The motto "E Pluribus Unum" ("out of many, one") could be applied to the Milky Way. Astronomers have obtained new evidence that our home galaxy contains pieces of many former galaxies. The findings strengthen the idea that large galaxies don't emerge whole from single, gigantic clouds of dust and gas. Rather, they grow by swallowing their neighbors.
http://sciencenow.sciencemag.org/cgi...ll/2009/1125/2