The injection of an appropriate caustic solution into the cavity of a varicose dilatation of the lower limbs can bring about an absolutely aseptic irritation of the endovein and the complete obliteration of the vessel; this is the principle on which is based this medical curative method. Furthermore, this obliteration of the vein takes place in most cases without pain and without any disturbance of the deep circulation, and does not interfere with the habitual occupations of the patient, which is one of its main advantages. Long ago, after the introduction of Pravaz's syringe injection, the idea arose of treating varicose dilatations by obliterating injections. I shall refer merely by way of record to the old attempts of Chassaignac and Pravaz, by means of ferric chloride; of Valette, by means of the iodotannic liquor, and of Schiassi, by means of red mercuric iodide. These former attempts failed because the liquid