"Heat by nerves and not by blood": the first major reduction in chiropractic theory, 1903.

Recalled as the demarcation between D.D. Palmer's magnetic healing and chiropractic, the Harvey Lillard case holds a special place in the history of the profession and its healing art. Less familiar to chiropractors today, but of considerable significance in the subsequent development of chiropractic theories, was Old Dad Chiro's 1903 "discovery" that thermoregulation was a neural rather than a circulatory phenomenon. This Santa Barbara incident established the first major alteration in D.D. Palmer's chiropractic concepts, and would set the stage for the earliest known acquittal of a DC for unlicensed practice four years later, which in turn created strong incentive for subsequent differentiation between "neural supremacy" and the osteopathic "rule of the artery." The nature of the 1903 insight and some of the reasons why it is not more widely remembered among chiropractors today are discussed.