The valvular lesions most apt to cause irregular action of the heart are mitral insufficiency or mitral stenosis. The lesion which is most apt to cause auricular fibrillation and more or less permanently irregular heart is perhaps mitral stenosis. Another frequent cause of more or less permanent irregularity is the excessive use of alcohol. While an irregular pulse and an irregular heart are always of more or less serious import, still, as the extrasystoles of the auricle are better understood and more frequently recognized, and the habits and life of the patients (most frequently men) are regulated and revised, frequently a pulse and heart which would be rejected by any medical examiner for an insurance company becomes, in a few weeks or a few months, a perfectly acting heart, and remains so sometimes for years. It also is not quite determinaible whether a heart that is so misbehaving has a recurrence of such misbehavior more readily than a heart which has never been so affected. However this may be, the cause having been determined or presumed by the physician, it should be so impressed on the patient that he does not again repeat the insult to his heart. AURICULAR FIBRILLATION: AURICULAR FLUTTER Auricular fibrillation is at times apparently a clinical entity much as is angina pectoris, but it is often a symptom of some other condition. At times auricular fibrillation is only a passing symptom, and is rapidly cured by treatment. A real auricular fibrillation shows a semiparalysis of the auricles, and during this condition normal systolic contractions do not occur, although there are small rapid twitchings of different muscle fibers in the auricles. Although it was once thought that the auricle was paralyzed in this condition, it probably simply loses its coordinate activity. Auricular fibrillation and auricular flutter are probably simply different degrees of the same condition, and any contractions of the auricles over 200 per minute may be termed an auricular flutter, and below that the term auricular fibrillation may be used. When ventricular fibrillation occurs, the condition is serious and the prognosis bad. Both auricular fibrillation and auricular flutter may be temporary or permanent, and the exact number of fibrillations or tremblings of the auricular muscle can be noted only by electrical instruments. Tallman, [Footnote: Tallman: Northwest Med., May, 1916] after examination of fifty-eight cases, classifies different types of auricular flutter: (1) such a condition in an apparently normal heart; (2) the condition occurring during chronic heart disease, and (3) an auricular flutter with partial or complete heart block.