It is hoped that this small volume may fill a want in the already crowded field of medical monographs. The author has endeavored to give to the general practitioner a readable, authoritative essay on a disease which is especially an outcome of modern civilization. To that end all the available literature has been freely consulted, and the newest results of experimental research and the recent ideas of leading clinicians have been summarized. The author has supplemented these with results from his own experience, but has thought it best not to burden the contents with case histories. The stress and strain of our daily life has, as one of its consequences, early arterial degeneration. There can be no doubt that arterial disease in the comparatively young is more frequent than it was twenty-five years ago, and that the mortality from diseases directly dependent on arteriosclerotic changes is increasing. Fortunately, the almost universal habit of getting out of doors whenever possible, and the revival of interest in athletics for persons of all ages, have to some extent counteracted the tendency to early decay. Nevertheless, the actual average prolongation of life is more probably due to the very great reduction in infant mortality and in deaths from infectious and communicable diseases. The wear and tear on the human organism in our modern way of living is excessive. Hard work, worry, and high living all predispose to degenerative changes in the arteries, and so bring on premature old age. The author has tried to emphasize this by laying stress on the prevention of arteriosclerosis rather than on the treatment of the fully developed disease. No bibliography is given, as this is not intended as a reference book, but rather as a guide to a better appreciation and understanding of a most important subject. It has been difficult to keep from wandering off into full discussions of conditions incident to and accompanied by arteriosclerosis, but, in order to be clear in his statements and complete in his descriptions, the author has to invade the fields of heart disease, kidney disease, brain disease, etc. It is hoped, however, that these excursions will serve to show how intimately disease of the arteries is bound up with diseases of all the organs and tissues of the body. Some authors have been named when their opinions have been given. Thanks are extended also to many others to whom the writer is indebted, but of whom no individual mention has been made. The author also takes this opportunity of expressing his appreciation of the kindness of Dr. D. L. Harris, who took the microphotographs, and to the publishers for their unfailing courtesy and consideration. LOUIS M. WARFIELD. St. Louis, August, 1908. CONTENTS PAGE CHAPTER I ANATOMY 25