But before we pursue the inquiry into the phenomena of Dream, it will be necessary to describe the material mechanism by the operations of which those phenomena are produced. This will be properly the theme of a distinct chapter. CHAPTER VI. THE MATERIAL MECHANISM OF DREAM. It is difficult to describe, without the use of technical terms, the structure of the mechanism by which Dream is produced. But as these are at once unintelligible and repulsive to the non-scientific reader, indulgence is entreated for an endeavour to present the subject in shape and language that may be understood by everybody. It must be premised that this description is partly derived from the recent treatise of Professor FERRIER on “The Functions of the Brain,”[1] in which he details the experiments that have thrown so much light alike upon physiology and psychology. The spinal cord expands at its upper end into a ganglion or cluster of nerves called the _medulla oblongata_. At this point the brain is said to cease and the nerve system to begin. But there is no perceptible beginning nor ending either of the brain or of the nerves. The entire nerve system is, in fact, only an extension of the brain. When a nerve is irritated at the point of the finger the brain as well as the nerve is affected. The nerve transmits the sensation and the brain feels it. Psychologists would venture a step further, and say, “It is not the brain that feels, but the intelligent individual entity, the living soul or self, of whom the brain is only the material transmitting organ.” It is at the extremity of this ganglion that the cords wrapped within that great bundle of nerve cords which constitutes the spinal cord cross each other and pass into opposite sides of the brain and of the body. The nerves that control the left side of the body pass into the right side of the brain, and those that control the right side of the body pass into the left side of the brain. As the consequence of this exchange, the right side of the brain controls and directs the left side of the body, and the left side of the brain the right side of the body. Above this basal ganglion, but connected with it, is a ganglion which anatomists have divided into two parts, but which for the present purpose it will be convenient to recognize as one whole lying at the base of the brain and crowned and inclosed by the cerebral hemispheres. From this great basal ganglion small white threads radiate into the two cerebral hemispheres in the form of a hollow cone.