The discovery of possible traces of life in a Martian meteorite [McKay et al., 1996] calls to mind a 100-year-old dispute between Sir William Thomson (later Lord Kelvin) and the Nobel Prize winning Swedish scientist, Svante August Arrhenius. Both scientists believed that life on our planet was brought from another planet, rather than having originated from inorganic matter here on Earth. However, the two scientists had very different ideas about the mechanism through which this life would be transported. Lord Kelvin believed that life was brought to Earth by "countless seed-bearing meteoritic stones" that could be produced through collisions between other inhabited planets in diferent parts of our galaxy [Thomson, 1871]. Svante Arrhenius agued that "The carbon found in meteorites has never exhibited any trace of organic structure," and if in fact meteorites are the "conveyor of life germs," those germs would be burned up in the atmosphere of the planet on which they descended [Arrhenius, 1908].