Although much remains obscure, and will long remain obscure, I can entertain no doubt, after the most deliberate study and dispassionate judgment of which I am capable, that the view which most naturalists until recently entertained, and which I formerly entertained--namely, that each species has been independently created--is erroneous.

I am fully convinced that species are not immutable; but that those belonging to what are called the same genera are lineal descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any one species are the descendants of that species.

Furthermore, I am convinced that natural selection has been the most important, but not the exclusive, means of modification.

Causes of Variability -- Effects of Habit and the use and disuse of Parts -- Correlated Variation -- Inheritance -- Character of Domestic Varieties -- Difficulty of distinguishing between Varieties and Species -- Origin of Domestic Varieties from one or more Species -- Domestic Pigeons, their Differences and Origin -- Principles of Selection, anciently followed, their Effects -- Methodical and Unconscious Selection -- Unknown Origin of our Domestic Productions -- Circumstances favourable to Man's power of Selection.