While this terns really signifies irregularity and intermittence of the heart, it may also be broadly used to indicate a pulse which is abnormally slow or one which is abnormally fast, a rhythm which is trot correct for the age, condition and activity of the patient. Irregularity in the pulse beat as to volume, force and pressure, except such variation in the pulse wave as caused by respiration, is always abnormal. While an intermittent pulse is of course abnormal, it may be caused in certain persons by a condition which does not in the least interfere with their health and well-being. As to whether a slow or a more or less (but not excessively) rapid pulse in any one is abnormal depends entirely on whether that speed is normal or abnormal for that person. As a general rule the heart is more rapid in women than in men. It is always more rapid in children than in adults, and generally diminishes in frequence after the age of 60, unless there is cardiac weakness or some cardiac muscle degeneration. The average frequence of the pulse in an adult who is at rest is 72 beats per minute, but a frequency of 80 is not abnormal, and a frequency of 65 in men is common; 60 is infrequent in men but normal, while up to 90 is not abnormal, especially in women, at the time the pulse is being counted.' It should always be considered that in the majority of patients the pulse is slightly increased while the physician is noting its rapidity. Anything over 90 should always be considered rapid, unless the patient is very nervous and this rapidity is considered accidental. Anything below 60 is abnormally slow. In children under 10 or 12 years of age, anything below 80 is unusual, and up to 100 is perfectly normal, at least at such time as the pulse is counted and the patient is awake. Referring to the first chapter of this book, it will be noted that many physiologic factors must enter into the production of the normal regularity of the pulse. The stimulus must regularly begin in the auricle, must be perfectly transmitted through the bundle of His to the ventricles, the ventricles must normally contract with the normal and regular force, the valves must close normally and at the proper time, the blood pressure in the aorta must be normally constant to insure the perfect transmission of the blood to the peripheral arteries and to insure the normal circulation through the coronary arteries, and the arterioles must be normally elastic. The nervous inhibitory control through the vagi must also be normal, and there must be no abnormal reflexes of any part of the body to interfere with the normal vagus control of the heart.