require particular mention. Dreams are not always limited to the revival and combination of the images of sensation. Intellectual combinations are sometimes thus presented to the mind. The most familiar illustrations of this fact are furnished by the experience of mathematicians who have worked out mathematical problems in their dreams. One of my patients, an expert book-keeper, dreamed of adding up six columns of figures at once. In the morning he still remembered his dream; and, on adding up the columns, found that he had actually produced the right sum in each case. A college student of my acquaintance, who was puzzled by a geometrical proposition, wrote out the correct solution during his sleep. This was something more than simple dreaming; it trenched upon actual somnambulism. Another acquaintance dreamed of being in heaven, and, while there, experienced relief from doubt regarding certain theological doctrines which had previously exercised his mind. I have myself composed several sentences during the course of a dream, and have, while dreaming, sometimes esteemed them worthy of preservation; but my waking recollection has never coincided in this particular with the opinions formed during sleep. Great difference between dreams may be remarked in their coherence and continuity of evolution. Some are composed of the most inconsistent elements without order or logical arrangement. In others the incidents follow very closely in the line of a natural and rational development, so that the dreamer seems to be present as a spectator of a perfectly coherent drama. It is probable that these differences depend upon variations in the degree of completeness with which the different parts of the brain and of the body are overwhelmed by sleep. If different and widely separated portions are sufficiently wakeful to suggest ideas to the mind, the resulting congeries will consist of discordant and incoherent elements. But if wakefulness is limited to a particular organ of the body or to a circumscribed territory of the brain, the resulting impressions in consciousness should be correspondingly restricted, and will manifest a more orderly connection with each other. In some cases a tendency to simultaneous wakefulness of particular portions of the cerebral register seems to become habitual, so that the same set of ideas may be often renewed in the same order during sleep, constituting a repetition of the same dream. In this way I have frequently dreamed of a volcanic eruption of molten lava from a lofty mountain. This frequent revival of the same train of images is probably due to the fact that in childhood I actually witnessed a volcanic outbreak, and that a very highly colored picture of Vesuvius in eruption hangs in my sitting room, so that my brain has become profoundly impressed with this particular image. When other portions of the brain are asleep, if the special region concerned with this picture be