Natural Reactivity and the Origin of Species

Abstract

DARWIN'S theory of the origin of species presupposes the occurrence of occasional variants from the parent stock, of which some are preserved and fostered by natural selection. The cause of this natural variation has been sought in various quarters; and indeed it is to be presumed that it is due not to one cause, but to many. It is our purpose in this note to direct attention to an agency which must play an important, and may prove to play the predominant, part in producing variations among plants and animals.