The Importance of the Crossing of Varieties

I do not believe that variability is an inherent and necessary contingency under all circumstances with all organic beings as some authors have thought. The effects of variability are modified by various degrees of inheritance and of reversion. In geese, from being valuable only for two purposes, food and feathers, and more especially from no pleasure having been felt in the display of distinct breeds. Species of the larger genera in any country vary more than the species of the smaller genera. Over all these causes of change, I am convinced that the accumulative action of selection, whether applied methodically and more quickly, or unconsciously and more slowly, but more efficiently, is by far the predominant power.