into the eyes, a noise may become perceptible, or some odoriferous matter may irritate the mucous membrane of the nose. In the spontaneous movements of sleep we may lay bare parts of the body and thus expose them to a sensation of cold, or through change of position we may produce sensations of pressure and touch. A fly may bite us, or a slight accident at night may simultaneously attack more than one sense. Observers have called attention to a whole series of dreams in which the stimulus verified on waking, and a part of the dream content corresponded to such a degree that the stimulus could be recognised as the source of the dream.
I shall here cite a number of such dreams collected by Jessen36 (p. 527), traceable to more or less accidental objective sensory stimuli. "Every indistinctly perceived noise gives rise to corresponding dream pictures; the rolling of thunder takes us into the thick of battle, the crowing of a cock may be transformed into human shrieks of terror, and the creaking of a door may conjure up dreams of burglars breaking into the house. When one of our blankets slips off at night we may dream that we are walking about naked or falling into the water. If we lie diagonally across the bed with our feet extending beyond the edge, we may dream of standing on the brink of a terrifying precipice, or of falling from a steep height. Should our head accidentally get under the pillow we may then imagine a big rock hanging over us and about to crush us under its weight. Accumulation of semen produces voluptuous dreams, and local pain the idea of suffering ill treatment, of hostile attacks, or of accidental bodily injuries."
"Meier (Versuch einer Erklärung des Nachtwandelns, Halle, 1758, p. 33), once dreamed of being assaulted by several persons who threw him flat on the ground and drove a stake into the ground between his big and second toes. While imagining this in his dream he suddenly awoke and felt a blade of straw sticking between his toes. The same author, according to Hemmings (Von den Traumen und Nachtwandeln, Weimar, 1784, p. 258) dreamed on another occasion that he was being hanged when his shirt was pinned somewhat tight around his neck. Hauffbauer dreamed in his youth of having fallen from a high wall and found upon waking that the bedstead had come apart, and that he had actually fallen to the