Recapitulation.

I will now recapitulate the course of this work, more fully with respect to the former parts, and briefly 〈as to〉 the latter. In the first chapter we have seen that most, if not all, organic beings, when taken by man out of their natural condition, and bred during several generations, vary; that is variation is partly due to the direct effect of the new external influences, and partly to the indirect effect on the reproductive system rendering the organization of the offspring in some degree plastic. Of the variations thus produced, man when uncivilised naturally preserves the life, and therefore unintentionally breeds from those individuals most useful to him in his different states: when even semi-civilised, he intentionally separates and breeds from such individuals. Every part of the structure seems occasionally to vary in a very slight degree, and the extent to which all kinds of peculiarities in mind and body, when congenital and when slowly acquired either from external influences, from exercise, or from disuse 〈are inherited〉, is truly wonderful. When several breeds are once formed, then crossing is the most fertile source of new breeds. Variation must be ruled, of course, by the health of the new race, by the tendency to return to the ancestral forms, and by unknown laws determining the proportional increase and symmetry of the body.