For many years, clinicians have been familiar with certain of the features which characterize the roentgenograms of rachitic human bones; but a careful analysis of them has not been made, nor has the interpretation of the picture in the light of histologic alterations received any great attention. This investigation, which was begun at, the suggestion of Dr. E. A. Park and carried on largely through his continued interest, was undertaken with a view to ascertaining the anatomic basis for the roentgen-ray changes in the skeleton in rickets.
The bones selected for study were cleaned of surrounding tissues and cut into slices from one-eighth to one-quarter inch thick through the epiphyseodiaphyseal junction. Roentgenograms were obtained, and the slices were then used for the preparation of histologic sections. Some of the tissues were partially decalcified in Müller's fluid; but in many instances, it was found possible to cut sections without preliminary