Thanks are especially due to friends for hearty co operation in illustrating this volume, and in particular to Dr. Kellogg, of Battle Creek and the F. A. Davis co., of Philadelphia, for the use of Plates III, IV, V, VIII. X, XI, XXIV, and Fig. 18; to Dr. Cecil Sharpe, of Matlock, for the loan of photographs and help in various ways; to the Bath Corporation for the Frontispiece, Plates I, II, XII, XIV, XV, and other figures; the Harrogate Corpor ation for Plate XXII Dr. Philp for Plate XX: Mr. A. M. Thiem, for Plate XXI; and to Mr. Dowsing and Mr. H. E. Greville for figs. 44 and 45, and Plates XIX and XX. The author is also Similarly indebted to The Fischer Kiefer co., and other manufacturers, for the loan of various photographs and illustrations, which have added to the clearness of the text. Many illustrations are from original drawings by Dr. Georges Dupuy, of London, and owe such merit as they possess to the combination of his artistic skill and medical knowledge. Dr. W. T. Ritchie has kindly gone over most of the proof sheets, and has made many helpful and valuable suggestions.