Showcase Ernest Haeckel's "ontogeny recapitulates phylogeny" theory with any of these historical biology attitude gifts! Haeckel's recapitulation theory claims that the development of advanced species passes through stages represented by adult organisms of more primitive species. In other words, each successive stage in the development of an individual represents one of the adult forms that appeared in its evolutionary history. This biological hypothesis has long been discredited. Includes Romanes's 1892 copy of Ernst Haeckel's controversial embryo drawings. Gifts for all who go through successive stages of development!