Further, by studying the effects of removal or extirpation, or of pathologic changes in various parts of the nerve system it has been demonstrated that the Brain is the center for those higher forms of activity known as psychic, for the power of accelerating or inhibiting the responses of the lower centers of the nerve system to stimulation from without, and for the conveyance of authority to act to all the lower centers. The Nerve System is the morphologic, physiologic, and dynamic center of the organism and the Brain the center of the Nerve System. We may, then, logically expect to find in the Brain, or in the channels by which power is distributed from the Brain to lower centers or organs, the initial step in the disease process, which is our present quest. One Nerve System All nerve tissue in the body is organized and linked together in a complicated aggregation of individual units, communicating by _contact_, and forming one great Nerve System having its directing center in the Brain. It is said by some writers to consist of two distinct systems--cerebro-spinal and sympathetic--but would better be described as consisting of central organs--brain and spinal cord--and peripheral organs--cranial, spinal, and sympathetic peripheral axons connecting with cells in the central axis and linked together in a net-work improperly separable into separate or distinct divisions, the fibres of different parts being bound together in such a way as to establish an intricate intercommunication, closest on the one hand between the cranial and sympathetic and on the other between the spinal and sympathetic. The sympathetic system may be regarded as nothing more than a medium for proper distribution of impulses originating in the cerebro-spinal system, and a series of reflex centers deriving their power to act from the central axis. The proper action of sympathetic ganglia has been demonstrated to depend upon the integrity of the spinal nerve fibres, or rami communicantes, which pass to and terminate in the ganglia with their telodendria (terminal arborizations) in contact with the dendrites (cellulipetal processes) of the ganglion cells. It will appear that interference with one division or part of the nerve system may be followed by effects partly manifested through a distant part; that excitation or inhibition of a spinal nerve may correspondingly excite or inhibit sympathetic fibres. Chiropractic Hypothesis Chiropractic has accepted, as a convenient working hypothesis amply justified by years of clinical experiment and anatomical and physiological research, the proposition that all disease in the human body is primarily made possible by injury to (stimulation or inhibition of) some part of the nervous mechanism.