In 1925, J.B. Collip (1925) reported that extracts of parathyroid gland contained an activity that raised calcium levels in the blood of parathyroidectomized animals, and suggested that this was due to a hormone produced in the parathyroid gland. The story of parathyroid hormone discovery was indicative of ever-increasing sophistication in sample preparation and protein isolation techniques. This paper resolved earlier controversies over the function of the parathyroid glands and c- trol of blo