No, famously ensconced in the Old Wives Tales Hall of Fame. It is true, however, that tadpoles are able to regrow their severed tails, but they lose this ability as they mature. Salamanders, on the other hand, are able to regrow severed legs and tails, but science is unsure as to why. The application of retonic acid to frogs whose leg has been experimentally amputated sometimes grow two or three legs back to replace it, but at this time, no one understands the process. The experiments are conducted in the hopes of enabling mammalian regeneration, extending, perhaps, to humans...