One of the most elaborate studies ever made of morphinism was that of Erlenmeyer,[228] whose work on this subject reached nearly five hundred pages in its third edition. The mental disturbances associated with intoxication he divides into two groups—transitory and permanent. The former includes anxious states, hallucinations of vision and stuporous attacks; the latter, the intellectual and emotional deteriorations already described. There is a definite character change strongly suggesting "moral insanity," an artificial "senium praecox" being induced. He also refers to distinct psychoses resulting from chronic morphinism, the most common one being of the paranoid variety. Abstinence symptoms of sudden development include collapse and delirium. Restless anxiety and insomnia may usher in a mild delirious condition. Of these he described two forms,—one, a quiet, partially clouded dream state and another, with excitement, elation and hallucinations. The first form is the more common. The second is usually of short duration but may last for several weeks or even months, often manifesting paranoid ideas. Kraepelin[229] calls attention to the important fact that morphine stimulates mental activities as well as inhibiting psychomotor processes, and is not therefore a logical drug for the production of sleep. The habitué feels himself capable of much greater exertions but is handicapped by an inhibition of will power. This psychological mechanism determines the difference between the intoxication of morphine and that of alcohol. Nissl found the cortical cells of dogs poisoned with morphine decreased in size but not destroyed. The stainable substance was rarefied and weakly stained, the achromatic substance, on the other hand, being unusually prominent. In chronic morphinism Kraepelin found memory uncertain, mental capacity diminished and fatigability increased. There are alternating periods of comparatively good health and dull somnolence with exhaustion or nervous restlessness. The mood is variable,—depressed, discouraged, hypochondriacal, irritable, or even confident and overbearing. Anxious states occasionally occur at night and suicidal attempts may be made. Character changes are also described by Kraepelin. The patients become complaining, oversensitive to pain and to opposition, are indolent, irresolute, irresponsible and neglect their work. Their interest is more and more confined to the drug. Their untruthfulness and deceitfulness are well known. Sleep is much disturbed, often by visual hallucinations. Phantastic delusional ideas are also manifested. Paresthesias and hyperesthesias are common. The reflexes are active and usually increased. The gait is unsteady or even ataxic. Speech disturbances, paralysis of the muscles of the eye, diplopia and loss of accommodation have been noted. A typical Korsakow's complex was observed by Heymann. Appetite is lost, bodily weakness and loss of weight appear and sugar is often present in the urine.