_Rupture_ may take place through the skin, on a mucous or serous surface, or into the cellular tissue. The first hæmorrhage is often slight and stops naturally, but it soon recurs, and is so profuse, especially when the blood escapes externally, that it rapidly proves fatal. When the bleeding takes place into the cellular tissue, the aneurysm is said to become _diffused_, and the extravasated blood spreads widely through the tissues, exerting great pressure on the surrounding structures. The _clinical features_ associated with rupture are sudden and severe pain in the part, and the patient becomes pale, cold, and faint. If a comparatively small escape of blood takes place into the tissues, the sudden alteration in the size, shape, and tension of the aneurysm, together with loss of pulsation, may be the only local signs. When the bleeding is profuse, however, the parts beyond the aneurysm become greatly swollen, livid, and cold, and the pulse beyond is completely lost. The arrest of the blood supply may result in gangrene. Sometimes the pressure of the extravasated blood causes the skin to slough and, later, give way, and fatal hæmorrhage results. The _treatment_ is carried out on the same lines as for a ruptured artery (p. 261), it being remembered, however, that the artery is diseased and does not lend itself to reconstructive procedures. _Suppuration_ may occur in the vicinity of an aneurysm, and the aneurysm may burst into the abscess which forms, so that when the latter points the pus is mixed with broken-down blood-clot, and finally free hæmorrhage takes place. It has more than once happened that a surgeon has incised such an abscess without having recognised its association with aneurysm, with tragic results. #Treatment.#--In treating an aneurysm, the indications are to imitate Nature's method of cure by means of laminated clot. _Constitutional treatment_ consists in taking measures to reduce the arterial tension and to diminish the force of the heart's action. The patient must be kept in bed. A dry and non-stimulating diet is indicated, the quantity being gradually reduced till it is just sufficient to maintain nutrition. Saline purges are employed to reduce the vascular tension. The benefit derived from potassium iodide administered in full doses, as first recommended by George W. Balfour, probably depends on its depressing action on the heart and its therapeutic benefit in syphilis. Pain or restlessness may call for the use of opiates, of which heroin is the most efficient. _Local Treatment._--When constitutional treatment fails, local measures must be adopted, and many methods are available.