Sentence:  It was to be introduced into the wound in its closed state, the ring then drawn back to enable it to lay hold of the substance, pushed forward again to close upon it, and withdrawn. It was named, after its inventor, the <WSD>Alphonsin</WSD>. 
Meaning of the word marked with <WSD> tags:  A surgical instrument, consisting of three prongs surrounded by a ring, which close when the ring is drawn forward and open when the ring is drawn back.