affinities of all the beings of the same class have sometimes been represented by a great tree. I believe
largely speaks the truth. The green and budding twigs may represent existing species; and those produced during each former year may represent the long succession of extinct species . . . The limbs divided into great branches, and these into lesser and lesser branches,. .
. From the
branch, so by generation I believe it has been with the Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching
ramifications" (Charles Darwin, 1859).