Where the disease depends on the _interrelation_ of neurons in a complex group, on _association of systems_ of neurons, the condition is _psychopathic_ in nature. In psychopathic troubles the neuron itself may remain unaffected, may be perfectly normal and healthy. The disorder is due to association with systems of neurons which are usually not called into action by the function of that particular neuron system. By _Organopathies_ or _Necropathies_ I indicate a group of psychophysiological symptoms, accompanied by structural, necrotic changes of the neuron, terminating in the ultimate death of the neuron systems, involved in the pathological process. By _Neuropathies_ I indicate a group of psychophysiological manifestations due to pathological functional neuron modifications, capable of restitution through normal metabolism. By _Psychopathies_ I designate pathological phenomena of psychophysiological dissociation and disaggregation of neuron systems and their functions in clusters, the neuron itself and its special function remaining undamaged. The psychopathies are further subdivided into _Somatopsychoses_ and _Psychoneuroses_ or _Neuropsychoses_. The _Somatopsychoses are characterized by somatic symptoms_, by disturbances of bodily functions, such as paralysis, contractures, convulsions, anesthesia, analgesia, hyperalgesia, and other sensory disturbances, as well as by intestinal, cardiac, respiratory, and genito-urinary troubles. The _psychoneuroses or Neuropsychoses are characterized by mental symptoms_. The patient’s whole mind is occupied with mental troubles. Such conditions are found in obsessions, fixed ideas, imperative impulses, emotional compulsions, and other allied mental and nervous maladies. Somatopsychoses simulate physical and organic nervous troubles. Thus, many “hysterical” forms simulate tabes, or paralysis agitans, hemiplegia, paraplegia, or epilepsy, while many of the neurasthenic, hypochondriacal, and their allied states may simulate tumor, cancer, intestinal and glandular derangements, cardiac, laryngeal, pneumonic, hepatic, splanchnic ovarian, tubal, uterine, renal, and other bodily afflictions. The neuropsychoses or psychoneuroses simulate all forms of mental disease, beginning with melancholia and mania, and ending with general paresis and dementia. _Psychoneurosis_ and _somatopsychosis_ are diseases of the subconscious; in the former mental, in the latter physical symptoms predominate. _Psychopathic states should be rigidly differentiated from other disturbances, such as neuropathies and organopathies, or necropathies._ The following diagram may be of help: [Illustration: _Nervous and Mental Diseases_ DIAGRAM I] CHAPTER VIII FEAR AND THE HYPNOIDAL STATE In my work on “Sleep” I report a series of interesting experiments carried out by me on guinea pigs, rabbits, cats, dogs, children, and adults.[4] I discovered one of the most important states of animal life, a state which I termed _hypnoidal_.