Not all impingement is sufficient to produce noticeable disease. To a certain extent the power of adaptation inherent in the body can overcome its deleterious effects and suppress all signs of its existence until an overtax upon bodily energy lessens this adaptative power. Then disease appears and we say that the overtax caused it. Excitation or Inhibition A slight impingement serves as a mechanical irritant to increase the action of the nerve and the functions of the attached peripheral organs. Such stimulation beyond the normal is always followed by a reaction, or fall to subnormal action. Heavy impingement, especially the impingement due to marked occlusion of foramina, partly or wholly paralyzes the affected nerves. Often the impingement produces only a latent weakness in some organ, a weakness which may be brought to light only through the introduction of some secondary cause which takes advantage of the susceptibility of the organ to produce some definite disease. As an instance of this we may mention typhoid fever. No typhoid case is found without subluxation in the region of the second Lumbar; yet the latent weakness produced by that subluxation may not have been observed until the typhoid germ found a fertile feeding and breeding ground in the weakened tissue and proceeded to multiply there and develop its toxins. Effect Upon Single Cell Each nerve cell is trophic to its processes and to the tissue cells to which these processes are distributed. The growth, nutrition and repair of each cell of the body is dependent upon the integrity of the axon which supplies it. The effect of nerve impingement upon the single cell is a weakening of cell structure and a disturbance, slight or great, of the special function possessed by that cell. Dunglisson says of diseases, “All ... are dependent upon modified cell-action.” Effect Upon Organs Each organ is but an aggregation of cells of some special type or kind. Nerve Impingement usually involves either a whole nerve trunk or many of its fibres and thus weakens either the entire organ or many of its cells and increases or diminishes its special function. Some organs are innervated by more than one nerve and may be injured only in part by a localized impingement. Alteration of the action of one organ often tends to affect the entire body, as in subluxation of the fourth Dorsal interfering with the nerve supply to the liver the secretion of bile becomes altered in character or quantity and the entire system suffers, through deranged digestion, from this alteration in a necessary secretion. Every disease presents symptoms only indirectly referable to the organ which is primarily affected and the problem of the diagnostician is to so discriminate between direct and indirect symptoms as to be able to _locate_ disease. Simple Subluxation Disease