but that the AMOUNT of difference in the several branches or groups, though allied in the same degree in blood to their common progenitor, may differ greatly, being due to the different degrees of modification which they have undergone; and this is expressed by the forms being ranked under different genera, families, sections or orders.
baina adar edo taldeen barnean gertatzen diren ezberdintasunen zenbatekoa, nahiz eta guraso komunarekiko odolkidetasun gradu bereko ahaideak izan, oso ezberdina izan daitekeela, jasan dituzten eraldatze gradu diferenteen eraginez; eta horixe adierazten da forma ezberdinak genero, familia, sekzio edo ordenatan sailkatzean.