Excerpt from Lectures on the Comprising the Herter Lectures, (Baltimore); A Harvey Lecture, (New York) And an Address to the Faculty of Medicine at McGill Uiversity, (Montreal) The five lectures comprising this book were delivered during a brief visit to the American continent in the Autumn of 1914. The Herter lectures were written to emphasise the advantages of intimately combining clinical and laboratory observations. Co-operation between wards and laboratories, as my visit has clearly taught me, is nowhere more freely or widely cultivated than in the Medical Schools of America. To these lectures, the Harvey lecture, which deals with questions of physiological interest, seems a fitting introduction. The address at Montreal serves to illustrate in a more extended manner the application of laboratory methods to questions of immediate and practical consequence. It is a pleasure to acknowledge my indebtedness to the Committee of the Herter Foundation, and to the Harvey Society, who have kindly sanctioned the publication of the lectures in this form.