Pig Bladder Powder Regrows Fingers

Lee Spievack accidentally cut off his fingertip working on an airplane. His brother, a research scientist, sent him powder made up partially out of pig's bladder and told him to sprinkle it on his fingertip. The finger regrew itself in four weeks. How did it work? » 3/26/08 6:00pm 3/26/08 6:00pm