Reverting for a moment to the primitive segmental arrangement which is none the less persistent and important because in the completed human the regularity of contour of the segments has been wholly lost and aberrant organs have moved from their original positions carrying their nerve supply with them, let us first state and then illustrate a general law. Any violence applied to the body tends to affect the spinal column. Such violence does or does not produce permanent displacement of a spinal segment according as it does or does not succeed in overcoming the internal resistance. But whatever effect upon the spine is accomplished will occur most noticeably in the same body segment to which violence was applied. That is, force applied to any body segment tends to subluxate the vertebra which would impinge the nerves controlling that segment. Thus diseases are primarily segmental and later general just as the body is primarily segmental and later co-ordinated into complicated functional systems, all more or less interdependent. If a man falls so that he strikes first on the point of his shoulder the force will be transmitted almost directly across the line of the spine, at right angles, and may subluxate the sixth or seventh Cervical or first Dorsal. If subluxation occurs it is because the law of gravity causes the remainder of the body to keep moving downward after the shoulder strikes and until it too comes to rest. The subluxation which results is a right one if the left shoulder be struck and vice versa. Now the brachial plexus is chiefly controlled by these three vertebrae and a right subluxation tends to impinge most the nerves on the left side, so that if any permanent effect of the fall follow it will be a permanent weakness or disease of the left shoulder or arm, with possible slight extensions along other branches of the same plexus, as to the latissimus dorsi. Also by the internal sympathetic communications from this same region the larynx, trachea, or large bronchi may be affected, occasionally the heart, all structures segmentally associated with the arm. This law applies throughout the body and can be fully demonstrated by any one having a complete knowledge of nerve connections and body segmentation upon being furnished with a complete and accurate history of any injury to the body. It goes further than this. Toxins or other secondary causes operating within the body tend always to produce their motor reactions and consequent effect upon any subluxated vertebrae in the same body segment with the peripheral irritation, so that if the stomach contain a poison which affects the spine the sixth or seventh Dorsal vertebrae will be most affected and the stomach itself the organ to suffer most.