The subject of forming a roentgenographic film library has been before the Radiological Society for several years. Experience in carrying out this project presented many difficulties. The methods used at first were costly in time, effort, and money. The suggestions that came from members of the Society increased the difficulties and presented problems that at the time were impossible of solution. Through the annual scientific exhibit the subject has been kept alive; loan exhibits for the annual meeting have improved each year, and the exhibit has been instructive and interesting to a large proportion of the members. The keen interest and quest for information at these annual exhibits more and more made evident the necessity for a national library of films that shall be available to all members of the profession interested in roentgenology. In developing a roentgenographic film library in The Mayo Clinic, methods have been devised which offer a solution of many problems. In the majority of lesions of bone ...