On the whole, we may conclude that habit, or use and disuse, have, in some cases, played a considerable part in the modification of the constitution and structure; but that the effects have often been largely combined with, and sometimes overmastered by, the natural selection of innate variations.
Oro har, ondorio hauxe atera genezake, alegia, azturak, edo erabilera eta erabilerarik ezak, zeregin handia izan duela kasu batzuetan osaera eta egituraren eraldaketan, baina honen ondorenak sortzetiko aldakuntzen hautespen naturalarekin konbinatu direla hein handian, eta batzuetan berau izan dela nagusi.