In order to prevent recurrence, a tube of _radium_, to which a silk thread is attached, is inserted into the space from which the tumour was removed; the thread is brought out at the drain-opening, and at the end of a week or ten days the tube of radium is removed by pulling on the thread. Radium causes a reaction in the tissues attended with exudation from the vessels, for the escape of which provision must be made. If radium is not available, the affected area is repeatedly exposed to the action of the _X-rays_ as soon as the wound has healed. The employment of these measures has diminished to a remarkable degree the recurrence of sarcoma after operation. It will readily be understood that the less thoroughly or radically the growth has been removed, the more do we depend upon radium or the X-rays for bringing about a permanent cure, and that in advanced cases of sarcoma and in cases in which, on account of their anatomical situation, removal by operation is necessarily incomplete, the prospect of cure is still more dependent on the use of radium or of the X-rays. Finally, there are cases in which removal by operation is impossible, the so-called _inoperable sarcoma_; a tube of radium, to which a silk thread is attached, is inserted into the substance of the tumour, either through an opening made by a large trocar, or, when necessary, by open dissection. A second tube of radium is placed upon the skin over the tumour and is secured there by a stitch or by a strip of plaster, thus securing a cross-fire action of the radium rays, both from within and without, as this is found to be much more efficacious in destroying or inhibiting the cellular elements of the growth. The tubes of radium are left _in situ_ for from eight to fourteen days, according to the power of the radium employed, but are moved about every second day or so in order that every part of the tumour may be efficiently radiated. If the tumour shrinks in size after the use of radium and becomes operable, it should be removed before time is given it to resume its growth. It will depend upon the subsequent course of the disease, whether or not a second, or it may be even a third, application of radium will be required. Where neither radium nor X-rays is available or applicable, recourse may be had to the injection of Coley's fluid, a preparation containing the mixed toxins of the streptococcus of erysipelas and the bacillus prodigiosus; or of selenium. EPITHELIAL TUMOURS An excessive and erratic growth of epithelium is the essential and distinguishing feature of these tumours. The innocent forms are the papilloma and the adenoma; the malignant, the carcinoma or cancer.