Frogs lay eggs under water. When they hatch they are called tadpoles. After a time as tadpoles they undergo metamorphosis where they grow legs and lungs and become the little friendly hippidy hoppidy guys you see on your porch every night.
Answer:
For a limb to regenerate, you need bone, muscle, blood vessels and nerves. There are adult stem cells, a kind of undifferentiated cell that can become specialized, that regenerate muscle, but they don't seem to activate.
The salt most likely will raise the boiling and freezing points of the solution slightly.