As soon as osteopathy and chiropractic were properly established, the more broad-minded exponents of both systems began mutual investigation and amalgamation. As a result, we find that only seven years after the birth of chiropractic, osteopathic literature began to mention vertebral subluxations as pressing on nerves, thereby causing disease. On the other hand, advanced chiropractors soon began to realize the importance of relaxing tense muscles prior to delivering their thrusts. They also began to pay attention to the bony lesions other than those occurring in the spine. Many of the chiropractic principles and much of its technique of today has been gleaned from osteopathy, while the reverse statement holds equally true. Naprapathy The "connective tissue doctrine of disease" was first proclaimed by Dr. Oakley Smith in 1907. It may be briefly stated as follows: A vertebra does not become misplaced without being fractured or completely dislocated. What is called a bony lesion by the osteopath and a subluxation by the chiropractor, is in reality a "ligatight," that is, a shrunken condition of the connective tissue forming the various ligaments that bind the vertebrae together. Ligatights are best "corrected" by means of naprapathic "directos." These differ from chiropractic thrusts in that they aim not at adjusting subluxated vertebrae but at stretching definite strands of shrunken connective tissue. Ligatights occur not only in the spine but also in other parts of the body. Neuropathy This system of manipulative treatment was originated in 1899 by Drs. John Arnold and Harry Walter of Philadelphia. Their claims may be briefly stated as follows: Morbid matter, poisons and irritants of various kinds, acting upon the vasomotor nerves which control the blood vessels, produce abnormal changes in circulation which, if perpetuated, finally lead to disease manifestations. The nerve impulses coming from diseased parts travel to the spinal cord and, like all other nerve impulses, are transmitted along those branches of the spinal nerves which supply the structures (muscles, blood vessels, etc.) along each side of the spine. Here these impulses bring about abnormal circulatory changes similar to those found in the diseased organs or parts. Since nerve impulses are transmitted from diseased organs to the spine, it is evident that they can be made to travel also in the reverse direction. Neuropathic treatment, therefore, consists of manipulations and thermal applications which aim at correcting the abnormal circulatory changes as found in the spine, thereby correcting corresponding abnormal processes in the organs or parts supplied by the nerves coming from that region of the spine.