As the author states, the following pages are presented rather as a report of the progress and findings of this growing subject. The development of the Roentgen rays, therapeutic and diagnostic, has been one of the most striking features of the past seven or eight years, and their possibilities seem only to be beginning to be developed. To one, however, who wishes a general résumé of the subject, giving the principal, relative facts, as far as known, in detail, the present work will be a satisfactory one. To show how the literature of the subject grows, a rather extensive appendix of some 50 pages has had to be added. Instruction as to the methods of examination and the needs of the x-ray equipment are first given, and the illustrations are very useful in aiding the text. Following this is the use of the x-rays in the diagnosis of