 Blending would therefore directly oppose natural selection.In addition, Darwin and others considered Lamarckian inheritance of acquired characteristics entirely possible, and Darwin's 1868 theory of pangenesis, with contributions to the next generation (gemmules) flowing from all parts of the body, actually implied Lamarckism as well as blending.August Weismann's idea, set out in his 1892 book "Das Keimplasma