We are profoundly ignorant of the cause of each slight variation or individual difference; and we are immediately made conscious of this by reflecting on the differences between the breeds of our domesticated animals in different countries, more especially in the less civilized countries, where there has been but little methodical selection.
Erabat ezjakinak gara aldakuntza edo aldaketa indibidualei buruz; eta berehala ohartzen gara honetaz, etxe-animali arrazen artean herrialde diferenteetan-batik bat hautespen metodiko gutxi izan duten herri gutxi zibilizatuetan-dauden ezberdintasunez gogoeta eginez.