allowed to be descended from a pair of ancestral wolves; all of the plants called “liverworts” and their close affinities from an ancestral form; all human beings from an ancestral pair. In this case the original progenitor of each great group was totally unconnected with every other. I may venture at this point to remind you, though probably the caution is needless, that the question as to whether the present popular theory of evolution is or is not a fact, is not purely a scientific one as a number