellectually there is a definite lack of orientation, the patient is unable to identify himself or his surroundings in time and space. He cannot clearly understand what goes on around him, that is, consciousness is “clouded;” the clouding may be of such extreme degree the patient’s mind becomes blank, due to complete psychic inhibition. This is referred to as stupor. The emotional life plays a secondary role subordinate to the intellectual content. The patient may be greatly excited for example, resulting from a frightful hallucination. The hallucinations are mainly of the visual type and are almost always present. The patient lives in a perpetual state of sense deception as if he were constantly dreaming; the hallucinations for the most part are of distressing, disagreeable or even frightful character. These may give rise to delusions, which are manifold, often fantastic and usually transitory.