Page:Popular Science Monthly Volume 74.djvu/360

356 University. That he collected assiduously at times during portions of this expedition, is evidenced by his having brought home specimens of 193 species of the 225 species which, after his specimens had been studied, were known to inhabit the Galapagos Islands and by the fact that about 100 species new to science were represented in his Galapagos collection. He noticed the extraordinary distribution of species or races on the several islands of this group, many of them inhabiting only a single island, and he laid the foundation for all subsequent study of insular floras. The narrative of observations and experiences during this memorable voyage is replete with interesting facts and suggestions concerning plants, and his conclusion that "Nothing can be more improving to a young naturalist than a journey in distant countries," is one that should be reiterated by all teachers of natural science, and such experience should be sought by all students who propose engaging in investigation. Darwin is commemorated in botanical taxonomy by many species named in his honor. The beautiful barberry, Berberis Darwinii of Hooker, native of Chiloe, is occasionally seen in cultivation. Darwinia, an Australian genus of the myrtle family, named by Rudge in 1813, commemorates his grandfather, Erasmus Darwin.

The beginnings of Darwin's theory of descent of animals and plants from preexistent species, with modifications, were made during the voyage of the Beagle, and from the year after his return to England, when, he tells us, he opened the first note-book on the subject. For twenty-two years he was interrogating gardeners and breeders, botanists and zoologists, and diligently observing plants and animals. He first thought of publishing on the theory of descent in 1839, but delayed for twenty years. During the studies which led up to the publication, in 1859, of "The Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life," Darwin closely observed a great number of wild and cultivated plants, with reference to variation in nature and under domestication, the struggle for existence due to competition for food and sunlight, the facts of geographic distribution, the succession of plant life on the earth as indicated by the fossils of successive geologic periods, and a great range of other facts and phenomena. The recorded observations of other botanists were also freely utilized and discussed. Nearly all the chapters of this epoch-making work contain conclusions drawn from his own botanical observations. He was especially impressed by the divergent views of different botanists relative to the taxonomic treatment of highly polymorphic genera such as Hieracium (hawk-weeds), Rubus (blackberry), Quercus and Rosa, and he employed this consideration to great advantage in his argument for derivation during descent. Rudimentary organs were considered with much interest and readily explained by Darwin as vestiges of structures which were useful to the plant in