a length of 20 mm. in front of her. The further question arises, why does the automatism appear in the visual and not in the acoustic sphere? There are several grounds for this choice of the visual sphere. (1) The patient is not gifted acoustically; she is, for instance, very unmusical. (2) There was no stillness corresponding to the darkness which might have favoured the appearance of sounds; there was a lively conversation. (3) The increased conviction of the near presence of spirits, because the automatism felt so strange, could easily have aroused the idea that a spirit might be seen, thus causing a slight excitation of the visual sphere. (4) The entoptic phenomena in darkness favoured the occurrence of hallucinations. The reasons (3) and (4)--the entoptic phenomena in the darkness and the probable excitation of the visual sphere--are of decisive importance for the appearance of hallucinations. The entoptic phenomena in this case play the same rôle in the auto-suggestion, the production of the automatism, as the slight tactile stimuli in hypnosis of the motor centre. As stated, flashes preceded the first hallucinatory twilight-state. Obviously attention was already at a high pitch, and directed to visual perceptions, so that the retina's own light, usually very weak, was seen with great intensity. The part played by entoptic perceptions of light in the origin of hallucinations deserves further consideration. Schüle[43] says: "The swarming of light and colour which stimulates and animates the field of vision, although in the dark, supplies the material for phantastic figures in the air before falling asleep. As we know, absolute darkness is never seen; a few particles of the dark field of vision are always illumined; flecks of light move here and there, and combine into all kinds of figures; it only needs a moderately active imagination to create out of them, as one does out of clouds, certain known figures. The power of reasoning, fading as one falls asleep, leaves phantasy free play to construct very vivid figures. In the place of the light spots, haziness and changing colours of the dark visual field, there arise definite outlines of objects."[44] In this way hypnagogic hallucinations arise. The chief _rôle_ naturally belongs to the imagination, hence imaginative people in particular are subject to hypnagogic hallucinations.[45] The hypnopompic hallucinations described by Myers arise in the same way.