The assumption referred to above is incorrect. As noted, wire brushes, toothpicks, paper, etc. were used before "replica plating" was invented. Thus the "idea" of replica plating was not Joshua Lederberg's idea (this is also pointed out on the NLM's "Profiles in Science" website for Joshua Lederberg). However, Esther Lederberg's implementation was novel, in that it was hundreds of times more effecient than these early attempts to replicate bacterial colonies in a recognizable geometric configuration. This qualitatively increased efficiency is what made replica plating the adopted method of so many other researchers.