Kraepelin[155] describes concussion and compression, traumatic delirium, traumatic epilepsy and traumatic mental enfeeblement. He finds these conditions due to concussion, compression or injury to the brain substance either at the site of traumatism or at some point opposite. There may be contusions, lacerations of the brain tissue or hemorrhages, usually in the frontal, occipital or parietal regions. Injuries to the cortex are not demonstrable in all cases. The circulatory disturbances he considers an important factor and thinks that they account for smaller lesions of the cerebral tissue in many instances where no gross changes are apparent. More or less disturbance of consciousness is to be expected in these conditions. The patient is somewhat dull, drowsy, clumsy, forgetful and absentminded. Memory is sometimes much affected. In more severe cases there is a complete loss of consciousness which may last a few minutes only or be a matter of hours or days. On waking, the patient is bewildered and confused, with a marked disturbance of apprehension. Perception is involved as in the recognition of complicated pictures or the understanding of long and detailed statements. A clear comprehension of events and surroundings is lacking. The patients may know that they are in a hospital without knowing what hospital it is or why they are there and are unable to recognize persons around them. Occasionally hallucinations of sight or of hearing occur. At times delusional ideas are expressed, usually of a depressive type. They have no realization whatever of their own condition. The memory disturbance may take the form of a Korsakow's complex. Memory gaps appear sometimes for events just before the accident and in other cases cover long periods of time. While as a rule events of the remote past are retained, recent impressions are quickly lost. They cannot repeat what is read to them, do not remember the names of persons about them, and sometimes show evidence of falsification of memory with fabrication. All idea as to time is usually lost. Mental reactions become noticeably difficult. The patient is distractible, cannot count accurately, has difficulty in repeating dates and numbers and forms no correct judgment as to his own personal affairs. Many express themselves, however, on the other hand, with great facility and readiness. Some show considerable fatigability. The mood is often elated with a tendency to facetiousness, although frequently tearful and anxious, particularly at night. Irritable, faultfinding trends usually appear later. As a rule they are talkative, restless, sensitive, abusive or even insolent. Bonhöffer has reported stereotypies as well as stuporous and other catatonic types. In speech the patients often become incoherent, make mistakes, forget words or coin new ones. Similar mistakes appear in reading and writing. Asymbolism and parapraxia are observed. Residual symptoms of the brain