The instrument here presented is intended for the introduction of glass capillaries containing radium emanations (the so-called radium seeds) into the tumors of the esophagus.
In introducing radium seeds into readily accessible tumors, it is customary to introduce the needle and then withdraw it a short distance before ejecting the seed, so that the seed travels in a previously made channel. I have found, after several trials, that the emplacement of the seeds in a tumor of the esophagus through the esophagoscope cannot be accomplished with precision, because the tumor, as well as the esophagoscope, are in constant motion, but they do not move together. The position of the instrument cannot be controlled with any degree of accuracy.
To overcome the difficulty, I have constructed an instrument with an adjustable stop by means of which the depth of penetration of the needle can be previously fixed. When held firmly against