The present volume records a study of the heart rates of fifty-one normal men and fifty-two normal women by means of the cardiotachometer, a device which permits, within certain practical limits, a continuous record of the heart rate over twenty-four or more hours. With this instrument the heart rate was studied during waking and sleeping states. The data were correlated with certain body measurements. Furthermore, the cardiac rate was studied during certain daily activities. In chapters VII and VIII one finds studies on the pulse rate made during various types of anesthesia and in certain disease conditions (cardiac insufficiency, valvular disease, myocarditis, exophthalmic goiter, neurogenic sinus, tachycardia, auricular fibrillations and complete heart block). Chapter I contains a delightful historical account of the knowledge of the pulse rate from antiquity to the present time. The book is well written, and affords valuable data on the subject offered.