We shall have to recur to this subject; and I will here only add that their variability seems to result from their uselessness, and consequently from natural selection having had no power to check deviations in their structure.
Berriro ere etorriko gara kontu honetara, eta hemen hauxe besterik ez dut gehituko, alegia, badirudiela aldagarritasuna erabilgarritasun ezetik eta, ondorioz, hautespen naturalak beren egiturako desbideratzeak galarazteko ahalik ez izatetik datorkiela.