The most advanced form Kraepelin describes as senile dementia, a progressive mental enfeeblement in which the loss of apprehension and memory becomes a conspicuous feature. The perception of external impressions is diminished and delayed and there is a profound disorder of attention. Memory of the remote past is much better than it is for current events. Retrospective falsification is a common symptom. The patient is, moreover, unable to change old viewpoints or acquire new ones. Delusional manifestations such as childish egotism, foolish suspicions or notions of impending illness develop. Grandiose ideas often occur, delusions of great wealth being common. These symptoms are transitory and come and go without apparent reason. In some cases the hallucinations resemble those found in the alcoholic psychoses. Sooner or later there is a disturbance of consciousness leading to a dreamlike existence suggesting a delirium. There is a noticeable dulling of the emotional feelings. The patients become indifferent and apathetic, losing interest in their surroundings, and are often irritable and excitable. In a certain number of cases depressive states develop, sometimes with suicidal tendencies. The delusions may be hypochondriacal or nihilistic in character. Complaints of persecution are common. Some of the patients show a simple, childish deterioration with seclusive tendencies. Stuporous or cataleptic states may develop. Others become uneasy, wander in the streets, remove their clothes, collect rubbish, or show sexual excitement. Restlessness at night is especially suggestive. Delirious excited states ("Senile Delirium") characterized a certain number of Kraepelin's cases. In these, clouding of consciousness is marked. The presbyophrenic complex described by Kahlbaum often occurs. These cases are fairly clear mentally at first, as far as their surroundings are concerned, but show memory disturbances, particularly for recent events. Orientation is lost very soon and they fail to recognize old friends and relatives. Fabrications are resorted to for the purpose of remedying these defects of memory and delusions are very common. Nevertheless, judgment about many things is well retained. In some instances, however, orientation for time, place and person is completely lost. Kraepelin is in doubt as to whether presbyophrenia should be looked upon as constituting a definite entity or only a form of senile insanity. It may last for years or terminate in a marked deterioration. In some of the senile cases arteriosclerotic changes in the cortex are very pronounced. This is more noticeable in the depressive and anxious forms and in the incoherent varieties. These individuals become clouded, incoherent, and deteriorate rapidly.